How does your body ultimately recover from a cold?

How does your body ultimately recover from a cold?

We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

Is it the eradication of the virus (assuming rhinovirus) by white blood cells? Or does your body somehow adapt to presence of the virus?

Great question.

Rhino Virus

For the rhinovirus in particular, it is eradicated.


However for some of the retroviruses and other virus that contain an enzyme called 'integrase', they actually integrate their DNA with yours. That way as your cells go about their business, they make the virus genes too. However, you have some white blood cells called CD8 T Cells that mark these 'compromised cells' for death.


Some viruses though can remain cleverly hidden and don't turn on their own genes in your genome until the immune response goes down, or you stop taking anti-retroviral drugs. HIV is a great example of a virus you can also 'live' with but never actually eradicate. The medicines you take can kill all the circulating virus down to a non detectable level. However, when you stop taking your meds, the DNA integrated in your genome will start making the virus again, thus you will always 'live' and can never eradicate it.

Guide to Biohacking

Biohacking is what you get when you combine biology with hacking. It’s a way for individuals to effectively “hack” their bodies to achieve certain goals.

Sometimes, this hack is as simple as taking a nootropic supplement every day to boost your cognitive ability.

Other more advanced methods of biohacking include installing a do-it-yourself body enhancement. In some cases, biohacking refers to scientists researching genetic sequencing to identify genes with the most positive qualities.

Biohacking is a term that few people have heard of. However, as modern technology grows, biohacking is bound to become more and more popular.

Today, in our beginner’s guide to biohacking, we’re going to explain everything you need to know about the exciting world of biohacking.

Life after death: the science of human decomposition

J ohn had been dead about four hours before his body was brought into the funeral home. He had been relatively healthy for most of his life. He had worked his whole life on the Texas oil fields, a job that kept him physically active, and in pretty good shape. He had stopped smoking decades earlier, and drank moderate amounts of alcohol.

Lately, his family and friends had noticed that his health – and his mind – had started to falter. Then, one cold January morning, he suffered a massive heart attack, apparently triggered by other, unknown, complications, fell to the floor at home, and died almost immediately. He was just 57 years old. Now, he lay on the metal table, his body wrapped in a white linen sheet, cold and stiff to the touch, his skin purplish-grey – tell-tale signs that the early stages of decomposition were well under way.

Most of us would rather not think about what happens to our selves and loved ones after death. Most of us die natural deaths and, at least in the West, are given a traditional burial. This is a way of showing respect to the deceased, and of bringing a sense of closure to bereaved family. It also serves to slow down the decomposition process, so that family members can remember their loved one as they once were, rather than as they now are.

For others, the end is less dignified. A murderer might bury his victim in a shallow grave, or leave their body at the scene of the crime, exposed to the elements. When the body is eventually discovered, the first thing that the police detectives and forensics experts working on the case will try to establish is when death occurred. Time of death is a crucial piece of information in any murder investigation, but the many factors influencing the decomposition process can make it extremely difficult to estimate.

The sight of a rotting corpse is, for most of us, unsettling at best, and repulsive and frightening at worst, the stuff of nightmares.

Far from being ‘dead,’ however, a rotting corpse is teeming with life. A growing number of scientists view a rotting corpse as the cornerstone of a vast and complex ecosystem, which emerges soon after death and flourishes and evolves as decomposition proceeds.

We still know very little about human decay, but the growth of forensic research facilities, or ‘body farms,’ together with the availability and ever-decreasing cost of techniques such as DNA sequencing, now enables researchers to study the process in ways that were not possible just a few years ago. A better understanding of the cadaveric ecosystem – how it changes over time, and how it interacts with and alters the ecology of its wider environment – could have important applications in forensic science. It could, for example, lead to new, more accurate ways of estimating time of death, and of finding bodies that have been hidden in clandestine graves.

Decomposition begins several minutes after death, with a process called autolysis, or self-digestion. Soon after the heart stops beating, cells become deprived of oxygen, and their acidity increases as the toxic by-products of chemical reactions begin to accumulate inside them. Enzymes start to digest cell membranes and then leak out as the cells break down. This usually begins in the liver, which is enriched in enzymes, and in the brain, which has high water content eventually, though, all other tissues and organs begin to break down in this way. Damaged blood cells spill out of broken vessels and, aided by gravity, settle in the capillaries and small veins, discolouring the skin.

Body temperature also begins to drop, until it has acclimatised to its surroundings. Then, rigor mortis – the stiffness of death – sets in, starting in the eyelids, jaw and neck muscles, before working its way into the trunk and then the limbs. In life, muscle cells contracts and relax due to the actions of two filamentous proteins, called actin and myosin, which slide along each other. After death, the cells are depleted of their energy source, and the protein filaments become locked in place. This causes the muscles to become rigid, and locks the joints.

“It might take a little bit of force to break this up,” says mortician Holly Williams, lifting John’s arm and gently bending it at the fingers, elbow and wrist. “Usually, the fresher a body is, the easier it is for me to work on.”

Williams speaks softly and has a happy-go-lucky demeanour that belies the gruesome nature of her work. Having been raised in a family-run funeral home in north Texas, and worked there all her life, she has seen and handled dead bodies on an almost daily basis since her childhood. Now 28 years old, she estimates that she has worked on something like 1,000 bodies.

Her work involves collecting recently deceased bodies from the Dallas-Fort Worth area, and sometimes beyond, and preparing them for their funeral, by washing and embalming them. Embalming involves treating the body with chemicals that slow down the decomposition process, primarily to restore it as closely as possible to its natural state before death. Williams performs this so that family and friends can view their departed loved one at the funeral. Victims of trauma and violent deaths usually need extensive facial reconstruction, a highly skilled and time-consuming task.

“Most of the people we pick up die in nursing homes,” says Williams, “but sometimes we get people who died of gunshot wounds or in a car-wreck. We might get a call to pick up someone who died alone and wasn’t found for days or weeks, and they’ll already be decomposing, which makes my work much harder.”

John lay on Williams’ metal table, his body wrapped in a white linen sheet, cold and stiff to the touch. Photograph: Mo Costandi

During the early stages of decomposition, the cadaveric ecosystem consists mostly of the bacteria that live in and on the human body. Our bodies host huge numbers of bacteria, with every one of its surfaces and corners providing a habitat for a specialised microbial community. By far the largest of these communities resides in the gut, which is home to trillions of bacteria of hundreds or perhaps thousands of different species.

