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Are human bodies programmed to die?

Are human bodies programmed to die?


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Following from this question: What is the evolutionary advantage of death?:

Is there any evidence that human bodies have systemic self-destruction built into their developmental program? I'm not talking about the cell death response, which I know is an important part of growth, development and cancer prevention.

I've read some things about telomere-shortening but don't know if this is a cause or an effect.


From a certain point of view you could argue that our bodies have an inherently limited lifespan;

  • Telomeres are extensions to the end of chromosomes that prevent damage or loss of genetic information during cell division. Telomeres are not replaced (in normal cells), which gives rise to a replicative lifespan; the number of times a cell can divide before permenantly leaving the cell cycle (senescence).
    • This is generally viewed as an anti-cancer mechanism to protect against errors creeping in to the genome through many cell divisions. In order to become cancerous, a cell must first overcome its replicative lifespan [ref.]. This is achieved by activating the (normally inactive) telomerase enzyme that extends the telomeres - embryonic stem cells are one of the few cell types that normally express this enzyme.

There are other ways in which you could argue that our lifespans are fundamentally limited, but it is important to note that the objective is not 'to die', but to increase fitness (in a Darwinian sense) earlier in life. This is known as antagonistic pleiotropy; when an advantageous trait early in life is disadvantageous later in life.

Telomere shortening is just one example of antagonistic pleiotropy (protects against cancer when younger, but limits the number of times your cells can divide).

Other traits that inherently limit lifespan include;

  • Neurons (as a rule) do not replicate, and last for your whole life time. This certainly excludes them from replicate senescence, however it means they are highly susceptible to 'wear and tear'; oxidative stress is a natural by-product of respiration, and the vast majority of damage done by these species (e.g. reactive oxygen species) is repaired by the cell, however some will always remain unchecked, and eventually this leads to neurological dysfunction and cognitive decline. Without intervention this is inevitable in each individual (the rate of aging differs between people, but aging and age-dependent diseases are disorders are a natural part of living).
  • The same is true for cardiac and smooth muscle - whilst much repair can be carried out, it is inevitable that damage will creep in over a life time, and thus the vast majority of human age-related deaths are due to cardiac problems in one way or another.

So there is no 'programmed' limit to life span, in that we have not evolved to die, but our bodies are inherently limited by the systems that have evolved. Life expectancy a few thousand years ago was ~20 years (if you lived beyond infancy!), whereas now in the developed world this is ~80 years, so our bodies can already survive way beyond our 'natural' life span, and thus we now succumb to age-related disease. Evolution has spent millions of years giving us every possible advantage that leads to reproductive success. Natural selection of traits beyond reproduction are secondary to those beforehand, and thus we have fundamentally limited life spans.


There is an argument for an evolutionary advantage of limited lifespan. This seems at first counter-intuitive, until you consider that natural selection does not act on individuals, but genes. It is proposed to be advantageous (in some circumstances) for an organism to have a shorter life span, as this increases the turn-over of individuals in that population. This in turn increases their evolvability - clearly advantageous for the gene(s) influencing this trait if it increases the likelihood of successful reproduction and thus passing on that gene/allele/trait…

I like this hypothesis, and can see that natural selection may favour it. I think mice are great examples here; they have much shorter lifespans than us, yet they 'age' (biologically) the same (cardiac problems, diabetes, cancer) but at a faster rate to give a higher population turnover). In a high mortality environment, the most adaptable animals will be more successful.

However, I think this is likely to be secondary to the pressures on other survival traits that more directly increase the chances of successful reproduction.


I'm not very knowledgeable about evolutionary biology, so I'm going to answer this from the perspective of molecular/cell biology.

The short answer is: No, there isn't any evidence that I know of for a built-in "death".

The long answer:

  1. Telomeres are shortened over repeated copying of chromosomes (so as cells divide repeatedly, the telomeres shorten). Shorter telomeres make chromosomes more unstable, and can lead to some of the symptoms of aging (like limiting organ regeneration). But this is more a side effect of humans not having the most efficient telomerase ever.

In the end, while shortened telomeres contribute to limiting the number of times a cell can replicate (Hayflick limit), we also have stem cells that can then replace those senescent cells. (This is also true in the brain and heart: stem cells are present in the heart and even in highly restricted areas of the brain, and produce neurons throughout life: https://pubmed.ncbi.nlm.nih.gov/10834848/.) So the telomere problem alone doesn't predetermine death.

  1. Other factors that contribute to aging can be divided into two categories, genetic factors and accumulation of damage.

