Transcript Acc_Bio_Circulation_Notes_wiki


Functions
 Transport system
 nutrients from digested food  all body cells
 oxygen from the lungs  all body cells
 metabolic wastes (CO2)  organs to be excreted
 hormones  target tissues

Regulates body temperature
 in a warm environment blood vessels dilate,
allowing more heat to leave the body
 in a cold environment blood vessels constrict,
preventing heat from escaping from the body

Arteries – carry oxygenated blood away from the
heart
 arterioles – small arteries
 thick elastic walls to withstand the pumping action
of the heart
 high blood pressure

Capillaries – connect arterioles to venules
 Walls are only one cell thick so molecules can easily
diffuse across
 Nutrients diffuse from capillaries  body cells
 Wastes diffuse from body cells  capillaries
 Capillaries are vey narrow; thickness of a single
RBC

Veins – carry deoxygenated blood back to the heart
 thin walls due to low blood pressure
 have valves to help prevent backflow of blood

A muscular pump that
propels blood through
the blood vessels
 Atria – two upper
chambers that receive
blood returning to the
heart
 Ventricles – two lower
thick–walled chambers
that pump blood away
from the heart

Pericardium –
protective sac around
the heart

Vena cava – largest veins
 Superior – drains blood
from the upper body
into right atrium
 Inferior – drains blood
from the lower body
into right atrium

Aorta – largest artery
 comes from left
ventricle and branches
to deliver blood to the
entire body

Pulmonary arteries –
carry blood from the
heart to the lungs

Pulmonary veins – carry
blood from the lungs
back to the heart

Coronary arteries – delivers blood to cardiac muscle

When the coronary arteries become blocked a heart
attack occurs

Stroke – when blood supply is cut off to the brain and
an area of the brain dies.


Valves – prevent the backflow of blood as it is being
pumped through the heart
Named according to where they lead or how they
look
 Atrioventricular Valves – between the atria and
ventricles
 tRicuspid – on the Right side
 bicuspid – on the left side (a.k.a. as the mitral v.)
 Semilunar Valves – between the ventricles and
arteries
 pulmonary – right ventricle  pulmonary artery
 aortic – left ventricle  aorta

Vena cava  right atrium tricuspid valve 
right ventricle  pulmonary valve 
pulmonary artery  lungs pulmonary veins 
left atrium bicuspid valve  left ventricle 
aortic valve  aorta


The left side of the heart
pumps oxygen–rich blood
out to the body through
a network of arteries
Oxygen–poor blood is
returned to the right side
of the heart through
veins.



The right side of the
heart pumps oxygen–
poor blood through the
pulmonary arteries to
the lungs.
Gas exchange (release
of C02 and and pick up
of O2) occurs in the
lungs.
The oxygen–rich blood
then returns to the left
side of the heart
through pulmonary veins

In the pulmonary circuit
the oxygen content of
the vessels is reversed!
 The pulmonary artery
carries oxygen–poor
blood away from the
heart to the lungs
 The pulmonary vein
carries oxygen–rich
blood from the lungs
back to the heart


Sinoatrial (SA) node
 acts as the pacemaker
for the heart
 cluster of cells located in
the upper wall of the
right atrium
 sends a rhythmic
electrical stimulus
causing both atria to
contract pushing blood
into the ventricles
Atrioventricular (AV) node
 in between the atria
 causes contraction of the
ventricles just after the
atria contract pushing
blood out of the heart