Lesson 8 Circulatory System Pt 1 Blood Vessels PDF

(Circulatory System Pt 1) Blood Vessels Unit D Lesson 8 10.1, 10.4 Lesson 8 Goals Definitions Curriculum ○ Arteries ○ D 2.3k - describe the structure and function of aorta blood vessels; i.e., arteries, veins and ○ Art...

(Circulatory System Pt 1) Blood Vessels Unit D Lesson 8 10.1, 10.4 Lesson 8 Goals Definitions Curriculum ○ Arteries ○ D 2.3k - describe the structure and function of aorta blood vessels; i.e., arteries, veins and ○ Arterioles capillaries ○ Capillaries ○ Venules ○ Veins Vena cava ○ Vasodilation ○ Vasoconstriction What we have learned, and where we are going  The Circulatory System The circulatory system plays many important roles, including: Carrying nutrients to cells Carrying waste away from cells Transporting chemical messengers throughout the body Distributes heat throughout the body Maintains levels of body fluid Helps defend against invaders (immune system) Don’t worry about memorizing this diagram  Blood Vessels Your circulatory system has 96 000 km of blood vessels (!) That is long enough to go around the world twice! These can be split into 3 categories: 1. Arteries + Arterioles 2. Capillaries 3. Venules + Veins  Arteries Arteries are blood vessels that carry blood away from the heart Blood travelling through arteries is is higher pressure than in capillaries and veins Arteries have thick, highly elastic walls The aorta is the largest artery in the body  Arterioles Blood from arteries are passed onto arterioles Arterioles are branches of arteries that carry blood to the capillaries  Capillaries Capillaries are the site of fluid and gas exchange in the circulatory system The narrowest blood vessel, only one cell thick ○ Capillaries are so thin that red blood cells must travel through them single file Very fragile, it is the bursting of capillaries that results in bruising  Capillary Fluid Exchange High pressure inside Low pressure inside arteriole end venus end Pressure in ECF is in between that of arteriole end and venous end Capillary Fluid Exchange  Venules Capillaries merge to become slightly larger venules Venules carry blood to veins The walls of venules contain smooth muscle  Veins Venules merge into veins Veins carry blood towards the heart The walls of veins are much thinner than arteries The largest vein in the body is the vena cava Blood flow in veins is low compared to arteries, so veins contain valves to help move blood back to the heart  Veins Venous valves and skeletal muscle work together to pump blood back to heart Arteries vs Veins Summary of Blood Flow  Vasodilation and Vasoconstriction The autonomic (unconscious) nervous system regulates the diameter of the blood vessels Vasodilation is the widening of blood vessels, increasing blood flow Vasoconstriction is the narrowing of blood vessels, decreasing blood flow  Vasodilation and Vasoconstriction Vasodilation of arterioles in the face helps the body release excess heat when you are nervous, resulting in blushing Vasoconstriction of arterioles in the face diverts blood to the muscles in response to a threat or danger, resulting in a pale face  Blood Vessel Disorders Varicose Veins Pooling of blood in veins resulting from venous valves failing to close, causing the backwards flow of blood  Blood Vessel Disorders Arteriosclerosis Group of disorders that cause blood vessels to thicken, harden, and lose their elasticity Atherosclerosis A type of arteriosclerosis characterized by the degeneration of blood vessels caused by an accumulation of fat deposits on the inner wall  Blood Vessel Disorders Aneurysm A bulge that forms in the weakened wall of a blood vessel, usually in arteries An aneurysm rupturing leads to cell death as nutrients and oxygen are not delivered to tissues Aneurysms in the brain can cause a stroke (when blood flow to the brain is blocked) Next Lesson Lesson 8 Summary Definitions ○ Arteries: carry blood away from the heart Aorta: biggest artery in the body ○ Arterioles: branches of arteries ○ Capillaries: site of gas and fluid exchange ○ Venules: branches of veins ○ Veins: carry blood to the heart Vena cava: biggest vein the body ○ Vasodilation: widening of blood vessels ○ Vasoconstriction: narrowing of blood vessels Lesson 8 Summary Important Concepts ○ Blood flow always follows this pattern: heart → arteries → arterioles → capillaries → venules → veins → heart ○ Arteries are thick walled, have no valves, and carry blood away from the heart ○ Veins are thin walled and rely on valves and skeletal muscle to pumped blood back to the heart ○ Capillaries are the site of gas exchange ○ Vasodilation is the widening of blood vessels, vasoconstriction is the narrowing of blood vessels ○ Know the various blood vessel disorders (varicose veins, arteriosclerosis, atherosclerosis, aneurysm, stroke)