Brainscape's Knowledge GenomeTM

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


See full index

Exercise physiology > Cardiovascular 2 > Flashcards

Cardiovascular 2 Flashcards

1
Q

Blood pressures throughout the circulation

A
  • Blood pressure oscillates continuously, at least in the arterial circulation.
  • High blood pressure in the large arteries is linked to ventricular contraction.
  • Blood pressure falls steeply across the “resistance vessels”, capillaries and venules, collectively called the microcirculation.
  • The microcirculation belongs to organs or tissues.
  • Blood pressure is very low in veins.
  • The pressure difference from left to right side of the heart creates a driving force (∆P) for blood flow through the systemic circulation.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Arterial pressure profiles in systemic and pulmonary circulations

A
  • Cardiac cycle - the time between one beat and another
  • Systole - heart contracting
  • Diastole - heart relaxing
  • Elevation - dicrotic notch (aortic valve closing)
  • Flows between circuits are the same
    • Resistance is lower in the pulmonary circuit - pulmonary blood pressure is lower then systemic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Arterial blood pressure during rest

A
  • Arterial (systemic) blood pressure is ‘regulated’ within a narrow range
  • Each heart beat is different
  • Heart rate is not constant
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Young vs Old arterial blood pressure responses during cycling

A

Young people
- Diastolic pressure will not change, however systolic pressure will increases as a function of exercise intensity increases

Older people

  • Diastolic pressure will not change, however systolic pressure will increases as a function of exercise intensity increases
  • Ageing increases blood pressure
  • Stiffer arterial system
  • Larger difference between systolic pressure and diastolic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Blood pressure responses during maximum graded exercise

A
  • The peak blood pressure are not affected by training
  • In young healthy individual regardless of their training status, the percent change in their mean arterial pressure from rest to the peak value (VO2Max) is roughly equal to 30%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Blood pressure responses in trained vs untrained

A

Pressure is similar for both states because there is a counter balancing influence

  • Trained - high flow, low resistance
  • Untrained - low flow, high resistance

Graph - MAP increases by about 30%

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

Does it operate during exercise? (NOT IN NOTES)

  • Vasodilation
  • Baroreflex
A
  • Evidence for rapid vasodilation (fall in TPR) leasing to fall in blood pressure and then a compensatory increase in TPR
  • This suggests the baroreflex is ‘active’ during exercise and that the regulation of blood pressure during exercise involves counterbalancing adjustments of cardiac output and TPR.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Equation for pressure

A

∆P = Q(dot) x R

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

Arterial blood pressure is affected by cardiac output and arterial resistance
- Blood flow into and leaving systemic arteries

A
  • Blood flow into the systemic arteries is generated by contraction of the left ventricle, and this blood flow is called cardiac output.
  • Blood flow leaving the systemic arterial system is controlled by the resistance of the arteries.
  • Increasing either cardiac output (increasing flow in) or arterial resistance (decreasing flow out) will increase arterial blood volume and pressure.
  • Therefore, arterial blood pressure is determined by cardiac output and arterial resistance (or ‘total peripheral resistance’).
  • MAP = CO × TPR (arterial resistance)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Regulation of arterial blood pressure occurs through the control of cardiac output and arterial resistance
- During exercise

A
  • Arterial blood pressure (MAP) varies as a function of CO and TPR (below).
  • MAP is maintained with narrow limits, is considered to be a ‘regulated variable’, and is perhaps the most important CV variable.
  • CO and TPR can be varied across a wider range than MAP and are thought of as controlled variables.
  • Thus the regulation of MAP occurs through the control of CO and TPR.
  • During exercise, rapid dilation of blood vessels in contracting muscles reduces TPR and, if CO did not change, would cause MAP to fall and reduce blood flow to all organs.
  • But this does not normally occur and the fall in TPR is somewhat counterbalanced by an increase in cardiac output so that MAP changes minimally (lower intensities) or increases by a small amount (higher intensities).
  • This regulation of BP through adjustments of CO and/or TPR is the hallmark of the ‘baroreflex’
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Physiology of BP regulation during exercise

A

Blood Flow - increases as intensity increases then plateaus
Mean Pressure - Increases by 30% during maximal graded exercise
- Systolic pressure: slowly increases at lower intensities but increases rapidly at higher intensity
- Diastolic pressure: Constant
Vascular Resistance - Decreases due to vasodilation

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

Baroreflex concept

A
  • The regulation of blood pressure (maintaining constancy) requires a set-point value for BP about which a system of cardiovascular sensors and effectors operate.
  • The set-point is a ‘normal’ value which the system tries to maintain.
  • When BP is driven away from its set-point value in a short timeframe (seconds), the cardiovascular system (sensors and effectors) restores BP back to its set-point.
  • This response is the arterial baroreceptor reflex, or ‘baroreflex’.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Cardiovascular Sensor and what do they detect

