Human Physiology
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Journal 2001 |
By:
Amy D & Kari P
The most amazing systems in the body are the car- diac and circulatory systems.
A body can remain alive with no brain activity as long as oxygenated blood
is being car- ried throughout the body transferring the essential nutrients
of life to all of the vital organs. The systems have many func- tions such
as the delivery of nutrients of oxygen, the delivery of waste to the excretory
system, regulation of the body's pH,
The heart is a pump. It is comprised of almost all muscle, being the only place in the body containing cardiac muscle, an involuntary muscle. All other hollow organs that are involuntary contain smooth, rather than cardiac, muscle. There are four chambers in the heart: 2 atria and 2 ventricles. The atria are responsible for receiving blood. They pump deoxygenated blood into the ventricles. The ventricles hold the real power in blood pumping, they must force blood away from the heart with enough force to make the blood make a complete circuit of the entire circulatory system and back to the heart between heartbeats. Separating these chambers are valves. They are located between the atria and ventricles to allow blood flow in only one direction.
Muscle fibers in the heart are self-excitatory, which means that they don't need stimulus from the brain in order to contract. The walls of the heart are made up of muscle called myocardium, which must have oxygen-rich blood at all times to survive. The four valves determine in which way the blood flows, how much of it goes in and out of each section of the heart, and when the blood stops going into each section of , the heart. The tricuspid valve is called so because it has 3 cusps, which allow blood flow into the right ventricle when the heart is relaxed. The mitral valve controls the blood flow between the left atrium and the left ventricle. The pulmonic valve controls blood flow between the right ventricle and the pulmonary artery, which supplies the lungs with blood. The aortic valve separates the left ventricle from the aorta, allow- ing blood flow to the body when the heart contracts. These valves, working in unison with the heart's contractions, en- sure that blood gets to the cells in the body, and control the blood to make sure it doesn't go elsewhere.
The circulatory system, at first glance, seems very uncomplicated. However, it is just the opposite. It is the road system of the human body: it is responsible for supplying all the cells in the body with oxygenated blood. This is not all it does, though. In addition to supplying blood, the circulatory system acts !IS a transport system. Waste in every cell in the body is pushed through the protective membranes and picked up by the blood. As waste is removed, nutrients and other things needed by the cell diffuse into the cells. The trash from the cells, now in the blood, is filtered out when the blood passes through one of the 2 million nephrons (the filtering system of the kidneys) and is excreted in urine.
The circulatory system is comprised of arteries and arterioles, which carry oxygenated blood away from the heart and to the many parts of the body and Veins and capillaries, which carry the deoxygenated blood back to the heart to be- gin the cycle again. The arteries directly linked to the heart are the coronary arteries, which supply blood to the heart. There are branches off of the coronary arteries. There is a left main coronary artery, which breaks into two, and runs in front of the heart. The two branches are the left circumflex artery and the left anterior descending artery. There is also an artery called the right coronary artery, which supplies the back and the bottom of the walls of the heart with blood.
Blood is pumped out to the body through the aorta, which then transfers blood into arteries. Because of the force used to push the blood out of the aorta, arteries are under a great deal of pressure, which explains why they are buried deep within the body, to protect them from injury (in the event an artery is punctured, the force from the pumping heart causes rapid blood loss). The arterial walls are extremely elastic, so that the amount fblood needed for one place cannot hurt or ruin the arteries. Arteries keep dividing and dividing, until they are so small that they are called capillaries. Capillaries are one or two cells thick. They deliver oxygenated blood to every part of the body. "In a section of body tissue no bigger than the head of a pin, there are between one and tWo thou- sand capillaries." (Rippe, p. 22)
Veins are responsible
for bringing all of the deoxy- genated blood and waste into a large vein into
the middle of the body called the inferior vena cava, moving into the supe-
rior vena cava, which then return to the right atrium, into the right ventricle
to be pumped back into the lungs for oxygen.
By: Lisa S &
Ruchita P
Men's health issues
are often ignored. When a per- son looks at a health magazine they are usually
dominated by issues concerning women. Men often do not see a doctor as much
as they should, and could have more problems with their body than they realize.
This paper will explore two health issues concerning men. One ofthemis heart
diseases, which are experienced more by men than by women. The other issue
this paper will discuss is various prostate prob- lems. Since the prostate
is an organ only men have these problems are non-existent in females and are
often ignored by men.
There are many diseases related to the heart. One of the most common of these
is coronary artery disease, which is a kind of heart disease. There are two
coronary arteries in the heart, the right coronary artery and the left coronary
ar- tery. The right coronary artery supplies blood to the right side of the
heart and the back side of the heart. The left coronary artery divides into
two branches, the Circumflex Artery, and the Left Anterior Descending Artery.
They carry blood to the septum and the left side of the heart.
These arteries are usually flexible and smooth. But some- times these arteries
can become clogged with fatty deposits called plaque. This can reduce blood
flow into the heart
muscle. When the arteries are only partially blocked, this can cause angina
(chest pain).
