Control of Blood Pressure

Question 1

What are the main factors that influence blood pressure

Answer 1

• Cardiac Output (CO)
• Peripheral Resistance (PR)
• Blood Volume

Question 2

What equation can be made using Blood Pressure, Cardiac Output and Peripheral Resistance

Answer 2

Blood Pressure = Cardiac Output x Peripheral Resistance

Question 3

What is the the Frank-Starling Law of the heart

Answer 3

Within physiological limits, the heart pumps all blood that comes into it without allowing excessive build up of blood in veins

Question 4

Neural control of blood pressure involves reflex arcs that involve what 3 structures

Answer 4

• Baroreceptors
• Vasomotor centres of the medulla and vasomotor fibres
• Vascular smooth muscle

Question 5

What is the vasomotor centre and where is it found

Answer 5

A cluster of sympathetic neurons in the medulla that oversee changes in blood vessel diameter

Question 6

How does the vasomotor act to control blood pressure

Answer 6

Maintains blood vessel tone by innervating smooth muscles of blood vessels, especially arterioles

Question 7

What is the cardiovascular centre made up from

Answer 7

Vasomotor centre and cardiac centres

Question 8

What nerve from the cardiovascular centre is cardio inhibitory

Answer 8

Vagus nerve

Question 9

What nervous system from the cardiovascular centre is cardio excitatory

Answer 9

SNS

Question 10

What does the cardiovascular centre alter to control blood pressure

Answer 10

Cardiac output

Blood vessel diameter

Question 11

Where can you find arterial baroreceptors

Answer 11

Cartoid sinus

Arch of the Aorta

Question 12

Describe the reflex that occurs when a baroreceptor detects increased blood pressure, include the nervous systems activated and inhibited

Answer 12

Increased BP stimulates the cardio inhibitory centre to increase parasympathetic and decrease sympathetic effects.

• Increases vessel diameter
• Decrease heart rate, cardiac output, peripheral resistance and blood pressure

Question 13

Describe the reflex that occurs when a baroreceptor detects decreased blood pressure, include the nervous systems activated and inhibited

Answer 13

Decreased BP stimulates cardioacceleratory centre:

• Increase cardiac output and peripheral resistance
• Low Bp also stimulates vasomotor centre to constrict blood vessels

Question 14

Chemoreceptor reflexes regulate BP and are sensitive to

Answer 14

Oxygen

Carbon Dioxide

Question 15

Where are A and B type stretch receptors found (volume receptors)

Answer 15

In the left and right atrium

Question 16

What do A and B fibres respond to and what information do they convey

Answer 16

A fibres respond to atrial systole and report heart rate

B fibres respond to ventricular systole and report atrial volume

Question 17

Atrial stretch will activate B fibres and this will have a direct neuronal effect, name the effects it will have

Answer 17

1. increase the heart rate (Bainbridge reflex)
2. Decrease sympathetic tone to the kidney causing increased filtration and urine formation
3. Decrease production of ADH
4. Atrial stretch also causes atria to make atrial natriuretic peptide (ANP) - vasodilator/ decreased Na+ reabsorption

All of these act to lower blood volume

Question 18

Name some Adrenal Medulla hormones and what their effect is

Answer 18

Norepinephrine and epinephrine increase BP

Question 19

What effect does ADH have on controlling BP

Answer 19

Causes intense vasoconstriction in cases of extremely low BP

Question 20

What causes AT2 release and what effect does AT2 have on controlling BP

Answer 20

Kidney release of renin generates AT2, which causes intense vasoconstriction