Heart valves vessels and nodal tissue Blood vessels
Heart: valves, vessels and nodal tissue Blood vessels: structure and function
Heart Valves
Coronary Blood vessels
Nodal Tissue
Blood vessels: Structure and Function 1. Arteries 2. Arterioles 3. Capillary 4. Venules 5. Veins
Blood vessels : Arteries: thick, elastic walls - Lumen: holds blood - 3 layers: outer connective tissue - middle layer of smooth muscle & elastic fibers (stretch) - inner endothelium - allows stretching/response to large change in pressure
Arterioles - carry blood away from heart/ between arteries and capillaries - vasodilation and vasoconstriction allows vessels to change diameter, affecting blood pressure and heat loss - 3 layers: middle layer mostly smooth muscle surrounded by elastic fibers. - Vasodilation= elastic fibers relax=increase in diameter=decrease in blood pressure - Vasoconstriction= elastic fibers contract= decrease in diameter= increase in blood pressure
Capillaries - exchange of nutrients and wastes, oxygen and carbon dioxide via diffusion - connect arterioles to venules - one cell thick facilitates diffusion - highly branched capillary beds increase surface area - sphincters at beginning of some beds regulates blood flow affecting blood pressure and tissue use of nutrients & oxygen
Venules - conduct low pressure blood from capillaries to veins - thin walls… middle layer not well developed - don’t need to be thick-walled or elastic since blood in them is under very low pressure
Veins - Carry low-pressure blood towards heart - Act as blood reservoirs. Iif blood pressure is too low, can constrict and force more blood through system, increasing b. p. - 3 layers. thin elastic layer due to low b. p. - one way valves prevent backflow of blood
- Slides: 10