Brainscape's Knowledge GenomeTM

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


See full index

Physiology > WK 5+6: Cardiovascular responses to exercise > Flashcards

WK 5+6: Cardiovascular responses to exercise Flashcards

1
Q

What factors need to be controlled within Homeostasis

A
  1. Temperature
  2. Mean arterial blood pressure
  3. PCO2
  4. Glucose
  5. PO2
  6. pH
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the aim of the cardiovascular system

A
  • Get blood where its needed quickly
  • maximise availability
  • maintain homeostasis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is meant by graded response

A
  • getting the blood to where it is needed as close to the tissues that need it as quickly as possible
  • the graded response is linear as exercise intensity increases
  • the initial response is anticipatory as it takes place before exercise starts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What sets the limit to the cardiovascular response

A
  • volume of blood
  • cardiac output
  • number of blood vessels
  • ability to redistribute the flow
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is meant by central drive and where does it come from

A

Central drive causes the anticipatory rise in HR…

Central drive comes from your motor cortex, and is directly linked through to the medulla - your cardiorespiratory control centre

At the medulla you get a withdrawal of parasympathetic outflow and stimulation of the sympathetic outflow
- this causes the anticipatory rise in HR

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

what does the vagus nerve do

A

it starts off in the medulla and causes slowing of the heart - a parasympathetic response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what does the sympathetic nerve do

A

chains down the ganglia and branches off to the heart taking the epinephrine to the SA node to control the beating of the heart

It also controls the secretion of adrenaline from the medulla

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

what is the difference between the exercise response of a normal HR and the HR response after a heart transplant

A

after a heart transplant…
The anticipatory rise has gone, the response is flatter because the vagal tone isn’t actually there anymore so you have to wait for adrenaline.

The cardiac nerves have been blunted so there are no nerve interactions with your heart so the response is more gradual and is paced by circulatory factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Cardiac output values at rest and during exercise

A

At rest = 3.4/4 litres per minute

During exercise = 25-30 L.min

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

Describe the cardiac response (supply to demand)

A
  • Non-linear response, get an elevation in SV triggered by gastronomic action on the cardiac muscle itself
  • This provides an elevation of calcium current going into each cell of the heart and causes contraction
  • More current = stronger contraction
  • Also phosphorylation occurring of troponin within the cardiac muscle
  • this allows the heart to relax a bit faster
  • deeper breaths enhance cardiac return
  • … increased pressure in the thorax to hope draw blood back to the heart faster
  • contractibility increases causing stimulation of the heart and the atria contracts stronger to preload the ventricles with more blood
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Your blood is saturated with oxygen at what level of VO2max

A

40-50% VO2 max

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What causes an increase in HR in the cardiac response

A

Recruitment of motor cortex and stimulation of the medulla

& the additional component of adrenaline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

VO2 max is set by…

A

Maximal cardiac output = the amount of oxygen you can get to the tissues

arterial - venous = how much of it they can actually use

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is Ficks law/equation

A

VO2 = Q x (CaO2 - CvO2)

You can determine VO2 by sampling venous and arterial blood so you know what the difference in O2 is

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the local control factors that determine where oxygenated blood goes to…

A
  • increasing local adenosine
  • falling local pH
  • elevated local K
  • elevated local CO2
  • decreased local O2
  • increased NO
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are local control factors competing with

A

Local control factors stimulate dilation, they are in competition with the sympathetic nerve which is secreting adrenaline that activates receptors on the blood vessels causing constriction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what are the adaptions to exercise training on sympathetic vasoconstriction in skeletal muscle

A

Those who are heavily trained can dilate more so so reduce blood flow further, this is due to:

  • more blood vessels and so bigger response
  • their blood vessels may be more responsive to sympathetic tone and so improve re-direction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is NOS and where is is found

A
  • NOS (nitric oxide synthase) is a vasodilator and is secreted during stress
  • NOS is commonly found in blood vessel walls, as the endothelium of the walls secretes nitric oxide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the process of nNOS signalling

A

Ca+ release causing contraction can also use the release in NO which causes smooth muscle to relax and therefore vessels to dilate

  • Ca+ activates GTP and so protein kinase G is activated which causes the dilation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is meant by single vs multi limb exercise capacity

