Skin accounts for about 7% of total body weight.
We get a new layer of epidermis (top layer of skin) every 25-45 days).
Freckles are local accumulations of melanin.
Sweat has a pH between 4 and 6.
Sweat is 99% water, with sodium chloride, vitamin C, dermicidin (antibody), urea, uric acid, ammonia and lactic acid.
Hair (pili) averages 2.5mm growth per week. We lose an avg. of 90 scalp hairs per day. The follicles of the scalp remain active for six to ten years before becoming inactive for a few months.
Under normal conditions, as long as the environmental temperature is between 88-90 F. sweat glands continuously secrete unnoticeable amounts of sweat (about 500ml/day.
Dermal vascular supply of blood is about 5% of the body's total blood volume.
The skin can develop more than 1000 different conditions.
Burned skin is sterile for about 24hrs. (This is why replacing lost fluids is most important initially, followed by concern for infection).
Healthy bone is half as strong as steel in resisting compression and fully as strong as steel in resisting tension.
Most bones stop growing during adolescence; however, some facial bones, such as those of the nose and lower jaw, continue to grow almost imperceptibly throughout life.
Every week we recycle 5 to 7% of our bone mass, and as much as half a gram of calcium may enter or leave the adult skeleton each day. Spongy bone is replaced every 3 - 4 yrs, compact bone every 10 years. The distal part of the femur (thigh bone) is fully replaced every 5-6 months).
The human body contains 1200-1400g of calcium. (less than 1.5g in blood) Blood calcium is kept between 9-11mg /100ml of blood.
The skull contains 22 bones.
Rigor mortis: most muscles begin to stiffen 3-4hrs after death. Peak rigidity occurs at 12hrs and then gradually dissipates over the next 48-60hrs.
Only about 40% of the energy released during muscle contraction is converted to useful work. (the rest is given off as heat)
Disuse atrophy can cause muscle strength to decrease at a rate of 5% per day. When totally deprived of neural stimulation, a paralyzed muscle may atrophy to one-quarter its initial size.
Smooth muscle takes 30 times longer to contract and relax than doe skeletal muscle and can maintain the same contractile tension for prolonged periods at less than 1% of the energy cost.
For postural reflexes nerve fibers can transmit impulses at 100m/s.
The avg. adult man’s brain is 1600g (3.5lbs); that of a woman averages 1450g. In terms of brain mass per body mass, males and females have equivalent brain sizes. Cerebral hemispheres account for 83% of total brain mass.
Norepinephrine, a neurotransmitter involved in memory processing of emotionally charged events, is released when we are excited or “stressed out,” which helps to explain this phenomenon.
Blood is slightly alkaline, with a pH between 7.35 and 5.45, and its temperature (100.4 F) is always slightly higher than body temperature.
Blood accounts for approximately 8% of bodyweight. Avg. volume in males 5-6L (1.5 gallons). Females: 4-5L.
By injecting EPO, healthy athletes increase their normal RBC volume from 45% to as much as 65%.
RBC counts of 6-8 million per cubic millimeter are common in people living in high altitudes.
65% of the body’s iron supply (about 4000mg) is in hemoglobin. The avg. daily loss of iron is 1.7mg in women and 0.9mg in men.
List leukocytes in order from most abundant to least abundant. (Never Let Monkeys Eat Bananas) neutrophils, lymphocytes, monocytes, eosinophils, basophils). The lifespan of granulocytes is 0.5 – 9 days.
Lossoes of 15-30% of blood cause weakness. Loss of more than 30% of blood volume results in severe shock and possibly death.
The shleft life of collected blood @ 4 C is about 35 days.
Hemophilia A (deficient in factor 8) accounts for 83% of the cases of hemophilia.
The avg. heart has a mass of 250-350g (less than a pound)
Bradycardia: <60bpm. Tachycardia: >100bpm.
The blood vessels in the adult human stretch for about 100,000km (60,000 miles).Blood pressure cycles over a 24hr. period, peaking in the morning in response to waxing and waning levels of retinoic acid in blood.
When the body is at rest, the brain receives about 13% of the total blood flow, the heart 4%, kidneys 20%, and abdominal organs 24%. Skeletal muscles normally receive about 20% of total blood flow.
Blood flow to the brain averages 750ml/min.
About 3L of lymph enters the bloodstream every 24hrs.
In children younger than 12 the spleen will regenerate if a small part of it is let in the body.
AIDS is now the fifth leading killer of all Americans ages 25 – 44.
Lung cancer accounts for 1/3 of cancer deaths in the U.S. more than 90% of lung cancer patients were smokers. Most victims die with in one year of diagnosis, overall five-year survival of those with lung cancer is about 7%
Marieb, Elaine. Anatomy & Physiology. San Francisco: Pearson/Benjamin Cummings, 2005.
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