Download ESDM-chapter2-Cardiovascular system

‫به نام خدا‬
‫‪English for the Students of Disaster Management & Related Subjects‬‬
‫‪By: Dr. Gholamreza Poorheidari‬‬
‫انتشارات‪ :‬هوسسه آهوزش عالي علوي‪-‬كاربردي هالل ايراى‬
‫تابستاى ‪87‬‬
‫فصل دوم‬
‫‪Unit 2‬‬
‫)‪Human Body (2‬‬
‫تهيه كننده ‪ :‬اعظن ضياء بروجني‬
‫شواره دانشجويي‪884700131049 :‬‬
‫دانشجوي هديريت اهداد سوانح‬
‫هعرفي به استاد‬
‫‪1390‬‬
‫‪1‬‬
Part I
Section A: The Circulatory System
The circulatory system is made up of the blood, the heart, and the
blood vessels. Blood is the great delivery system for cells
throughout the body. It carries nutrients and other products from the
digestive tract in its plasma, and oxygen from the lungs in its
hemoglobin. It also transports wastes produced by the cells to the
lungs, kidneys, and other excretory organs for removal from the
body.
Heart
The human circulatory system is a completely closed circuit of tube
like vessels through which blood flows. The heart, by contracting and
relaxing, pumps blood through the vessels. It is a powerful, hollow,
muscular organ about as big as a man's clenched fist, shaped like a
pear, and located in the left center of the chest, behind the sternum
(breast bone). The heart is divided by a wall in the middle. Right and
left compartments are divided into two chambers, atrium above, and
ventricle below. Check valves are located between each atrium and its
corresponding ventricle and at the exit of the major arteries leading
out of each ventricle.
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The opening and shutting of these valves at just the right time in the
heartbeat keeps the blood from backing up.
At each beat, or contraction, the heart pumps blood rich in carbon
dioxide and low in oxygen from the right ventricle to the lungs and
returns oxygen-rich blood to the left atrium of the heart. The left
ventricle pushes blood rich in oxygen freshly obtained to the rest of
the body and returns oxygen-poor blood to the right atrium. At each
relaxation of the heart, blood flows into the left atrium from the lungs
and into the right atrium from the rest of the body.
Answer the following questions orally:
1.What is the circulatory system?
2.How does the blood act in the body?
3.What is the role of the heart in the body?
4.Do you know about the heart compartments?
5.What do the heart valves do?
6.What does happen at each beat?
Section B: Blood Vessels & Blood Pressure
The arteries are elastic, muscular tubes that carry blood away from the
heart. They begin at the heart as two large tubes: the pulmonary
artery, which carries blood to the lungs for the carbon dioxide-oxygen
exchange, and the aorta, which carries blood to all the other parts of
the body. The aorta divides and subdivides until it ends in networks of
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extremely fine vessels smaller than hairs. Through the thin walls of
the capillaries, oxygen and food pass out of the bloodstream into the
stationary cells of the body, while the body cells discharge their waste
products into the bloodstream. In the capillaries of the lungs, carbon
dioxide is released and oxygen is absorbed. Capillaries, having
reached their limit of subdivision, begin to join together again into
veins.
The veins become larger and larger and finally form major trunks that
empty blood returning from the body into the right atrium and blood
from the lungs into the left atrium.
It is impossible to prick normal skin anywhere without puncturing
capillaries. Because the flow of blood through the capillaries is
relatively slow and under little pressure, blood merely oozes from a
punctured capillary and usually has time to clot, promptly plugging
the leak.
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Each time the heart contracts, the surge of blood can be felt as a
pulse at any point where an artery lies close to the surface of the
body, near the skin surface and over a bone. When an artery is cut,
blood spurts out. There is no pulse in a vein because the pulse is lost
by the time the blood has passed through the capillaries. Hence,
blood from a cut vein flows out in a steady stream. It has much less
pressure behind it than blood from a cut artery. Major locations for
feeling pulses include the following:
Carotid: the major artery of the neck, which supplies the head with
blood. Pulsations can be palpated (felt) on either side of the neck (do
not try to feel both at the same time). Use the carotid to check an
unconscious person's pulse.
