Notes Circulatory System
Heart Facts
1. The heart is about the size of your fist
2. The heart is located in the left center of the chest, protected by the sternum and
ribs.
3. The heart is made of cardiac muscle
4. It has four chambers that beat in coordination, this is controlled by the pacemaker
5. The chambers are separated by valves
6. The heart has its own separate blood supply from the rest of the body, this is
called coronary circulation.
How the heart works
1. The heart is split into two sides the right and left, divided by a thick wall called
the septum
2. The two sides have different jobs.
a. The right side receives blood from the body that has low levels of oxygen
and pumps it into the lungs
b. The oxygen rich blood from the lungs is pushed into the left side of the
heart and then pumped back into the rest of the body
3. The two sides are split into two sections called chambers.
4. The upper chambers are called the right and left atrium
5. The lower chambers are called the right and left ventricles
6. The heart beats from the top down to the bottom. The atrium beats then; the
ventricles beat, giving the heart the lub dub sound.
7. The valves in the heart keep the blood flowing in one direction only. No back
flow
Types of Circulation
 Circulation is divided in to three areas, coronary, pulmonary, and systemic
circulation.
 Coronary circulation: the heart has its own blood vessels that supply it
with oxygen and nutrients.
Blockage of one or more of these blood vessels can cause a heart attack.
 Pulmonary circulation: the flow of blood from the heart to the lungs and
back is called pulmonary
circulation. The pulmonary arteries are the only arteries in the body to
carry oxygen poor blood from the heart. And the pulmonary veins are the
only veins to carry oxygen rich blood.
Systemic circulation: oxygen rich blood flows from the heart through the
vast network of arteries, capillaries, and veins, delivering oxygen to the
bodies’ cells, systemic circulation completes the trip bring the oxygen poor
blood back to the heart and lungs.
The Path of Blood through the heart
Blood flows from the vena cava into the right atrium; blood is then pumped into
the right ventricle. The blood is pumped from the ventricle to the pulmonary artery into
the lungs. The pulmonary veins take the oxygen rich blood back to the heart into the left
atrium; blood is pumped into the left ventricle and then into the aorta and the rest of the
body.
Blood vessels
1. There are 3 types of blood vessels Arteries, Veins and Capillaries.
2. Arteries: Arteries carry blood away from the heart; they have thick
walls that have muscles around them that squeeze the blood away
from the heart.
3. Arteries have the highest blood pressure of all the blood vessels,
because of this you can feel the beat of your heart through the arteries
this rise and fall of blood pressure is your pulse.
4. The largest artery in your body is the aorta, the inside diameter is
about as big around as your thumb.
5. Veins: Carry blood towards the heart. The walls of veins are not as
thick as arteries and the pressure is not as high. Because of this veins
have valves that keep blood from backing up or not moving.
6. The largest vein in your body is the vena cava. Veins are sandwiched
between the skeletal muscles, when the muscles flex they help move
blood through the veins.
7. Capillaries are the links between the arteries and the veins; these
blood vessels are the smallest of the 3 types.
8. Capillaries are the blood vessels that deliver oxygen, and nutrients to
the cells. The walls of capillaries are thin; the walls are only one cell
thick to allow for the transfer of material back and forth from cells.
For this reason capillaries are easily broken.
Tools to listen to your heart
1. Stethoscope: allows a doctor to listen to your heart and lungs
2. Sphygmomanometer, or blood pressure cuff allows a doctor to
measure the amount of pressure in your arteries
3. Blood Pressure: the upper # is called the systolic pressure it is the
highest pressure in the artery when the ventricle ejects blood from the
heart. The lower # is the diastolic pressure, this is the lowest pressure
in the artery when the ventricle is filling up with blood from the
atrium.
Problems with the heart and veins
1. Heart disease: is the leading cause of death in the US
2. Types of heart disease: Hypertension or high blood pressure,
Arteriosclerosis or the build up of fatty plaque on the walls of arteries
caused by high cholesterol.
Stroke, Heart attack, Aneurysm, blood clots
Stroke, a stroke is an event that happens when the blood supply is cut
off to a section of the brain long enough for the tissues of that section to die.
A stroke can be caused by blockage, such as a blood clot or by plaque
building up on the walls of the blood vessel. Or can be caused by an
aneurysm. Mild or severe brain damage can occur because of this damage,
and it can lead to death.
Heart attack, one of the major causes of death in the US and one of the
leading causes of death in women in recent years is also called a myocardial
infarction
Blood
Functions of blood
1. Blood carries oxygen to the cells of your body from your lungs. It also carries
Carbon dioxide to the lungs to be exhaled or remove from your body.
2. Blood carries waste products from your cells to the kidneys to be removed.
3. Blood carries nutrients to your cells.
4. Cells and molecules in blood fight infections and help heal wounds.
Parts of blood
1. Plasma: the liquid part of blood, it makes up 55% of the volume of blood.
2. Red blood cells: are disk shaped and contain no nuclei. They contain
hemoglobin, a molecule that carries oxygen and carbon dioxide. Hemoglobin is
rich in iron, this mineral is important in binding with oxygen. The more iron in
your blood the more oxygen you can carry. Red blood cells have a life span of
about 120 days. Red blood cells are made in the marrow of long bones like the
femur.
3. Red blood cells make up the majority of the cells in the blood, about five million
red blood cells, in the body at one time, they are always dying and being replaced
4. White blood cells: fight viruses, bacteria, and other foreign invaders of your body.
Your body responds to infection by increasing the number of white blood cells.
White blood cells can live for a few days to many months. White blood cells are
bigger than red blood cells but you don’t have as many of them in your body.
5. Platelets: irregularly shaped cell fragments that help clot blood. Platelets live for
four to nine days. Platelets are responsible for making blood clots.
Clotting
Platelets produce a chemical called fibrin that helps form blood clots, fibrin
releases sticky strands like spider webs that forms a wall of trapped red, and white blood
cells sealing off the break in the blood vessel.
Blood Types
 There are 4 blood types.
 Chemical tags called antigens on the red blood cells
identify the blood types.
 The four types are: A, B, AB, and O
Blood Types
Blood Type
A
B
AB
O
Antigen
A
B
A and B
None
Antibody
Anti-B
Anti-A
None
Anti-A and Anti-B
 A type blood has A antigens on the red blood cells, B
type has B antigens, AB has A and B type antigens,
and O has none. Each type of blood has specific
antibodies that keep different types from mixing; the
antibodies react as though the different type blood is a
foreign invader and try to destroy it. This results in
clumping called agglutination, which can result in
death to the person that it happens to.
 This means only certain blood types can mix, the
following table shows which ones can mix together.
Blood Transfusion Possibilities
Can receive
Type
O, A
A
O, B
B
All
AB
O
O
Can donate to
A, AB
B, AB
AB
All
 O is called the universal donor because every type
of blood can receive transfusions of O type blood.
 AB is called the universal recipient because every
type of blood can donate to an AB type person.
The Rh factor
 Antigens are only one type of chemical marker on the
blood; another marker is the Rh factor. A person is
either positive + or negative – for the Rh factor.
 Any Rh- person receiving blood from an Rh+ person
will produce antibodies against the Rh+ factor. This
can cause agglutination.
 This can happen when a Rh- mother is carrying a Rh+
baby, at the end of the pregnancy the mother passes
antibodies to the baby because of the Rh factor this
could cause agglutination, and possibly killing the
baby.
 Transfusions in the womb or immediately after birth
can correct this problem. Mothers can also receive an
injection that causes them to stop producing Rh
antibodies.