Another cause is age. The olde. a person is, the more likely they will get coronary artery disease. As a per- son passes the age of 65, the likelihood that they will have coronary artery disease increases. Also, men have coronary artery disease more frequently. They will generally develop the disease about ten years earlier than their female counter- parts. But, when women reach menopause they develop coro- nary artery disease just as often as men.
Another factor that is controllable is high blood pres- sure, often called
hypertension. Coronary artery disease is three to five times more common in
people who have hyper- tension. If a person gets a blood pressure reading
of more than 140/90 they are considered to have high blood pressure. About
thirty-five million Americans suffer from hyperten- sion. (bodyworks 6.0,
CD ROM) High blood pressure over- works the heart and can eventually make
the arteries become stiff and brittle.
Diabetes is another element that can cause coronary artery disease. When your
body can't bum enough sugar it results in a high level of plaque-forming triglycerides.
In diabetes the body doesn't produce insulin (which is a hor- mone that bums
sugar), so the rate of heart attacks among diabetics is at least three times
greater than non diabetics. (bodyworks 6.0, CD ROM)
Another type of heart problem is rhythm abnonnali- ties. Rhythm abnormalities account for about one half of all deaths by heart attack. Types of rhythm abnormalities are Ventricular fibrillation, tachycardia, and bradycardia. Ven- tricular fibrillation, also reterred to as cardiac arrest, is the most serious of these. When a person has this abnormality "the cells fire chaotically across the heart and the heart loses all power to pump blood"(Bodyworks 6.0, CD ROM). If a person has tachycardia their heart-beat is abnormally fast, and if a person has bradycardia their heart-beat is abnormally slow.
Another type of heart problem is valve problems. Rheumatic fever is 9ne of
the diseases that can damage the heart valves. Rheumatic fever is caused by
a reaction of a person's body to specific strains of the streptococcal bacte-
ria. The person will most likely recognize the symptoms of rheumatic fever
after two to four weeks of having "strep throat" infection.. This
fever mostly occurs in young people age 5 to 15.
Mitral Stenosis can also damage the heart valves and also cause scarring.
The cause of having this disease is Rheumatic Fever.
One of the treatments for heart problems is Coro- nary artery bypass grafting.
The principle of this surgery is to create a detour for the blood to go around.
This surgical process was first done by Rene Favaloro, an Argentinean surgeon
working in the United States in 1969. Thirty-thou- sand operations on the
coronary artery bypass grafting are performed every year in the United States.
"Bypass Opera- tion is appropriate in people who have a blocked left
main coronary artery, those with disease in many vessels and poor function
of the left ventricle, and individuals with debilitat- ing angina. For these
people, a bypass operation can en- hance or prolong their life."(Mayo
Clinic Heart Book, page- 322).
The other treatment for heart disease is valve re- placement. This treatment
works especially for heart valve disease. Charles Hufnagel performed the first
artificial valve replacement in 1952. He didn't succeed. But Albert Star,
a surgeon from Oregon, and Lowell Edwards, an engineer, developed a valve
in 1950 and used it successfully in 1960. This is the favored treatment for
aortic valve disease that needs treatment beyond medication.
There are many tYPes of prostate problems that men can have. One problem is
prostatitis. Some estimates say that up to twenty-five percent of visits to
doctors by men for urinary or genital problems are related to prostatitis..
Pros- tatitis is the inflammation of the prostate gland, and can be caused
by several factors. One factor is acute bacterial in- fection. Although this
is the most severe form of prostatitis it is the least common. It is generally
caused by bacteria in the urinary tract or large intestine. Symptoms for this
dis- ease are fever, chills, a general flu-like feeling, pain in the lower
back and genital area, pain or a burning sensation when urinating, decreased
urine flow, inability to empty bladder during urination, a frequent and sometimes
urgent need to urinate, blood in urine, and painful ejaculation. It can also
lead to serious problems such as inability to urinate and in- fection in the
bloodstream(bacteremia).
Another cause for prostatitis is chronic bacterial infection. This is less
severe than acute bacterial infection and the symptoms tend to develop more
slowly. The symp- toms are similar, tho"ugh with. chronic bacterial infection
it is also possible to have a pain or burning sensation when uri- nating,
nocturia (excessive night-time urination), pain in the lower back and genital
area, occasional blood in semen, and recurring bladder infection. The causes
are similar to those of acute bacterial infection. Other possible causes may
in- clude a bladder or blood infection. This may result from the insertion
of an instrument such as a catheter into the urethra. The infection, wherever
it may come from, is difficult to get rid of because antibiotics have a hard
time penetrating pros- tate tissues.
Another cause for prostatitis is chronic nonbacte- rial. This is the most
common tYPe of prostatitis. It is also the most difficult to diagnose and
to treat. Many doctors try to treat the symptoms rather then to try to cure
the disease. The symptoms are similar to that of chronic bacterial pros- tatitis.
The cause of this tYPe of prostatitis is unknown. Pos- sible causes are sexual
activity (or lack of), infectious agents, anxiety or stress, stop and start
urination, heavy lifting, ex- posure to a large amount of vibration, bicycling,
or jogging. Chronic non bacterial prostatitis can be confused with a con-
dition caused by prostatodynia. The symptoms are similar but the problem is
not with the prostate gland, but for the pelvic floor muscles. This can be
caused by stress, because when a person is under stress they may not relax
the muscles supporting the bladder and urethra. This can cause difficul- ties
when urinating. Also, many people who are marathon runners,bicyclists, triathletes,
weight lifters, and truck driv- ers have this condition.
