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Circulatory System Notes
Functions:
 Transporting nutrients and oxygen to cells all over the body
 Transporting wastes (urea, carbon dioxide, salt) to excretory organs
 Fighting disease and infections
Vocabulary:
 Pulmonary – means anything dealing with the lungs
 Cardiac – means anything dealing with the heart
Organs:
 Heart – pumps the blood through the body
 Arteries – carry blood away from the heart
 Veins – Carry blood back to the heart
 Capillaries – Tiny blood vessels, where exchange of materials occurs
Heart:
 The human heart has 4 chambers
 2 atria (on top)
 2 ventricles (on bottom)
 There are valves between the chambers, arteries and veins to keep blood in the proper
compartments
 Remember when looking at the heart your left is its right
 Unoxygenated blood flows into the right atrium from the vena cava.
 When the tricuspid valve opens up, the blood enters the right ventricle. The ventricle is
more muscular and is used to pump the blood throughout the body.
 Then the right ventricle squeezes shut it pushed the blood through the pulmonic valve.
 The blood enters the pulmonary arteries which take it to the lungs.
 The red blood cells have iron, which binds to oxygen and the blood releases carbon dioxide
 After the blood exchanges gases in the lungs it returns to the left atrium through the
pulmonary veins.
 When the mitrial valve opens up the oxygenated blood flows from the left atrium into the
left ventricle.
 The left ventricle is the most muscular chamber because it must pump the blood through
the entire body.
 The left ventricle squeezes the blood through the aortic valve into the aorta.
 The aorta takes the blood to other arteries that will carry the blood to all the major organs of
the body.
 The organs take the oxygen and from the blood
 Blood picks up nutrients from the villi in the small intestine.
 The now unoxygenated blood then returns to the right atrium through the vena cava to star
the cycle all over again!
 This cycle happens about once second! Your heart pumps 100,000 times a days and moves
2,000 gallons of blood a day!
Blood:
 Your blood is made up of:
 Red blood cells (erythrocytes) – contain hemoglobin (which makes them red),
hemoglobin allows the blood to bind to oxygen and carry it to cells that need it.
 White blood cells (leukocytes) – fight infection, blood carries them to the sites of
infection to kill germs in the body.
 Platelets – This allows the blood to clot, when the blood is exposed to air platelets
group together and mix with fibrogen to form a scab
 Plasma – fluid that composes that makes up the blood, mostly water (90%), but also
contains salts and minerals.
 Each blood cells has certain antigens attached to it, which allows the body to recognize it
 There are four different blood types:
 A – has A-antigens, and B-antibodies (so if type B blood is introduced into the body it
will be destroyed)
 B – has B-antigens, and A-antibodies
 AB – has A and B antigens, and no antibodies (universal recipient)
 O – has no antigens, and A and B antibodies (universal donor)
Blood
Type
A
Antigens
Antibodies
B
AB
O
Your blood will also have a Rh factor, making it negative or positive.
If you are Rh positive, you have D-antigens on the surface of your red blood cells.
If you are Rh negative you do not have these antigens.
This may become a problem during pregnancy because the baby shares blood with the
mother, but the mother can be Rh negative and baby Rh positive.
 Both the ABO system and Rh factors need to be taken into account when finding a donor.
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Sino-Atrial Node:
 In your heart you have a group of cells in your right atrium, which controls your heart beat.
 You have many pacemaker cells, but only one will be active at one time.
 These cells send an electric charge through the cells of the heart causing it to beat.
 These are independent from the brain.