The Circulatory System Wednesday, February 3 rd , 2009
Dec 28, 2015
The Blood Vessels
TODAY’ S TARGETS:
Identify the functions of the circulatory system
C5b: Structure of types of vessels
C5c: Distinguish between the pulmonary and systemic circuits
C5a: Identify the functions of several vessels
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?
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
ArteriesArteries carry blood AWAY from the heart
have THICK walls composed of elastic and muscular fibers Why?
Aneurysms
Aortic aneurysm
ArteriolesArteries 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
Veins and VenulesTake blood from the capillaries TO the heartVenules 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
veinartery
VeinsVeins 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 researchhttp://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)
Quiz yourself on Venous return
• http://www.phschool.com/science/biology_place/biocoach/cardio2/venousreturn.html
CapillariesSmallest 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
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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
Pulmonary vein
Right atrium
Right ventricle
Posteriorvena cava Capillaries of
abdominal organsand hind limbs
Aorta
Left ventricle
Left atrium
Pulmonary vein
Pulmonaryartery
Capillariesof left lung
Capillaries ofhead and forelimbs
Anteriorvena cava
Pulmonaryartery
Capillariesof right lung
Aorta
Figure 42.5
1
10
11
5
4
6
2
9
33
7
8
Pulmonary and Systemic Circuits
Quiz Yourself• http://www.phschool.com/science/
biology_place/biocoach/cardio2/naming.html• http://www.phschool.com/science/
biology_place/biocoach/cardio2/pumping.html
Video• http://www.youtube.com/watch?v=oHg5ZvrI4NY
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.
PLO Journal
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
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.
PLO Journal