Transcript Circulation1

The Circulatory System
Wednesday, February 3rd, 2009
TODAY’ S TARGETS:
 Identify the functions of
the circulatory system
The Blood
Vessels
 C5b: Structure of types of
vessels
 C5c: Distinguish between
the pulmonary and
systemic circuits
 C5a: Identify the
functions of several
vessels
Think About It
• What are the functions of the circulatory
system?
Functions of the Circulatory System
• Primary function is to transport necessary
materials to all the cells of an animal’s body,
and to transport waste products away from
the cells where they can be released into the
environment
• What necessary materials?
• What waste products?
Think About It
• What are the types of vessels in the human
body?
• What is their function?
Characteristics of Blood Vessels
• The part of the circulatory system that
transports blood throughout body
• 3 layers:
– External layer of connective tissue
– Middle layer of smooth muscle &
elastic tissue
– Inner layer of endothelium
Arteries
Arteries carry blood AWAY from the heart
 have THICK walls composed of elastic and
muscular fibers  Why?
Aneurysms
Aortic aneurysm
Arterioles
Arteries branch into arterioles
 small branches of arteries about 0.2 mm in
diameter or smaller
 arterioles can dilate or constrict to control blood
distribution to tissues
Arterial
Structure
Veins and Venules
Take blood from the capillaries TO the heart
Venules drain blood from capillaries and
then join to form a vein
Vein walls are thinner than arterial walls, have
less elastic & smooth muscle, less rigid
vein
artery
Veins
Veins have valves  Why?
Valves allow blood to flow only toward the
heart when they are open and prevent the
backward flow of blood when they are closed
Prosthetic Valve under research
http://gtresearchnews.gatech.edu/newsrelease/vein-valve.htm
Think About It
• Predict how blood returns to the heart through
veins (works against gravity & low blood
pressure)
14
Varicose Veins
Quiz yourself on Venous return
• http://www.phschool.com/science/biology_pl
ace/biocoach/cardio2/venousreturn.html
17
Capillaries
Smallest and narrowest vessels in the body
Gas and nutrients/wastes exchange across
capillary walls (O2, CO2, glucose, etc.)
Only single-celled layer of endothelium  Why?
Sphincter muscles encircle the entrance to each
capillary
18
Diameter of capillaries only one cell thick  Why?
19
Some numbers…
Average human body has ~5-6 L of blood (7-8% of body’s
weight)
At any one time the veins contain about 75% of the body's
blood; about 20% is in the arteries; only about 5% is in the
capillaries.
 You have close to 100,000 km of blood vessels!
Largest vessel in human  aorta (diameter of garden hose)
Capillaries very small  about 10 together = 1 human hair
Pulmonary Circuit
 Path of blood from heart  lungs  heart
 Deoxygenated blood from all tissues RIGHT ATRIUM (heart) 
pumped to the right ventricle  sent to pulmonary trunk, which
divides into PULMONARY ARTERIES, which divide up into the
arterioles of the lungs.
Pulmonary Circuit
 These arterioles take blood to the pulmonary capillaries, where CO2 is
released in exchange for O2 .
 The oxygenated blood then enters pulmonary venules, then the
PULMONARY VEINS, and finally back to the LEFT ATRIUM (heart).
Systemic Circuit
Includes all blood vessels except
those in the pulmonary circuit.
It takes oxygenated blood from
the LEFT VENTRICLE of the
heart, through the tissues &
organs of the body, and brings
deoxygenated blood back to
the RIGHT ATRIUM of the heart.
• The mammalian cardiovascular system
7
Capillaries of
head and
forelimbs
Anterior
vena cava
Pulmonary
artery
Aorta
Pulmonary
artery
9
6
Capillaries
of right lung
Capillaries
of left lung
2
4
3
11
Pulmonary
vein
5
1
Right atrium
3
Left atrium
Pulmonary
vein
10
Left ventricle
Right ventricle
Aorta
Posterior
vena cava
8
Figure 42.5
Capillaries of
abdominal organs
and hind limbs
Pulmonary and Systemic Circuits
Quiz Yourself
• http://www.phschool.com/science/biology_pl
ace/biocoach/cardio2/naming.html
• http://www.phschool.com/science/biology_pl
ace/biocoach/cardio2/pumping.html
Video
• http://www.youtube.com/watch?v=oHg5ZvrI4
NY
PLO Journal
C5-a:
• Complete worksheet on blood vessels.
C5-b:
• List the 5 different vessel types.
Artery, arterioles, capillaries, venules, veins
• In a chart compare the structure and function of arteries, veins,
and capillaries.
Artery
Vein
Capillary
•Thick muscular, elastic
walls
•Takes blood AWAY from
heart
•Thin, less rigid walls
•Has valves (except veins
coming from head)
•Delivers blood TO heart
•Walls one-cell thick
•Site of gas/nutrient
exchange with tissue cells
PLO Journal
C5-c:
• Fill in the missing blanks:
Systemic Circulation:
Oxygenated blood travels from the heart (left ventricle) to body cells/tissues
through arteries.
Deoxygenated blood travels from body cells/tissues to the heart (right atrium)
through veins.
Pulmonary Circulation:
Oxygenated blood travels from capillaries of lung tissues to the heart (left atrium)
through the pulmonary veins.
Deoxygenated blood travels from the heart (right ventricle) to capillary beds in
the lungs through the pulmonary arteries.