WEEL 11

Question 1

describe the 2 steps that occur with cardiac output max in relation to maximal muscle blood flow

Answer 1

1) the pre capillary arterioles represented as taps that can be either turned on or off

2) because these vessels are the primary site of resistance to flow in the vascular system, the sum of the amount of opening or closing of all the taps is the main determinant of the resistance to flow out of the arterial system. = TOTAL PERIPHERAL SYSTEM)

Question 2

what are the 7 factors that occur when there is an increased in exercise intensity

Answer 2

1) muscle vo2 increases

2) local metabolites cause vasodilation

3) muscle blood flow increases

4) muscle pump causes an increase of venous return

5) in turn increases left ventricular filling

6) in turn causes an increase of stroke volume via the frank starling effect

7) increase of cardiac output.

Question 3

what are the cardiovascular responses to large muscle mass exercise step by step (from rest to 50% peak power)

Answer 3

1) muscle activity causes marked vasodilation causing total peripheral resistance to fail

2) increased SNS activity causes vasoconstriction of vascular beds of many non- active tissues. this helps to minimise the decrease in TPR and redirects blood flow to exercising muscle

3) exercising muscle remains vasodilated despite an increase in SNS

Question 4

what are the cardiovascular responses to large muscle mass exercise step by step ( 75% to 100% peak power)

Answer 4

1) to increase heavily in SNS activity further vasoconstriction to non-exercising vascular beds

2) further increase in local metabolites should cause an increase in further exercising muscle blood flow

3) however, nad from heavily increased SNS activity to exercising muscle now ‘overrides’ local metabolites.

Question 5

describe q max and vo2 max (x2)

Answer 5

• cardiac output is the product of heart rate and stroke volume
• during exercise increases in both heart rate and stroke volume results in an increase in both heart rate and stroke volume results in an increase of cardiac output

Question 6

what are the two factors that affect cardiac max

Answer 6

1) HRmax - influenced by age and individual difference

2) sv max influenced by the activity level and other factors

Question 7

what are the two effects of breath holding during forceful muscle efforts

Answer 7

1) high intrathoracic pressure collapses the vena cava to reduced preload and reduced stroke volume and therefore reduced q

2) therefore, MAP drops and syncope can occur

Question 8

describe circulatory effects of isometric exercise (x3)

Answer 8

• results in mechanical compression of circulatory system
• impedes (occludes) blood flow
• leads to an increase in after load

Question 9

describe the pressor reflex and what are the implications of it

Answer 9

• results in exaggerated circulatory response to static exercise (increase in TPR over and above increased cause by blood flow occlusion)

implications = the physiological response to to isometric exercise is disproportional to the external / dose applied should be prescribed with caution

Question 10

describe reactive hyperaemia

Answer 10

post intense contraction ‘muscle pump’ increased BF, not ‘magic’ hypertrophy

Question 11

describe the circulatory effects after prolonged steady state exercise (x3)

Answer 11

• stroke volume is mediated by reduced sympathetic and increased parasympathetic
• this is then mediated by circulatory demands of exercise and recovery
• mediated by reduced sympathetic vasoconstriction in the presence of metabolic vasodilators.