The so-called gut microbiome is one of the hottest research topics in biology at the moment. Some researchers are convinced that gut bacteria play essential roles in human health and disease, but we still know very little about our make-up of these mysterious microbial passengers, let alone about how they might influence our bodily functions.

We know even less about what happens to the microbiome after a person dies, but pioneering research published in the past few years has provided some much needed details.

Most internal organs are devoid of microbes when we are alive. Soon after death, however, the immune system stops working, leaving them to spread throughout the body freely. This usually begins in the gut, at the junction between the small and large intestines. Left unchecked, our gut bacteria begin to digest the intestines, and then the surrounding tissues, from the inside out, using the chemical cocktail that leaks out of damaged cells as a food source. Then they invade the capillaries of the digestive system and lymph nodes, spreading first to the liver and spleen, then into the heart and brain.

Last year, forensic scientist Gulnaz Javan of Alabama State University in Montgomery and her colleagues published the very first study of what they have called the thanatomicrobiome (from thanatos, the Greek word for ‘death’).

“All of our samples came from criminal cases involving people who died by suicide, homicide, drug overdose, or in traffic accidents,” she explains. “Taking samples this way is really hard, because we have to ask the [bereaved] families to sign our consent forms. That’s a major ethical issue.”

Javan and her team took samples of liver, spleen, brain, heart, and blood from 11 cadavers, at between 20 and 240 hours after death, then used two different state-of-the-art DNA sequencing technologies, combined with bioinformatics, to analyse and compare the bacterial content of each sample.

They found that samples taken from different organs in the same cadaver were very similar to each other, but were very different from those taken from the same organs in other bodies. This may be due partly to individual differences in the composition of the microbiome of the individuals involved in the study.

The variations may also be related to differences in the period of time that had elapsed since death. An earlier study of decomposing mice had revealed that although the animals’ microbiome changes dramatically after death, it does so in a consistent and measurable way, such that the researchers were able to estimate time of death to within 3 days of a nearly 2-month period.

Javan’s study suggests that this “microbial clock” may also be ticking within the decomposing human body, too. The first bacteria they detected came from a sample of liver tissue obtained from a cadaver just 20 hours after death, but the earliest time at which bacteria were found in all samples from the same cadaver was 58 hours after death. Thus, after we die, our bacteria may spread through the body in a stereotyped way, and the timing with which they infiltrate first one internal organ and then another may provide a new way of estimating the amount of time that has elapsed since death.

“The degree of decomposition varies not only from individual to individual but also differs in different body organs,” says Javan. “Spleen, intestine, stomach and pregnant uterus are earlier to decay, but on the other hand kidney, heart and bones are later in the process.” In 2014, Javan and her colleagues secured a US$200,000 grant from the National Science Foundation to investigate further. “We will do next-generation sequencing and bioinformatics to see which organ is best for estimating [time of death] – that’s still unclear,” she says.

One thing that already seems clear, though, is that different stages of decomposition are associated with a different composition of cadaver bacteria.

Once self-digestion is under way and bacteria have started to escape from the gastrointestinal tract, putrefaction begins. This is molecular death – the break down of soft tissues even further, into gases, liquids and salts. It is already under way at the earlier stages of decomposition, but really gets going when anaerobic bacteria get in on the act.

Putrefaction is associated with a marked shift from aerobic bacterial species, which require oxygen to grow, to anaerobic ones, which do not. These then feed on the body tissues, fermenting the sugars in them to produce gaseous by-products such as methane, hydrogen sulphide and ammonia, which accumulate within the body, inflating (or ‘bloating’) the abdomen and sometimes other body parts, too.

This causes further discoloration of the body. As damaged blood cells continue to leak from disintegrating vessels, anaerobic convert haemoglobin molecules, which once carried oxygen around the body, into sulfhaemoglobin. The presence of this molecule in settled blood gives skin the marbled, greenish-black appearance characteristic of a body undergoing active decomposition.

As the gas pressure continues to build up inside the body, it causes blisters to appear all over the skin surface, and then loosening, followed by ‘slippage,’ of large sheets of skin, which remain barely attached to the deteriorating frame underneath. Eventually, the gases and liquefied tissues purge from the body, usually leaking from the anus and other orifices, and often also from ripped skin in other parts of the body. Sometimes, the pressure is so great that the abdomen bursts open.

Bloating is often used a marker for the transition between early and later stages of decomposition, and another recent study shows that this transition is characterised by a distinct shift in the composition of cadaveric bacteria.

Staff at the Southeast Texas Applied Forensic Science (STAFS) Facility in Huntsville, TX. Left to right: Research assistant Kevin Derr, STAFS director Joan Bytheway, morbid entomologist Sybil Bucheli, and microbiologist Aaron Lynne. Photograph: Mo Costandi

The study was carried out at the Southeast Texas Applied Forensic Science Facility in Huntsville. Opened in 2009, the facility is located within a 247-acre area of National Forest, which is owned by the university and maintained by researchers at Sam Houston State University (SHSU). Within, a nine-acre plot of densely wooded land has been sealed off from the wider area, and further subdivided, by 10-foot-high green wire fences topped with barbed wire.

Here, scattered among the pine trees, are about a half dozen human cadavers, in various stages of decay. The two most recently placed bodies lay spread-eagled near the centre of the small enclosure, with much of their loose, grey-blue mottled skin still intact, their rib cages and pelvic bones visible between slowly putrefying flesh. A few meters away lies another cadaver, fully skeletonized, with its black, hardened skin clinging to the bones, as if it were wearing a shiny latex suit and skullcap. Further still, beyond other skeletal remains that had obviously been scattered by vultures, lay another, within a wood and wire cage, this one nearing the end of the death cycle, partly mummified and with several large, brown mushrooms growing from where an abdomen once was.

In late 2011, SHSU researchers Sibyl Bucheli and Aaron Lynne and their colleagues placed two fresh cadavers here, left them to decay under natural conditions, and then took samples of bacteria from their various parts, at the beginning and the end of the bloat stage. They then extracted bacterial DNA from the samples, and sequenced it to find that bloating is characterised by a marked shift from aerobic to anaerobic species.

As an entomologist, Bucheli is mainly interested in the insects that colonise cadavers. She regards a cadaver as a specialised habitat for various necrophagous (or ‘dead-eating’) insect species, some of which see out their entire life cycle in, on and around the body.

When a decomposing body starts to purge, it becomes fully exposed to its surroundings. At this stage, microbial and insect activity reaches its peak, and the cadaveric ecosystem really comes into its own, becoming a ‘hub’ not only for insects and microbes, but also by vultures and scavengers, as well as meat-eating animals.

