The Circulatory System
Bringing It All Together
• The role of the circulatory system is basically
to connect all of the other systems through
transport.
• Our bodies are made of a number of
specialized parts that all contribute
something to the whole organism (you). It is
essential to your health that the benefits of
each body part are shared with the other
parts and this is where the circulatory
system comes into play.
• Through the circulation of blood, items from
various parts of the body are shared with all
of the other body parts. The blood carries a
number substances in it that were put there
by various body parts and delivers them
throughout.
Parts of a Circulation System
• Any system of circulation has
three essential components:
1. Pump – The heart is the pump that
provides the force to move the
blood.
2. Fluid – The blood is the fluid that is
circulated throughout the body.
3. Vessels – Your blood vessels act as
the pipes or channels through
which the blood is moved within the
body.
Components of Blood
•
Your blood has four main components:
1. Red Blood Cells (Erythrocytes) – They carry
oxygen from the lungs to the cells of the
body. A protein called hemoglobin allows
them carry O2. Iron is a key part to the
structure of hemoglobin.
2. White Blood Cells (Leukocytes) – They are
in charge of immune response and protect
you from foreign invaders called pathogens.
3. Platelets – These are cell fragments that
respond to damaged blood vessels and heal
them through blood clotting.
4. Plasma – The fluid part of blood. It carries
dissolved substances and allows the blood
to be moved. Plasma is 55% of your blood
and the plasma itself is 90% water.
Components of Blood
Circulation Circuits?...
•
•
Isn’t that like saying, “Allow myself to
introduce…myself.”
Your blood circulates through three
different circuits or loops – each with its
own job.
1.
2.
3.
Pulmonary Circuit – Blood flow from the heart to
the lungs and back to the heart. Oxygen must be
loaded into the blood and sent back out to the
body.
Systemic Circuit – Blood flow from the heart to
the cells of the body and back to the heart.
Oxygen in the blood gets used up and sent back to
the heart for more oxygen.
Coronary Circuit – Blood flow from the heart to the
muscle of the heart and back. The heart works
very hard so it has coronary arteries that feed it
blood full of nutrients and oxygen.
Circulation Circuits
The Heart
• The heart is the major organ of the
circulatory system. It is a muscular
organ about the size of your fist that
works continuously to pump the blood
throughout the body.
• The heart has several layers of muscle
tissue in its make up:
– Myocardium – The think muscular walls of
the heart.
– Endocardium – Tissue lining the inside of
the heart.
– Pericardium – The outer lining of the heart.
Chambers of the Heart
• We have a four-chambered heart. A
chamber is a hollow compartment in the
heart.
• The chambers of the human heart are
named according to their position within
the heart. The upper chambers are called
atria (atrium for singular) while the lower
chambers are the ventricles. We have two
atria and two ventricles in our heart. We
divide the pairs based on what side of the
heart they are on – left or right.
• This means we have a right atrium and
right ventricle and a left atrium and left
ventricle.
The Heart
Blood Flow Through the Heart
•
1.
2.
3.
4.
5.
6.
7.
We will start with deoxygenated blood coming back to
the heart through the vena cavas.
Blood enters the heart at the right atrium.
Blood goes through tricuspid valve into right ventricle.
Blood is squeezed up through pulmonary valve into the
pulmonary arteries.
Blood goes through pulmonary arteries to the lungs,
picks up O2, and back to the heart via the pulmonary
veins.
The oxygenated blood enters the heart through the left
atrium and is squeezed down through the bicuspid
valve down into the left ventricle.
The left ventricle squeezes blood up through the aortic
valve and into the aorta and out to the rest of the body
cells.
It gets used up and comes back to the heart through
the vena cavas.
Blood Flow
Bump-Bump…Bump-Bump…
• The heart is controlled by the medulla oblongata
– same part that looks after your breathing.
• The brain sends impulses down to the
pacemaker, called the sinoatrial node (SA
Node). It is located in the upper wall of the right
atrium and it receives the impulses and causes
the atria of the heart to contract. (First Bump!)
• Right after the SA node fires, the atrioventricular
node (AV node) receives the impulse and it
causes both ventricles to contract. (Second
Bump!)
• The heart then takes a brief rest and then the
cycle repeats itself.
• Bump-Bump…Bump-Bump…Bump-Bump…
Blood Pressure
• Blood pressure is the amount of force placed on the
walls of the blood vessels as your blood is forced
through them.
• Think of a garden hose…The more water you force
through it, the harder the hose gets because there’s
more pressure on the inner wall of the hose.
• Your blood pressure consists of two numbers (for
two pressures):
– Systolic pressure – The pressure placed on the
vessels when the heart contracts. (High #)
– Diastolic pressure – The pressure exerted on the
walls of the vessels when the heart is at rest.
(Lower #)
• A sphygmomanometer is the inflatable cuff thing
used to measure blood pressure.
Blood Vessels
• Arteries – Carry blood
away from the heart.
• Arterioles – Smaller
arteries.
• Veins – Carry blood
back to the heart.
• Venules – Smaller
veins.
• Capillaries – Very
small and thin vessel –
the site of exchange
between the blood and
the cells of the body.
Artery vs. Vein
ARTERIES
VEINS
• Thicker muscular
wall.
• Muscular wall but
not as thick as
artery.
• Vein valves – Help
carry blood back
up to heart –
usually an uphill
battle!
• No valves.
And That’s All I Got…