Download CIRCULATORY SYSTEM

CIRCULATORY SYSTEM NOTES
“I’d be tender, I’d be gentle
and awful sentimental
regarding love and art,
I’d be friends with the sparrows
and the boy who shoots the arrows,
if I only had a heart.”
~ The Tin Man from “The Wizard of Oz”
The circulatory system is also known as the CARDIOVASCULAR system.
The circulatory system has FOUR major functions:
1.
2.
3.
4.
OXYGEN AND CARBON DIOXIDE TRANSPORTATION
NUTRIENT AND WASTE TRANSPORTATION
HORMONE CIRCULATION
TEMPERATURE MAINTENANCE
Circulation from the heart to the LUNGS and back is called PULMONARY circulation.
Circulation from the heart to the REST OF THE BODY and back is called SYSTEMIC circulation.
The circulatory system consists of THREE parts:
1. THE HEART
2. BLOOD
3. BLOOD VESSELS
a. ARTERIES
b. ARTERIOLES
c. CAPILLARIES
d. VEINULES
e. VEINS
(5 TYPES)
~ carry blood AWAY from the heart
~ smaller arteries
~ “capillus” is Latin for “HAIR”
~ tiny tubes (about 8 micrometers ** in diameter)
~ exchange of oxygen, carbon dioxide, nutrients, etc.
through the process of DIFFUSION
between blood and cells occurs through capillaries
** 1 micrometer = .000001 meters  1/25,000 of an inch
~ smaller veins
~ carry blood TOWARDS the heart
~ contain one-way valves to permit blood to flow in only
one direction
COOL FACT: The network of blood vessels in the average adult human measures over 60,000
miles! If unraveled, it could wrap around the Earth’s equator over two times!
BRAIN POWER: An empty artery is a hollow tube (like a pipe). An empty vein, however, will
collapse (like an empty balloon). This is because the walls of veins are thinner and weaker than
the walls of arteries. Why would the walls of arteries need to be thicker and stronger?
BLOOD FLOWS IN ARTERIES AT 16 INCHES PER SECOND
BLOOD FLOWS IN VEINS AT .02 INCHES PER SECOND
ARTERIAL WALLS NEED TO WITHSTAND MORE PRESSURE THAN VEINS.
The largest ARTERY in the body is the AORTA, which carries blood away from the heart to the
rest of the body (except for the lungs).
The two largest VEINS in the body are the superior and inferior VENA CAVA,
Which carry blood toward the heart from the rest of the body (except for the lungs).
The Heart:
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The word “cardio” is Greek for “HEART”
The human heart (as with other mammals and birds) consists of 4 chambers
COOL FACT: The only animals with a 4-chambered heart, other than mammals and birds are
the crocodilians.
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There are two ATRIA, or upper chambers.
There are two VENTRICLES, or lower chambers.
The right and left side of the heart are separated by the SEPTUM.
The heart is contained in a sac-like membrane called the PERICARDIUM,
which secretes a fluid to lubricate the heart.
The Heartbeat:
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The heartbeat is regulated by electrical signals from the sinoatrial node (a.k.a.
Pacemaker), located in the upper RIGHT ATRIUM.
The two atria contract almost simultaneously (at the same time).
The two ventricles contract almost simultaneously (at the same time).
A heart beat consists of two sounds:
1. low-pitched “LUB” (closing tricuspid and mitral valves)
2. high-pitched “DUB” (closing of the pulmonary and aortic valves)