BPH(Benign Prostatic Hypertrophy} is a enlarge- ment of a certain part of
the prostate. The prostate gland is a region of smooth muscle. Within this
muscle there are a se- ries of glandular chambers known as periurethral gland.
These glands and their drainage ducts make up transition zone of the prostate,
which is the area whereBPH originates. The growth of transitional zone compresses
the wall of the ure- thra inward. This squeezing effect ofBPH often reduces
the urine flow. There are different shapes of BPH. In lateral lobe enlargement,
the BPH press in from either side of ure- thra. When BPH grows more in the
middle of the urethra and protrudes upward into the bladder, it is called
median lobe hypertrophy. When they both occur together, it called trilobar
hypertrophy.
Another type of prostate problem is prostate can- cer. Cancer is a group of
abnonnal cells that grow more rapidly than nonnal cells and refuse to die.
Prostate cancer usually grows slow and remains in the prostate, but some forms
are aggressive. The causes of prostate cancer is un- known. Some possible
causes are genetic predisposition, ethnicity, hormones, diet, and environment.
In 1999, 179,300 men were diagnosed with prostate cancer, and 37,000 died.
In comparison 17,500 women were diagnosed with breast cancer and 43,300 died.
Though more men have prostate cancer than women have breast cancer less die
from it than women die from breast cancer.
As is apparent men have a lot of possible problems they may not know about.
Many of the problems discussed in this paper can be cured if they are detected
in their early stages. Unfortunately, many men do not see a doctor as of-
ten as they should and so these problems are not detected early. The only
way this can change is ifmen are educated. Only then may the era of men ignoring
their health problems end.
"Cloning Humans: It's going to happen"
By: Shwetha A
Ever since scientists and doctors cloned Dolly, the sheep, everyone is asking, "What do you think of cloning?" Chet Raymo, a professor in science, thinks a cloned sheep or two will not perplex even the most morally fastidious mind, but the prospect of cloned humans is enough to set alarm bells ringing. He believes that what can be done to sheep can be done to humans.
The technique for cloning involves taking the nucleus from a cell of the individual to be cloned and placing it in an egg cell from which the nucleus has been re- moved. The nucleus holds the genetic information that tells the egg how to develop into an adult Organism. The egg is then implanted into any uterus and allowed to grow.
Dolly was not the first animal cloned; with this method. But only very young embryos were cloned. In Dolly's, the genetic information was taken from a mammary cell of a SIX year old adult sheep. The cloned individual was more than just a microscopic cluster of similar cells. The cloning of Dolly was an unproven technology; it might be years before it could be applied to humans with a reasonable chance of success. Still we can expect rapid progress in the techniques of cloning mammals. 1 Fann animals and racehorses are commercial candidates for cloning, although an anonymous millionaire has agreed to 1 pay $2.3 million to scientists for a duplicate or his dog, Missy.
Still the big question
is "Will human cloning follow?" A physicist Richard Seed has announced
that he wants 4
to clone himself, with his wife bearing the resulting embryo.
All the process needs is expertise and money. If he raises the money, there
will certainly be expertise to help him.
There are also benefits out of cloning. For example, helping infertile couples have a child, producing a child whom could donate bone marrow to a dying person, replacing a dead child.
Michigan and California have passed laws banning human cloning, and Congress may do the same for the nation. But human-cloning entrepreneurs will find limits some- where in the world that tolerates their activities.
There arc many people supporting both sides of cloning. Such as ethicist Leon Kass has said that a society that permits cloning "has forgotten how to shudder." "Trust our gut instincts," he says. There also people who are okay with the idea of cloning. For example, philosopher David Papineau wonders if gut feelings of alienation are reliable enough to ethical behavior. In the New York Times Book Review, he writes "If it had been left to gut reactions, interracial marriage would probably still be banned, and slavery still be allowed."
It is important
to say that nature even produces human clones in cases, such as twins. And
nobody despises that. Even though somebody could probably clone our look,
traits, and other genetics, they could never clone our experiences, hopes,
and dreams
By: Louis M
Global Warming
-The gradual increase of the temperature of the earth s lower atmosphere
as a result of the increase in greenhouse gases since the Industrial Revolution.
The temperature
of the atmosphere near the earth's surface is warmed through a process called
the greenhouse effect. Short wave light comes from the sun to the earth, passing
through a thermal or greenhouse gas composed of water vapor, carbon dioxide,
methane, nitrous oxide, and ozone. Radiation reflects off the planet's surface
toward space but does not pass through the thermal blanket. Some of it is
trapped and reflected downward the planet, keeping the planet at a temperature:
that can sustain life, 60 - 65 degrees. .
At around the turn
of the century the US and many other countries started: major industrial cities,
these cities started to produce major amounts of pollution, which over many
years started to eat away at the ozone layer thus off setting the balance
of the planets temperature.