Lecture 4

Question 1

Preload/frank starling law of the heart

intrinsic reg

volume vs force relationship

Answer 1

the heart will pump whatever blood it receives
volume in = volume out

intrinsic reg bc properties related to heart and how much it fills

filled too much = stretched too much = not enough overlap of actin and myosin to contract
resting = too much overlap, no room to slide back
sweet spot = overlap is minimal but a lot of room to slide

Question 2

afterload

Answer 2

P vents must overcome to open valves and eject blood from heart
ex. P in vent must be higher than P In aorta to push blood out

Question 3

extrinsic influences on SV

Answer 3

change contractility w/o changing EDV

increased Ca influx
1. sympathetic stimulation = inc strength of contraction and rate of contraction + relaxation( to fill up)
2. drugs = digoxin = inc heart contractility
dec number of beats but stronger
as opp, to many but lower SV

Question 4

how norepinephrine inc heart contractility via cyclic AMP

Answer 4

NE beings to receptor
activates G protein
G protein activates enzyme that turns ATP to cAMP
cAMP activates protein kinase
which phospohoralates Ca channels in mb + in SR
which inc release from SR + ECF
so inc Ca conc= inc Ca binding to troponin
inc cross bridge binding for contractions
= inc force of contraction

Question 5

flow fo blood through vessels

Answer 5

arteries
arteroiles
cappilaries
venules
veins

arteries carry blood away from heart
veins carry towards heart
caps directly serve cells

Question 6

layers of arteries

Answer 6

inner to outer

Tunica Intima =
endothelium
subendothelial layer
internal elastic mb (bc they stretch = veins don’t have bc don’t stretch)

Tunica Media
external elastic mb

Tunica externa
vasa vasorum = small network that serves the walls of the vessels to meet the needs of the cells of that vessels

***muscles are thicker in arteries

Question 7

layers of veins

Answer 7

Tunica intima =
endothelial
sub endothelia layer
NO ELASTIC ON MUSCLE

tunica media

tunica externa *
vasa vasorum

• thicker in veins

Question 8

layers of caps

Answer 8

has endothelial cells
basemenent mb

don’t want thick barriers,
but pores thin enough for exchange to occur

Question 9

3 types of arterial vessels

Answer 9

elastic/conducting arteries
musclular/distributing artereis
arterioles

Question 10

elastic/conducting arteries

Answer 10

thick walled
large diameter near heart
biggest # of elastin
regulates P fluctuations,
recoil helps maintains pressure + flow of blood

Question 11

musclular/distributing artereis

Answer 11

delivers blood to specific organs/tissye
controls how much goes where

more smooth muscle than elastin =
allows it to regulate diameter
dilate = more blood sent to certain location/pathway
contract = less blood sent

Question 12

arterioles

Answer 12

smaller diameter
tunica media primarily smooth muscles
det whcih capillary beds get access, minute to minute

ex. when excercising, more to muscles

one layers, or deccccc of layers

Question 13

3 types of capillaries

Answer 13

continuous capillaries
fenesteres capillaires
sinusoidal capillaires

least to most leaky

Question 14

continuous

Answer 14

least leaky, not much exchange

in skin, muscle, brain
endothelial cells linked by tight ins = uninterrupted lining
are intercellular cleats that allow limited passage of fluids + small solutes, NOT IN CNS

Brain is kept separate, minimize infections

Question 15

fenestered

Answer 15

similar to above but endothelial cells are riddled w pores (fenestrations)
inc permeability to fluids/small solutes

small int. endocrine organs, kidneys

Question 16

sinusoidal caps

Answer 16

leakiest
fenestered, fewer tight ins, large clefts for passage of proteins, RBC,

liver, bone marrow, lymphoid tissue,

Question 17

microcirculation

Answer 17

flow of blood from arteriole to venous via cap. bed

flow is det/reg by diameter of terminal arteriole
contract if movement not allowed

Question 18

veins

Answer 18

blood reservoirs that return blood to heart
have 65% of blood in veins
venules
post cap venules = just endothelium
larger = couple layers of smooth muscles

veins = 3 tunics but thinner walls and larger lumens

less smooth muscle in tunica media, less elastin,

Question 19

blood flow

Answer 19

measured ml/min
can be regulated independently for various organs + tissues
reg for what body needs

Question 20

blood pressure

Answer 20

force per unit area exerted on walls of a blood vessel by its contained blood

travels to a pressure gradient, high to low

Question 21

blood pressure drops as it travels through he body bc of

Answer 21

resistance, in vessels, against the walls

a dec in blood vessel diameter inc resistance to 4th power.

