Lec5 Circulation

Lec5 Circulation - Chapter 5 Cardiovascular System Heart...

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Unformatted text preview: Chapter 5 Cardiovascular System: Heart and Blood Vessels Readings • Mader 10th edition Chapter 5 What is the cardiovascular system? • Includes the heart and blood vessels • Brings nutrients to cells and helps get rid of wastes • Blood is refreshed in the lung, kidneys, intestine and liver • Lymphatic vessels help this system by collecting excess fluid surrounding tissues and return it to the cardiovascular system What are the function of the cardiovascular system? 1. Generate blood pressure 2. Transport blood 3. Exchange of nutrients and wastes at the capillaries 4. Regulate blood flow as needed What is the main pathway of blood in the body? • Heart – arteries – arterioles – capillaries - venules – veins – back to the heart… Arteries and arterioles : • Resistance vessels • Carry blood away from the heart • Their walls have 3 layers: – Thin inner epithelium – Thick smooth muscle layer – Outer connective tissue • Arterioles are small arteries that regulate blood pressure Capillaries: • Microscopic vessels between arterioles and venules • Made of one layer of epithelial tissue • Form beds of vessels where exchange with body cells occurs • Combined large surface area Exchange at the capillary beds is primarily a result of osmotic and blood pressure Blood Pressure-Due to pumping of Heart Diffusion- Movement of substances from high to low concentration Osmotic pressure- Difference of solute concentration either side of membrane (capillary wall) Side with highest concentration of solutes will experience pressure Movement of Substances from Capillaries • Arterial End of Capillary – Arterial blood bright red (oxy-hemoglobin) – Nutrient rich – Blood pressure (30 mm Hg) > osmotic pressure (21 mm Hg) – Water, small molecules exit – RBC’s, plasma proteins to big to pass walls – Water, small molecules form tissue fluid – Like plasma less plasma proteins Midsection Capillary • Concentrations of O 2 , nutrients > tissue fluid • Continue to leave capillary • Concentrations CO 2 , wastes < tissue fluid • Continue to enter capillary Venous end of Capillary • Blood pressure now 15 mm Hg • (Cross section capillaries larger at venous end) – Less than osmotic pressure • Water enters capillaries • Brings wastes along with it. • Only 85% H 2 O lost arterial end recovered • Balance brought back in via lymphatic system Veins and venules: • Capacitance vessels • Venules are small veins that receive blood from the capillaries • Venule and vein walls have 3 layers: – Thin inner epithelium – Thick smooth muscle layer – Outer connective tissue...
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Lec5 Circulation - Chapter 5 Cardiovascular System Heart...

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