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KP322 > circulatory system > Flashcards

circulatory system Flashcards

1
Q

2 major adjustments to BF during exercise

A
  1. inc CO…move more blood out of heart/min
  2. blood flow redistribution to active tissues
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2
Q

SA node

A

sets heart rate at rest

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3
Q

resting heart rates of diff ppl

A

avg = 70bpm
trained = 60bpm
elite athletes = 50bpm

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4
Q

what determines heart rate at rest vs at exercise

A

at rest:
- ventricles eject 2/3 volume
- HR 70-75bpm
- SA node determines rate

at exercise:
- HR max abt 180bpm
- dec cardiac cycle, short phases
- HR steadily inc w exercise, indicates intensity

if HR is low for high workload, indicates heart efficiency

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5
Q

PNS and SNS during exercise

A

initial HR increase: due to PNS withdrawal
- rest to 100bpm (SA node)
- PNS fibres release Ach, which causes hyperpolarization…makes it harder to depolarize
- PNS slows HR, so withdrawal causes initial inc

continued HR increase: from SNS activity
- cardiac accelerator nerves allow SNS to inc HR

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6
Q

max HR calc

A

220 - age in yrs (+/- 12_

= 208 - (0.7 x age)

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7
Q

heart rate variability

A

standard deviation of peak to peak interval over period of time

sympathovagal balance: balance b/w PNS and SNS

wide variation = healthy
- low HRV = predictor of CV morbidity and mortality
- patients w CVD have low HRV

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8
Q

myocardial cells

A

contract tgt to generate enough force
- act as single unit

greater force of contraction = more blood pumped

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9
Q

stroke volume

A

volume of blood pumped by ventricles/beat

SV = EDV - ESV

EDV: end diastolic vol, volume in ventricles at end of diastole

ESV: end systolic volume

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10
Q

what determines stroke volume

A
  1. EDV: found by frank and starling…aka pre-load
    - as ventricle stretched, SV inc bcs inc actin-myosin overlap
    - venous return: amount of blood returning to blood, alters EDV
  2. vascular resistance: aortic pressure, aka afterload
    - ability of vascular system to receive SV
    - as resistance dec, SV inc
    - arteriole vasodilation will dec afterload, makes it easier for arterial system to receive blood
  3. contractility: force of heart contraction
    - altered by circulating SNS catecholamines (NE and E)
    - inc NE/E will inc contractility…inc SV
    - also inc EDV
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11
Q

what affects EDV

A
  1. vasoconstriction: inc pressure on venous system, pumps blood
  2. muscle pump: musc contract and send blood to heart
  3. respiratory pump: pressure in veins less than in lungs, blood moves down gradient to heart
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12
Q

effects of exercise

A

inc EDV, dec ESV
inc BF

increases SV until PLATEAUS at 40-60% vo2max
- endurance athletes can have stroke vol 2000ml/beat

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13
Q

cardiac output

A

Q/CO = HR X SV

in L/min

reflects functional capacity of CV system

amount blood pumped/beat

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14
Q

what regulates blood flow in capillaries

A

scphincter constriction/relaxation
- opens capillaries to inc BF

factors affecting it:
1. driving force of increased local BP, intrinsic neural control
2. local metabolites

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15
Q

how is arterial blood pressure expressed

A

systolic BP/diastolic BP

i.e. 120/80

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16
Q

pulse pressure

A

SBP - DBP

i.e. 120 - 80 = 40

17
Q

MAP

A

mean arterial pressure
- avg pressure during cardiac cycle

MAP = DBP + 0.33(SBP - DBP)

equation doesn’t work during exercise bcs based on timing of cardiac cycle

18
Q

how is blood pressure regulated

A

short term:
1. SNS
2. baroreceptors: on aorta and carotid artery
- info sent to CVCC/cardiovascular centre
- inc BP results in dec afferent info (dec Q)
- dec BP increases afferent info (inc Q)

long-term:
- via volume control in kidneys
- stimulate to either retain/increase BV, or remove blood volume
- Q helps maintain BP, which drives blood flow

