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Human Circulatory System:
• Also known as the
cardio-vascular system
• It is a closed system,
which means that blood
is confined within
vessels
The Human Circulatory
System contains 3 parts:
1. Heart
2. Blood Vessels
3. Blood
The Heart
A. Your heart is a muscle,
mostly cardiac muscle
– It continually beats
without stopping for
your entire life
– It pumps about 1/3 cup
of blood with each beat,
and about 2,000 gallons
of blood daily
The Heart:
b.. Birds and mammals
have a 4-chambered heart
(2 atria and 2 ventricles)
*Fish have 2 chambers and
reptiles have 3 chambers
Function of the heart:
• Every cell in your
body needs oxygen
in order to live and
function.
• The purpose of the
heart is to deliver
the oxygen-rich
blood to every cell in
the body
The 4 main parts
of the heart are:
1. The Atria
2. The Ventricles
3. The Septum
4. Valves
1. The Atria:
• Top two chambers of
the heart
• Have thin walls
• They collect blood
returning to the heart
from the body
• They then pump blood
to ventricles through
valves
2. The Ventricles
• Bottom two chambers
• Have much thicker walls
• More powerful than the atria,
• The left ventricle is the
strongest chamber because is
pumps blood to the rest of the
body.
• The right ventricle pumps
blood to the lungs to pick up
oxygen
The Septum
• Thick tissue that separates the two sides
of the heart so that blood does not mix
Heart Valves
• There are 4 valves in the heart
that help to direct blood flow
• Blood should only move in
one direction to avoid
contamination between
oxygen-poor blood and
oxygen-rich blood
– As they open and close, the
valves produce sounds that can
be heard with a stethoscope
– These sounds can often tell your
doctor about your heart’s
function
Semilunar Valve
There are 3 main types
of blood vessels:
•Arteries
•Veins
•Capillaries
Arteries
• Carry oxygenrich blood AWAY
from the heart
toward the body.
Veins
• Carry oxygen-poor
blood from
capillaries back to
the heart and lungs
Capillaries
• Thin-walled blood vessels
in which gases, nutrients,
wastes, and hormones are
exchanged
• Are only one cell layer
thick and microscopic in
size
Capillary Bed
There are 3 different types of
Circulation throughout your
body:
1. Coronary (to the heart)
2. Pulmonary (to the lungs)
3. Systemic (to the body)
Coronary Circulation
• Refers to the movement
of blood through the
tissues of the heart
Pulmonary Circulation
• The movement of
blood from the
heart to the lungs
and back to the
heart again
• Blood flows to the
lungs to pick up
oxygen
Systemic Circulation
• The movement of nutrient-rich blood to all of the
tissue located throughout your body
What is Blood Pressure?
• Pressure exerted by
the blood against
artery walls
• Consists of 2 numbers:
– Systolic
– Diastolic
Blood Pressure:
NOT IN NOTES!
• Systolic Pressure:
– The pressure as a
result of contraction
of the left ventricle
• Diastolic Pressure:
– Pressure as a result
of the relaxation of
the left ventricle
What should my blood
pressure be?
• Typical blood
pressure for an adult
is:
120 Systolic
70
Diastolic
High Blood Pressure:
• Also known as
hypertension
• Result of stretched out
arteries which makes the
heart work harder to
force blood through
• Can also result from a
narrowing of arteries
What is my Pulse?
• A measure of how fast the
heart is contracting
• Pulse is taken in an artery
• Normal resting pulse rate
for an adult is 60-80 bpm
(beats per minute)
Pulse
Sites
Does our heart rate change as we age?
Age
Newborn
3 months
6 months
1 year
2 years
3 years
4 years
6 years
8 years
12 years
Adult
Pulse
130
140
130
120
115
100
100
100
90
85
60-100
Two problems of the circulatory
system we will be discussing are:
1.Stroke
2.Heart Attack
Stroke
• Results from a
blockage of artery
(Carotid artery)
towards the head
• As a result, nervous
tissue in the brain
dies
HEART ATTACK!
Heart Attack
•
When part of the
heart muscle is
damaged or dies due
to lack of oxygen.
•
Oxygen is carried to
the heart by the
arteries
•
Most heart attacks
are caused by a
blockage in these
arteries.
What causes a Heart Attack?
HIGH FAT
DIET!!!!
How does circulation
maintain homeostasis?
• The heart keeps the blood flowing
through the body which regulates
body temperature and also delivers
nutrients that the body needs, thereby
maintaining homeostasis
How does your heart keep
beating?
• The answer lies in a special group of cells that have the
ability to generate electrical activity on their own.
• These cells separate charged particles.
• This produces electrical impulses in the pacemaker cells
which spread over the heart, causing it to contract.
• These cells do this more than once per second to produce a
normal heart beat of 72 beats per minute.
• The natural pacemaker of the heart is called the Sinoatrial
node (SA node). It is located in the Right Atrium.
• The heart also contains specialized fibers that conduct the
electrical impulse from the pacemaker (SA node) to the rest
of the heart
Steps of Pulmonary Circulation:
1. Veins bring oxygen-poor blood back to the heart through
the Vena Cava.
2. Right atrium fills with the de-oxygenated blood and then
contracts, pushing the blood through a one-way valve into
the right ventricle
3. The right ventricle fills and then contracts, pushing the
blood into the pulmonary artery which leads to the lungs.
(the blood entering the lungs will be dark red in color
because it has little oxygen)
4. In the lung capillaries, CO2 is dropped off and O2 is picked
up
5. The fresh, oxygen-rich blood (bright red) enters the
pulmonary veins and returns to the heart, re-entering
through the left atrium
6. Now, oxygen-rich blood is ready to go to the body!