Two species closely linked with decomposition are blowflies, flesh flies and their larvae. Cadavers give off a foul, sickly-sweet odour, made up of a complex cocktail of volatile compounds, whose ingredients change as decomposition progresses. Blowflies detect the smell using specialised smell receptors, then land on the cadaver and lay its eggs in orifices and open wounds.

Each fly deposits around 250 eggs, that hatch within 24 hours, giving rise to small first-stage maggots. These feed on the rotting flesh and then molt into larger maggots, which feed for several hours before molting again. After feeding some more, these yet larger, and now fattened, maggots wriggle away from the body. Then they pupate and transform into adult flies, and the cycle repeats over and again, until there’s nothing left for them to feed on.

Under the right conditions, an actively decaying body will have large numbers of stage-three maggots feeding on it. This “maggot mass” generates a lot of heat, raising the inside temperature by more than 10°C. Like penguins huddling, individual maggots within the mass are constantly on the move. But whereas penguins huddle to keep warm, maggots in the mass move around to stay cool.

Back in her office on the SHSU campus – decorated with large toy insects and a collection of Monster High dolls – Bucheli explains: “It’s a double-edged sword – if you’re always at the edge, you might get eaten by a bird, and if you’re always in the centre, you might get cooked. So they’re constantly moving from the centre to the edges and back. It’s like an eruption.”

The presence of blowflies attracts predators such as skin beetles, mites, ants, wasps, and spiders, to the cadaver, which then feed on or parasitize their eggs and larvae. Vultures and other scavengers, as well as other, large meat-eating animals, may also descend upon the body.

In the absence of scavengers though, it is the maggots that are responsible for removal of the soft tissues. Carl Linnaeus, who devised the system by which scientists name species, noted in 1767 that “three flies could consume a horse cadaver as rapidly as a lion.” Third-stage maggots will move away from a cadaver in large numbers, often following the same route. Their activity is so rigorous that their migration paths may be seen after decomposition is finished, as deep furrows in the soil emanating from the cadaver.

Given the paucity of human decomposition research, we still know very little about the insect species that colonise a cadaver. But the latest published study from Bucheli’s lab suggests that they are far more diverse than we had previously imagined.

The study was led by Bucheli’s former Ph.D. student Natalie Lindgren, who placed four cadavers on the Huntsville body farm in 2009, and left them out for a whole year, during which time she returned four times a day to collect the insects that she found on them. The usual suspects were present, but Lindgren also noted four unusual insect-cadaver interactions that had never been documented before, including a scorpionfly that was found feeding on brain fluids through an autopsy wound in the scalp, and a worm found feeding on the dried skin around where the toenails had been, which was previously only known to feed on decaying wood.

Insects colonise a cadaver in successive waves, and each has its own unique life cycle. They can therefore provide information that is useful for estimating time of death, and for learning about the circumstances of death. This has led to the emerging field of forensic entomology.

“Flies will arrive at a cadaver almost immediately,” says Bucheli. “We’ll put a body out and three seconds later there’ll be flies laying eggs in the nose.”

Insects can be useful for estimating time of death of a badly decomposing body. In theory, an entomologist arriving at a crime scene can use their knowledge of insects’ life cycles to estimate the time of death. And, because many insect species have a limited geographical distribution, the presence of a given species can link a body to a certain location, or show that it has been moved from one place to another.

In practice, though, using insects to estimate time of death is fraught with difficulties. Time of death estimates based on the age of blowfly maggots found on a body are based on the assumption that flies colonised the cadaver right after death, but this is not always the case – burial can exclude insects altogether, for example, and extreme temperatures inhibit their growth or prevent it altogether.

An earlier study led by Lindgren revealed another unusual way by which blowflies might be prevented from laying eggs on a cadaver. “We made a post-mortem wound to the stomach [of a donated body] then partially buried the cadaver in a shallow grave,” says Bucheli, “but fire ants made little sponges out of dirt and used them to fill in the cut and stop up the fluid.” The ants monopolised the wound for more than a week, and then it rained. “This washed the dirt sponges out. The body began to bloat then it blew up, and at that point the flies could colonise it.”

Even if colonization does occur just after death, estimates based on insects’ age may be inaccurate for another reason. Insects are cold-blooded, and so their growth rate occurs relative to temperature rather than to the calendar. “When using insects to estimate post-mortem interval, we’re actually estimating the age of the maggot and extrapolating from that,” says Bucheli. “We measure insect birth rate by accumulated degree hours [the sum of the average hourly temperature], so if you know the temperature and the growth cycle of a fly, you can estimate the age of a fly within an hour or two.”

If not, time of death estimates based on information about insect colonization can be wildly inaccurate and misleading. Eventually, though, Bucheli believes that combining insect data with microbiology could help to make the estimates more accurate, and possibly provide other valuable information about the circumstances of death.

Every species that visits a cadaver has a unique repertoire of gut microbes, and different types of soil are likely to harbour distinct bacterial communities, the composition of which is probably determined by factors such as temperature, moisture, and the soil type and texture.

All these microbes mingle and mix within the cadaveric ecosystem. Flies that land on the cadaver will not only deposit their eggs on it, but will also take up some of the bacteria they find there, and leave some of their own. And the liquefied tissues seeping out of the body allow for the exchange of bacteria between the cadaver and the soil beneath.

When they take samples from cadavers, Bucheli and Lynne detect bacteria originating from the skin on the body and from the flies and scavengers that visit it, as well as from soil. “When a body purges, the gut bacteria start to come out, and we see a greater proportion of them outside the body,” says Lynne.

Lindgren and Bucheli found a scorpionfly, Panorpa nuptialis, feeding on brain fluids through an autopsy incision. Photograph: Natalie Lindgren

Thus, every dead body is likely have a unique microbiological signature, and this signature may change with time according to the exacting conditions of the death scene. A better understanding of the composition of these bacterial communities, the relationships between them, and how they influence each other as decomposition proceeds, could one day help forensics teams learn more about where, when and how a person died.

For instance, detecting DNA sequences known to be unique to a particular organism or soil type in a cadaver could help crime scene investigators link the body of a murder victim to a particular geographical location, or narrow down their search for clues even further, perhaps to a specific field within a given area.

“There have been several court cases where forensic entomology has really stood up and provided important pieces of the puzzle,” says Bucheli. “Bacteria might provide additional information and could become another tool to refine [time of death] estimates. I hope that in about 5 years we can start using bacterial data in trials.”