A

VO2 max of one legged exercise is 75-80% of two legged exercise

Higher blood flow can be achieved to the active muscle in one legged exercise

This is because if both legs were dilated to the same extent as during one legged exercise then blood pressure would fall to a level where the individual would lose consciousness as the brain wouldn’t get enough oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What percentage of blood flow goes to skeletal muscles during rest and exercise

A

at rest 15-20% of blood flow = skeletal muscle

During exercise = 80-85%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what happens to systolic and diastolic BP during exercise

A

Systolic BP rises to optimise perfusion of the tissue as you need to get more cardiac output out

Diastolic BP should remain the same as it represents the BP in-between the heart beats - you want the difference between the two to increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Why does systolic BP increase

A

The baroreceptor thats wrapped around the carotid body stretches with increased blood pressure

This sends signals back to the brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

The rise in BP during exercise is sensitive to what signals

A
  • baroreceptors
  • thermosensitive receptors
  • mechxnosensitive receptors
  • chemosensitive receptors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the exercise presser reflex

A

the change in response to the baroreceptor during exercise, this occurs by…

  • changing the set point of the receptor
  • where you regulate BP
  • changes how sensitive you are to changes in BP
26
Q

what happens to HR and BP control during exercise

A

You don’t change the sensitivity of the response - you change the set point

This is set in the medulla for BP

During exercise, you move to a greater range
But you do hit limits

27
Q

How do you increase venous return

A

Increasing blood volume:

  • contract spleen
  • constrict splanchnic supply
  • constrict capacitance veins

Increase return:

  • contract veins
  • constrict supply to other tissues
28
Q

What is the role of the muscle pump

A
  • The muscles squeeze the veins and therefore cause increased return
  • The valves allow movement of blood in one direction but not the other
  • Activity increases venous return
  • If valves fail it can cause pooling in the veins (varicose veins)
29
Q

What is the role of the thoracic pump

A

Negative pressure in the thorax increases venous return
Instigated with deeper/faster breathing of exercise
During high-load exercise with breath-holding the opposite applies
- this is ‘valsalva manoeuvre’ which also increases the after load and can lead to fainting

30
Q

What is the relationship with cardiac output and training

A

Cardiac output increases in both trained and untrained individuals with exercise but trained have a higher peak cardiac output

The pattern is the same for O2 uptake at a given work rate suggesting efficiency is the same but trained athletes have a larger capacity

the untrained athlete plateaus earlier than the trained athlete mean they can work at a higher work rate with a higher cardiac output

31
Q

what is the relationship between HR and training

A

Trained = lower resting HR

Linear response between HR and work rate until you reach max HR (same max for both trained and untrained)

The trained person HR is more gradual, meaning at any given work rate they have a lower HR and so can work at higher work rates for longer before max

32
Q

Training and HR normal values

A

Untrained max HR ~ 200 bmp

After 4 months endurance training ~ 199 bro

Top endurance athlete ~ 190 bpm

33
Q

what is the effect of upper vs lower body exercise

A

larger muscle mass involvement improves venous return and stroke volume during leg exercise

Larger muscle mass involvement and consequent vasodilation means pressure doesn’t rise the same

Thoracic pressure diminishes respiratory pump effect listing venous return

34
Q

What are the differences between cardiac muscle in trained and untrained athletes

A

trained have a higher muscle mass - functional mass

posterior wall thickness is larger but you wouldn’t want it higher than 13mm or it can’t contract well

as there is extra muscle and good contractibility you can eject a greater volume

35
Q

what are signals for change of in cardiac muscle

A
  • cellular load (stretch, tension and calcium)
  • growth hormone
  • IGF (insulin-like growth factor)
  • adrenaline / nor-adrenaline
  • angiotensin II
  • endothelin
36
Q

what is the role of plasma growth hormone with exercise

A

with exercise there is a large change in the % of plasma growth hormone.
an increase in plasma growth factor stimulates insulin like growth receptors

37
Q

Role of IGF (insulin like growth factors)

A

Insulin like growth factors act on many cells including cardiac cells.
IGF is often anchored to proteins like distrophine.
Coupled with adrenergic activation - transcription factors

38
Q

Role of angiotensin

A

Angiotensin receptors are often found in the heart and lungs.
In the heart angiotensin II can be produced very locally.
The receptors on the heart (angiotensin) can cause fibrosis and remodelling.
It also leads to MEF-2 that causes transcription of new proteins.

