L12 - Blood vessels

• What are the three major types of blood vessels?

  Arteries, veins, and capillaries
• What is the primary function of arteries?

  Carry blood away from the heart
• What is the primary function of veins?

  Carry blood toward the heart
• What is the primary function of capillaries?

  Exchange gases/nutrients with tissues
• What type of blood do systemic arteries carry?

  Oxygenated blood
• What type of blood do systemic veins carry?

  Oxygen-poor blood
• What type of blood do pulmonary arteries carry?

  Oxygen-poor blood
• What type of blood do pulmonary veins carry?

  Oxygenated blood
• What is the endothelial cell lining of blood vessels called?

  Endothelium
• What additional layers do arteries and veins have?

  Smooth muscle and connective tissue
• What are the three layers (tunics) of blood vessels?

  Tunica intima, tunica media, tunica externa
• What is the function of the tunica intima?

  Reduces friction between vessel walls and blood
• What is the function of the tunica media?

  Controls vasoconstriction and vasodilation
• What is the function of the tunica externa?

  Protects, reinforces, and anchors vessels
• What happens to blood pressure as blood travels through the circulatory system?

  Blood pressure decreases from arteries to veins
• What are elastic arteries?

  Large arteries that conduct blood with low resistance
• What is the function of elastic arteries during the cardiac cycle?

  Expand and recoil to maintain continuous flow
• What are muscular arteries?

  Medium-sized arteries that distribute blood to organs
• What is the primary function of arterioles?

  Regulate blood flow from arteries into capillaries
• What is the primary characteristic of capillaries?

  Thin-walled vessels for diffusion
• What do pre-capillary sphincters do?

  Determine capillary exchange area within tissue
• What are the three types of capillaries?

  Continuous, fenestrated, and sinusoidal
• What type of capillary is the least permeable?

  Continuous capillaries
• What type of capillary has intermediate permeability?

  Fenestrated capillaries
• What type of capillary is the most permeable?

  Sinusoidal capillaries
• Where are continuous capillaries commonly found?

  Skin, lungs, muscles, and CNS
• What is the function of fenestrated capillaries?

  Increase exchange of substances
• Where are fenestrated capillaries commonly found?

  Small intestines and kidneys
• What is the primary characteristic of sinusoidal capillaries?

  Allow large molecules to pass between blood and tissue
• Where are sinusoidal capillaries commonly found?

  Liver, spleen, and bone marrow
• What are venules?

  Formed where capillaries converge
• What is the function of small postcapillary venules?

  Allow fluid and leukocytes to move easily
• What is the primary function of veins?

  Act as blood reservoirs
• What percentage of blood volume do systemic veins and venules contain?

  About 64%
• What is the pressure gradient in veins compared to the right atrium?

  ~15 mmHg in veins to ~0 mmHg
• What are the three adaptations to increase venous return?

  Skeletal muscle pump, respiratory pump, sympathetic vasoconstriction
• What is the function of the skeletal muscle pump?

  External venous compression increases venous pressure
• What do venous valves do?

  Allow unidirectional flow of blood
• What is vascular anastomosis?

  Connection between blood vessels supplying the same region
• What is the importance of vascular anastomoses?

  Provide alternative routes for blood supply