blood vessels Flashcards
vaso vasorum
small blood vessels that supply blood to the cells of the walls of the arteries and veins
tunica intima
simple squamous epithelium know as endothelium, basement membrane, internal elastic lamina
tunica media
circular smooth muscle & elastic fibers
tunica adventitia
elastic & collagen fibers
endothelium layer
selectively permeable barrier to material entering or leaving the bloodstream
what are the functional properties of arteries?
elasticity & contractility
elastic arteries
large conducting arteries with more elastic fibers and less smooth muscle in tunica media. receive blood under pressure and propel it onward. they function as a pressure reservoir. aorta, common carotid arteries, vertebral arteries, common iliac arteries
muscular arteries
medium sized distributing arteries with more smooth muscle than elastic fibers in tunica media. capable of greater vasoconstriction and vasodilation to adjust rate and direction of flow
anastomoses
union of 2 or more muscular arteries supplying the same body region
collateral circulation
alternate route of blood flow through an anastomosis
arterioles
very small artery that branch from muscular arteries. regulate blood flow into a capillary bed through vasoconstriction and vasodilation of the arteriole
continuous capillaries
uninterrupted endothelium with intercellular clefts between neighboring cells. skeletal muscle, ct and lungs
fenestrated capillaries
plasma membranes have many small holes. kidneys, small intestine, choroid plexuses and endocrine glands
sinusoids
very large holes separate cells and basement membrane. liver and spleen. rbc and proteins
precapillary sphincter
ring of smooth muscle located at origin of each capillary from an arteriole. controls blood flow in capillary bed.
vasomotion
the intermittent contraction and relaxation of sphincters
venous return
the rate of blood flow back to the heart
diffusion
most important method of capillary exchange. substances such as O2, CO2, glucose, amino acids, hormones. all plasma solutes except large proteins pass freely across their concentration gradient
transcytosis
passage of material across endothelium in tiny vesicles by endocytosis and exocytosis. large, lipid-insoluble molecules such as antibodies
bulk flow
movement of large amount of dissolved or suspended material in same direction. move in response to pressure
filtration
blood hydrostatic pressure & interstitial fluid osmotic pressure
reabsorption
blood colloid osmotic pressure & interstitial fluid hydrostatic pressure
blood hydrostatic pressure(BHP)
fluid pressure within capillaries, tends to push fluid out
blood colloid osmotic pressure(BCOP)
generated by plasma proteins trapped in capillaries, tends to draw fluid in
interstitial fluid hydrostatic pressure(IFHP)
pressure of IF pressing on outside capillary wall, typically negligible, may become inward force
interstitial fluid osmotic pressure(IFOP)
force of osmosis created by small proteins that leaked into interstitium, pulls fluid outward
inflammation
histamines released cause vasodilation, drops BHP, favors reabsorption
hemorrhage
drops BHP, favors reabsorption
hypertension
increase in BHP, favors filtration
hemodynamics(flow of blood)
is effected by pressure(velocity of blood flow, volume of blood flow, blood pressure), peripheral resistance, venous return
blood flow
increase flow, increase BP
increase resistance, decrease blood flow
peripheral resistance
the opposition to blood flow as a result of friction between blood and the walls of the blood vessels. depends on diameter, blood viscosity & blood vessel length.
directly proportional to BP
volume of blood flow
CO
increase BP, decrease volume
velocity of blood flow
speed of blood flow in inversely related to cross sectional area of blood vessels
blood pressure
pressure exerted by blood on walls of vessel
systolic BP
peak arterial pressure
@ ventricular contraction
diastolic BP
minimum arterial pressure@ ventricular relation between heartbeats. provides information about systemic vascular resistance
pulse pressure
difference between systolic & diastolic. provides measure of stress provided on small arteries by pulse
autoregulation
the ability of a tissue to automatically adjust its own blood flow to match its metabolic demand for supply of O2 and nutrients and removal of waste. tissue secrete NO, relax precapillary sphincters, lower BP
carotid sinus reflex
maintains normal BP in brain
aortic reflex
maintains general systemic BP
angiotensin II
vasoconstrictor stimulates thirst Stimulates adh(increased water absorption at kidney stimulates aldosterone(increased Na &H2O reabsorption by kidneys)
epinephrine(also norepinephrine)
directs blood from skin and abdominal organs to the skeletal muscles.
increase HR,SV,CO, thus increases BP
ADH(vasopressin)
targets kidneys to retain water, also stimulates vasoconstriction at high levels
atrial natriuretic peptide (ANP)
stimulates vasodilation, increase Na and water loss, antagonizes aldosterone, inhibits thirst
lowers blood volume—>lowers blood pressure
portal systems
blood flows through two connective capillary networks before returning to the heart. bypasses circulation. transports products of one region directly to another region
aneurysm
weak pt in an artery of in the heart wall. it forms a thin walled, bulging sac and may eventually rupture. caused by arteriosclerosis(hardening of the arteries) and hypertension
hydrostatic pressure
the physical force exerted by a liquid against a surface
colloid osmotic pressure
is a form of osmotic pressure exerted by proteins in a blood vessel’s plasma that usually tends to pull water in. It is the opposing force to hydrostatic pressure
vasomotor tone
vessels in a state of partial contraction. maintains the diameter of the blood vessels and therefore is important in maintaing blood pressure.
increase sympathetic ns–>increase VT
increase parasympathetic ns–>decrease VT