A

Baroreceptors - detect changes in stretch

  • Carotid baroreceptors
  • Aortic baroreceptors

Send message to effecter - medulla oblongata

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

Cardiovascular Effectors

A

Medulla oblongata which controls TPR & CO

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

Baroreflex

- If blood pressure falls below…

A

Sensing (stimulus) -> Adjusting (response)

  • If blood pressure falls below set point, the nerves running out of the medulla to the heart and blood vessels increase their firing rate to cause an increase in blood output in the heart and increase constriction of blood vessels - high frequency firing due to fall in blood pressure
  • Opposite for an increase in blood pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The ‘baroreflex’ and exercise

  • How is the fall in BP sensed? How is the BP readjusted?
A
  • The arterial baroreceptor reflex – ‘baroreflex’ -operates all the time and adjusts blood pressure according to a setpoint value.
  • For example, assume a set-point of 100 mm Hg. Standing up causes an immediate fall in blood pressure - from approximately 100 to 80 mm Hg - which is rapidly sensed and then quickly readjusted back to 100 mm Hg.

How is the fall in BP sensed? How is the BP readjusted?

  • Exercise (muscle contractions) adjusts the baroreflex setpoint to a higher value.
  • The amount of adjustment is related to the exercise intensity.
  • Consequently, the mean arterial blood pressure is “allowed” to rise to a higher value and somewhat proportional to the level of effort.
  • Descending ‘motor drive’ from the motor cortex – ‘central command’ – along with sensory feedback from muscles are thought to adjust the baroreflex set-point.
17
Q

Cardiac output, stroke volume and heart rate during graded exercise

A

CO - increases
HR - increases
SV - increases at lower intensity and then plateaus

18
Q

Stroke volume

- SV during exercise

A
  • The left and right ventricles pump together.
  • The volume of blood ejected from each ventricle in a single beat is the stroke volume (unit = ml/beat).
  • Stroke volume is equal to the difference between the ventricular volumes at the end of diastole (relaxation) and systole (contraction).
  • The increase in SV during exercise is related to an increase in the filling of ventricles (increased EDV) and emptying of ventricles (decreased ESV).
  • CO (ml/min) = SV (ml/beat) × HR (beat/min).
19
Q

The change in cardiac output during exercise is due to…

A

increases in stroke volume and heart rate

CO at rest: 5600ml/min
CO at max: 21600ml/min

20
Q

Cardiac output is controlled by controlling stroke volume and heart rate

  • Mean arterial pressure
  • CO
A

Mean arterial pressure is effected by

  • Total peripheral resistance
  • Cardiac Output

Cardiac Out is effected by

  • Stroke volume
  • Heart rate
21
Q

The beating heart

A
  • No external nerves that regulate the rhythmic beating of heart
  • Sinoatrial node - primary pacemaker
    Atrioventricular node - pacemaker
    • The cells within the pacemakers depolarise, discharge and generate a current that flows through the rest of the wiring system
  • P wave - transmission of electrical current through the atria and the excitation of contractile cells
  • QRS - movement of electrical impulse through the ventricles
  • T wave - recharging of the fibres on the ventricles
22
Q

Neural control of the heart

A
  • Nerves that run out from the medulla on the left hand side go directly to the pacemakers of the heart
  • Left vagals nerve (part of sympathetic system) innervates the atrioventricular node
  • Right vagal neve innervates the sinusoidal node
  • Adjustments of the rate of the heart beating is dependent on these vagal nerves
  • Left cardiac sympathetic nerve - innervates the contractile tissue of the heart - control the power of contraction and thus SV
  • Right cardiac sympathetic nerve - innervates the pacemakers - control heart rate

Heart rate can be adjusted by adjusting vagal activity and/or sympathetic activity

23
Q

Control of heart rate during exercise

A
  • Heart rate is increased by decreasing parasympathetic activity – ‘vagal withdrawal’ – and increasing sympathetic activity.
  • At low heart rates (< 100 bpm), heart rate is varied by altering vagal activity.
  • Beyond ~100 bpm, heart rate is altered by adjusting sympathetic activity
24
Q

Physiological factors that influence stroke volume

A
  • Preload: Filling pressure
  • After load: Arterial pressure opposing ejection (negative effect - as afterload increases, SV decreases)

Other things

  • Energy of contraction
  • Contractility
    • Sympathetic nerves
    • Circulating agents
25
Q

Neural control of stroke volume

A
  • Stroke work is proportional to SV

- Increasing the firing of cardiac sympathetic nerve increases the stroke work and thus SV

26
Q

Aerobic training and the heart

A
  • The chambers of the heart for the athlete are larger
  • Training increases the size, mass and chamber volumes of the heart
  • For resistance training - walls of the heart will be thicker to accommodate for high blood pressure from training

Trained (compared to untrained)

  • Higher cardiac output during exercise
  • Lower heart rate at rest
  • Higher SV at both rest and exercise

Exercise physiology (12 decks)

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