39
Q

why can new proteins be made as a result of angiotensin.

Example of a protein…

A

The receptors on the heart (angiotensin) lead to MEF-2 that causes transcription of new proteins.
New proteins = myosin - more of the proteins associated with myofibrils can be stuck on the end or in parallel with existing proteins
You can also make more ribosomes - higher capacity to make proteins as transcription occurs at a faster rate.
Ca+ can cause growth of the heart cells

40
Q

What is physiological hypertrophy

A

responding to transient stressors

41
Q

What is pathological hypertrophy

A

responding to stress - can cause fibrosis and scaring - heart not as efficient

42
Q

what is normal hypertrophy

A

normal hypertrophy = desired

  • wall stress is proportional to pressure and radius
  • even balance between size and thickness
43
Q

what is concentric hypertrophy

A

intense weight and aerobic training, large pressure stress

44
Q

what happens during hypertrophy

A

at 5% elongation of cardiac myocytes, wall increase volume = 16%
Cells also add sarcomeres in parallel and series - sarcomere length remains constant
- needs to be kept at its peak so contractibility doesn’t become weaker (starling mechanism)

45
Q

how and why do you want to increase plasma volume

A

why:
you want to increase plasma volume so you dilate more blood vessels without reducing venous return
How:
as you engage in exercise you get renin activation which is released by the kidneys due to a drop in BP, or because of adrenergic input e.g. adrenaline.
Renin increase triggers angiotensin II - this is a diuretic
You overall get an increased plasma volume

46
Q

What is blood plasmas response to exercise

A

plasma volume can increase by 20% - this means blood plasma increases.
A 200-300 ml volume expansion can increase VO2 max by ~4%
Hematocrit is unchanged

47
Q

what sets the lower resting HR in trained athletes

A

Vagal tone

  • the vagal tone is switched off during exercise
  • They also have reduced response to sympathetic tone which may cause the reduced minimum HR
48
Q

what process can accelerate the time to contract the heart

A

troponin phosphorylation

49
Q

what is a benefit of a lower HR

A

longer to fill

50
Q

what is the frank starling relationship

A
  • sarcomere length is the same therefore same length tension relationship
  • higher pressure in the ventricle = you stretch the myofilaments and elevate the length tension relationship and get more contractibility
51
Q

how can you eject more blood from the heart

A
  • pack more blood in
  • have a bigger heart
  • contract harder
  • reduce the load its working against
52
Q

what is peripheral resistance

A

the resistance against which the heart must work

53
Q

what increases peripheral resistance

A

isometric muscle contraction

54
Q

what are the effects of training on peripheral resistance

A

with training, vascular responsiveness improves and sympathetic tone withdrawal is improved

55
Q

how can you improve the exchange of oxygenated blood to the muscle

A
  • increase area for diffusion
  • shorten distances
  • increase time available
  • make more capillaries
56
Q

what is the effect of shear stress on the capillary wall

A
  • causes release of NO
  • this causes dilation and therefore less stress
  • it also increases the release of VEGF
57
Q

what is VEGF

A

VEGF increases in release as a result of shear stress on the capillary wall
- it causes capillaries to split so you get growth and branching of capillaries

58
Q

what is the effect of a vasodilation dose in a trained athlete

A

there can up to 3x the amount of blood flow

meaning they can get a greater delivery of O2

59
Q

effect of training on capillaries

A

there is an increase in capillaries with training meaning the distance between the capillary and mitochondria is less
There is greater SA for diffusion

60
Q

what are the consequences of the training adaptions on capillaries

A
  • muscle can use cardiac output more efficiently
  • muscle therefore demands less blood flow at sub-max exercise
  • peak blood flow and cardiac output is enhanced
  • during sub-max exercise cardiac output can however be the same
61
Q

what are the advantages of increased cardiac output

A
  • improved lactate removal and lactate threshold
  • improved exercise tolerance/resistance to fatigue
  • sustained gluconeogenesis
  • improved heat tolerance

Physiology (9 decks)

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