To this end, more knowledge about the human microbiome and how it changes across a person’s lifespan – and after they have died – will be crucial. Researchers are busy cataloguing the bacterial species in and on the human body, and studying how bacterial populations differ between individuals. “I would love to have a data set from life to death,” says Bucheli. “I would love to meet a donor who’d let me to take bacterial samples while they’re alive, through their death process, and while they decompose.”

A decomposing body significantly alters the chemistry of the soil beneath, causing changes that may persist for years. Purging releases nutrients into the underlying soil, and maggot migration transfers much of the energy in a body to the wider environment. Eventually, the whole process creates a ‘cadaver decomposition island,’ a highly concentrated area of organically rich soil. As well as releasing nutrients into the wider ecosystem, the cadaver also attracts other organic materials, such as dead insects and faecal matter from larger animals.

According to one estimate, an average human body consists of 50-75% and every kilogram of dry body mass eventually releases 32g of nitrogen, 10g of phosphorous, 4g of potassium, and 1g of magnesium into the soil. Initially, some of the underlying and surrounding vegetation dies off, possibly because of nitrogen toxicity, or because of antibiotics found in the body, which are secreted by insect larvae as they feed on the flesh.

Ultimately, though, decomposition is beneficial for the ecosystem – the microbial biomass within the cadaver decomposition island is greater than in other nearby areas nematode worms also become more abundant, and plant life more diverse. Further research into how decomposing bodies alter the ecology of their surroundings may provide a new way of finding murder victims whose bodies have been buried in shallow graves.

“I was reading an article about flying drones over crop fields to see which ones would be best to plant in,” says Daniel Wescott, director of the Forensic Anthropology Center at Texas State University in San Marcos. “They were imaging with near-infrared and showed organically rich soils were a darker colour than others.”

An anthropologist specialising in skull structure, Wescott collaborates with entomologists and microbiologists to learn more about decomposition. Among his collaborators is Javan, who has been busy analysing samples of cadaver soil collected from the facility in San Marcos.

Lately, Wescott has started using a micro-CT scanner to analyse the microscopic structure of the bones that are brought back to the lab from the San Marcos body farm. He also works with computer engineers and a pilot who operates a drone and uses it to take aerial photographs of the facility.

“We’re looking at the purging fluid that comes out of decomposing bodies,” he says. “I thought if farmers can spot organically rich fields, then maybe our little drone will pick up the cadaver decomposition islands, too.”

Furthermore, grave soil analysis may eventually provide another possible way of estimating time of death. A 2008 study of the biochemical changes that take place in a cadaver decomposition island showed that the soil concentration of lipid-phosphorous leaking from a cadaver peaks at around 40 days after death, whereas those of nitrogen and extractable phosphorous peak at 72 and 100 days, respectively. With a more detailed understanding of these processes, analyses of grave soil biochemistry could one day help forensic researchers to estimate how long ago a body was placed in a hidden grave.

Another reason why estimating time of death can be extremely difficult is because the stages of decomposition do not occur discretely, but often overlap, with several taking place simultaneously, and because the rate at which it proceeds can vary widely, depending largely on temperature. Once maggot migration has ended, the cadaver enters the last stages of decay, with just the bones, and perhaps some skin, remain. These final stages of decomposition, and the transition between them, are difficult to identify, because there are far fewer observable changes than at earlier stages.

In the relentless dry heat of the Texas summer, a body left to the elements will mummify rather than decompose fully. The skin will quickly lose all of its moisture, so that it remains clinging to the bones when the process is complete.

The speed of the chemical reactions involved doubles with every 10°C rise in temperature, so a cadaver will reach the advanced stage after 16 days at an average daily temperature of 25°C, and after 80 days at an average daily temperature of 5°C.

The ancient Egyptians knew this. In the pre-dynastic period, they wrapped their dead in linen and buried them directly in the sand. The heat inhibited the activity of microbes, while burial prevented insects from reaching the bodies, and so they were extremely well preserved. Later on, they began building increasingly elaborate tombs for the dead, in order to provide even better for their afterlife, but this had the opposite of the intended effect, hastening the decomposition process, and so they invented embalming and mummification.

Morticians study the ancient Egyptian embalming method to this day. The embalmer would first wash the body of the deceased with palm wine and Nile water, remove most of the internal organs through an incision made down the left-hand side, and pack them with natron, a naturally-occurring salt mixture found throughout the Nile valley. He would use a long hook to pull the brain out through the nostrils, then cover the entire with body with natron, and leave it to dry for forty days.

Initially, the dried organs were placed into canopic jars that were buried alongside the body later, they were wrapped in linen and returned to the body. Finally, the body itself was wrapped in multiple layers of linen, in preparation for burial.

Skeletonised human remains near the entrance to the Forensic Anthropology Center at Texas State University in San Marcos, TX. Photograph: Mo Costandi

Living in a small town, Williams has worked on many people she knew, or even grew up with – friends who overdosed, committed suicide, or died texting at the wheel. And when her mother died four years ago, Williams did some work on her, too, adding the final touches by making up her face: “I always did her hair and make-up when she was alive, so I knew how to do it just right.”

She transfers John to the prep table, removes his clothes and positions him, then takes several small bottles of embalming fluid from a wall cupboard. The fluid contains a mixture of formaldehyde, methanol and other solvents it temporarily preserves the body’s tissues by linking cellular proteins to each other and ‘fixing’ them into place. The fluid kills bacteria and prevents them from breaking down the proteins and using them as a food source.

Williams pours the bottles’ contents into the embalming machine. The fluid comes in an array of colours, each matching a different skin tone. Williams wipes the body with a wet sponge and makes a diagonal incision just above his left collarbone. She ‘raises’ the carotid artery and subclavian vein from the neck, ties them off with pieces of string, then pushes a cannula into the artery and small tweezers into the vein to open up the vessels.

Next, she switches the machine on, pumping embalming fluid into the carotid artery and around the body. As the fluid goes in, blood pours out of the incision, flowing down along the guttered edges of the sloped metal table and into a large sink. Meanwhile, she picks up one of his limbs to massage it gently. “It takes about an hour to remove all the blood from an average-sized person and replace it with embalming fluid,” Williams says. “Blood clots can slow it down, so massaging breaks them up and helps the flow of the embalming fluid.”

Once all the blood has been replaced, she pushes an aspirator into John’s abdomen and sucks the fluids out of the body cavity, together with any urine and faeces that might still be in there. Finally, she sews up the incisions, wipes the body down a second time, sets the facial features, and re-dresses it. John is now ready for his funeral.

