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The Circulatory System Wednesday, February 3 rd, 2009.

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Presentation on theme: "The Circulatory System Wednesday, February 3 rd, 2009."— Presentation transcript:

1 The Circulatory System Wednesday, February 3 rd, 2009

2 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

3 Think About It What are the functions of the circulatory system?

4 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?

5 Think About It What are the types of vessels in the human body? What is their function?

6 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

7 Arteries  Arteries carry blood AWAY from the heart  have THICK walls composed of elastic and muscular fibers  Why?  Aneurysms Aortic aneurysm

8 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

9 Arterial Structure


11 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

12 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

13 Think About It Predict how blood returns to the heart through veins (works against gravity & low blood pressure)

14 14

15 Varicose Veins

16 Quiz yourself on Venous return ace/biocoach/cardio2/venousreturn.html ace/biocoach/cardio2/venousreturn.html

17 17

18 Capillaries  Smallest and narrowest vessels in the body  Gas and nutrients/wastes exchange across capillary walls (O 2, CO 2, glucose, etc.)  Only single-celled layer of endothelium  Why?  Sphincter muscles encircle the entrance to each capillary 18

19 Diameter of capillaries only one cell thick  Why? 19

20 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

21 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.

22 Pulmonary Circuit  These arterioles take blood to the pulmonary capillaries, where CO 2 is released in exchange for O 2.  The oxygenated blood then enters pulmonary venules, then the PULMONARY VEINS, and finally back to the LEFT ATRIUM (heart).

23 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.

24 The mammalian cardiovascular system Pulmonary vein Right atrium Right ventricle Posterior vena cava Capillaries of abdominal organs and hind limbs Aorta Left ventricle Left atrium Pulmonary vein Pulmonary artery Capillaries of left lung Capillaries of head and forelimbs Anterior vena cava Pulmonary artery Capillaries of right lung Aorta Figure 42.5 1 10 11 5 4 6 2 9 3 3 7 8

25 Pulmonary and Systemic Circuits Quiz Yourself ace/biocoach/cardio2/naming.html ace/biocoach/cardio2/naming.html ace/biocoach/cardio2/pumping.html ace/biocoach/cardio2/pumping.html Video NY NY

26 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 ArteryVeinCapillary 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

27 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

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