CARDIOVASCULAR SYSTEM
THORACIC CAVITY
The lungs and heart are located in the thoracic cavity.
THE HEART
The heart is the simplest organ in the body. It does only one thing: pumps blood. It beats
42 million times a year. It’s about the size of your clenched fist. (Show life-size model
of heart). Some of you have big fists, some have smaller fists. Its location is deep to the
sternum. Take your fist and place it on the sternum, then angle the bottom of your wrist
to the left. When you say the Pledge of Allegiance, your hand is not over your heart. It’s
not on the left, it’s in the center.
HEART BEATS
The pressure of blood against blood vessel walls is called blood pressure.
Blood pressure is recorded systole over diastole. Normal resting blood pressure is said
to be 120/80.
When blood pressure is too high, it is called HYPERTENSION.
The sound your heart makes when it is beating is the sound of the valves closing.
The heart normally beats at a rate of 60-80 beats per minute. A faster or slower heart
rate is an indication of a problem.
ARRHYTHMIA = improper heart beat; needs medicines or a pacemaker.
FIBRILLATION is when the heart beat is rapid and dangerously uncoordinated,
and doesn’t contract rhythmically and just quivers without pumping blood. It needs an
electric shock from a defibrillator. This machine is never used when someone’s heart is
beating, even irregularly, because it can cause the heart to stop. Whatever caused the
fibrillation in the first place is not treated, so it may not work, but it’s worth a try! Most
large public facilities have them. There are three on this campus. Disneyland has one
every 100 yards.
THE HEART NEEDS ITS OWN BLOOD/O2
The blood vessels for the actual muscle that makes up the heart comes from vessels that
are on the outside of the heart = CORONARY ARTERIES.
The more you exercise, the more branches of these arteries are formed, and the better the
blood supply to the heart. Blockage in the coronary arteries is called a heart attack.
For a narrow artery, you can do a CORONARY BYPASS. Take another blood vessel
graft (from thigh) and go around the blockage. For double or triple bypasses, that’s how
many vessels are affected.
HEART ATTACK
Severe pain from lack of blood to the heart is called ANGINA.
If there is complete blockage  not enough O2 to that area  that part of heart muscle
dies = MYOCARDIAL INFARCTION= HEART ATTACK. Heart muscle never
regenerates. If a large area dies, person will die.
What are symptoms of a heart attack? Besides chest pain or pressure, symptoms can
include pain down left arm, shortness of breath, nausea, feeling of indigestion or
heartburn, even pain in the jaw that is mistaken for a toothache. A common symptom is
death. 50% of first heart attacks are fatal. About ¾ million people die each year from
heart attacks.
Reasons for blockage
ATHEROSCLEROSIS = build-up of fat inside artery (called a PLAQUE) 
narrowing of artery  blood clot. If clot is big, it can break off and go to the lungs.
When a clot lodges in an artery, all the tissue beyond that point gets deprived of oxygen
and dies.
BLOOD VESSELS
There are 100,000 miles of blood vessels.
With the exception of cartilage (which does not have a blood supply, no cell in the body
is more than a few cell diameters away from a blood vessel, so they can get oxygen,
nutrients, remove waste.
Arteries get smaller and thinner and are then called arterioles.
Arterioles get smaller and thinner until they are just one cell thick. At this point, they are
called capillaries, and this is where the oxygen exchange takes place. Capillaries then get
larger as they take waste products away from the cells in the capillary bed and head back
to the heart; now they are called venules. As venules get bigger, they are called veins
until they return to the heart. From the heart the blood is pumped to the lungs to get more
oxygen. During this trip, they get smaller again until they are capillaries, then they get the
oxygen from the lungs and drop off the waste products (carbon dioxide). Then the blood
returns to the heart to get pumped out to the body again.
CAPILLARIES are the only sites of nutrient, gas exchange, and waste exchange in the
cardiovascular system.
Veins are the only blood vessels that have valves. Allows blood to move in only one
direction. What pushes the blood? The muscle of the body constrict, squeezes the
vessels.
LYMPHATIC VESSELS
You have a whole network of arteries. You have a whole network of veins. You have a
whole network of lymph vessels. Lymph vessels look like veins and also have valves.
The lymph system retrieves excess tissue fluid (plasma that leaks out of the blood
vessels) and filters it and cleans it and returns it to the blood. This plasma is now
called lymphatic fluid. It is sent through the lymph nodes through out the body. There are
hundreds of lymph nodes in the body, occurring in clusters. Each lymph node filters the
lymph fluid to get rid of bacteria and viruses, and returns the fluid back into the blood.
There are large clusters of lymph nodes in the armpit, neck, and groin regions.
The lymph that filters the breast area will drain into the nodes in the armpit, so that is
where cancer would spread first. It is detected by lymph node biopsy. If cancer is found,
the surgeon will have to remove all the lymph nodes from the armpit, and afterwards,
there is no lymph drainage for that arm, and there will be problems with swelling.
GIANT LYMPH NODES
The SPLEEN not only destroys old red blood cells, it is also a giant lymph node.
TONSILS are also lymph nodes, but they can be removed if they are chronically
infected.
CIRCULATORY DISEASE CONDITIONS
The leading cause of untimely death in the Western countries of the world is
cardiovascular disease.
There are several hereditary factors that influence whether a person will get
cardiovascular disease:
1. family history of heart attack
2. gender (males are high risk)
3. race/ethnicity (African Americans high risk)
Whether or not you have a hereditary factor, there are some things you can do to prevent
heart disease with diet and exercise. Included in this is knowing your cholesterol level,
lowering your LDL intake, use olive and canola oil rather than butter/cream.
Some studies also suggest that antioxidant vitamins (A, E, and C) may help, but
remember that too much vitamin A and E cause a lot more harm to the liver than good to
the circulation.
1. ATHEROSCLEROSIS is fat and cholesterol deposits underneath the lining of
arteries.
When it builds up in a lump in one place, it is called a PLAQUE. It causes the lumen to
narrow, restricting blood flow. If this plaque breaks off and travels in the bloodstream, it
is now called an EMBOLISM.
In a coronary artery, it will cause ANGINA (heart pain). If a platelet catches on a piece
of this fat, it can start a blood clot. If a piece of the clot breaks off and enters the
circulation, it can lodge in a smaller blood vessel and block the oxygen to all the tissue
past that point, and the tissue dies.
If this occurs in the coronary arteries  myocardial infarct (Heart attack).
If it occurs in an artery in the brain  stroke
2. ARTERIOSCLEROSIS is known as “hardening of the arteries”. It is caused by
calcium deposits in the artery walls. The blood vessel becomes hard like a rock; it can’t
expand or contract, causes increase in blood pressure. Diet and exercise don’t help this
much. Both arteriosclerosis and atherosclerosis cause high blood pressure.
3. HYPERTENSION (High Blood Pressure)
High blood pressure is due to high pressure of blood against the walls of the blood vessels;
the blood vessels compensate by developing a thicker wall. The vessels can no longer
expand during systole, so the vessel gets thicker and thicker, and the blood pressure goes up
more. If the blood pressure gets too high, an ANEURYSM can form, which is a weakening
in the wall of the blood vessel, causing it to expand like a balloon. If it ruptures, it’s very
dangerous. The aorta is the first artery that leaves the heart. It is under high pressure, so it is
susceptible to rupture; you’ll be dead in three heart beats. Can also get aneurysms in the
brain that cause stroke. Aneurysms have no symptoms.
VARICOSE VEINS
An inflammation of the veins, usually due to lack of movement. One treatment of
superficial varicose veins is stripping (removing) the vein. Not a problem because there
are so many. In the rectum, a varicose vein is called a HEMORRHOID.
ARTIFICIAL HEART