Question 22

resistance = R

influences by

Answer 22

total of frictional forces that slow flow
flow and R are inversely related

influenced by
viscosity
vessel length
vessel diameter

Question 23

how does viscosity affect R

Answer 23

inc viscosity bc of formed elements
dehydrated, blood doping
not a natural change

Question 24

vessel L

Answer 24

more cumulative resistance
for ex if put on weight = inc # of tissue that has to be vascularize
more length = more workload = big enough push to go through entire length

Question 25

vessel Diam

Answer 25

can be reg, if more fluid not touching walls moves faster since less R

Question 26

pulse pressure

Answer 26

vigrot of contraction of ventricles provides information on elasticity of aorta and major arteries- how? bc aorta + large vessels branch out won't stretch, so sys bp inc won't recoil as much so won't move fwd as much so diastole bp Inc

Question 27

mean arterial pressure = MAP

Answer 27

pressure that propels blood to tissue during cardiac cycle dec w distance from heart by end of arterial tree, blood flow is steady and pulse pressure has disappeared

Question 28

capillary blood pressure

Answer 28

low P, bc are fragile, High P would rupture them most caps are extremely permeable, so lots of exchange at low bp

Question 29

venous bp

Answer 29

steady and changes slightly during cardiac cycle is a gradient, and veins will provide more open paths so blood will keep moving fwds

Question 30

factors aiding venous return

Answer 30

venous valves + muscular pumps respiratory pump sympathetic venoconstriction

Question 31

venous valves + muscular pumps

Answer 31

muscles in legs, contract + push on outside of veins, push upwards, when sitting/stadnig, is harder bc of gravity could get fluid+ blood pooling/buildup so moving helps blood move

Question 32

resp pump

Answer 32

as it travels from Lower limbs to heart passes though visceral organs, past lungs as we breath = P changes occur inc P = squeeze on vessels going up/fwds dec P = pulls blood up on last part twas R atrium

Question 33

sympathetic venoconstriction

Answer 33

bc 60% in venous sys SNS = stim contraction fo smooth vessels in veins to push on blood pushing it fwds push makes 60% move more quickly to start circulating

Question 34

pulse

Answer 34

P wave bc of expansion and recoil of arteries to find pulse, push surface artery against firm tissue

Question 35

pressure points

Answer 35

if lots of blood loss, press on pressure points to reduce blood loss,

Question 36

blood pressure usually measured in + numbers

Answer 36

usually measured in brachial artery Systolic P = 120 pressure ejecting blood Dyastoic P = 80 filling in

Question 37

short tem vs long term reg of BP

Answer 37

works w total peripheral R (blood vessel d) and CO vs works w blood volume = level of kidney

Question 38

main goal of ST reg

Answer 38

alter blood distribution to specific demands maintain adequate MAP by altering bed reflex arcs involving = baroreceptors, vasomoto centre, vascular smooth muscles b= measures amount of stretch, thrfr measures bp vsm = smooth muscles of vessel reg d of vessels more contracted vs relaxed

Question 39

vasomotor tone + vasomotor centre

Answer 39

vasomotor centre = cluster of sympathetic neurons in medulla part of cardiovascular centre = responds to baroreceptor, chemoreceptors, higher brain centres vasomotor tone = constant output = low levels of SNS output, can be opened/closed as needed inc in sympNS = vasoconstriction, inc in bp, dec = reverse, esp in GI system, can fn w less blood flow

Question 40

baroreceptors

Answer 40

in carotid sinuses, aortic arch, and other large arteries of neck and thoracic, = monitor bp when MAP inc, it stretch receptors, so response is 1. dilate arteriles = keep bp under control so won't get too high 2. venodilation to shift blood to venous reserves 3. stimulate paraNS and inhibit symp N, dec HR + froce. communicate w heart to slow it down, push less forcefully, to bring bp closer to what it should be when MAP dec. = opp reponses

Question 41

goal of baroreceptors

Answer 41

protect against ST changes in bp bc of changing positions ineffective in chronically, so if chronically have high bp, body will stop trying to Lowe it and body will be used to having high bp vales

Question 42

chemoreceptor initiated refelces

Answer 42

causes = drop in O2, rise of Co2, drop of pH chemoreceptors in aortic arch + large arteries of neck to vasomotor centres = vasoconstriction result = inc in bp, speeds return of blood to heart and lungs

Question 43

influences of higher brain centres

Answer 43

Fight of flight, stress, excretes, cerebral cortex and hypothalamus get involved bc you are aware

Question 44

Hormones of ST reg of bp

Answer 44

Adrenal medulla hormones = E/NE, Fi/Fl increase cardiac output vasocontriciton *same as activating sympNS angiotensin II intense generalized vasocontriciton ANP made by atria of heart when bp is too high dec bp by vasodilation ADH = mostly for LT, but if insanely low bp, more ADH is released, high levels cause vasoconstriction

Question 45

kidneys and LT regulation of Bp

Answer 45

adjust blood volume, a more complete response, but longer

Question 46

direct action

Answer 46

inc blood volume = inc bp = in rate of filtrate formation = not enough time to reclaim water = inc volume of urine

Question 47

indirect action

Answer 47

renin-angiotensin system is MAP dec = kidney cells release renin = eventually leads to producing angiotensin II a vasoconstrictor angiotensin II stimulates release of aldosterone aldosterone = inc renal absorption of Na so inc water absorption also sit release of ADH = inc water absorption inc thirst via hypothalamus constricts vessels