Embalmed bodies eventually decompose too, but exactly when, and how long it takes, depends largely on how the embalming was done, the type of casket in which the body is placed, and how it is buried. Bodies are, after all, merely forms of energy, trapped in lumps of matter waiting to be released into the wider universe. In life, our bodies expend energy keeping their countless atoms locked in highly organized configurations, staying composed.

According to the laws of thermodynamics, energy cannot be created or destroyed, only converted from one form to another, and the amount of free energy always increases. In other words, things fall apart, converting their mass to energy while doing so. Decomposition is one final, morbid reminder that all matter in the universe must follow these fundamental laws. It breaks us down, equilibrating our bodily matter with its surroundings, and recycling it so that other living things can put it to use.

How to Fight Through the 5 Stages of a Cold

For as common as colds are, it’s rare that we stop and think about their actual progression. Yet understanding the early warning signs of a cold can help you take steps toward relief sooner and accurately identifying when a cold is truly waning can help keep you from jumping back into work before your body is really ready.

So, here are the five stages of a cold you should know and the related remedies to consider that can help get you through – and of course, be sure to talk to your healthcare professional if you have any questions.

Stage 1: Onset
It’s roughly 1-3 days since you came into contact with a cold virus and your body is starting to show mild symptoms like mild fatigue, runny or stuffy nose, and a sore throat. Even though you’re busy, try not to ignore these warning signs! Get ample rest and stay especially well hydrated.

Stage 2: Progression
Your cold is really settling in, as is the cough and congestion. Now’s the time to make a full on TLC Kit stocked with chicken soup, tea, honey, cough drops, soft tissues and lip balm. Zinc is a staple of a balanced and healthy immune system, so stock up on zinc-rich foods like eggs, garbanzo beans, pumpkin seeds and whole grains.

Stage 3: Peak
Your cold is in full swing and you’re feeling knocked out. Body aches and a low-grade fever are normal, but double up on your liquids - water, broth and juices - to stay hydrated. To relieve congestion and sinus pressure, use hot, steamy showers and humidifiers and consider an over-the-counter nasal decongestant.

Stage 4: Remission
As your fever breaks and your aches start to subside, you know you’ve turned the corner toward wellness. As you gain back your strength, take the time to nix persistent germs by disinfecting surfaces in your home, car and office. Throw all bedding and clothes into the wash for a good scrubbing, and don’t forget to sterilize personal items like toothbrushes and cell phones that could also harbor and spread germs.

Stage 5: Recovery
Finally, you’re on your feet and feeling back to normal! Treat any minor, lingering symptoms like a cough or runny nose, with the appropriate over-the-counter medicine and stick to an especially healthy, balanced diet as your body reboots.

Remember, cold weather isn’t the source of a cold – hence many of us come down with it in the summer, too! Rather, viruses transmitted through miniscule droplets are the cause. So the best prevention method is to disinfect the spaces around you regularly and wash hands for a full 20 seconds at least five times a day.

Everything you need to know about hypothermia

Hypothermia happens when the body temperature falls below a safe level, and it can be fatal. Infants and older people are especially at risk.

Under healthy conditions, the body maintains a relatively stable temperature of around 98.6˚F or 37˚C.

If the environment gets too cold or the body is unable to produce sufficient heat, the core temperature can drop, and hypothermia can develop.

Between 2003 and 2013, more than 13,400 people died from hypothermia in the United States, according to the Centers for Disease Control and Prevention (CDC) .

Share on Pinterest Hypothermia happens when the body cannot produce enough energy to keep warm. Older people and children are especially susceptible.

Hypothermia is a severe condition in which the body temperature drops to an abnormally low level. It occurs when the body is unable to produce enough heat to counter the heat that it is losing.

The part of the brain that controls body temperature is called the hypothalamus. When the hypothalamus recognizes changes in body temperature, it initiates body responses to bring the temperature back in line.

The body produces heat during routine metabolic processes in cells that support vital bodily functions. Most heat leaves the body through the skin’s surface by the processes of convection, conduction, radiation, and evaporation.

If the environment becomes colder, the body shivers. This increase in muscle activity generates more heat. However, if the body loses heat more quickly than it can make it, the core temperature will fall.

As the temperature falls, the body shunts blood away from the skin to reduce the amount of heat that escapes.

Instead, it directs blood flow to the vital organs of the body, such as the heart, lungs, kidney, and brain. The heart and brain are most sensitive to lower temperatures, and electrical activity in these organs slows down when they become cold.

If the body temperature keeps falling, the organs begin to fail, ultimately leading to death.

Hypothermia is the opposite of hyperthermia, which involves an elevated body temperature and can present as heat exhaustion or heat stroke.

Share on Pinterest A person can become disoriented and may not take action to get warm.

As hypothermia sets in, it becomes more challenging to think, move, and take preventive action. This is dangerous because it means that people who have hypothermia will not seek to keep themselves warm and safe.

The body starts to slow down as the temperature drops. If the person stops shivering, it can be a sign that their condition is getting worse.

The individual is at risk of lying down, falling asleep, and dying. In some cases, people will paradoxically remove their clothes just before this occurs.

Treatment depends on the degree of hypothermia, but the aim will be to make the person warm.

Treatments include the following:

First aid treatment

Anyone with symptoms of hypothermia will need immediate medical assistance.

Until medical assistance arrives, taking the following action can help:

  • moving the person to a warm, dry place, if possible, or sheltering them from the elements
  • removing wet clothing, cutting items away if necessary
  • covering their whole body and head with blankets, leaving only the face clear
  • putting the individual on a blanket to insulate them from the ground
  • monitoring breathing and carrying out CPR if breathing stops
  • providing skin-to-skin contact, if possible, by removing clothing and wrapping yourself and the individual in the blanket together to transfer heat
  • providing warm drinks, if the individual is conscious, but no alcohol or caffeine

It is vital not to use direct heat, such as heat lamps or hot water, as this can damage the skin. It can also trigger irregular heartbeats and, potentially, lead to cardiac arrest.

Do not rub or massage the person either, as these potentially jarring movements could also cause cardiac arrest.

Clinical treatment

According to an article published in the American Family Physician (AFP), the journal of the American Academy of Family Physicians (AAFP), the following techniques can help treat hypothermia.

Passive external rewarming: This uses the individual’s heat-generating ability. It involves removing their cold, wet clothing, ideally replacing it with adequately insulated, dry clothing, and moving them to a warm environment.

Active external rewarming: This involves applying warming devices, such as hot-water bottles or warmed forced air, externally to truncal areas of the body. For example, the individual could hold a hot-water bottle under each arm.

