Chapter 15: Cardiovascular System Flashcards
blood vessels
organs of the cardiovascular system; forms closed circuits and transport blood from heart, to body cells, and back to heart
types of blood vessels (5)
- arteries
- arterioles
- capillaries
- venules
- veins
arteries
carry blood away from ventricles of the heart
arterioles
receive blood from arteries & carry it to capillaries
capillaries
1 cell layer thick; endothelial, sites of exchange between body cells & blood
venules
receive blood from the capillaries & conduct it to veins
veins
receive blood from venules & carry it back to atria of heart
3 layers of arteries
- interna
- media
- externa
interna
innermost layer of arteries
media
smooth muscle & elastic tissue; thicker in arteries than in veins
externa
outer layer, connective tissue of arteries
what do arteries do?
transport blood under high pressure; give rise to arterioles
what can both arteries & arterioles undergo?
vasocontstriction & vasodilation
what do capillaries do?
- connect smallest arterioles & smallest venules
- blood flow regulated by precapillary sphincters
precapillary sphincters
smooth muscles surrounding capillary when it branches off arteriole or met arteriole
what type of endothelium do capillaries have?
simple squamous
vasoconstriction
decrease diameter
vasodilation
increase diameter
capillary exchange
exchange gas, nutrients, & metabolic by products between blood and tissue around cells
methods of capillary exchange
- diffusion
- osmosis
- filtration
diffusion
- most important
- lipid soluble substances diffuse through membrane
- water soluble substances diffuse through slits
filtration
- hydrostatic pressure forces molecules through membrane
- pressure derived from ventricular contraction
osmosis
- presence of impermeant solute inside capillaries creates osmotic pressure
- osmotic pressure draws water into capillaries, opposing filtration
venule function
- microscopic blood vessels that transport blood from capillaries to veins
- thinner walls & less smooth muscle than arteries
arterial end
moves blood out
vein function
- function as blood reservoirs
- carry blood under low pressure
- thin walls
- flap like valves
how much blood is in veins & venules?
2/3
blood pressure
force the blood exerts against inner walls of blood vessels; blood moves higher to lower pressure
systolic
max pressure reached during ventricular contraction
diastolic
min pressure remaining before next ventricular contraction
pulse pressure
difference between systolic & diastolic pressure
mean arterial
average pressure in arterial system; average force driving blood to tissue
how is blood pressure measured?
SP/DP; mmHg
normal BP
120/80