But in both of those groups, the cause isn't that genetically we're programmed to die at a certain time. It is always a case of the systems used to repair or regenerate failing after a time: DNA mutation repair becoming incapable of keeping up with the rate of mutations; failure of clonal deletion leading to autoimmunity; inhibition of autophagy by mTOR leading to accumlation of old and damaged cell parts; failure of senescent cells to undergo apoptosis.

There are many other hallmarks of aging, but the common thread we see is not that there is a set program leading to an organism's death, but rather a failure (through accumulation of damage) of the systems that keep us alive.


In Richard Dawkin's book "The Selfish Gene" it seems that there is a programmed purposeful death of the body. The genes are in control. They seek out a mate to produce offspring that will be even better suited to pass it's genes on again. The meaning of life as we have seen and observed it is really for the genes to perpetuate their existance into the future. Once passed on the body that did the passing is of little use. The more complex the organism like a human mates may be selected by life span of parents and relatives. There doesn't seen to be any Newtonian law that states a cell cannot just keep replicating and essentially avoid aging. Our bodies are doing that for a purpose. One we just don't understand.


Human Enhancement

H uman enhancement is at least as old as human civilization. People have been trying to enhance their physical and mental capabilities for thousands of years, sometimes successfully – and sometimes with inconclusive, comic and even tragic results.

Up to this point in history, however, most biomedical interventions, whether successful or not, have attempted to restore something perceived to be deficient, such as vision, hearing or mobility. Even when these interventions have tried to improve on nature – say with anabolic steroids to stimulate muscle growth or drugs such as Ritalin to sharpen focus ­– the results have tended to be relatively modest and incremental.

“We’re fast approaching the moment when humans and machines merge,” Time magazine declared in its 2011 issue.

But thanks to recent scientific developments in areas such as biotechnology, information technology and nanotechnology, humanity may be on the cusp of an enhancement revolution. In the next two or three decades, people may have the option to change themselves and their children in ways that, up to now, have existed largely in the minds of science fiction writers and creators of comic book superheroes.

Both advocates for and opponents of human enhancement spin a number of possible scenarios. Some talk about what might be called “humanity plus” – people who are still recognizably human, but much smarter, stronger and healthier. Others speak of “post-humanity,” and predict that dramatic advances in genetic engineering and machine technology may ultimately allow people to become conscious machines – not recognizably human, at least on the outside.

This enhancement revolution, if and when it comes, may well be prompted by ongoing efforts to aid people with disabilities and heal the sick. Indeed, science is already making rapid progress in new restorative and therapeutic technologies that could, in theory, have implications for human enhancement.

It seems that each week or so, the headlines herald a new medical or scientific breakthrough. In the last few years, for instance, researchers have implanted artificial retinas to give blind patients partial sight. Other scientists successfully linked a paralyzed man’s brain to a computer chip, which helped restore partial movement of previously non-responsive limbs. Still others have created synthetic blood substitutes, which could soon be used in human patients.

One of the most important developments in recent years involves a new gene-splicing technique called “clustered regularly interspaced short palindromic repeats.” Known by its acronym, CRISPR, this new method greatly improves scientists’ ability to accurately and efficiently “edit” the human genome, in both embryos and adults.

The new gene-splicing technique “CRISPR” greatly improves scientists’ ability to accurately and efficiently “edit” the human genome. (Credit: Getty Images)

To those who support human enhancement, many of whom call themselves transhumanists, technological breakthroughs like these are springboards not only to healing people but to changing and improving humanity. Up to this point, they say, humans have largely worked to control and shape their exterior environments because they were powerless to do more. But transhumanists predict that a convergence of new technologies will soon allow people to control and fundamentally change their bodies and minds. Instead of leaving a person’s physical well-being to the vagaries of nature, supporters of these technologies contend, science will allow us to take control of our species’ development, making ourselves and future generations stronger, smarter, healthier and happier.

The science that underpins transhumanist hopes is impressive, but there is no guarantee that researchers will create the means to make super-smart or super-strong people. Questions remain about the feasibility of radically changing human physiology, in part because scientists do not yet completely understand our bodies and minds. For instance, researchers still do not fully comprehend how people age or fully understand the source of human consciousness.

There also is significant philosophical, ethical and religious opposition to transhumanism. Many thinkers from different disciplines and faith traditions worry that radical changes will lead to people who are no longer either physically or psychologically human.

We are no longer living in a time when we can say we either want to enhance or we don’t. We are already living in an age of enhancement.

— Nicholas Agar, Victoria University

Even minor enhancements, critics say, may end up doing more harm than good. For instance, they contend, those with enhancements may lack empathy and compassion for those who have not chosen or cannot afford these new technologies. Indeed, they say, transhumanism could very well create an even wider gap between the haves and have-nots and lead to new kinds of exploitation or even slavery.

Given that the science is still at a somewhat early stage, there has been little public discussion about the possible impacts of human enhancement on a practical level. But a new survey by Pew Research Center suggests wariness in the U.S. public about these emerging technologies. For example, 68% of Americans say they would be “very” or “somewhat” worried about using gene editing on healthy babies to reduce the infants’ risk of serious diseases or medical conditions. And a majority of U.S. adults (66%) say they would “definitely” or “probably” not want to get a brain chip implant to improve their ability to process information.

And yet, perhaps ironically, enhancement continues to captivate the popular imagination. Many of the top-grossing films in recent years in the United States and around the world have centered on superheroes with extraordinary abilities, such as the X-Men, Captain America, Spiderman, the Incredible Hulk and Iron Man. Such films explore the promise and pitfalls of exceeding natural human limits.

HUMAN ENHANCEMENT IN POPULAR CULTURE

Not only is enhancement unquestionably part of today’s cultural zeitgeist, questions about humanity’s quest to move beyond natural limits go back to our earliest myths and stories. The ancient Greeks told of Prometheus, who stole fire from the gods, and Daedalus, the skilled craftsman, who made wings for himself and his son, Icarus. In the opening chapters of Genesis, the Hebrew Bible depicts a successful incident of human enhancement, when Adam and Eve ate the fruit from the tree of the knowledge of good and evil because the Serpent told them it would make them “like God.”

Of course, while Adam and Eve gained a new awareness and self-understanding, their actions also led to their expulsion from paradise and entry into a much harder world full of pain, shame and toil. This theme – that hidden dangers may lurk in something ostensibly good – runs through many literary accounts of enhancement. In Mary Shelley’s “Frankenstein” (1818), for instance, a scientist creates a new man, only to eventually die while trying to destroy his creation.

Whether these fears surrounding human enhancement are real or unfounded is a question already being debated by ethicists, scientists, theologians and others. This report looks at that debate, particularly in light of the diverse religious traditions represented in the United States. First, though, the report explains some of the scientific developments that might form the basis of an enhancement revolution.


Unplanned Cell Death

Cells die in an unplanned manner when exposed to a variety of harmful environmental agents. These include both chemical and physical events, or “insults,” and range from radiation, heat, toxic substances, bodily trauma or injury and lack of oxygen. Injured cells swell up, burst, spill their contents and cause surrounding cells to react defensively. This often involves inflammation and the calling in of specialized immune cells to deal with cleanup and isolation of the damaged tissue.


About the Show

Explore the internal mechanics of the human body through pioneering graphics and captivating scientific case studies. Witness the fascinating and finely tuned systems that keep the body motoring and the scientists guessing.

Your body is the most sophisticated organism on earth. It is a scientific marvel and much about it remains a mystery. "The Amazing Human Body" uses cutting-edge graphics to reveal the surprisingly beautiful biological processes that keeps you alive.

Discover the ingenious ways your body develops, adapts and endures. How does your brain communicate with your body in order to help you learn new skills? What is the connection between a teenager’s craving for fatty foods and sudden growth spurts? And how does cell regeneration allow an octogenarian to compete in a grueling triathlon and live to tell the tale?

Case studies from across the globe showcase the dazzling secret science of the human body. A child prodigy in Phoenix demonstrates the brain’s ability to prioritize mental development over physical growth, a chilling dip in an icy lake reveals how shivering might just save our lives, and low-level torture in a London laboratory highlights the way our bodies block pain.

Witness the fascinating and finely tuned systems that keep your body motoring – and the scientists guessing.


Why does Emory need my body?
Almost all bodies used at Emory Medical School are donated by generous individuals who wish to be useful to the living after death. We all cannot endow a hospital or establish a clinic, but each of us has the opportunity to make one valuable gift to medical science - the gift of his or her body after death.

May I donate my organs and still donate my body to Emory?
Removal of organs and/or tissue for transplantation may make body donation impractical. The Body Donor Program encourages organ donation, but cannot assure the donor that the body will be accepted.

Will I be paid for leaving my body to Emory?
No. Emory does not buy bodies nor do other medical schools in the United States. Donation does relieve the family of many expenses involved in a funeral service.

Will Emory pay for the transportation of the body?
No. The donor's representative will be asked to pay the cost of transporting the body to Emory. The Body Donor Program will make arrangements with a transportation service to ensure the donor is safely transported to the medical school. 

How are bodies used for education and training?
Many bodies are dissected by closely supervised medical students and other health professionals in training either at Emory or at another accredited institution. Others are used by the medical school faculty and residents to develop new surgical or diagnostic procedures or to provide continuing education to physicians or other health professionals.

Is this the same as an autopsy?
No. An autopsy determines the cause of death and takes only a short time. Anatomical dissection requires detailed examination of the entire body or individual components, with emphasis on normal structure. No reports of any kind are furnished to the donor's family.

Will my body be treated with respect?
Yes. Faculty, students, residents, and fellows in training are aware that the body from which they learn is a generous donation. No disrespect is permitted. All use of the body is closely supervised, and the identity of the body is known only to a few faculty and staff members. Bodies are NOT displayed to the public.

Does my religion approve of body donation?  
Most religions approve of body donation. If you are uncertain of your religion's position on the use of the dead body, consult your Minister, Pastor, Rabbi or Priest.

Must my family agree with my wish to give my body to Emory?
Emory normally requests consent from the next of kin before accepting a body. It is wise to consult your family so they will be emotionally prepared to carry out your wishes. They are the ones who must understand why you feel that the donation of your body is a gift to all future generations. Emory will decline a body when close family members oppose the donation.

May my survivors have a funeral for me if I donate my body to Emory?
With proper coordination the family may have the body embalmed for viewing and/or a funeral. Otherwise, Emory must receive the body immediately after death.

Is the body returned to the family for burial?
No. After study, it is cremated at no expense to the family. This may be up to 24 months after death. Ashes may be returned to the family for private disposition, if requested. Ashes will be returned by Registered United States Mail. There will be a nominal fee for preparation and shipping.

What is done with the ashes if they are not returned?
They will be buried, after a memorial service, at Decatur Cemetery in Decatur, Georgia. There is no expense to the family.

What happens if I die far from Emory?
Essentially, there are two options: 
 (1) The body may be offered to a nearby medical school that needs bodies. 
 (2) The body may be buried or cremated in the usual manner at the expense of the family or estate. 

May Emory refuse my body after death?
Yes. Emory reserves the right to decline bodies not suitable for medical study. Suitability will be determined before the body is transported to Emory. You should have alternate plans for disposition of your body in the event it is not accepted by the Medical School.

Who should be notified of my death?
The physician, hospital, or nearest relative should immediately call the Body Donor Program at Emory University: (404) 727-6242. This number is answered twenty-four hours a day.

May friends and/or relatives make contributions to the Department of Cell Biology in my memory?
Yes. Gifts are tax-deductible, should be made payable to Emory University School of Medicine, and be directed to the Body Donor Program at the  address below . Gifts will be acknowledged to the donor and to your family. Funds from such gifts will be used only for medical education and research.

How may I leave my body to Emory?  
A simple gift form is required. You must personally sign the form and return it to Emory at least 30 days before your death. Expressing your wishes in your will is not sufficient for Emory to accept your body. Your signature should be witnessed by two (2) individuals who are not family members. Your nearest relatives should also personally sign the form. Return one copy of the form to Emory. When Emory receives the properly completed form, you will be sent a card identifying you as a Body Donor. You may obtain the forms by calling (404) 727-6242, by  email  to Susan Brooks or by writing:


How running made us human: Endurance running let us evolve to look the way we do

Humans evolved from ape-like ancestors because they needed to run long distances &ndash perhaps to hunt animals or scavenge carcasses on Africa's vast savannah &ndash and the ability to run shaped our anatomy, making us look like we do today.

That is the conclusion of a study published in the Nov. 18 issue of the journal Nature by University of Utah biologist Dennis Bramble and Harvard University anthropologist Daniel Lieberman. The study is featured on Nature's cover.

Bramble and Lieberman argue that our genus, Homo, evolved from more ape-like human ancestors, Australopithecus, 2 million or more years ago because natural selection favored the survival of australopithecines that could run and, over time, favored the perpetuation of human anatomical features that made long-distance running possible.

"We are very confident that strong selection for running &ndash which came at the expense of the historical ability to live in trees &ndash was instrumental in the origin of the modern human body form," says Bramble, a professor of biology. "Running has substantially shaped human evolution. Running made us human &ndash at least in an anatomical sense. We think running is one of the most transforming events in human history. We are arguing the emergence of humans is tied to the evolution of running."

That conclusion is contrary to the conventional theory that running simply was a byproduct of the human ability to walk. Bipedalism &ndash the ability to walk upright on two legs &ndash evolved in the ape-like Australopithecus at least 4.5 million years ago while they also retained the ability to travel through the trees. Yet Homo with its "radically transformed body" did not evolve for another 3 million or more years &ndash Homo habilis, Homo erectus and, finally, our species, Homo sapiens &ndash so the ability to walk cannot explain anatomy of the modern human body, Bramble says.

"There were 2.5 million to 3 million years of bipedal walking [by australopithecines] without ever looking like a human, so is walking going to be what suddenly transforms the hominid body?" he asks. "We're saying, no, walking won't do that, but running will."

Walking cannot explain most of the changes in body form that distinguish Homo from Australopithecus, which &ndash when compared with Homo &ndash had short legs, long forearms, high permanently "shrugged" shoulders, ankles that were not visibly apparent and more muscles connecting the shoulders to the head and neck, Bramble says. If natural selection had not favored running, "we would still look a lot like apes," he adds.

I Run, Therefore I Am

Bramble and Lieberman examined 26 traits of the human body &ndash many also seen in fossils of Homo erectus and some in Homo habilis &ndash that enhanced the ability to run. Only some of them were needed for walking. Traits that aided running include leg and foot tendons and ligaments that act like springs, foot and toe structure that allows efficient use of the feet to push off, shoulders that rotate independently of the head and neck to allow better balance, and skeletal and muscle features that make the human body stronger, more stable and able to run more efficiently without overheating.

"We explain the simultaneous emergence of a whole bunch of anatomical features, literally from head to toe," Bramble says. "We have a hypothesis that gives a functional explanation for how these features are linked to the unique mechanical demands of running, how they work together and why they emerged at the same time."

Humans are poor sprinters compared with other running animals, which is partly why many scientists have dismissed running as a factor in human evolution. Human endurance running ability has been inadequately appreciated because of a failure to recognize that "high speed is not always important," Bramble says. "What is important is combining reasonable speed with exceptional endurance."

Another reason is that "scientists are in developed societies that are highly dependent on technology and artificial means of transport," he adds. "But if those scientists had been embedded in a hunter-gatherer society, they'd have a different view of human locomotor abilities, including running."

Why Did Humans Start Running?

The researchers do not know why natural selection favored human ancestors who could run long distances. For one possibility, they cite previous research by University of Utah biologist David Carrier, who hypothesized that endurance running evolved in human ancestors so they could pursue predators long before the development of bows, arrows, nets and spear-throwers reduced the need to run long distances.

Another possibility is that early humans and their immediate ancestors ran to scavenge carcasses of dead animals &ndash maybe so they could beat hyenas or other scavengers to dinner, or maybe to "get to the leftovers soon enough," Bramble says.

Scavenging "is a more reliable source of food" than hunting, he adds. "If you are out in the African savannah and see a column of vultures on the horizon, the chance of there being a fresh carcass underneath the vultures is about 100 percent. If you are going to hunt down something in the heat, that's a lot more work and the payoffs are less reliable" because the animal you are hunting often is "faster than you are."

Anatomical Features that Help Humans Run

Here are anatomical characteristics that are unique to humans and that play a role in helping people run, according to the study:

  • Skull features that help prevent overheating during running. As sweat evaporates from the scalp, forehead and face, the evaporation cools blood draining from the head. Veins carrying that cooled blood pass near the carotid arteries, thus helping cool blood flowing through the carotids to the brain.
  • A more balanced head with a flatter face, smaller teeth and short snout, compared with australopithecines. That "shifts the center of mass back so it's easier to balance your head when you are bobbing up and down running," Bramble says.
  • A ligament that runs from the back of the skull and neck down to the thoracic vertebrae, and acts as a shock absorber and helps the arms and shoulders counterbalance the head during running.
  • Unlike apes and australopithecines, the shoulders in early humans were "decoupled" from the head and neck, allowing the body to rotate while the head aims forward during running.
  • The tall human body &ndash with a narrow trunk, waist and pelvis &ndash creates more skin surface for our size, permitting greater cooling during running. It also lets the upper and lower body move independently, "which allows you to use your upper body to counteract the twisting forces from your swinging legs," Bramble says.
  • Shorter forearms in humans make it easier for the upper body to counterbalance the lower body during running. They also reduce the amount of muscle power needed to keep the arms flexed when running.
  • Human vertebrae and disks are larger in diameter relative to body mass than are those in apes or australopithecines. "This is related to shock absorption," says Bramble. "It allows the back to take bigger loads when human runners hit the ground."
  • The connection between the pelvis and spine is stronger and larger relative to body size in humans than in their ancestors, providing more stability and shock absorption during running.
  • Human buttocks "are huge," says Bramble. "Have you ever looked at an ape? They have no buns." He says human buttocks "are muscles critical for stabilization in running" because they connect the femur &ndash the large bone in each upper leg &ndash to the trunk. Because people lean forward at the hip during running, the buttocks "keep you from pitching over on your nose each time a foot hits the ground."
  • Long legs, which chimps and australopithecines lack, let humans to take huge strides when running, Bramble says. So do ligaments and tendons &ndash including the long Achilles tendon &ndash which act like springs that store and release mechanical energy during running. The tendons and ligaments also mean human lower legs that are less muscular and lighter, requiring less energy to move them during running.
  • Larger surface areas in the hip, knee and ankle joints, for improved shock absorption during running by spreading out the forces.
  • The arrangement of bones in the human foot creates a stable or stiff arch that makes the whole foot more rigid, so the human runner can push off the ground more efficiently and utilize ligaments on the bottom of the feet as springs.
  • Humans also evolved with an enlarged heel bone for better shock absorption, as well as shorter toes and a big toe that is fully drawn in toward the other toes for better pushing off during running.

The study by Bramble and Lieberman concludes: "Today, endurance running is primarily a form of exercise and recreation, but its roots may be as ancient as the origin of the human genus, and its demands a major contributing factor to the human body form."

Story Source:

Materials provided by University Of Utah. Note: Content may be edited for style and length.


What happens to cells in our bodies when they die?

There are 2 main types of cell death: apoptosis (programmed cell death) & necrosis (due to lack of blood flow, ischaemia). But where do these dead cells go?

Asked by: Phil Hibbs, Birmingham

Cells on the surface of our bodies or in the lining of our gut are sloughed off and discarded. Those inside our bodies are scavenged by phagocytes – white blood cells that ingest other cells.

The energy from the dead cells is partly recycled to make other white cells.

Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.

Authors

Luis Villazon

Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.


DEPARTMENT OF HEALTH AND HOSPITALS

Q. Why are human bodies donated to the Bureau of Anatomical Services or one of its member institutions? A. They are an indispensable aid in medical teaching and research. The basis of all medical knowledge is human anatomy human anatomy can be learned only by a study of the human body. Without this study there could be no doctors, no surgery, no alleviation of disease or repair of injury.

Q. Is this a normal and acceptable procedure? A. Definitely yes.

Q. Are there religious objectives to donating one's body to medical science? A. The practice is approved, and even encouraged, by Catholic, Protestant and Reformed Jewish religious leaders.

Q. Is there an urgent need for body donations? A. The need is great and will be further increased by the demand for more doctors, dentists, nurses and other health service practitioners. A lack of anatomical subjects would necessitate a curtailment of vitally important teaching and research programs and thus have an adverse effect on the health and welfare of the population.

Q . Is donating one's body difficult or complicated? A. No, it is a very simple and easy procedure. One needs only to complete a donation form which requires a few items of information, the donor's signature and the signature of two witnesses.

Q. Can a donation take place against the wishes of the spouse or next of kin? A. Under the Uniform Anatomical Gift Act, your wishes take legal precedence over those of your next of kin. However, the BAS is not inclined to accept a body under conditions in which there is an objection to donation or dissension among members of the family who are legally responsible for final disposition of the body. Donors are advised to notify all persons likely to be concerned of their intentions and plans to make a donation of their body. In this way, any difference of opinion can be resolved in advance of the time of death when decisions must be made in haste and under the handicap of grief.

Q. Can the next of kin donate the body of a recently deceased relative to medical science? A. In some instances donations may be made by the next of kin. However, since previously registered donors are given first priority, the family or hospital must contact the BAS on an individual basis to see if there is a need at the moment. When this is done, the following release statement should accompany the body:

* I/We, (the person(s)' name), being the nearest next of kin [as outlined in RS: ] or by individual having legal authority for final disposition to (name of deceased) do hereby agree to release his/her body to the Bureau of Anatomical Services (or University of choice) for medical education and/or research.*

Q . Must a person be of legal age to sign a donation form? A. Yes, a donor and all witnesses must be at least 18 years of age and there is no maximum age limit.

Q . How are bodies that are donated utilized? A. Many bodies are used to teach medical, dental, nursing and allied health students basic human anatomy. Some are used by the faculty and residents to develop new surgical or diagnostic procedures. Others are utilized for Post Graduate course and continuing education for practicing Health Care providers. This is not comparable to an autopsy. No reports of any kind are furnished to the donor's family.

Q . May I alter, cancel or revoke my donation if I change my mind? A. Yes, at any time by notifying the BAS in writing of your desire to cancel your donation. In contact of these uses we do not have the capability of performing an autopsy therefore no reports of any kind are furnished to the donor's family of the cause of death and diseases, etc.

Q . Will I or my family be paid for my body? A. No. Payment to individuals for an anatomical donation is not permitted by federal and state laws/regulations.

Q. Will signing the back of my driver's license ensure that my remains are given to your program? A. No. Signing the back of your driver's license will not get your whole body donated to science. Your signature on the back of your driver's license allows medical personnel to harvest designated organs from your body for transplant purposes, but usually under optimum conditions only.

Q . Are bodies acceptable if the eyes or organs have been donated to other agencies? A. Yes. Eyes and organs can be donated to other agencies, but it is the donor's responsibility to contact and register with those agencies. The telephone numbers for several agencies are listed below:

National Kidney Foundation - (504) 861-4500 (accepts other organs besides the kidneys)

Louisiana Organ Procurement Agency - (504) 837-3355

Q. Are there any restrictions on the condition of bodies accepted? A. Normally, most bodies are acceptable. However we are unable to accept the remains of persons who die when an infectious disease present, such as AIDS, hepatitis, sepsis, etc. Remains will also be refused if an autopsy or embalming has been performed, or should the President of the Bureau deem the body unsuitable. You should have an alternative plan for the disposition of your body in the event it is not accepted by BAS.

Q. What is the time period before utilization of the body is completed? A. This will vary markedly according to the medical education and research. In some instances, donations will be utilized relatively quickly where others may require up to three or more years.

Q. What if my death occurs away from my place of residence? A. An identification card, stating that the bequest has been made, is provided by the BAS. This card should be carried in your purse or wallet at all times (the donor would be wise to note on the card the name of the person(s) to be notified in the event of sudden and unexpected death).

Q. What if my death occurs in another state? A. Your family could attempt to donate your remains to a similar donor program in that state. Or, if it is still your family's wish to honor your original donation of your remains to the BAS, they may do so, but will incur the transportation charges to have your remains returned to Louisiana.

Q. What if I should move to another state? A. The original bequest should be revoked in writing and a substitute arrangement be made with a similar program nearest your new home unless your family estate or survivors or opt to honor your original request in which the family will pay the transportation charges to transport your remains to Louisiana.

Q. Must I be a resident of Louisiana to donate my body? A. As of January 1994, the Bureau discontinued taking new donations from outside the State of Louisiana. However, a prospective donor who lives outside of Louisiana, if the family agrees to pay transportation, the remains may be accepted by the Bureau of Anatomical Services. Out of State agreement must be filled out in which the person responsible accepts the payment of transportation. (Copies of this form are available upon request.)

Q . May a customary or traditional type of funeral service be held prior to the transfer of the body to the Bureau for Anatomical Services? A. We do not recommend that a traditional funeral service be held. If the family wishes to conduct a service, we suggest that they hold a memorial service.

Q. What organization should my family contact to request a death certificate*? A. For insurance and banking purposes, a certified death certificate is required and can be obtained from the contracted funeral home (for a additional fee) or from:

Vital Records Registry
P. O. Box 60630
New Orleans, Louisiana 70160-0630
(504) 219-4500
or VitalChek (877) 605-8562
www.vitalcheck.com

* Allow eight weeks or longer from the time of death for the death certificate to be processed.

Q . What happens when the utilization of the donation is concluded? A. The remains will be cremated. If requested (in writing) to do so, the Bureau will return the ashes, in a suitable container, to the surviving relatives. If no such request is made, the ashes will be buried in a cemetery designated for the BAS with an appropriate ceremony.


How Many Types of Cells Are in the Human Body?

You may know that your skin is made of cells, your bones are made of cells, and your blood is made of cells. But these cells aren't all the same types of cells. Different types of cells each do unique jobs in your body. Together, they let your body function as a whole. So to put it in a joke format, how many types of cells does it take so that an adult human can screw in a light bulb? Any guesses? Over 200.

Even within a specific tissue (like blood, bone, or muscle) there are many different cell types. For example, bone tissue cells include osteocytes, osteoblasts, and osteoclasts. Image by Department of Histology, Jagiellonian University Medical College.

There are about 200 different types of cells in your body. These cells make up your organs and tissues, as well as help to defend your body as a part of your immune system. Your cells are constantly being replaced as they die.

For example, the skin cells on the surface of your body live for about 30 days and then are replaced as they fall off. When red blood cells are old and need to be replaced, they are filtered out of your blood in the spleen, and new red blood cells are made in your bone marrow to replace them.

As cells get old and die, they are replaced, so your body is always made up of healthy living cells. Some dead cells stick around too, making up the outer layers of your skin, your fingernails, and your hair.

Looking for the number of total cells in the human body? Visit Building Blocks of Life.

