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SBI 3U CIRCULATORY SYSTEM

SBI 3U CIRCULATORY SYSTEM. Circulatory System heart, blood, and blood vessels transport oxygen and nutrients to organs and tissues throughout the body carry away waste products. I. Functions. Increases blood flow meet increased energy demands during exercise regulates body temperature

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SBI 3U CIRCULATORY SYSTEM

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  1. SBI 3U CIRCULATORY SYSTEM

  2. Circulatory System • heart, blood, and blood vessels • transport oxygen and nutrients to organs and tissues throughout the body • carry away waste products

  3. I. Functions • Increases blood flow • meet increased energy demands during exercise • regulates body temperature • conveys disease-fighting elements of immune system to regions under attack • white blood cells and antibodies • sends clotting cells and proteins to the affected site • stop bleeding and promote healing

  4. II.Circulatory System Components • Heart - divided into four chambers • right atrium, right ventricle, left atrium, left ventricle

  5. Chamber walls composed of myocardium • contracts continuously and rhythmically to pump blood.

  6. Pumping action of the heart -two stages for each heart beat • Diastole-when the heart is at rest • Systole-when the heart contracts to pump deoxygenated blood toward the lungs and oxygenated blood to the body.

  7. During each heartbeat, typically about 60 to 90 ml (about 2 to 3 oz) of blood are pumped out of the heart. • If the heart stops pumping, death usually occurs within four to five minutes.

  8. Three types of blood cells • oxygen-bearing red blood cells • disease-fighting white blood cells • blood-clotting platelets, all of which are carried through blood vessels in plasma • plasma is yellowish, consists of water, salts, proteins, vitamins, minerals, hormones, dissolved gases, and fats.

  9. Three types of blood vessels • arteries carry blood away • thicker walls to withstand the pressure of blood being pumped from heart • veins - toward heart • lower pressure • one-way valves to prevent blood from flowing backwards away from heart • capillaries • tiny links b/w arteries and veins where oxygen and nutrients diffuse to body tissues • smallest of blood vessels, are only visible by microscope ten capillaries lying side by side are barely as thick as a human hair.

  10. Inner layer of blood vessels • lined with endothelial cells - create a smooth passage for blood transit • surrounded by connective tissue and smooth muscle for: • Expansion - during exercise to meet demand for blood and to cool body • Contraction - after injury to reduce bleeding and/or conservebody heat

  11. If all the arteries, veins, and capillaries in the human body were placed end to end, the total length would equal more than 100,000 km (more than 60,000 mi)—they could stretch around the earth nearly two and a half times.

  12. Arteries, veins, and capillaries - divided into two systems: • Systemic - carries oxygenated blood from heart to all tissues in body except lungs and returns deoxygenated blood carrying waste products, such as carbon dioxide, back to heart. • oxygen-rich blood ejected under high pressure out of heart's main pumping chamber (L. ventricle) through largest artery (aorta) • smaller arteries branch off from aorta to various parts of the body • smaller arteries in turn branch out into even smaller arteries (arterioles) • arterioles become progressively smaller eventually forming capillaries - blood pressure is greatly reduced

  13. interstitial fluid fills the gaps between the cells of tissues or organs • dissolved oxygen and nutrients then enter the cells from interstitial fluid by diffusion • carbon dioxide and other wastes leave the cell via interstitial fluid, cross capillary walls, and enter blood. • after delivering oxygen to tissues and absorbing wastes, deoxygenated blood in capillaries then starts the return trip to heart

  14. capillaries merge to form tiny veins, called venules • venules join together to form progressively larger veins • veins converge into two large veins: • inferior vena cava-brings blood from the lower half of body • superior vena cava-brings blood from upper half • Both join at the right atrium of heart

  15. FYI • Varicose Veins • pressure is dissipated in arterioles and capillaries • blood in veins flows back to heart at very low pressure, often running uphill when a person is standing • Flow against gravity allowed by one-way valves • several centimeters apart in veins • Veins with defective valves (allow the blood to flow backward) become enlarged or dilated to form varicose veins

  16. Varicose veins

  17. Pulmonary Circulation • deoxygenated blood returning from organs and tissues travel from R. atrium to R. ventricle. • pushed through pulmonary artery to lung • pulmonary artery divides forming pulmonary capillary region • microscopic vessels pass adjacent to alveoli (air sacs) - gases are exchanged across thin membrane • oxygen crosses membrane into blood while carbon dioxide leaves blood through same membrane • newly oxygenated blood then flows into pulmonary veins and is collected by L. atrium of the heart (collecting pool for L.ventricle) • contraction of L. ventricle sends blood into aorta completing circulatory loop

  18. SUP. VENA CAVA AORTIC ARCH PUL. VEINS L. LUNG R. LUNG PUL. ARTERY HEART AORTA INF. VENA CAVA

  19. On average, a single blood cell takes roughly 30 seconds to complete a full circuit through both the pulmonary and systemic circulation.

  20. III. Additional Functions & Features • Transports nutrients and removes toxins • Absorbed through intestine wall via network of capillaries and veins that drain the intestine - hepatic portal circulation (HPC) • HPC – carries nutrients/toxins to the liver for further metabolic processing. • Liver stores sugars, fats, and vitamins & releases to the blood as needed • Liver also cleans blood by removing waste product and toxins. After hepatic portal blood has crossed the liver cells veins converge to form the large hepatic vein that joins the vena cava near the right atrium.

  21. Body Temperature Regulation • exercise = muscles generate heat • blood supplying muscles with oxygen and nutrients absorbs much heat and carries to other parts of body • If body gets too warm, vessels near skin enlarge = disperse excess heat outward through skin • If cold, blood vessels constrict to retain heat.

  22. Hormone Transportation • Endocrine system = collection of hormone-producing glands • Regulates rate of metabolism, growth, sexual development, and other functions. • chemical messengers (hormones) released directly into bloodstream • transported to specific organs and tissues

  23. WBC & Antibody Transport and Clotting • WBC and antibodies circulate in blood • transported to infection sites • coagulationsystem - composed of • Platelets and clotting factors circulate in blood • Damaged blood vessels are repaired by forming clots

  24. Supporting Organs • Brain/nervous system • monitor blood circulation • send signals to heart or blood vessels to maintain constant blood pressure. • Bone Marrow • Site of new blood cell manufacture • Spleen • Old blood cells are broken down • valuable constituents, such as iron, are recycled • Kidneys • metabolic waste products removed from blood • also screens for excess salt • maintains blood pressure • balance of minerals and fluids

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