Blood Vessels Flashcards
arteries
away from heart
elastic arteries
from the heart; largest in diameter; not resistant; walls have elastic connective tissue
Dont scrub pressure away
Walls bounce back and push blood forward
muscular arteries
more smooth muscle tissue
tunica interna
superficial layer, lines the lumen and made of simple squamous ET; smooth flat surface
Capillaries only have this!
tunica media
middle layer, made of smooth muscle, can contract
SNS uses NE to stimulate vasoconstriction
Can change diameter nervously and chemically
tunica externa
outermost layer, CT, lots of collagen; anchors blood vessels in place
vasa vasorum
blood vessels in walls of thick walled blood vessels
continuous capillaries
most common, almost everywhere
Endothelial junction= liquid transport
Pinocytic vesicles= transport liquid
fenestrated capillaries
tiny hole, more permeable, greater amount of exchange, but still not big things
ie) kidneys, endocrine organs, intestines
sinusoidal capillaries
big holes so proteins, cells, etc. can pass through
ie) spleen, liver, bone marrow
terminal arteriole
deliver blood
metarteriole
shortcut on arterial side
thoroughfare channel
short cut on venue side
post capillary venule
receiving end
vascular shunt
total shortcut
true capillaries
paths around
pre capillary sphincters
regulatory structure
microcirculation controller
artery characteristics
Thick walls Small lumen Thicker tunica media Lower blood volume Higher blood pressure No valves
vein characteristics
Thin walls Large lumen Thinner tunica media Higher blood volume At anytime more blood in veins Lower blood pressure Venous valves Fight gravity mechanism to get blood back to the heart
muscular pump
muscle pushes into blood vessels and assists blood movement
respiratory pump
veins closest to heart have lowest pressure; pressure differentials in breathing
collateral channels
alternate pathways
blood flow
volume of blood flowing through body at any time
Constant but where it goes can change
Directly proportional to difference in BP (greater difference, more blood goes there)
Inversely proportional to peripheral resistance (opp of flow due to friction)
peripheral resistence
opposition to flow
mean arterial pressure
diastolic pressure/ (pulse pressure/3)
counteracting brief fluctuations
change blood flow in capillaries; in response to needs
Increase by opening true capillaries
Alter vessel diameter
vasomotor center
in medulla sympathetic nerve fibers use NE and cause smooth muscle contraction
vasomotor tone
cause blood vessels to be partially contracted; allows for more dilation
Neural reflex arcs
neural reflex arcs
Baroreceptors detect change in pressure as it flows out of heart
Vasomotor center inhibited
Peripheral resistance and pressure reduced
chemical reflex arcs
Chemoreceptors detect drop in oxygen level or ph or increase in CO2
Cardioacceleratory center stimulated
Increase heart rate
Pump blood faster for more exchange
Vasomotor center stimulated
Vessels constrict
Blood pressure increases
ANP
Increase in stretch causes ANP increase in urine output, changing blood pressure and volume
ADH
Posterior pituitary
Affect kidney
Increase blood volume, stimulated by low BP
angiotensin 2
Cause vasoconstriction
Aldosterone
Low BP → renin → angiotensin II
Increase in BP leads to decrease renin
endothelium derived factors
chemical produced by blood vessels
inflammatory chemicals
histamine
decrease BP
alcohol
Low blood volume and blood pressure
Inhibits ADH and vasomotor center
Cause vasodilation
Cause direct dilation of blood vessels
nicotine
same effect as NE and E
direct renal mechanism
increase in blood pressure or blood volume speeds up filtration rate in kidneys
Greater urine
indirect renal mechanism
renin angiotensin mech.
Decrease in BP causes kidneys to release renin
Renin stimulates angiotensin II production
Angiotensin II stimulates aldosterone production
Blood pressure rises
tissue perfusion
Matches need If needs change then blood supply can change Delivers oxygen and nutrients to tissues Removes wastes from tissue Exchanges gases in lungs Forms urine in the kidneys
blood velocity
speed; inversely related to cross-sectional area of vessels and regulated locally by modifying diameter of arterioles
metabolic mechanism for blood velocity
Low levels of nutrients or oxygen cause vasodilation and relaxation of precapillary sphincters
Based on needs
myogenic mechanism for blood velocity
Changes in stretch of vessel causes response in smooth muscle of vessel
angiogenic mechanism for blood velocity
Angiogenesis increases number and size of vessels
LT effect; angiogenic
Production of new blood vessels (mostly capillaries)
how things pass through capillaries
Respiratory gases and lipid soluble molecules pass via direct diffusion
Water soluble solutes pass through intercellular clefts and fenestrations
Large molecules pass through caveoli
Fluids pass through pinocytic vesicles
capillary fluid dynamics
Fluid forced out through clefts at arterial end
Most returns at venous end
Flow regulated by balance between hydrostatic pressure and colloid osmotic pressure
Colloid is accumulation of proteins
hydrostatic pressure
force exerted by fluid pressing against a wall
Capillary hydrostatic pressure drops along length of capillary bed
colloid osmotic pressure
force created by presence of large, nondiffusible molecules
Functions in opposition to hydrostatic pressure
Does not vary along length of capillary bed
net filtration pressure
Interaction between hydrostatic and colloid osmotic pressures
Determines if there is a net gain or loss of fluid from capillaries
Major regulator is blood pressure
Net flow out of capillary
portal system
Extra set of capillary beds
Veins to capillaries to veins
Serves specific regional tissue needs
circulatory shock
can’t circulate blood properly
hypovolemic shock
lose too much blood
vascular shock
vasodilation
low BP
blood won’t flow properly
cariogenic shock
heart attack
pump not working properly
blood vessel development in fetus
Mesoderm cells form the endothelial lining of blood vessels
These collect as blood islands
Connect to form vascular tubes
Platelet-derived growth factor signals mesenchymal cells to form muscular and fibrous coats