19
Q

blood o2 carrying capacity

A

o2 rich blood: 20g/100ml
= 2000g of o2/L (bcs Q measured in L/min)

o2 depleted blood = 150g/L
- we don’t use much o2 at rest
- have large capacity to inc a-v o2 difference

each gram carries 1.34ml of o2

20
Q

a-v o2 difference

A

arteriovenous o2 difference

measures amt o2 taken up by tissues from blood

21
Q

fick principle

A

vo2 determined by amount of blood pumped from lungs and amount extracted from lungs

VO2 = Q x a-v o2 difference

FUNDAMENTAL CONCEPT

must convert to L/min

22
Q

what impacts blood flow

A
  1. viscosity
  2. length
  3. radius: dec radius will inc resistance

BF = delta P/R

23
Q

poiseulle’s law

A

shows that radius affects blood flow the most

vasodilation/constriction of smaller arterial BVs are mechanism to regulate regional BF
- arterioles greatest resistance

even small change can have large impact

24
Q

redistribution of blood flow

A

inactive tissues need less o2, whereas active need more
- inc Q, body “knows” where to redirect

local metabolites begin vasodilation of active tissues to inc CO

at rest: Q mainly to liver, kidneys, musc

84% to musc during exercise
- heart gets more Q, though relative amount
- brain gets more Q, though lower relative to normal

always 4-5L in body, though amount PUMPED can inc w exercise

25
Q

emotional influence on exercise

A

if emotionally charged, inc BP and HR bcs of inc SNS activity

does not impact peak HR/BP
- exercising lowers HR as emotion reduced and focus on activity

26
Q

rest to exercise to recovery

A

rapid inc in Q and HR w/in seconds

if work rate constant and below lactate threshold, will steady state

recovery depends on intensity, duration, fitness

27
Q

cardiovascular drift

A

progressive inc in HR and dec of SV
- when exercise is prolonged and in heart

insufficient venous return dec EDV
- compensates by inc HR to deal w low SV

drifts up to 20bpm
- why HR not good target
- work harder to reach lower values

classic explanation: blood flow goes to skin for cooling

new explanation: if increase b-receptor action, no drift bcs keeps HR suppressed
- w drugs

28
Q

incremental exercise and arm work

A

HR and BP recovery b/w increments

avf HR is misleading bcs impacted by rest periods
- depends on fitness, duration, intensity

arm work > leg work
- more SNS activity
- vasoconstriction during arm work keeps more blood volume in upper body

29
Q

double product/rate pressure product

A

HR x SBP

indicates work of the heart
- inc linearly w intensity

30
Q

what causes inc o2 supply

A

increased blood flow during exercise
- ONLY inc BF causes this

31
Q

effect of body position

A

blood pools into lower body when standing

if lying down, more BF in system
- dec HR, inc SV
- dec hydrostatic load

32
Q

resistance exercise

A

vascular compression, inc total peripheral resistance and dec musc perfusion

to restore BF, must inc SNS, Q, MAP

acute CV strain dangerous to ppl w heart disease

33
Q

central command theory

A

motor signal from w/in brain, changes at onset of exercise bcs of centrally generated CV motor system

signals set general pattern of CV response

34
Q

fine tuning of blood flow/CV

A

heart and muscle mechanoreceptors
chemoreceptors
baroreceptors

35
Q

sudden death in exercise

A

unexpected natural death w/in 6h of exercise
- 30% cardiac
- less than 20/yr

kids:
- genetic anomalies
- myocarditis/heart inflammation
- lethal cardiac arrhythmia

adults
- coronary artery disease
- cardiomyopathy

36
Q

protection of endurance exercise

A

regular exercise is cardio protective
- dec indicidence of MI and inc survival from heart attack

exercise dec damage from heart attack

KP322 (7 decks)

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