For more simplified information on cells, check out Cell Bits and Cell Parts Bits.


Body Systems and Functions

As you have probably already concluded, the different human body systems have a vast array of overlapping and complementary functions. The sympathetic and parasympathetic control of heart rate is an example of the nervous system function interacting with the circulatory system. (The parasympathetic effect on heart rate is to slow it sympathetic input accelerates it.)

The Circulatory System: Also called the cardiovascular system, the heart and blood vessels have the job of delivering oxygen and nutrients to the rest of the body and collecting waste products for removal from the body by other systems.

The Respiratory System: Your lungs allow you to inhale and exhale air to exchange gases between blood and lung space deep within the lungs themselves. The carbon dioxide produced in metabolism is "off-loaded," while oxygen from air is "on-loaded" to red blood cells.

The Skeletal System: Your bones, cartilage and ligaments provide a structural framework for the rest of you, like a scaffolding for organs and tissues. This system affords protection of vital organs and permits locomotion of the organism the bone marrow in the middle of long bones makes immune cells.

The Muscular System: Muscles comes in three main types. Skeletal muscles move you around and perform other functions when you contract them voluntarily. Smooth muscle lines organs such as the gut and bladder and operates involuntarily. Cardiac muscle is a specialized kind of muscle in the myocardium of the heart.

The Integumentary System: This includes the skin, hair and nails, mostly the former. This physical barrier helps keep out microorganisms, regulates the moisture level of the organism and keeps temperature steady. The skin and other parts of the integumentary system work hand-in-hand with the body's immune system, such as keeping out germs and bacteria. Sometimes the immune system is listed separately from the integumentary system, leading to 12 body systems and functions rather than 11.

The Digestive System: This system converts ingested foods into smaller molecules your cells can harvest energy from.

The Nervous System: Your brain, spinal cord and a great many peripheral nerves make up this system, which is responsible for collecting, processing and transmitting information.

The Endocrine System: When you hear the word "hormones," think "endocrine system." This system regulates the internal environment of the organism via the dispersal of chemicals (hormones) that act at certain receptors throughout the body. The pancreas, pituitary gland and thyroid gland are part of this system,

The Excretory/Urinary System: Your kidneys help eliminate waste by filtering the blood, keep the acid-base levels of the blood steady, and regulate the amount of blood in the body via electrolyte and other solute balance.

The Lymphatic System: The structures in this system of channels are akin to a second circulatory system, which also includes the spleen, make cells that combat foreign invaders and help return tissue fluid to the blood vessels.

The Reproductive System: This system is responsible for creating gametes, or sex cells (testes in males, ovaries in females) that participate in fertilization and propagation of genes into the next generation of organisms. It includes the uterus in females and external genitalia regardless of sex.


Apoptosis

Apoptosis (from Ancient Greek ἀπόπτωσις, apóptōsis, "falling off") is a form of programmed cell death that occurs in multicellular organisms. [1] Biochemical events lead to characteristic cell changes (morphology) and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, chromosomal DNA fragmentation, and global [ vague ] mRNA decay. The average adult human loses between 50 and 70 billion cells each day due to apoptosis. [a] For an average human child between the ages of 8 and 14, approximately 20–30 billion cells die per day. [3]

In contrast to necrosis, which is a form of traumatic cell death that results from acute cellular injury, apoptosis is a highly regulated and controlled process that confers advantages during an organism's life cycle. For example, the separation of fingers and toes in a developing human embryo occurs because cells between the digits undergo apoptosis. Unlike necrosis, apoptosis produces cell fragments called apoptotic bodies that phagocytic cells are able to engulf and remove before the contents of the cell can spill out onto surrounding cells and cause damage to them. [4]

Because apoptosis cannot stop once it has begun, it is a highly regulated process. Apoptosis can be initiated through one of two pathways. In the intrinsic pathway the cell kills itself because it senses cell stress, while in the extrinsic pathway the cell kills itself because of signals from other cells. Weak external signals may also activate the intrinsic pathway of apoptosis. [5] Both pathways induce cell death by activating caspases, which are proteases, or enzymes that degrade proteins. The two pathways both activate initiator caspases, which then activate executioner caspases, which then kill the cell by degrading proteins indiscriminately.

In addition to its importance as a biological phenomenon, defective apoptotic processes have been implicated in a wide variety of diseases. Excessive apoptosis causes atrophy, whereas an insufficient amount results in uncontrolled cell proliferation, such as cancer. Some factors like Fas receptors and caspases promote apoptosis, while some members of the Bcl-2 family of proteins inhibit apoptosis.



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