Anatomy Final: Aging, Senescence, and Death

What are some of the nine conditions that must be absent to declare death and for how long must they be absent?

no response to commands, fixed pupils, no corneal reflex, no gag reflex, no spontaneous respiration (spinal reflexes remain) must be absent for >12 hrs (6 if organ donor)

In the US, OLDER people (+__) deaths clearly relate to _________ of organ systems. Specifically in order of most - least common, _______,______,__________,_________(including ______)

55; senescence; heart disease, stroke, cancer, lung disease, COPD

Cross-Linking Theory.

One-fourth of the body's protein is collagen. With age, collagen becomes cross-linked by more disulfide bridges, thus making them stiffer. This is thought to be a factor in several noticeable changes of the aging body: stiffening of the joints, lenses and arteries. Cross linkage also occurs DNA, altering its function

Causes of death vary with _____, largely because of ______ rates among ________ and the upswing in _____ rates among ______ (rise in ______ cancer over __ and lung and related cancer b/c incr. in women ______)

gender; accident rates among males; cancer rates among women; breast cancer over 34; smokers

What is longevity?

life span of an individual

What has caused the increase in life expectancy?

victories over infant and child mortality

what is considered the legal time of death?

when the brain and the brain stem have irreversibly lost all neurological function

Programmed Cell Death Theory

Cells have a limited life span. After a certain number of cell division or at a certain age, cells may activate a "suicide program" that destroys their own DNA

Biological Clock Theory.

It has been speculated that senescence is genetically determined by "pacemaker" cells in the brain. Hypothalamic control of the anterior pituitary affects many other organs. The hypothalamus regulates the autonomic nervous system as well. Therefore, brain regulation can affect the whole body.

What is life expectancy?

average length of life in a given population

The Hayflick Phenomenon.

cells will only divide a certain number of times before the degenerate and die --Leonard Hayflick --fibroblasts divide50 times

What is aging?

changes in structure and function that are predictable over time

What is senescence?

degeneration in an organ system after age of peak functional efficiency; group of deleterious effects that lead to decrease in efficient functioning of an organ (incr. probability of death)

Life expectancy has __________ _________ in industrialized countries from what it was in the beg. of the ____ century (_____ yo.) when ___people died of __________ ________. Today boys are expected to live to _____ and girls to _____.

increased steadily; 20th; 45-50; 1/2; infectious diseases; 74; 80.

________ has not increased for many _______. There is no record of anyone living longer than _____ and the hypothesized upper limit would be _____yo. because any longer would require reversing _______, ________, and ______ programming of every ___________.

life span; centuries; 122; 150; senescence, genetic and biochemical; organ system

There is ______ evidence that things we do/dont do prolong our life with the exception of _______ which can _______ life expectancy by _____ years.

little; smoking; decrease; 6-7

What is life span?

max age attainable by humans

As a whole, it is _____ ______ risk factors (not ___ _______) that are the leading cause of mortality in the US. ___% deaths are a result of _____ and _____, but the leading cause of mortality remains _______ with ___% of US deaths

modifiable behavior; natural senescence; 16.6%; poor diet and physical inactivity; smoking; 18.1%

There is ___ _________ instance of BIOLOGICAL DEATH. Instead, it is a ___________ of events over time (some _______ function for an ______ or more after ________ _______)

no definable; sequence; organs; hour; heart stops

As we age, senescence affects our _______ __ ____. There is ______ _____ that what we do/dont do affects _________ (_______ and _______ results in senescence more than any other causes). ________ and ______ are the best ways to slow progress.

quality of life; clear evidence; senescence; obesity and insufficient exercise. Good nutrition and exercise

What are two things physicians might additionally require before pronouncing brain death?

EEG (electroencephalogram) and CBF (cerebral blood flow study -- BF=light color, no BF=black)

Other Protein Abnormalities.

Other proteins beside collagen exhibit increasingly abnormal structure in older tissues. The changes are not in the amino acid sequence (not attributable to DNA mutations) but the way the proteins are folded and how other compounds are attached to them. We accumulated more dysfunctional protein as we age.

Autoimmune Theory.

Some of the altered macromolecules described previously may be recognized as foreign antigens and stimulate lymphocytes to mount an immune responses and make antibodies. --Autoimmune diseases such as rheumatoid arthritis do become more common in old age

What are some examples of the genetic component of longevity?

--Unusually long and short lives tend to run in families --Monozygotic (identical) twins are more likely to die at a similar age than dizygotic twins --A genetic defect called "progeria" is characterized by greatly accelerated senescence. Symptoms begin at age 2 and most victims die in early adolescence from advanced atherosclerosis.

In the US, CHILDREN (age __-__) die most commonly from _________ and ______. This is not the case around the world. Instead, children die most commonly from ______,_______, and _______.

1-14; abnormalities and accidents; neonatal deaths, acute respiratory infections, and diarrheal disease.

What two things does aging include?

1. growth, development, and increasing efficiency from childhood --> adulthood 2. degenerative changes -- senescence

How does the senescence of organ systems occur both specifically and generally?

1. organ systems do not degenerate at the same rate (30-80: 10% loss nerve conduction, 60% loss funct. kidney glomeruli) 2. Age of senescence varies (atherosclerosis in infants, no female reproductive change until menopause) 3. Most physiological performance peaks ~30 and declines at rate influenced by level of use

Free Radical Theory.

A free radical is a particle with an odd number of electrons. They are very reactive in the body and have very destructive effects on large molecules. Free radicals are produced by normal metabolic reactions (like white blood cells killing bacteria and just by anaerobic respiration!), by radiation, and by chemicals. Antioxidants are substances that neutralize free radicals. Some of these antioxidants become less abundant with age and damage from free radicals can accumulate.

Telomere Theory.

All chromosomes have a "cap" at each end called a telemere that consists of nucleotides that do not replicate. One of its functions may be to stabilize the chromosome and prevent it from unraveling or sticking to other chromosomes. Every time DNA is replicated, 50-100 bases are lost from the telomere. This may be a factor on the Hayflick limit on the number of times cells can divide

In the US, COLLEGE-AGE young adults die primarily from _______, _________, and ________, accounting for ___% of all young adult deaths. ______ is #1, accounting for ___%

accidents; homicide; suicide; 73.3%; Automobile (MV) accidents; 30%

CLINICAL DEATH was once defined as loss of _________ ________ and __________ (these can now be ______ ________ for ________). Today, clinical death is lack of ________ _________ (i.e._______) aka when ______ brain, including ______ ______ has irreversibly lost all ______.

spontaneous heartbeat and respiration; artificially maintained for years; cerebral activity; brain death; entire; brain stem; function