Active core rewarming: This uses warmed, intravenous fluids to irrigate body cavities, including the thorax, peritoneum, stomach, and bladder. Other options include getting the individual to inhale warm, humidified air, or applying extracorporeal rewarming by using a heart-lung machine.

Do not give a person alcohol if they have signs of hypothermia, and avoid giving any drinks to an unconscious person.

A person with severe hypothermia may not seem to have a pulse or be breathing. If they appear to be dead, the CDC advise bystanders to give CPR while keeping the person warm and waiting for emergency help. It is possible that this may resuscitate them.

Hypothermia generally progresses in three stages from mild to moderate and then severe.

According to the AAFP, the signs and symptoms of these stages are as follows:

StageBody temperatureSigns and symptoms
Mild90°F to 95°F (32.2°C to 35°C)High blood pressure, shivering, rapid breathing and heart rate, constricted blood vessels, apathy and fatigue, impaired judgment, and lack of coordination.
Moderate82.4°F to 90°F (28°C to 32.2°C)Irregular heartbeat, a slower heart rate and breathing, lower level of consciousness, dilated pupils, low blood pressure, and a decrease in reflexes.
SevereLess than 82.4°F (28°C)Labored breathing, nonreactive pupils, heart failure, pulmonary edema, and cardiac arrest.

Additional symptoms of hypothermia may include:

  • shivering may stop
  • slurred speech
  • significant confusion
  • drowsiness
  • apathy or lack of concern
  • weak pulse

When a person has severe hypothermia, they may no longer know what they are doing, due to a change in mental consciousness.

Paradoxical undressing

Back in 1979, researchers described a phenomenon known as paradoxical undressing.

In paradoxical undressing, people remove their clothes despite the cold. As a result of doing this, they lose more body heat, which can be fatal. This can happen during the later stages of hypothermia as the person becomes disoriented, confused, and possibly combative.

Although there is a lack of research on this situation, anecdotal evidence suggests that 20–50 percent of deaths from hypothermia are due to paradoxical undressing.

In infants

Infants lose body heat more easily than adults, and they cannot shiver to keep warm.

Infants with hypothermia may have:

Infants should not sleep in a cold room. Using extra blankets is not a solution as there is a risk that these can smother the infant.

The CDC suggest making alternative arrangements if it is not possible to maintain a warm space where an infant can sleep.

Understanding and being prepared for hypothermia is integral to its prevention.

People are at higher risk if they:

  • work outdoors in cold weather
  • practice snowsports, watersports, or other outdoor activities
  • are at home during winter weather, especially older people
  • are stranded in a vehicle in severe winter conditions
  • are sleeping rough
  • have other medical conditions
  • use alcohol or illicit drugs

At home

To prevent hypothermia indoors, the National Institute on Aging (NIA) recommend the following:

  • heating the room you are using to 68–70°F and closing off other rooms to save on heating bills
  • insulating your home, by either making building improvements or laying down rolled-up towels to stop drafts
  • arranging for someone to check on you regularly if you live alone

Stranded in a motor vehicle

Anyone who becomes stranded in a motor vehicle should move everything they need from the trunk into the vehicle.

They should run the car for 10 minutes every hour, making sure that snow is not covering the exhaust pipe and keeping the window open a crack to prevent a buildup of fumes.

People should also consider creating a winter survival kit to keep in the car. The kit should contain nonperishable food, blankets, a first aid kit, water, and necessary medications.

Outdoor activities

Tips for avoiding hypothermia when outdoors include:

  • checking the weather conditions in advance and preparing accordingly
  • wearing multiple layers of clothing with the innermost layers made of wool, silk, or polypropylene because these materials retain heat better than cotton
  • layering clothing to trap multiple layers of air

Overexertion will not help, as this can lead to exhaustion and result in sweat-drenched clothing, both of which contribute to heat loss.

A person who begins to experience or show signs of mild hypothermia should retreat to a warmer place immediately to prevent progression to a life-threatening condition.

Other tips

Other tips for a cold environment include:

  • wearing a hat or thick scarf on the head, even indoors
  • avoiding alcohol
  • eating a sufficient number of calories, as additional fat under the skin can protect against cold during a winter weather spell

Hypothermia in summer

Hypothermia can happen in summer too. Excessively cool air-conditioning or water-based activities pose a risk, especially for infants and older people who may not be able to express how they are feeling.

The National Institutes of Health (NIH) recommend keeping room temperatures at 68°F (20°C) or above and closing off rooms that are not in use.

Observing symptoms and taking a person’s temperature with a thermometer can show whether or not they are experiencing hypothermia.

The BMJ define hypothermia as when a person’s body temperature below 95°F (35°C).

An oral thermometer may not show a temperature this low. In either case, it is vital to seek urgent medical attention.

Hypothermia can result from a chronically cold environment, such as during winter, or it can happen suddenly, for example, if a person falls into cold water.

The CDC stress that temperatures do not have to be excessively cold for hypothermia to develop. If the air temperature is 40°F (4.4°C) and a person is wet, they can develop hypothermia.

Hypothermia in water

People lose heat more quickly in water than on land. Water temperatures that would be comfortable as outdoor air temperatures can lead to hypothermia.

According to an article published in Scientific American, people in water that is 41°F (5°C) can lose muscle strength and coordination in as little as 10 minutes.

Even at 79°F (26°C), a person spending an extended period in the water may be at risk of hypothermia.

Indoor causes

Indoors, a lack of heating, excessive air conditioning or taking an ice bath can result in hypothermia.

Indoor hypothermia often has a poor outcome, because it tends to affect older people, and the diagnosis often comes at a late stage.

Vulnerable populations

Results of a study published in 2018 showed that 75 percent of people who received medical treatment in New York City hospitals for cold-related illness were outdoors when this happened.

Around half were sleeping rough, and another 25 percent had no heating at home. Substance abuse or having a mental or physical health condition increased the risk.

Most of the deaths and illnesses did not occur during periods of extreme cold.

The researchers noted, “Although the climate is warming, cold exposure is an ongoing concern during the winter.”

Medical causes

Other causes of hypothermia include metabolic disorders that result in a lower basal metabolic rate. These disorders cause the body to generate less heat internally.

Exposure to toxins and dysfunction of the thyroid, adrenal, or pituitary glands may also be underlying causes.

Show/hide words to know

Adrenal gland: two glands involved in the body's stress response. These glands are located on top of the kidneys.

Endocrine system: the collection of organs and glands that help control how the body works by adjusting the amount and type hormones that are in the body. more

Gland: an organ that releases materials for use in certain places in the body or on the outside of the body. more

Homeostasis: the ability to keep a system at a constant condition.

