Exam 4: Blood Vessels Flashcards
arteries
carry blood away from heart, branch into smaller vessels, arterioles
blood vessel path with blood flow
arteries thn arterioles then capillaries, then venules, veins
vasa vasorum
network within the blood vessel wall to supply blood vessels with oxygen and nutrients
3 layers of arteries
tunica intima (interna) tunica media tunica adventitia (externa)
tunica intima
endothelium
internal elastic lamina
supported by basement membrane to receive blood and then recoil
tunica media
smooth muscle with elastic fibers
muscular layer
more elastic tissue
tunica adventitia (externa)
external elastic lamina
connective tissue outside
elastic arteries
- larger arteries of body: aorta, brachiocephalic, common carotid, subclavian, vertebral, common iliac
- tunica media: more elastic fibers, less smooth muscle
- provides P during recoil (after systole)
maintains BP in diastole!!
muscular arteries
- medium sized arteries: axillary, brachial, radial, intercostal, splenic, mesenteric, femoral, popliteal, tibial
- higher amount of smooth muscle
- regulate bloodflow to organs through constriction and dilation
structure of arterioles
- transition between arteries and capillaries
- part closest to artery: tunica intima and tunica media like the artery
- media: fewer elastic fibers
- proximal end may have a tunica externa
-part closest to capillary: endothelium surrounded by scattered smooth muscle fibers
how do arterioles regulate blood flow to tissues
precapillary sphincters
structure of capillaries
- endothelium and basement membrane
- filtration and diffusion
- most are continuous (endothelial cells tightly bound together - diffusion of gas, ions water molecules)
- fenestrated: have pores, the opening can be controlled
mainly in kidneys, intestinal villi, choroid plexus, ciliary bodies, endocrine glands
structure of venules
close to capillary: endothelium and tunica externa
near vein: shows evidence of tunica media
structure of veins
same 3 layers as arteries but thinner tunica intima and tunica media layers
- walls not as strong as arteries
- have one-way Semilunar valves to prevent backflow
- also compression from adjacent skeletal muscle helps to keep blood moving
anastomosis
connection between 2 or more vessels
2 critical arterial anastomoses
circle of Willis : around brain, surrounds pituitary
- most ppl do not have complete circle of willis
coronary anastomosis :on back of heart arteries fuse together
- if one vessel blocked or damages it can get bloodflow with collateral circulation
sinusoids
modififed capillary beds
in liver, spleen, bone marrow
what do sinusoids contain in the liver that are phagocytes involved in immune defense
Kupffner cells
what are quiescent cells in liver that activate to repair damage
stellate cells
venous sinuses
veins that have no smooth muscle
- around bone, blood flow drains into sinus
- flow fo blood keeps things moving since no muscle
- diameter can NOT be altered cannot constrict or dilate since no medial layer
- supported by dense connective tissue
blood pressure
pressure exerted by blood against vessel wall
P generated by CO and vessel resistance
P measured in arteries since they maintain the bloodflow
P sows most variability in elastic arteries
highest P is in? lowest P is in?
elastic arteries
veins - vena cava coming back to heart
clinically how is BP recorded
systolic/diastolic
120/80
systolic: 90-140
diastolic: 60-90
MAP
diastolic + (pulse pressure/3)
normal: 70-110
minimum 60 - if lower, organs not getting enough oxygen and become hypoxic
pulse pressure
systolic-diastolic
factors affecting BP (5)
- CO: primary factor; P varies with CO
- blood volume: direct proportion
- peripheral resistance: affected by blood viscosity (direct); vessel length (direct); vessel diameter (inverse)
- autonomic responses: sympathetic inc, parasympathetic dec
- hormone/chemical: epinephrine, ADH, inflammation
2 forces in capillary filtration/absorption
hydrostatic P - fluid against vessel all, pushing out
osmotic P- pullin P, solute drawing fluid toward it
NFP equation
(HPc +OPit) - (HPit + OPc)
filtration forces
hydrostatic P of capillary and oncotic P of int
absorption forces
hydrostatic P of int
oncotic P of capillary
