March 3, 2017 Blood Vessels

Types of Blood Vessels

Blood Vessel Tunics All vessels except capillaries have three layers, or tunics Capillaries have a single layer of epithelial cells

Comparison of blood vessels What are the differences? How do they relate to function? Veins also have valves and are flexible

Blood vessel micrograph What is a? What is b? How do you know? B A

How does blood return to the heart? Muscular pump Respiratory pump Describe the action of these pumps in 1-2 sentences

Capillary Bed What is the difference between the vascular shunt and true capillaries?   What is the function of precapillary sphincters?

Capillary Exchange Capillary exchange is the movement of substances (water, gases, nutrients, wastes, etc.) between capillaries and the interstitial fluid of tissues Capillaries have special features which increase their permeability: Intercellular clefts: spaces between cells Fenestrations: very thin membrane- covered spots, or pores http://www2.sunysuffolk.edu/pickenc/Capillary%20Exchange.swf

Capillary Exchange Capillary exchange is the movement of substances (water, gases, nutrients, wastes, etc.) Capillaries have special features which increase their permeability: Intercellular clefts: spaces between cells Fenestrations: very thin membrane -covered spots, or pores Clefts and fenestrations are most important for the diffusion of what kinds of substances? Water, and other lipid-insoluble substances What can get through without their help? O2, CO2, fats http://www2.sunysuffolk.edu/pickenc/Capillary%20Exchange.swf

Capillary Exchange Capillary exchange is the movement of substances (water, gases, nutrients, wastes, etc.) Capillaries have special features which increase their permeability: Intercellular clefts: spaces between cells Fenestrations: very thin membrane -covered spots, or pores What type of capillaries don’t have fenestrations or intercellular clefts? Capillaries in the brain – work with astrocytes to form blood-brain barrier http://www2.sunysuffolk.edu/pickenc/Capillary%20Exchange.swf

Capillary Exchange Differences in pressure in blood pressure and osmotic pressure help fluids move out of capillaries at the arterial end and into capillaries at venous end. Watch me! http://www2.sunysuffolk.edu/pickenc/Capillary%20Exchange.swf; oncotic pressure – osmotic pressure due to proteins such as albumin; hydrostatic is more like fluid pressure

Closure Explain the statement: “All other blood vessels exist to service the capillaries” How does what we did today relate to our unit question?

Exit Ticket Describe the structure of a capillary and explain how it facilitates it’s function. (2 pts) Describe 2 differences in the structure of arteries and veins and explain how these differences facilitate their functions. (4 pts)