1. Blood Vessels

2. Vessels Arteries Veins Capillaries
Strong elastic vessels that carry blood away from the heart
Smallest ones are called arterioles – connect to capillaries
Veins
Thinner, less muscular vessels that carry blood toward the heart
Smallest ones are called venules – connect to capillaries
Contain valves
Capillaries
Penetrate nearly all tissues
Walls are single-layered squamous cells
Very thin
Function: allow gas/nutrient/waste exchange

3. Control of Blood Flow Precapillary sphincters Vasoconstriction
Circular, valve-like muscle at arteriole-capillary junction
Vasoconstriction
Narrowing blood vessels’ lumen (passageway)
Vasodilation
Expanding blood vessel’ lumen

4. Control of Blood Flow Through veins – very inefficient
Slow, weak arteriole pushing doesn’t help much
What helps
Contraction of diaphragm
Pumping action of skeletal muscles
Valves

5. Blood Pressure
Average is 120/80 (systolic/diastolic)

6. Major Blood Vessels Aorta – largest artery, leaves heart from LV
Ascending aorta, aortic arch, descending aorta, abdominal aorta
Pulmonary Trunk
Leaves RV
Splits left and right and lead to lungs
Pulmonary Veins
Return blood from lungs to heart
Connects to LA
Superior and inferior vena cava
return blood from head (superior) and body (inferior) to the heart
Connects at RA

7. Disorders
MVP – mitral valve prolapse – mitral valve doesn’t close all the way; creates a clicking sound at the end of the cardiac cycle
Heart murmurs – valves do not close completely; causing a harmless sound

8. Disorders
Myocardial infarction – a blood clot obstructs a coronary artery – commonly called a heart attack
Hypertension – high blood pressure, force within arteries is too high

9. Disorders Atherosclerosis
Deposits of fatty materials (cholesterol) which form a plaque and block blood flow
Treatment:
Insertion of catheter and balloon to open the vessels
Can also do a bypass
Vein is inserted to replace the artery to supply blood to the heart