Circulatory System
Blood
Flow
Summary
Blood
Vessels
The Blood
The
Heart
You Gotta Have Heart
The Circulatory System
Circulatory System Consists of…
 Blood
 Blood
 Heart
Vessels
Circulatory System
BLOOD VESSELS
Two Pathways

Pulmonary Circulation
– Carries blood to lungs and
back

Systemic Circulation
– Carries blood to body and
back
Your Blood Vessels:
Pathway of Circulation

3 types of vessels
– Arteries (mostly
shown as Red because
blood has O2)
– Capillaries (Red and
Blue because some O2
lost to tissues)
– Veins (mostly shown
as Blue because O2
lost to tissues)
Red Blood and Blue Blood
Blood is never blue!!!!!!!!!!!!!!!!!!
 Oxygenated blood is bright red and
deoxygenated blood is dark red
 Veins appear blue because of the way light
reflects off the blood vessel
 We don’t see arteries because they are too
deep.
 We draw them blue to distinguish them on
diagrams and simplify things

Arteries vs. Veins
What you need to know about
the STRUCTURAL differences
between Arteries and Veins:
- Artery walls are much
thicker, are very elastic
and have more muscle
- Veins are thin walled and
contain valves to push the
blood along
Arteries vs. Veins

Why are arteries and veins the
way they are?
– Blood is under very high pressure
when it leaves the heart and enters
the arteries
 Therefore, arteries need to be
strong!!
– Once it has left the tissues and
enters the veins, the blood is under
a very low pressure
 Therefore, veins are weak
Arteries:
Carry blood Away from heart
–
–
–
–
Large
Thick-walled, Muscular
Elastic
Oxygenated blood

Exception Pulmonary Artery
– Carried under great pressure
– Steady pulsating (used to measure pulse)
Arterioles: smaller vessels, enter tissue
Capillaries
– Smallest vessel
– Microscopic
– Walls one cell
thick
– Located at the tissue
– Nutrients and gases
(O2, CO2) diffuse
here
Veins:
Carry blood to the heart
–
Carries blood that contains
waste and CO2

–
–
Exception pulmonary vein
Blood under low pressure
Valves to prevent back flow
due to gravity
Venules: small veins, larger
than capillaries
Mechanism of Vein and Varicose Veins Videos
Blood Vessels
The Aorta – The largest blood vessel
Blood Vessels
Blood flow is like a round trip to grandma’s house
- You leave your home (The Heart)
- You jump on the Highway (Arteries)
- You get off at grandma’s street (Arterioles)
- You pull in to grandma’s driveway (capillaries)
- You go inside her house (The Cell) and give her a kiss
(Glucose and Oxygen)
- You leave with leftovers (CO2)
- Get back into your car and exit driveway (capillaries)
- You drive back along her street (Venuoles)
- You get back on the highway (Veins)
- Arrive back at home (The Heart)
Circulatory System
BLOOD
The Blood
Body contains 4-6 L
 Consists of

–
–
–
–
Water
Red Blood Cells
Plasma
White blood cells and
platelets
Your Blood: Fluid Transport
Liquid Portion Carries
 Blood cells (made in bone marrow)
– Erythrocytes (RBC - red blood
cells)
– Leucocytes (WBC - white blood
cells)
 Platelets (fragments of the cells in
bone marrow – no nucleus)
 Proteins
 Nutrients - Digestive System
 Gases - Respiratory System
Oxygen in the Blood



Hemoglobin, iron
containing molecule –
found in RBC
Loosely picks up
oxygen in the lungs
Releases oxygen in
areas low in oxygen –
body tissues
O2
O2
O2
O2
Carbon Dioxide in the Blood

Hemoglobin also carries CO2

CO2 is a waste product of cellular
respiration

Travels to the lungs to be exhaled
What does blood contain?

50% Water

45% Erythrocytes (RBC)

4% Plasma with Substances

1% Leukocytes (WBC) + Platelets
Erythrocytes (RBC)





Transporters of
– Oxygen
– Carbon Dioxide
RBC
– Lack a nucleus
– Contain hemoglobin
– Disk-shaped
RBC are produced in the
bone marrow
Lives for ~120 days
Old RBC are destroyed in
liver and spleen
Leukocytes (WBC)

WBC fight infection
–



Less abundant
Created in the
bone marrow
Some live for
months
–


Attack foreign
substances
Most just a few days
Several types
ALL contain nuclei
Platelets
PLATELETS are for
CLOTTING blood
 Cell fragments
 Produced in bone
marrow
 Short life span (1 week)
 Form a web trapping
blood cells

Blood Clotting
Break in Capillary Wall
Clumping of Platelets
Clot Forms
Blood vessels injured.
Platelets clump at the site
and release a protein
Protein creates a net
creating a clot. The clot
prevents further loss of
blood.
How does Blood Clot?
Circulatory System
HEART
Heart Anatomy
Your Heart

Pumps blood around
your body to keep you
alive!

