Lecture 3

Question 1

By how much does sympathetic stimulation increase heart rate and contractility? and cardiac output.

Answer 1

Heart rate 2-3 x. Contractility 2 x. Increases CO by 5x.

Question 2

Inhibiting the sympathetic system will do what to the heart?

Answer 2

Decrease heart rate by 20-40% and moderately decrease contractility.

Question 3

Parasympathetic stimulation decreases heart rate and contractility by how much?

Answer 3

Can significantly slow or stop heart beat and decrease contractility by 20-30%.

Question 4

If the parasympathetic system is inhibited, what happens to the heart?

Answer 4

Increase heart rate seven-fold, small increase in contractility.

Question 5

What is the vasomotor centre?

Answer 5

Centre in the cardiovascular control centre that transmits sympathetic impulses to virtually all arteries, arterioles and veins.

Question 6

Where is the vasomotor centre located?

Answer 6

Bilaterally in the reticular substance of the medulla and lower third of the pons.

Question 7

Which vessels do not receive sympathetic innervation?

Answer 7

Capillaries, precapillary sphincters and metarterioles.

Question 8

What is the aim of sympathetic innervation of blood vessles?

Answer 8

Vasoconstriction to increase resistance and reduce blood flow.

Question 9

Do veins or arteries have more adrenergic fibres?

Answer 9

Arteries have more

Question 10

What are varicosities?

Answer 10

They are where neurotransmitter is released from within the smooth muscle walls of vessels.

Question 11

What receptor does NE act on in the vessels?

Answer 11

Alpha-1.

Question 12

What signalling cascade does NE on alpha-1 induce?

Answer 12

IP3 pathway leading to increased calcium ions

Question 13

What are the three neurotransmitters that cause sympathetic vasoconstriction ?

Answer 13

NE, ATP and neuropeptide-Y

Question 14

What receptor does ATP act on and what happens?

Answer 14

P2X which opens calcium ions

Question 15

Which type of veins have poor innervation?

Answer 15

Muscle veins

Question 16

Does sympathetic vasodilation occur in humans?

Answer 16

No

Question 17

Where specifically within the muscular arteries are the sympathetic vasoconstrictor fibres found?

Answer 17

The adventitia

Question 18

What are the 4 main endocrine systems that regulate blood pressure?

Answer 18

Adrenaline, ADH, renin-angiotensin-aldosterone, ANP

Question 19

Where does adrenaline come from?

Answer 19

Adrenal medulla

Question 20

What receptors does adrenaline act on in the heart?

Answer 20

Beta-1

Question 21

What receptor does adrenaline act on in the vessels for vasoconstriction?

Answer 21

Alpha-1

Question 22

What receptor does adrenaline act on in vessels for vasodilation?

Answer 22

Beta-2

Question 23

What percentages of adrenaline and noradrenaline does the adrenal medulla release?

Answer 23

80% adrenaline, 20% noradrenaline

Question 24

Which is better at increasing CO, adrenaline from the adrenal medulla or NE from sympathetic system?

Answer 24

Adrenaline from the medulla

Question 25

Where is ADH produced?

Answer 25

Hypothalamus- supraoptic nuclei and paraventricular nuclei

Question 26

Where is ADH released from?

Answer 26

Posterior pituitary gland

Question 27

What is the set point and range for ADH release in osmolar control mechanism?

Answer 27

280-300 mOsm

Question 28

What is the set point for ADH release in non-osmolar control?

Answer 28

10% blood volume loss.

Question 29

Does osmolar or non-osmolar control of ADH cause a larger release of ADH?

Answer 29

Non-osmolar control.

Question 30

What does ADH do?

Answer 30

Causes retention of water and vasoconstriction to increase blood pressure

Question 31

In a 15% blood volume loss, what does the set point for osmolar control change to?

Answer 31

265 mOsm

Question 32

In a 15% blood volume increase, what does the setpoint increase to?

Answer 32

290 mOsm

Question 33

What triggers the RAAS system?

Answer 33

A drop in blood pressure

Question 34

What organ releases renin?

Answer 34

Kidneys

Question 35

What does Renin do?

Answer 35

Converts angiotensinogen into angiotensin I

Question 36

What converts angiotensin I into angiotensin II?

Answer 36

ACE

Question 37

What organ predominantly releases ACE?

Answer 37

Lungs- high SA of enodtehlial cells

Question 38

What are the main effects of angiotensin II?

Answer 38

Vasoconstriction, increasing thirst and causes release of aldosterone