Module 1: Vascular System Objective Questions Flashcards
In general, the parallel arrangement of the vascular system enables each organ to receive its own separate arterial blood supply (True or False)
True
More blood flows through the capillaries during cardiac systole than during diastole (T or F)
False
The capillaries contain only 5 percent of the total blood volume at any given point? (true or false)
True
The same volume of blood passes through the capillaries in a minute as passes through the aorta, even though the blood flow is much slower in capillaries True or False
True
True or False: because capillary walls have no carrier transport systems all capillaries are equally permeable?
false
True or False because of gravitational effects, venous pressure in the lower extremities is greater when a person is standing up than when a person is lying down
True
Which change would increase the resistance in an arteriole?
a) a shorter length
b) A wider calibre
c) Increased sympathetic stimulation
d) decreased blood viscosity
c) increased sympathetic stimulation
Which of the following functions is (are) attributable to arterioles? (indicate all correct answers)
a) produce a significant decline in mean pressure, which helps establish the driving pressure gradient between the heart and organs
b) serve as site of exchange of materials between blood and surrounding tissue cells
c) act as main determinant of total peripheral resistance
d) determine the pattern of distribution of cardiac output
e) help regulate mean arterial blood pressure
f) convert the pulsatile nature of arterial blood pressure into a smooth, non-fluctuating pressure in the vessels farther downstream
g) act as a pressure reservoir
Arterioles:
a) produce a significant decline in mean pressure, which helps establish the driving pressure gradient between the heart and organs
c) act as main determinant of total peripheral resistance
d) determine the pattern of distribution of cardiac output
e) help regulate mean arterial blood pressure
f) convert the pulsatile nature of arterial blood pressure into a smooth, non-fluctuating pressure in the vessels farther downstream
Indicate whether the following factors increase or decrease venous return or has no effect on venous return:
a) sympathetically induced venous vasoconstriction: ________
b) Skeletal muscle activity: _______
c) Gravitational effects on the venous system: ______
d) Respiratory activity: ________
e) increased atrial pressure associated with a leaky AV valve:_________
f) Ventricular pressure change associated with diastolic recoil: _______
Indicate whether the following factors increase or decrease venous return or has no effect on venous return:
a) sympathetically induced venous vasoconstriction: increases
b) Skeletal muscle activity: increases
c) Gravitational effects on the venous system: decreases
d) Respiratory activity: increases
e) increased atrial pressure associated with a leaky AV valve: decreased
f) Ventricular pressure change associated with diastolic recoil: increased
Indicate what kind of compensatory changes occur in the factors in question to restore blood pressure to normal in response to hypovolemic hypotension resulting from severe haemorrhage
Increased?
Decreased?
No effect?
- rate of afferent firing generated by the carotid sinus and aortic arch baroreceptors
- sympathetic output by the cardiovascular centre
- Parasympathetic output by the cardiovascular centre
- Heart rate
- Stroke volume
- Cardiac output
- Arteriolar radius
- Total peripheral resistance
- Venous radius
- Venous return
- urinary output
- fluid retention within the body
- fluid movement from interstitial fluid into plasma across the capillaries
Indicate what kind of compensatory changes occur in factors in question to restore blood pressure to normal in response to hypovolemic hypotension resulting from severe haemorrhage
Increased?
Decreased?
No effect?
- rate of afferent firing generated by the carotid sinus and aortic arch baroreceptors: decreased
- sympathetic output by the cardiovascular centre: increased
- Parasympathetic output by the cardiovascular centre: decreased
- Heart rate: inreased
- Stroke volume: increased
- Cardiac output: increased
- Arteriolar radius: decreased
- Total peripheral resistance: increased
- Venous radius: decreased
- Venous return: increased
- urinary output: decreased
- fluid retention within the body: increased
- fluid movement from interstitial fluid into plasma across the capillaries: increased
Recall that the flow rate of blood equals the pressure gradient divided by the total peripheral resistance of the vascular system. The conventional unit of resistance in physiological systems is expressed in PRU (peripheral resistance unit) which is defined as (1L/min)/(1 mmHg).
At rest, Tom’s total peripheral resistance is about 20 PRU. Last week while playing racquetball his cardiac output increased to 30L/min and his mean arterial pressure increased to 120mmHg. What was his total Peripheral resistance during the game?
CO = MAP/TPR
TPR=MAP/CO
TPR=120mmHg / 30 L/min
TPR= 4PRU
Systolic pressure rises as a person ages. By age 85 an average male has a systolic pressure of 180mmHg and a diastolic pressure of 90mmHg
a) what is the mean arterial pressure of this average 85-year-old male?
b) from your knowledge of capillary dynamics, predict the result at the capillary level of this age-related change in mean arterial pressure if no homeostatic mechanisms were operating. (recall that mean arterial pressure is about 93mmHg at age 20)
a) what is the mean arterial pressure of this average 85-year-old male?
MAP = diastolic pressure + 1/3 pulse pressure
MAP = diastolic pressure + (systolic-diastolic)/3
MAP= 90mmHg + (180mmHg - 90mmHg)/3
MAP= 120mmHg
b) from your knowledge of capillary dynamics, predict the result at the capillary level of this age-related change in mean arterial pressure if no homeostatic mechanisms were operating. (recall that mean arterial pressure is about 93mmHg at age 20)
- Because the other forces acting across the capillary wall, such as plasma colloid osmotic pressure, typically do not change with age, one would suspect fluid loss from the capillaries into the tissues would occur as a result of the increase in capillary blood pressure
Compare the flow rates in the systemic and the pulmonary circulations of an individual with the following measurements:
Systemic mean arterial pressure = 95mmHg
Systemic Resistance = 19 PRU
Pulmonary mean arterial pressure = 20mmHg
Pulmonary resistance = 4PRU
systemic: 95mmHg/19PRU
=95mmHg/19mmHg/L/min
=5L/min
Pulmonary: 20mmHg/4PRU
=5L/min
Assume a person has a blood pressure recording of 125/77:
a) what is the systolic pressure?
b) What is the diastolic pressure
c) what is the pulse pressure
d) What is the MAP
e) would any sound be heard when the pressure in an external cuff around the arm was 130mmHg (yes or no)
f) Would any sound be heard when the cuff pressure was 118mmHg?
g) Would any sound be heard when the cuff pressre was 75mmHg?
Assume a person has a blood pressure recording of 125/77:
a) what is the systolic pressure?
125mmHg
b) What is the diastolic pressure?
77mmHg
c) what is the pulse pressure?
125-77= 48mmHg
d) What is the MAP?
MAP = diastolic+1/3pulse=93mmHg
e) would any sound be heard when the pressure in an external cuff around the arm was 130mmHg (yes or no)?
No: no blood would be able to get through the brachial artery so no sound would be heard
f) Would any sound be heard when the cuff pressure was 118mmHg?
Yes, blood would flow through the brachial artery when the arterial pressure was between 118 and 125mmHg and would not flow through when the arterial pressure fell below 118mmHg. Turbulence would create sound
g) Would any sound be heard when the cuff pressre was 75mmHg?
No, blood would flow continuously through the artery in smooth, laminar fashion so no sound would be heard
