Block 3

Question 1

what is the direction of blood flow

Answer 1

Question 2

Components of the vasculature

Answer 2

• 1. Arteries
     deliver oxygenated blood to the tissues.
     ■ are thick walled, with extensive elastic tissue and smooth muscle.
     ■ are under high pressure.
     ■ The blood volume contained in the arteries is called the stressed volume.
     
     2. Arterioles
        ■ are the smallest branches of the arteries.
        ■ are the site of highest resistance in the cardiovascular system.
        ■ have a smooth muscle wall that is extensively innervated by autonomic nerve fibers.
        ■ Arteriolar resistance is regulated by the autonomic nervous system
        ■ α1-Adrenergic receptors are found on the arterioles of the skin, splanchnic, and renal circulations.
        ■ β2-Adrenergic receptors are found on arterioles of skeletal muscle.

3. Capillaries
   ■ have the largest total cross-sectional and surface area.
   ■ consist of a single layer of endothelial cells surrounded by basal lamina.
   ■ are thin walled.
   ■ are the site of exchange of nutrients, water, and gases.
4. Venules
   ■ are formed from merged capillaries.
5. Veins
   ■ progressively merge to form larger veins. The largest vein, the vena cava, returns blood to the heart.
   ■ are thin walled.
   ■ are under low pressure.
   ■ contain the highest proportion of the blood in the cardiovascular system.
   ■ The blood volume contained in the veins is called the unstressed volume.
   ■ have α1-adrenergic receptors