If your heart stops you
will die!
Heart:
Structure and Function
Keeps blood
moving
 Large organ
composed of
– cardiac muscle
– rich in
mitochondria

The Structures of the Heart
Vena Cava
Vein that brings
oxygen-poor
blood from the
body to the heart
Pulmonary
Arteries
Sends OxygenPoor blood to the
Lungs
Receives
OxygenPoor blood
from the
body
Sends
Oxygen-Poor
blood to the
lungs
Aorta – Artery that supplies the
body with Oxygen-Rich Blood
Gets OxygenRich blood
from the Lungs
Pulmonary Arteries
Bring oxygen-poor blood
to the lungs
Pulmonary
Veins
Bring oxygenrich blood from
the lungs to the
left atrium
Sends OxygenRich blood to
the body
Structure of Heart (cont)

Four chambers
– Two upper (Atria)
 Walls thinner
 Less muscular
– Two lower
(Ventricles)
 Walls thicker
 More muscular
 Do more work
Heart Structure Animation
Blood Flow Through the Heart
Bloods Path Through the Heart

Both Atria fill at same time
– Right atrium receives oxygen POOR blood
from body from vena cavas
– Left atrium receives oxygen RICH blood from
lungs through four pulmonary veins

After filled with blood atria contract,
pushing blood into ventricle
Both ventricles contract
Right ventricle contracts and pushes
oxygen-poor blood toward lungs
 through the pulmonary arteries
Bloods Path Through the Heart
Left ventricle contracts and forces oxygen
rich blood out of heart
 Through the aorta (largest vessel)
The cardiac cycle
Animation of blood flow
Control of the Heart
The Heart is controlled by
nerves and hormones:
Nerves:

– Its own nerves 
pacemaker which keeps a
constant beat
 Heart will beat even if it is
disconnected from the brain
 Can be substituted by an
artificial pacemaker
- The Brain  can speed-up (exercise) or slow
down the heart (sleep) if needed

Heart Rate Animation

ECG and (Defibrillation) Paddles
discussion
Control of the Heart
Hormones:

Certain hormones such as epinephrine
(adrenalin) impact how the heart
operates
Heart Beat
Control of Heart Rate –
Class Demonstration
Resting Heart Rate
(beats per min.)
Heart Rate during exercise
(beats per min.)
Your Heart: The Vital Pump

At REST, the heart
beats about 60-80
times per minute
(~4.7L)

During EXTREME
EXERTION (exercise)
it can beat between
150-200 times per
minute (~38L)
Heart Rate Discussion

Why??
Brain sends a signal to increase HR
 Adrenal Gland secretes epinephrine
 Both work together to increase blood flow
around the body

– Increased blood flow = Increase O2/glucose
delivery to cells and CO2 removal
DISORDERS

Coronary Artery Disease
– Your heart needs Oxygen too!
– Is supplied with Oxygen by coronary arteries
– Coronary arteries can become partially
blocked by plaque (fat and cholesterol mainly)
 Causes by lifestyle choice and genetics
– This block limits the amount of oxygen
delivered to the heart
– Can cause  tiredness, dizziness and pain
Coronary Artery Disease
Can be diagnosed with an angiogram whereby a
fluorescent dye is injected into the bloodstream.
 This dye shows up on an x-ray and shows where
flow is disrupted

Disorders (cont)

Heart Attack
– Coronary Artery(ies) become completely
blocked
 No Oxygen can reach the heart muscle
 Heart muscle begins to die and eventually stops beating
 Symptoms
– Nausea, Shortness of breath, Severe chest pain, sweating,
dizziness, fatigue
IMMEDIATE MEDICAL ATTENTION NECESSARY
Heart Attack 1
Heart Attack 2

Disorders (cont)
Stroke
– Heart attack for the
brain
– Blood cannot reach the
brain due to a blockage
in its blood vessels or
severe brain bleed.
– Brain cells die due to
lack of oxygen
– Can lead to paralysis,
 loss of ability to
speak
 death
Causes a Stroke?
Current PREVENTION
Recommendations

Regular exercise

Weight control

Well balanced diet

Do not smoke

Diet low in saturated fat