Blood Pressure

Question 1

Causes of Increase in Blood Pressure

Answer 1

Increase in cardiac output
Increase in blood volume
Increase in peripheral resistance
CO = PR x HR

Question 2

Effect of exercise on blood vessels

Answer 2

peripheral vasodilation: muscle/skin
vasoconstriction: splanchnic circulation
BP systolic increases, diastolic decreases
Heart rate increases

Question 3

Effect of standing on blood vessels

Answer 3

Initially - drop in BP, then compensatory recovery
peripheral vasoconstriction
No change in systolic, increase in diastolic
Heart rate increases

Question 4

Pulmonary Circulation

Answer 4

High capillary density, low vascular resistance
Acts as blood reservoir and a filter
CO2, O2 and pH have opposite effects to those in systemic circulation
Low O2 –> arterioles constrict - minimises amount of poorly oxygenated blood

Question 5

1) Baroreceptors

2) Chemoreceptors

Answer 5

1) located in transverse aortic arch and carotid sinuses of coronary arteries
2) located in carotid and aortic bodies, detect low O2

Question 6

Factors affecting Preload

Answer 6

Increased: atrial contractility, ventricular compliance, aortic pressure, central venous pressure
Decreased: heart rate, venous compliance
(preload = initial stretching of myocytes during diastole

Question 7

Afterload

Answer 7

resistance that the chambers of the heart must overcome to eject blood
increased by back pressure
increases if exit valve fails to open properly

Question 8

Thoracic Pump

Answer 8

pulls blood to the right atrium during inspiration

Creates a pressure gradient (intrathoracic = negative, abdominal pressure = positive)

Question 9

Muscle Pump

Answer 9

rhythmical contraction of limb muscles as occurs during normal ocomotor activity
squeezes blood out of nearby veins

Question 10

Local Vasomotor Control

Answer 10

endothelial cells release vasodilator compounds (NO)
controlled by local blood flow conditions
hydrostatic pressure and shear force

Question 11

Control of systemic BP

Answer 11

Local: endothelial and NO
Neurological: autonomic system
Humoral: renal/pituitary/adrenal

Question 12

Autonomic control of BP

Answer 12

increase sympathetic –> constricts blood vessels, increases heart rate, cardiac output, peripheral resistance
parasympathetic (Vagus) –> no effect on BVs, relaxes heart