Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

FBS2 PPoS > CV1 > Flashcards

CV1 Flashcards

1
Q

what is the siphon principle

A

blood will continue to flow at a constant rate (standing or lying) if pump pressure is more than outflow presure
aka pressure in LV > RV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

on what basis will flow rate not chnge

A

if tubes are rigid and in a closed system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

mean capillary pressure at supine

A

30mmHg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

mean arterial and venous pressures in supine position:
outflow from heart
flow into heart
pressures at feet (artery and vein)

A

outflow = 100mmHg
inflow = 4mmHg
feet arterial = 96
feet veous = 10

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

mean arterial and venous pressures immediately after standing:
outflow from heart
flow into heart
pressure at feet (artery and vein)

A

outflow = 11 mmHg
inflow = 1 mmHg
feet arterial = 186
feet venous = 100

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what’s happens in the feet after standing

A
  • capillary pressure (hydrostatic) increases due to pressure by column of blood
  • more filtration = swell
  • pressure gradient is the same: all pressures increase by same amoung
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

main events that occur during orthostasis

A
  • decrease CO

- loss of plasma volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

why does CO decrease during orthostasis

A
  • venous valves in lower limb shut transiently so blood flow out of heart > going in
  • excess CO in veins for 45secs (300-500ml more)
  • increase pressure in veins = open valves
  • CVP reduced by 3mmHg so Frank starling = CO falls
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

why does plasma volume fall during orthostasis

A
  • no change in oncotic pressure

- hydrostatic > oncotic so more outflow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

describe the mechanism limiting effects of orthostasis by symp system and veno-arteriolar reflex

A
  • blood pools at feet - lower CO, stoke vol, flow to brain and MABP in the upper body
  • activate baro and volume (in heart) receptors
  • sympathetic: vasooconstriction, raise HR and TPR
  • local axon reflex: baro in veins sense distention = signals to arteriolar muscle to constrict
  • reduce capillary pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

describe the mechanism limiting effects of orthostasis physically

A

skeletal muscle pump

  • aids venous return
  • lower venous pressure to 20-30mmHg so therefore reduce capillary pressure behind
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

consequence of valve failure

A

more oedema

  • fail in veins next to muscle exposes them to high pressure = not empty =
  • varicose veins: remain distended
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what happens to the vein above heart on standing

A
  • veins outside craium collapse due to low pressure (flow through side margins to prevent sub-zero pressure)
  • arteriovenous pressure gradient falls (drives cerebral perfusion)
  • cerebral blood flow decreases by 20% on standing = faint
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what happened to veins in the cranium on standing

A
  • stay open
  • gravity causes downwards displacement of CSF in subarachnoid space so -ve intracranial pressure
  • expands bran and keeps veins open
  • negative pressure WITHIN vein = air embolism opened during surgery
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q 
how does the following change from supine to upright:
central blood vol
CVP
stroke vol
HR
CO
cerebral flow
A 
CBV: -400ml
CVP: -3 mmHg
stroke: -40%
HR: +25%
CO: -25% (net)
cerebral: -20%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what progressively happens with prolonged standing

A

progressive. ..
- venous poling
- fall in pulse presure
- rise in HR and TPR
- fall in mean pressure

17
Q

what suddenly happens in prolonged standing

A
  • fall in TPR (vasodilate)
  • fall in HR
  • steep fall in BP and cerebral blood flow results in syncope (faint)
18
Q

what is vasovagal syncope

A

vasodilation

vagally mediated bradycardia

19
Q

describe response of CV to exercise: describe the muscle energy sources

A
  1. immediate: muscle ATP and phosphocreatine
  2. non-oxidtive: anaerobic glycolysis , glycoen–> lactate
  3. oxidative: aerobic metabolism. uses glc, lacate and FA. Increase O2 to muscle, prolonged
20
Q

what is VO2 max

A

measure of ones ability to do exercise

reach max = small increase can e done anaerobically

21
Q

eqn for O2 consumption

A

CO x (arterial - mixed venous O2 content)

= CO x (mls blood delivered to tissue) - (mls O2 rmoved from each ml blood)

22
Q

what is O2 consumption determined by

A
  • O2 delivered to tissues

- what the o2 extract (used up)

23
Q

eqn for arterial O2 conc and what can affect this

A

[Hb] x arterial O2 saturation x 1.34

unaffected by exercise or fitness

24
Q

what happens to venous o2 content during exercise

A
  • falls as intensity increases

- can’t fall below certain level to maintain capillary pO2 to drive diffusion from blood to muscle (slow enough0

25
Q

what happens to CO with exercise

A

progressively increases as intensity increases

-max CO is the main factor for VO2 max

26
Q

what is the main control centre for CV adjustments to exercise

A

nucleus tract solitarii

27
Q

eqn for max HR

A

is relatively independent of fitness but dependent on age

= approx. 220-age

28
Q

eqn for BP

A

CO x TPR

29
Q

what happens to systolic and diastolic p with dynamic exericse

A

sys increases

dias changes less

30
Q

describe main ways to control regional flow in active muscle

A
  • vasodilationa and more capillaries open
  • due to local metabolites effects on vasular muscle (CO2, less O2, inc H, inc ADENOSINE - via endothlium)
  • opposed by symp vasocosntrit
31
Q

describe main ways to control regional flow in inactive muscle and splanchnic circulation

A

sympathetic vasoconstrict

32
Q

describe main ways to control regional flow in skin

A
  • initial vasoconstrict (symp) followed by vasodilation due to inc in temp
  • maximim exercise: vasoconstrict
  • net effect: fall in TPR
33
Q

why is increase in CO also needed during exercise

A

redistribution by vasoconstruction is not enough - increase muscle blood flow

34
Q

what is the increase in stroke vol due to exercise caused by

A

inc CVP, inc skeletal muslce pump – frank straling

-enhanced emptying (sympathetic - increases contractiliy) so greater ejection fraction

35
Q

describe changes to BP and HR with isometric exercise. when wil these changesbe seen

A

> 20% maximalvoluntary contraction (MVC)

  • progressive rise in BP and HR
  • systolid and dias both increase
  • BP rise is greater than in dynamic exercise and does not plateau
36
Q

net effect of dynamic exercise

A

-little diastolic change
inc in systolic
mean BP moderately increases

FBS2 PPoS (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions