circulation pt2 Flashcards
what is the Frank-Starling effect?
an increase in end-diastolic volume (blood in ventricle during diastole, before contraction) results in a more forceful contraction and increased SV (stroke volume)
length-tension relationship for muscle
heart automatically compensates for increases in volume of blood returning to the heart (AUTOREGULATION)
more blood enter ventricle, more forceful contraction (increase SV, more blood leave ventricle)
what would happen if the Frank-Starling effect did not occur?
blood would pool, large amounts of venous blood will be stuck in ventricle bc increased venous blood are entering the ventricle but blood leaving the ventricle remains the same
(more blood enter than leave ventricle)
level of sympathetic activity shifts the position of…
the cardiac muscle length-tension relationship
(stroke volume will be higher during increased sympathetic activity compared to basal level, even when end-diastolic volume are the same)
how do arterioles control blood distribution
arranged in parallel so can alter blood flow to various organs
by vasoconstriction of vasodilation (change resistance)
factors that control vasoconstriction and vasodilation
autoregulation (direct response of arteriole smooth muscle to blood pressure)
intrinsic factor (metabolic rate of tissue)
extrinsic factor (nervous and endocrine systems)
what are the 2 organs that receive the highest percentage of blood in humans?
why?
liver + digestive tract
kidneys
bc they detoxify blood
contraction of what reduces blood flow to capillary bed?
why do they want to reduce blood flow to certain areas?
contraction of pre-capillary sphincters
reduce tissues that are not being used and bring blood to tissues that need them more
what are some myogenic autoregulation of flow
smooth muscle cells in arterioles are sensitive to stretch and contract when blood pressure increases-> to keep things constant
(negative feedback loop, prevents excessive flow of blood into tissue) may have pooling in tissues without this response
what is the process for blood flow to match to metabolic requirements?
tissue metabolic rate up
O2 down, CO2 up, waste up
arteriolar smooth muscles sense this
vasodilation
resistance down
blood flow up
O2 delivery up, CO2 removal up, waste removal up
tissue O2 up, tissue CO2 down, waste down
(negative feedback loop)
hormones that cause vasoconstriction
Vasopressin (ADH) from posterior pituitary
Angiotensin II in response to decreased blood pressure
norepinephrine from sympathetic neurons
hormones that cause vasodilation
decreased sympathetic tone (norepinephrine)
atrial natriuretic peptide (ANP) in response to increased blood pressure
why does pressure and pulse decrease in arterioles
due to high resistance
how does the aorta act as a pressure reservoir
with elastic vessel wall, expands during systole and recoil during diastole
dampens pressure fluctuations
what is vein volume controlled by
sympathetic nerves-> venomotor tone
which contains more volume of blood vein or arteries
veins
what are the 2 pumps that assist in moving blood back to heart?
why do they need the pumps?
skeletal muscle (contraction of muscle squeezes vein) and respiratory pumps (pressure changes in thoracic cavity during ventilation)
because blood in veins is under low pressure
equation for mean arterial pressure
MAP = CO * TPR
CO= cardiac output
TPR= total peripheral resistance
what are baroreceptors?
where are they found?
what do they do?
stretch-sensitive mechano receptors in walls of many major blood vessels
in carotid arteries and aorta
send nerve signals to cardiovascular control center-> regulates MAP
how do kidneys help maintain blood volume?
excrete or retain water to adjust blood volume and pressure
what is the starling principle?
net filtration pressure = (Pcap - Pif) - (picap - piif)
Pcap= hydrostatic pressure of blood in the capillary
Pif= hydrostatic pressure of interstitial fluid
picap= osmotic pressure in the capillary
piif= osmotic pressure interstitial fluid
what is osmotic pressure caused by?
what does it do?
salts and proteins in solution
if osmotic pressure is higher in interstitial fluid than capillary, fluid will enter the capillary
what does capillary hydrostatic pressure do?
why does capillary hydrostatic pressure decrease over time?
forces fluid out of capillaries
bc of resistance
describe the osmotic pressure in capillary over time
stays the same
describe filtration and reabsorption as blood travels from aortic end to venous end
aortic end: pressure in capillary higher than osmotic pressure, fluid moves out of capillary-> net filtration
venous end: pressure in capillary lower than osmotic pressure, fluid enters capillary-> net reabsorption
what does the lymphatic system do?
collects excess filtered fluid and returns it to circulatory system
what do lymph nodes do?
filter lymph to remove pathogens
what is edema?
accumulation of interstitial fluid
equation for hydrostatic pressure
delta P = rho * g * delta h
how do body positions alter blood pressure and flow?
changes relative to gravity
standing up causes pooling of blood in lower body
(venous return down, SV down, MAP down)
what can bring the MAP back to normal when standing?
baroreceptor reflex
HR up, SV up, MAP up
what is orthostatic hypotension
low blood pressure upon standing when reflex is too slow
can result in fainting
what are some adaptations the giraffe has to overcome hydrostatic pressure?
very strong heart w/ low stroke volume and fast heart beat that generates super high MAP
muscular arteries
skin on legs very tight
tight endothelium
venous valves
how does hydrostatic pressure impact animals in water
blood and water have a similar density and hydrostatic effects outside the animal cancel out the gravitational effects
steps of tissue regeneration
wound healing
blastema formation
cells differentiate and tissue regeneration
what are the steps to wound healing
hemostasis
inflammation and proliferation
remodeling/ maturation
in humans, which organs can regenrate?
liver
organs such as thyroid gland, kidney, lungs have facultative regeneration (depend on type of damage and severity)
in the study, gill regeneration was higher in which treatment for the gills?
50% resection gills had higher levels of regeneration
(compared to 30% resection)
