1. Arteries

• three layers from deep to superficial

1. tunic interna - endothelium
2. tunic media - elastic fibers and smooth muscle
3. tunic externa - elastic and collagen fibers

• properties

1. elasticity - expansion/recoil
2. contractility - vasoconstriction/vasodilation

• anastomoses - connections provide alternate blood flow

2. Arterioles

• regulate BLOOD PRESSURE
• vasoconstriction via smooth muscle, blood flow to capillaries is restricted and blood pressure is increased
• vasodilation - blood flow is increased and blood pressure is reduced

3. Capillaries

• a single layer of squamous epithelium
• site of nutrient/waste exchange
• true capillaries branch off arterioles and contain a "door" called a precapillary sphincter

4. Venules - from capillary to veins

5. Veins

• contains 2/3 of peripheral blood
• three layers in very thin walls
• less elastic tissue and smooth muscle
• VENOUS RETURN: blood flow to heart depends on movement through veins

- skeletal muscle pump
- increased velocity as vessels widen
- inspirations decrease thoracic cavity pressure
- semilunar valves prevent back flow

6. Capillary filtration and reabsorption

• where and how the cardiovascular system works
• filtration

- movement from capillaries to interstitial fluid - pushes out
- BHP - blood pressure in capillaries - pushes out
- IFOP - osmotic pressure due to proteins in tissues - pushes out

reabsorption

- movement from interstitial fluid into capillaries
- BOP - osmotic pressure due to proteins in caps - pulls in

• Net Filtration Pressure =
  (Blood Hydrostatic Pressure + Interstitial Fluid Osmotic Pressure) minus Blood Osmotic Pressure

• this is how nutrients such as glucose, ions, amino acids, water leave the blood stream, and wastes move in

7. Edema

• increased filtration
• movement from capillary to interstitial fluid
• due to increase in BHP
• due to decrease in plasma proteins
• due to increase in capillary permeability
• due to a blocked lymphatic vessels

8. Blood Pressure

• artery -->arteriole -->capillary-->venule-->vein
• systolic pressure - force of blood pushing against brachial artery wall when left ventricle contracts
• diastolic pressure - force of blood in artery when left ventricle relaxes

9. Peripheral Resistance

• resistance to blood flow due to friction between blood flow and vessel wall
• resistance of a blood vessel is a reciprocal of its diameter
• a vessel with half the diameter has 16X more resistance
• blood viscosity affects peripheral resistance

- increased in polycythemia, dehydration, vasocontriction
- decreased in anemia, hemorrhaging, vasodilation