Neuroscience 11 - Sympathetic nervous system and renin angiotensin system Flashcards

1
Q

Where are noradrenaline and adrenaline systhesised in the neurone?

A

In the terminal varicosity.

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2
Q

What are the subdivisions of adrenoreceptors?

A

2 groups:

  1. Excitatory effects on smooth muscle = a-adrenoreceptor-mediated.
  2. Relaxant effects on smooth muscle + stimulatory effects on heart = b-adrenoreceptor-mediated.
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3
Q

Where are b1, b2 and b3 adrenoreceptors found?

A
  1. B1 = cardiac muscle, smooth muscle in GI.
  2. B2 = Bronchial, vascular and uterine smooth muscle.
  3. B3 = fat cells, smooth muscle in GI.
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4
Q

What are A1 and A2 adrenoreceptors?

A
  1. A1 = Located post-synaptically (on effector cells). Mediating constriction in resistance vessels.
  2. A2 = Located presynaptic (nerve terminal membrane). Activation by neurotransmitter causes negative feedback. HOWEVER, some are post-synaptic on vascular smooth muscle.
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5
Q

What is the mechanism for A1 adrenoreceptors?

A
  1. Based on G-proteins activating PLC enzyme.
  2. Produced IP3, which releases stored calcium in the cell.
  3. This causes activation of smooth muscle and platelets.
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6
Q

What is the mechanism for A2 and B arenoreceptors?

A
  1. G-protein linked.
  2. Activates cAMP.
  3. This is a relaxant in smooth muscle and GI. BUT stimulates heart by increasing intracellular Ca2+.
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7
Q

Which adrenoreceptors does noradrenaline activate?

A

A1, A2 and B1.

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8
Q

Which adrenoreceptors does adrenaline activate?

A

A1, A2, B1, B2.

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9
Q

Which adrenoreceptors does dopamine activate?

A

Weak effects on A1 and B1. Has its own receptors.

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10
Q

What are two synthetic catecholamines and which adrenoreceptors do they activate?

A

1, Isoprenaline = B1, B2.

2. Phenylephrine = A1.

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11
Q

What is the effect of systolic BP by noradrenaline, adrenaline and isoprenaline?

A
  1. Noradrenaline = Strong increase.
  2. Adrenaline = Increase.
  3. Isoprenaline = Slight increase.
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12
Q

What is the effect of diastolic BP by noradrenaline, adrenaline and isoprenaline?

A
  1. Noradrenaline = Increase.
  2. Adrenaline = Slight decrease.
  3. Isoprenaline = Decrease.
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13
Q

What is the effect of mean BP by noradrenaline, adrenaline and isoprenaline?

A
  1. Noradrenaline = Increase.
  2. Adrenaline = Slight increase.
  3. Isoprenaline = no change.
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14
Q

What is the effect of HR by noradrenaline, adrenaline and isoprenaline?

A
  1. Noradrenaline = Decrease.
  2. Adrenaline = Increase.
  3. Isoprenaline = Increase.
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15
Q

What causes Renin release? (3)

A
  1. Decrease in NaCl.
  2. Decrease in BP.
  3. B1 receptor activation in kidney by sympathetic nervous system.
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16
Q

What are ACE inhibitors?

A

Prevent the ACE enzyme converting angiotensin I to angiotensin II.

17
Q

What are B1 blockers?

A

They block B1 receptors in the kidney to prevent Renin released as a result of sympathetic activity.

18
Q

What are AT1 blockers?

A

Blocks angiotensin II receptors.

19
Q

What are loop diuretics?

A

They decrease Na+ getting into kidney = activate renin release.

20
Q

What are AT1 receptors?

A
  1. G-protein coupled receptors.
  2. Located in blood vessels, brain, adrenal, kidneys and heart.
  3. Activation of AT1 = increase BP.
21
Q

What is the Rapid pressor response? (3)

A

An effect of angiotensin II that occurs in minutes.

  1. Direct vasoconstriction.
  2. Enhanced action of peripheral NE.
  3. Release of catecholamines from adrenal.
22
Q

What is the Slow pressor response?

A

AN effect of angiotensin II that occurs in days.

  1. Direct effect to increase Na+ reabsorption in proximal tubule.
  2. Synthesis and release of aldosterone from adrenal cortex.
  3. Renal vasoconstriction.
23
Q

What is vascular and cardiac hypertrophy and remodeling?

A
  1. Increased preload and afterload of heart.

2. Increased vascular wall tension.

24
Q

Do ACE inhibitors prevent the conversion of angiotensin I to angiotensin II?

A

Yes but not completely, some angiotensin I is converted by chymase.

25
Q

What is the effect of ACE inhibitors on Bradykinin?

A

ACE inhibitors prevent the breakdown of bradykinin and hence increase vasodilation.

26
Q

What are the effects of aldosterone? (2)

A
  1. Increased Na+ retention = H2O retention.

2. Increased K+ excretion = H+ excretion.

27
Q

What causes the synthesis and release of aldosterone? (3)

A
  1. ACTH (minor influence).
  2. Angiotensin II.
  3. Increased plasma K+ (big effect).
28
Q

What are the main effects of the sympathoadrenal system and the renin-angiotensin system? (5)

A
  1. Increased BP.
  2. Increased HR.
  3. Increased Na+/H2O retention.
  4. Increased coagulation.
  5. Increased platelet activation.
29
Q

What happens if you have too much aldosterone? (2)

A
  1. Primary aldosteronism = high BP

2. Secondary aldosteronism = Heart and liver failure, Na+ retention, oedema and low BP.