Femoral: the major artery of the thigh supplying the lower
extremities with blood. Pulsations can be palpated in the groin area
(the crease between the abdomen and thigh).
Radial: the major artery of the lower arm. Pulsations can be palpated
at the palm side of the wrist on the thumb side. Use the radial to
check a conscious person's pulse.
Brachial: an artery of the upper arm. Pulsations can be palpated on
the inside of the arm between the elbow and the armpit. Use the
brachial to determine a pulse in an infant.
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Posterior tibial: located behind the inside ankle knob. Pulsations can
be palpated on the posterior surface of the medial malleolus.
Dorsal is paddies: Pulsations can be palpated on the top surface of
the foot (20% of the population has no pulsations).
Blood pressure
Blood pressure is a measure of the pressure exerted by the blood on
the walls of the flexible arteries. Blood pressure may be high or low
according to the resistance offered by the walls to the passage of
blood. This difference in resistance may be due to several causes. For
example, if blood does not fill the system, as following hemorrhage,
the pressure will be low (hypotension). High blood pressure
(hypertension) may be present when the arterial walls have become
hard and cannot expand readily.
Part II: Exercises
Exercise- 1: Read the following statements and decide whether they
are True or False
1.The heart is about the size of clenched fist and shaped like a pear.
A pulse happens where a vein passes near the skin's surface and over
a bone.
3.Hemorrhage is the term for profuse bleeding.
4.The heart receives its nutrients and oxygen via the coronary veins.
5.The right ventricle pumps blood to the body.
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6.The lungs absorb the oxygen.
7.The arteries are the muscular tubes that carry blood to the heart.
8.The pulmonary artery carries blood to the lungs for the carbon
dioxide oxygen exchange.
9.Hypertension will present if the arterial walls become hard and
cannot expand readily.
Part III: Homework
A. Reading Comprehension: Blood
Blood has liquid and solid portions. The liquid portion is called
plasma. The solid portion, which is transported by the plasma,
includes disk-like red blood cells; slightly larger, irregularly shaped
white blood cells; and an immense number of smaller bodies called
platelets.
Plasma, the liquid part of the blood, is about 90% water, in which
minerals, sugar, and other materials are dissolved. Plasma carries
food materials picked up from the digestive tract and transports them
to the body cells. It also carries waste materials produced by cells to
the kidneys, digestive tract, sweat glands, and lungs for elimination
(excretion) in urine, feces, sweat, and expired breath.
The red blood cells, which give blood its color, carry oxygen to the
organs. The white blood cells are part of the body's defense against
bacteria. These cells can go wherever they are needed in the body to
fight infection, for example, a wound in the skin or other tissue that
is diseased or injured. Pus, a sign of wound infection, gets its
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yellowish-white color from the innumerable white blood cells that
are fighting the invading bacteria.
Platelets are essential for the formation of blood clots. If blood
plasma did not clot at the site of a wound, the slightest cut or
abrasion would produce death from bleeding. Clots plug the
openings through which blood escapes from punctured blood vessels.
Bleeding from a large blood vessel may be too rapid to permit the
formation of a clot. Hemorrhage is the term for profuse bleeding.
Perfusion refers to the circulation of blood through an organ or a
structure. Hypo perfusion is the inadequate circulation of blood
through an organ or a structure. The average-size adult male has
about six quarts (12 pints) of blood.
Inadequate circulation is known as shock (hypo perfusion). Shock is
a state of profound depression of the vital processes of the body,
characterized by the following signs and symptoms: pale, cyanotic
(bluish), cool, clammy skin; rapid pulse; rapid breathing; restlessness,
anxiety, or mental dullness; nausea and vomiting; reduction in total
blood volume; low or decreasing blood pressure; and subnormal
temperature.
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