Hormone: a chemical message released by cells into the body that affects other cells in the body.

Hypothalamus: a part of the brain that controls things like thirst, hunger, body temperature, and the release of many hormones.

The body will actually lose heat faster if you’re exerting energy. Unless the shore, another boat, or another person are nearby, stay still and try to keep as much of your body out of the water as possible. Most people would not be able to swim a mile in water as cold as 50 degrees. Dunking your head underwater will speed up the hypothermia process.

The Heat Escape Lessening Posture (H.E.L.P.) is a good position that can help conserve energy if you’re wearing a personal flotation device — holding your arms against your sides and across your chest, and hugging your knees to your chest, will help maintain body heat for some time.


Cryotherapy chamber is an individual, tube-shaped enclosure that covers a person’s body with an open-top to keep the head at room temperature. [6] This is a specific type of low-temperature treatment used to reduce inflammation and painful effects. [7]

It was developed in the 1970s by Japanese rheumatologist Toshima Yamaguchi [8] [9] and introduced to Europe, USA and Australia in the 1980s [10] [11] and 1990s. [12]

Mechanism of action Edit

When the body is vulnerable to extreme cooling, the blood vessels are narrowed and make less blood flow to the areas of swelling. Once outside the cryogenic chamber, the vessels expand, and an increased presence of anti-inflammatory proteins (IL-10) is established in the blood. [13] Cryotherapy chamber involves exposing individuals to freezing dry air (below −100 °C) for 2 to 4 minutes. [14]

Main uses Edit

Proponents say that cryotherapy may reduce pain and inflammation, help with mental disorders, support exercise recovery performance and improves joint function. Cryotherapy chambers belong to the group of equipment associated with sports rehabilitation and wellness.

Cryosurgery is the application of extreme cold to destroy abnormal or diseased tissue. The application of ultra-cold liquid causes damage to the treated tissue due to intracellular ice formation. The degree of damage depends upon the minimum temperature achieved and the rate of cooling. [18] Cryosurgery is used to treat a number of diseases and disorders, most especially skin conditions like warts, moles, skin tags and solar keratoses. Liquid nitrogen is usually used to freeze the tissues at the cellular level. The procedure is used often as it is relatively easy and quick, can be done in the doctors surgery, and is deemed quite low risk. If a cancerous lesion is suspected then excision rather than cryosurgery may be deemed more appropriate. [19]

Ice pack therapy is a treatment of cold temperatures to an injured area of the body. Though the therapy is extensively used, and it is agreed that it alleviates symptoms, testing has produced conflicting results about its efficacy. [20] [21] [22] [23]

An ice pack is placed over an injured area and is intended to absorb heat of a closed traumatic or edematous injury by using conduction to transfer thermal energy. The physiologic effects of cold application include immediate vasoconstriction with reflexive vasodilation, decreased local metabolism and enzymatic activity, and decreased oxygen demand. Cold decreases muscle spindle fiber activity and slows nerve conduction velocity therefore, it is often used to decrease spasticity and muscle guarding. It is commonly used to alleviate the pain of minor injuries, as well as decrease muscle soreness. The use of ice packs in treatment decreases the blood flow most rapidly at the beginning of the cooling period, [24] this occurs as a result of vasoconstriction, the initial reflex sympathetic activity.

Ice is not commonly used prior to rehabilitation or performance because of its known adverse effects to performance such as decreased myotatic reflex and force production, as well as a decrease in balance immediately following ice pack therapy for 20 minutes. [25] However, if ice pack therapy is applied for less than 10 minutes, performance can occur without detrimental effects. If the ice pack is removed at this time, athletes are sent back to training or competition directly with no decrease in performance. [26]

Total knee replacement (TKR) is a common intervention for patients with end-stage osteoarthritis of the knee. Post-surgical management includes cryotherapy. Cryotherapy may slightly reduce the amount of blood loss and pain. It was generally safe and not associated with any serious adverse events. It may improve the range of movement at the knee in the first one to two weeks after surgery. Potential benefits of cryotherapy on blood loss, postoperative pain, and range of motion may be too small to justify its use, and the quality of the evidence was very low or low for all main outcomes. Well designed randomized trials are required to improve the quality of the evidence. In conclusion, the effectiveness of cryotherapy is unclear. [27]

In addition to their use in cryosurgery, several types of cold aerosol sprays are used for short-term pain relief. Ordinary spray cans containing tetrafluoroethane, dimethyl ether, or similar substances, are used to numb the skin prior to or possibly in place of local anesthetic injections, and prior to other needles, small incisions, sutures, and so on. Other products containing chloroethane are used to ease sports injuries, similar to ice pack therapy.

It is unclear if whole body cryotherapy (WBC) has any effect on muscle soreness, or improves recovery, after exercise. [12] There is no evidence that whole body cooling effectively treats Alzheimer’s, fibromyalgia, migraines, rheumatoid arthritis, multiple sclerosis, stress, anxiety, or chronic pain as its proponents claim. [28] In fact, whole body cyrotherapy is no more effective than taking a cold shower. [29]

This treatment involves exposing individuals to extremely cold dry air (below −100°C) for two to four minutes. To achieve the subzero temperatures required for WBC, two methods are typically used: liquid nitrogen and refrigerated cold air. During these exposures, individuals wear minimal clothing, which usually consists of shorts for males, and shorts and a crop top for females. Gloves, a woollen headband covering the ears, and a nose and mouth mask, in addition to dry shoes and socks, are commonly worn to reduce the risk of cold-related injury. The first WBC chamber was built in Japan in the late 1970s, introduced to Europe in the 1980s, and has been used in the US and Australia in the past decade. [12]

Adverse effects Edit

Reviews of whole body cryotherapy have called for research studies to implement active surveillance of adverse events, which are suspected of being underreported. [12] [30] If the cold temperatures are produced by evaporating liquid nitrogen, there is the risk of inert gas asphyxiation as well as frostbite. [31]

Partial body Edit

Partial body cryotherapy (PBC) devices also exist. If the cold temperatures are produced by evaporating liquid nitrogen, there is the risk of inert gas asphyxiation as well as frostbite. [31]

What, exactly, do you know about your body? Do you know how yourimmune system works? Or what your pancreas does? Or the myriad --and often simple -- ways you can improve the way your bodyfunctions?

