Transcript Structure of the Circulatory System

Structure of the
Circulatory System
Paul Buser, Courtney Green, Monica
Roberts and Michelle Silver
Circulatory System a.k.a
Cardiovascular
 Main Function: Transport substances
dissolved or suspended in the blood
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O2
CO2
Nutrients - digested food molecules
Cells of immune and other defense systems
Hormones
The Heart
Right Atrium:
receives deoxygenated
blood from
veins (blood
enters)
Taken from
body and
sent to lungs
to become
rich in
oxygen once
more
central pump for blood
Aorta
Vena Cava
Left Atrium:
Transfers
oxygenated
blood to the
arteries
(blood
leaves)
Taken from
lungs,
transferred
to body
Vena Cava
Types of Vessels in the body
 Arteries/Arterioles - carry blood away from
heart
--> high pressure
 Veins/Venules - carry blood back to the
heart
--> low pressure
 Capillaries - provide the link between
arterial and venous blood vessels, where
diffusion occurs
Vein
Artery
Arteriole
Venule
Capillary
Arteries and Arterioles
 Arteries (elastic and muscular)
Muscular arteries are farther from heart, deliver blood to
specific organ.
Elastic arteries (aorta) hold more blood, take blood from
the heart
 Structure = large-diameter blood vessels, have smooth muscle
 Function = efficiently transports oxygenated blood from the
heart at high pressures, high pressure necessary to push
blood, main force of blood to travel to tissues
 Exception: pulmonary artery transports de-oxygenated blood to lungs
 Arterioles
 Structure = smaller-diameter than the arteries, connect to
capillaries, have smooth muscle
 Function = controls the volume of blood flow through organs
Three Levels of the Artery
1. Tunica Intima: direct contact with blood, smooth/flat to
minimize resistance of flow
2. Tunica Media: muscle level, holds artery in place, deals with
high pressure-->contracts to adjust pressure
3. Tunica Adventitia: external layer, outer covering for protection
Veins and Venules
 Veins- low resistant transport tubes to the heart
 Structure = large in diameter, Valves + smooth muscles in
the venous wall. Thinner than arteries because lower
pressure
 Function = valves prevent back flow of blood against
gravity and smooth muscle controls venous pressure (low)
and volume, thus allowing veins to serve as blood
reservoirs. veins carry de-oxygenated blood to the heart
 Exception: pulmonary vein carries oxygenated blood.
 Low pressure of veins compliments high pressure of arteries
 Venules (little veins) - Capillaries merge into
venules venules then merge into the largerdiameter veins.
Vein: 3 Levels
1. Tunica Intima- has valves, direct contact with blood,
smooth/flat to minimize resistance
2. Tunica Media- thinner smooth muscle than artery
3. Tunica Adventitia- outer covering
Capillaries
 Structure: very thin, fragile tubes
 Only one cell thick, not visible without
microscope
 Function: exchange of CO2 and O2
through thin walls, connects arterioles
and venules
Types of Cells that Line Blood Vessels
Endothelial Cells
• They are very flat with a central
nucleus
Function
• They play a major role in arterial
diseases
•Flat/slick to allow blood to flow with
less resistance in all vessels
• Act as a filter –they regulate the
passage of gases, fluids, etc across
their cell membranes. Most transports
occur at capillary beds but a little bit
occurs for muscles in arteries and veins
• Different organs have different types of endothelial cells
that allow more or less passage of necessary nutrients or
gasses
Subcategories of Circulatory
System
1. Systemic Circulation
2. Pulmonary Circulation
3. Portal Circulation
Systemic Circulation
supplies blood to all body tissues, exchange of
nutrients and products of metabolism
 Systemic arterial systemtransfers oxygenated blood from heart to body
tissues
 Systemic venous systemreturns de-oxygenated blood from tissues,
rich in CO2, back to the heart
*This is the system that blood pressure is
measured in
Pulmonary Circulation
movement of blood between the heart and lungs
1.
De-oxygenated blood brought back to the heart
Vena Cavae --> Right Atrium --> Right Ventricle --> Pulmonary
Artery --> Lungs
2.
In lung capillaries there’s an exchange between
CO2 and 02
3.
Fresh, oxygenated blood enters the heart
Pulmonary Veins --> Left Atrium --> Left Ventricle --> Aorta -->
body
Portal Circulation
 The circulation of blood through larger
vessels, from capillaries of one organ
to capillaries of another organ
*normally there is just one capillary bed for each branch of
circuit, portal circulation has 2!
EX: blood travels from the gastrointestinal tract and
spleen to the liver: digested and absorbed
substances from the gut go right to the liver to be
synthesized/detoxify the blood
Blood Pressure
the force of the blood pushing against the
walls of the arteries
Factors affecting blood pressure
- Gravity – pulls blood towards ground, heart pumping is
needed to bring blood upwards.
- Radius of the vessel – smooth muscle can change radius
immediately if necessary.
-Amount of blood: more viscous= higher pressure
Types of Blood pressure
- Systolic is the peak blood pressure-when blood pumped
- Diastolic is the lowest pressure when the blood is
moving through the vessels-remaining pressure after
blood is pumped, enough flow to keep things moving
Highway Analogy
Sources
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Healthwise Incorporated. “Normal Heart.” Healthwise Incorporated.
Aug. 2008. 10 Nov. 2009.
<http://64.143.176.214/library/healthguide/enus/support/topic.asp?hwid=aa54865>
McGeachie, Professor John. "Blue Histology - more about Endothelial
Cells." School of Anatomy & Human Biology - Teaching Website
Index. N.p., n.d. Web. 11 Nov. 2009.
<http: //www.lab.anhb.uwa.edu.au/mb140/MoreAbout/
Endothel.htm>.
Ross, John. “Structure and Function of Blood Vessels.” Fortune City.
July 1999. 10 Nov. 2009.
<http://greenfield.fortunecity.com/rattler/46/vessels.htm>
Starr, Cecie and Ralph Taggart. Biology: The Unity and Diversity of
Life 9th Edition. Pacific Grove, CA: Brooks/Cole, 2001. Print.
The Franklin Institute. “The Human Heart.” The Franklin Institute.
1996-2009. 10 Nov. 2009.
<http://www.fi.edu/learn/heart/systems/pulmonary.html>