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Cardiovascular physiology > Lecture 3 > Flashcards

Lecture 3 Flashcards

1
Q

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

A

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

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2
Q

Inhibiting the sympathetic system will do what to the heart?

A

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

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3
Q

Parasympathetic stimulation decreases heart rate and contractility by how much?

A

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

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4
Q

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

A

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

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5
Q

What is the vasomotor centre?

A

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

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6
Q

Where is the vasomotor centre located?

A

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

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7
Q

Which vessels do not receive sympathetic innervation?

A

Capillaries, precapillary sphincters and metarterioles.

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8
Q

What is the aim of sympathetic innervation of blood vessles?

A

Vasoconstriction to increase resistance and reduce blood flow.

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9
Q

Do veins or arteries have more adrenergic fibres?

A

Arteries have more

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10
Q

What are varicosities?

A

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

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11
Q

What receptor does NE act on in the vessels?

A

Alpha-1.

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12
Q

What signalling cascade does NE on alpha-1 induce?

A

IP3 pathway leading to increased calcium ions

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13
Q

What are the three neurotransmitters that cause sympathetic vasoconstriction ?

A

NE, ATP and neuropeptide-Y

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14
Q

What receptor does ATP act on and what happens?

A

P2X which opens calcium ions

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15
Q

Which type of veins have poor innervation?

A

Muscle veins

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16
Q

Does sympathetic vasodilation occur in humans?

A

No

17
Q

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

A

The adventitia

18
Q

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

A

Adrenaline, ADH, renin-angiotensin-aldosterone, ANP

19
Q

Where does adrenaline come from?

A

Adrenal medulla

20
Q

What receptors does adrenaline act on in the heart?

A

Beta-1

21
Q

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

A

Alpha-1

22
Q

What receptor does adrenaline act on in vessels for vasodilation?

A

Beta-2

23
Q

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

A

80% adrenaline, 20% noradrenaline

24
Q

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

A

Adrenaline from the medulla

25
Q

Where is ADH produced?

A

Hypothalamus- supraoptic nuclei and paraventricular nuclei

26
Q

Where is ADH released from?

A

Posterior pituitary gland

27
Q

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

A

280-300 mOsm

28
Q

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

A

10% blood volume loss.

29
Q

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

A

Non-osmolar control.

30
Q

What does ADH do?

A

Causes retention of water and vasoconstriction to increase blood pressure

31
Q

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

A

265 mOsm

32
Q

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

A

290 mOsm

33
Q

What triggers the RAAS system?

A

A drop in blood pressure

34
Q

What organ releases renin?

A

Kidneys

35
Q

What does Renin do?

A

Converts angiotensinogen into angiotensin I

36
Q

What converts angiotensin I into angiotensin II?

A

ACE

37
Q

What organ predominantly releases ACE?

A

Lungs- high SA of enodtehlial cells

38
Q

What are the main effects of angiotensin II?

A

Vasoconstriction, increasing thirst and causes release of aldosterone

Cardiovascular physiology (15 decks)

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