This full-color, visually rich guide answers these questions andmore. Matthew MacDonald, noted author of Your Brain: TheMissing Manual, takes you on a fascinating tour of your bodyfrom the outside in, beginning with your skin and progressing toyour vital organs. You'll look at the quirks, curiosities, andshortcomings we've all learned to live with, and pick up justenough biology to understand how your body works. You'll learn:

That you shed skin more frequently than snakes do

Why the number of fat cells you have rarely changes, no matterhow much you diet or exercise -- they simply get bigger orsmaller

How you can measure and control fat

That your hair is made from the same stuff as horses'hooves

That you use only a small amount of the oxygen you inhale

Why blood pressure is a more important health measure thanheart rate -- with four ways to lower dangerously high bloodpressure

Why our bodies crave foods that make us fat

How to use heart rate to shape an optimal workout session --one that's neither too easy nor too strenuous

Why a tongue with just half a dozen taste buds can identifythousands of flavors

Why bacteria in your gut outnumbers cells in your body -- andwhat function they serve

Why we age, and why we can't turn back the clock

What happens to your body in the minutes after you die

Rather than dumbed-down self-help or dense medical text,Your Body: The Missing Manual is entertaining and packedwith information you can use. It's a book that may well change yourlife.

Reader comments for Your Brain: The Missing Manual,also by author Matthew MacDonald:

"Popular books on the brain are often minefields of attractive butinaccurate information. This one manages to avoid most of the hypeand easy faulty generalizations while providing easy to read anddigest information about the brain. It has useful tricks withoutthe breathless hype of many popular books." -- Elizabeth Zwicky,The Usenix Magazine

". a unique guide that should be sought after by any who want tomaximize what they can accomplish with their mental abilities andresources." -- James A. Cox, The Midwest Book Review - WisconsinBookwatch

"If you can't figure out how to use your brain after reading thisguide, you may want to return your brain for another." -- TheSacramento Book Review, Volume 1, Issue 2, Page 19

How Addiction Works

Stories about how addiction has ruined lives are common in our society today. Reports of the lengths addicts will go to and the dark acts they will commit to get drugs, like crack cocaine, heroin and even alcohol, abound -- serving as cautionary tales to keep others from following the same path.

­­There are many questions about the nature of addiction. Is denial a good indicator of addiction? Are some drugs as addictive as people say? There are even questions when it comes to drug- and alcohol-use prevention tactics. In order to persuade a person not to use a substance, the pitfalls of addiction are sometimes overstated. Overexaggeration can cause feelings of distrust.

Perhaps the best approach to the prevention of substance abuse is a clear, concise understanding of the process of addiction and the effects it can have on the user. To that end, researchers have arrived at a trim and science-based view of addiction. We have learned much in the last few decades, including the idea that addiction can come not only from abusing substances, but also with behaviors like sex and eating.

Though we've come far in the study of addiction, it's still a relatively new concept. Just a few hundred years ago, and for centuries before that, the general attitude toward alcohol was that it was consumed because people wanted to consume it, not because of any internal or external necessity [source: Levine]. But as reports and confessions came in from people who felt an irresistible urge to consume alcohol and drugs (once they became more accessible), our idea about some substances changed, and we developed the concept of addiction.

It was originally believed that some substances, like alcohol and, later, opium, possessed addictive properties, meaning their contents were to blame. That idea later shifted, and addiction was believed to be part of the addict's character. Dependence on drugs and alcohol was seen as a personality flaw -- that the person couldn't behave himself. Later, addiction came to be seen as something from which a person suffered, like a disease.

Although we know that certain substances act on the brain in ways that make the individual want to use more, drug addicts and alcoholics are still widely considered by society to be depraved after all, they chose to use drugs in the first place. And with all of the data available and medical advances achieved in identifying the different aspects of alcohol and substance abuse, science is still struggling with some key questions, like whether it's ultimately substances that are addictive or people who are addicted to substances -- or both.

In this article, we'll examine the current ideas about addiction and look at the ways science is continuing its research to understand, once and for all, the mystery of addiction.

Addiction as a 'Brain Disease'

We become addicted to a substance or activity for the same reason that we initially try it: Because we like the way it makes us feel. And although some people may try a drug, take a drink or eat a donut and never become hooked, almost all of us have the capability to become addicted. Users cross a threshold and undergo a transition to addiction.

Research has shone light on the changes that take place in the brain after this transition, developing the "brain disease" model of addiction. It's currently the most widely held view of addiction among the scientific community.

The way we learn to survive is based on a reward system. When we do something that aids in our survival, like eating or exercising, our brain's limbic system rewards us for this behavior by releasing dopamine, a chemical that makes us feel good. Since we like the way we feel, we learn to repeat the behavior.

Different substances approach the limbic system -- the reward center -- in our brains in different ways, but all substances of abuse cause the brain to release high levels of dopamine. This release can be two to 10 times the amount our brain releases normally, giving the user a sense of a "rush" or "high."

Because of this release and its impact on the brain's reward center, users learn very quickly to use a substance or engage in an activity. They learn this in the same way they learn to eat or exercise, but even faster and with more intensity, since the release of dopamine is so much larger. Since the amount of dopamine released is abnormal, the brain struggles to regain its normal chemical balance after a substance wears off. This produces a hangover, or withdrawal, from a substance, which can manifest in physical pain, depression and even dangerous behavior.

Over time, prolonged use of a substance can lead the brain to stop producing as much dopamine as it naturally does. This creates further withdrawal, leading to a physical dependency -- the addict needs to use more of the substance just to feel normal, creating a vicious cycle that can be difficult to break.

Because of this learning process and eventual physical dependence on a substance, the substance user becomes a substance abuser. As a result, the abuser loses control over the act of taking a substance or engaging in an activity. This has led to the idea that in order to cure an addiction, abstinence -- total discontinuation of substance use or behavior -- is necessary.

Under the disease model of addiction, the brain's motivational center becomes reorganized. The priorities are shuffled so that finding and using the substance (or another substance that will produce similar effects) becomes top priority as far as the brain is concerned. In this sense, the drug has essentially taken over the brain, and the addict is no longer in control of his behavior. An alcoholic won't, for example, have trouble deciding whether or not to get in his car and drive to the store to get more alcohol -- the urge will be irresistible.

But simply going to the store to buy alcohol is not a definitive sign of alcoholism. So how can you tell the difference between using a substance and being addicted to it? In the next section, we'll learn about the symptoms of addiction.

At the close of the 19th century, opiates like morphine could be found in a many tonics and medicines used for a variety of ailments. As a result, so many middle-age women had become addicted to opiates that drug addiction was viewed as a woman'­s problem, alongside premenstrual syndrome and menopause [source: Keire].

Watch the video: You Too Can Ultimately Stop Blushing Now (May 2022).