Transcript PP Ch_ 37-1_2_3 Circ and Resp

Circulation
Chapter 37-1
Circulatory System

Functions:
– Transports oxygen, nutrients, hormones
and waste products to and from body cells
– All materials pass into and out of the blood
vessels via diffusion

Consists of:
– Heart, arteries, veins and capillaries
The Heart
The size of your fist
 Made of four
chambers

– Two atria (The heart
receives blood into
these)
– Two ventricles (Blood
leaves the heart
through these)
Blood Flow in the Heart
Blood enters the
heart through the
atria (plural for
atrium)
 When the heart
contracts, blood is
forced into the
ventricles

– Valves prevent
backwash
– Movement of blood
through the body is
unidirectional
Pulmonary Circulation
The circulatory
system is divided into
two separate systems
 The right side of the
heart pumps blood to
the Pulmonary
circulation (lungs)

– This blood leaves the
heart oxygen poor,
picks up Oxygen at the
lungs and returns to
the heart oxygen rich
Systemic Circulation

Blood that leaves the
left side of the heart
is part of the
Systemic
circulation (body).
– This blood leaves the
heart loaded with
oxygen, drops it off at
the tissues (ex:
muscles, organs etc.)
and returns to the
heart oxygen poor
The two systems combined
The heartbeat


Your heartbeat is not controlled
by the nervous system directly
A small patch of cardiac muscle
cells (Sinoatrial node) on the
right atrium starts each heart
contraction
– Called the “pacemaker” of the heart

Each contraction starts on the
right atrium and spreads across
the heart to the left atrium and
then to the ventricles
Blood vessels

Arteries (Largest blood vessels, biggest one is AORTA):
– Blood leaves the heart through these
– They have thick smooth muscular walls and actively push blood along

Veins (Slightly smaller than above, biggest one is VENA
CAVA):
– Blood returns to the heart through these
– They have thinner walls and less muscle and cannot push blood
– They have valves that prevent blood from backwashing

Capillaries (Smallest blood vessels):
– One cell thick
– The bridge between arteries and veins
– This is where diffusion takes place
Path of Blood through the body

Blood starts in the Left Ventricle

Capillaries
– Leave through the Aorta
– Is carried through smaller and smaller arteries to organs and tissues
until it reaches the…
– At the capillaries, gases (O2 and CO2) exchange as well as nutrients and
water)
– Blood continues onto the …

Veins
– Blood returns to the body through veins which become larger and larger
until they reach the Vena Cave
– The Vena Cava dumps blood into the Right atrium

Blood is then moved into the Right Ventricle and out the
Pulmonary Artery on the way to the lungs
– Arteries get smaller and smaller until they reach the capillaries of the
lungs where O2 and CO2 diffuse
– Blood then returns through bigger and bigger veins to the heart until
they reach the Pulmonary Vein which dumps blood into the Left Atrium
and finally into the Left Ventricle where we started
Blood through the Body
Problems with the Circulatory
System
Heart disease is the #1 cause of death of
women in America
 Most heart diseases come from
Atherosclerosis, which is fatty plaque deposits
that build up in the walls of arteries

– Caused by diet, lack of exercise and/or not brushing
teeth enough!

High blood pressure (hypertension)
– Results in weakened heart and arteries which may
lead to heart attack or other complications
Problems Continued

Heart Attack:
– Atherosclerosis that occurs in the coronary arteries
(arteries that give blood to the heart itself) may
prevent the heart from receiving oxygen. Without
oxygen, the heart muscle begins to die.

Stroke:
– Blood clots may form as a result of atherosclerosis.
Some of these clots may break free and travel to the
brain, getting stuck in a blood vessel. This starves
part of the brain of oxygen and results in a stroke

PREVENTION OF CIRCULATORY PROBLEMS:
– Exercising regularly keeps your muscles healthy and
blood flow open. Eating a diet low in fats and excess
carbs prevents the formation of fatty plaques in your
arteries. Not smoking is a huge step to prevention.