Chapter 19 Flashcards
three major types of vessel
arteries, capillaries, and veins
— carry blood away from the heart, — carry blood toward the heart
arteries; veins
contact tissue cells and directly serve cellular needs
capillaries
wall of arteries and veins are composed of three tunies
tunica externa, tunica media and tunica interna (intima)
tunics
wall has 3 layers
tunica externa
- outermost layer
- collagen fibers protect reinforce vessels
- larger vessels contain vasa vasorum
- thicker wall vein compared to an artery
tunica media
- middle layer
- contains smooth muscles and may contain elastic fiber layer makes external elastic lamina
- controls vasoconstriction/vasodilation of vessels
tunica interna
- flat cells make endothelial lining (endothelium)
- produce basement membrane
- may contain internal elastic lamina
- veins contain valves inside
arteries
- larger vessels
- mostlu contain oxy blood
- wall has 3 tunies
2 types of arteries
elastic (conducting) arteries and muscular arteries
larger arteries
elastic (conducting) arteries
medium to smaller arteries
muscular arteries
elastic arteries
- thick-walled arteries near heart
- large lumen allow low-resistance in blood flow
- contain elastic fiber in all three tunics
- withstand and smooth out large blood pressure fluctuations
- allow blood to flow smoothly
muscular arteries
- branches of elastic arteries
- deliver blood to body organ
- have thick tunica media with more smooth muscle and less elastic tissue
- active vasoconstriction
atrioloes
- divisions of arteries
- collect blood from arteries and drain it to capillaries
capillaries
- microscopic blood vessels
- wall consists of endothelium and basement membrane
- exchanges carbon monoxide, oxygen, waste, and nutrient with tissue
- smallest blood vessels
- cosisting a thin tunica interna, consists a single layer of endothelial cells
on the outer surface help stabilize capillary walls
pericytes
contractile cells that wrap around the endothelial cells of capillaries and venules
pericytes (rouget cells or mural cells)
are abundant in the skin and muscles
continous capillaries
fenestrated capillaries
- absorption or filtrate formation occurs
- endothelial cells contain fenestrae (windows or pores)
- greater permeability solutes and fluids
sinisoids
- fenestrated capillaries with large lumens
- phagocytic kupffer cells
- found in liver, bone marrow, lymphoid tissue and some endocrine organs
- large molecules (proteins and blood cells) pass between blood and surrounding tissue
- blood flows sluggishly
capillary beds consist of two types of vessels
vascular shunts and true capilliaries
consist of metarteriole–thoroughfare channels connecting an arteriole directly to a venule
vascular shunts
10 to 100 per capillary bed
true capillaries
precapillary sphincter
- smooth muscle between arteriole and capillary
- controls flow of oxy blood to capillary
venules
- capillaries unite to form venules
- venules carry deoxy blood to veins
veins
- venules together make veins
- carry deoxy blood to heart
- has all 3 tunics
vascular sinus
- veins without smooth muscle
- cannot contrict or dilate
- fixed diameter
vascular anastomoses
- special interconnection of blood vessels to ensure blood supply
- organs receive blood from more than one arterial branches
- arterial anastomoses
- e alternate pathways for blood supply called collateral channels
blood pressure
- pressure created by blood on wall of blood vessel
- force per unit area on blood vessel wall
- clinically pressure of an artery
120 mm Hg
systolic pressure
80 mm Hg
diastolic pressure
100 mm Hg
mean systemic pressure
40 mm Hg (difference between systolic and diastolic pressure)
pulse pressure
93 mm Hg (= Diastolic pressure + Pulse pressure/3)
mean arterial pressure
force of friction between the blood and the wall of a blood vessel
resistance (R)
higher blood viscosity will cause higher resistance
blood viscosity
the longer the vessel, the more the resistance
length of vessel
the more the radius, the less the resistance
radius of vessel
capillary exchange
- blood flow through capillary is not constant, its intermittent
- due to vasomotion
- contraction and relaxation of precapillary sphincter (occur between 5-20 times per minute)
- during exchange process between blood and tissu, some fluid protein leave blood tissue space capillary wall
- part of fluid returned blood
4 pressure systems control this exchange process:
- blood hydrostatic pressure (bhp)
- interstitial fluid hydrostatic pressure (ifhp)
- blood osmotic pressure (bop)
- interstitial fluid osmotic pressure (ifop)
blood hydrostatic pressure (bhp)
- takes fluid out from the blood to the tissue
- BHP= 30 mm Hg at the arterial end and 15 mm Hg at the venous end of the capillary
interstitial fluid hydrostatic pressure (ifhp)
- tends to move fluid from the tissue to the blood
- IFHP is considered to be 0 at both ends of the capillary
blood osmotic pressure (bop)
- tends to move fluid back to the blood
- BOP= 28 mm Hg at both ends
interstitial fluid osmotic pressure (ifop)
- moves fluid from blood to the tissue
- IFOP= 6 mm Hg at both ends
systolic pressure below 90 mm Hg
hypotension
due to vasoconstriction of skin blood vessels
pale, cool skin
due to increased ADH
reduced urine production
increased lactic acid
acidosis
- increased heart rate
- due to inccreased epinephrine
tachy cardia
reduced cardiac output
weak pulse
