Nerves and the ANS Flashcards

1
Q

Neuronal action potential

A
  1. Negative at rest (polarised) due to potassium inside of cell and chloride outside
  2. Sodium ion channels open and sodium floods into cell - depolarisation
  3. Calcium channels open and cell fires
  4. Potassium channels open so potassium leaves cell - repolarisation
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2
Q

Myelinated nerve conduction

A

Faster
Saltatory conduction
Myelin sheaths called Schwann cells
Conduction jumps between gaps called nodes of Ranvier

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3
Q

Neurotransmission

A
  1. Depolarisation causes vacuoles of neurotransmitter to exocytose into synaptic cleft
  2. Neurotransmitter bnds to receptors on post-synaptic nerve or other targets
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4
Q

Central components of the ANS

A

Hypothalamus
Brain stem
Spinal cord

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5
Q

Peripheral components of the ANS

A

Sympathetic nerves

Parasympathetic nerves

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6
Q

Functions of the ANS

A

Mediates neuro-humoral regulation of the internal environment
Prepares body for normal and life-threatening stress

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7
Q

Function of the SNS

A

Fight or flight

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8
Q

Function of the PSNS

A

Rest and digest

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9
Q

Stress causing activation of SNS

A

Low BP
Low oxygen
Increased temperature
Mental stress

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10
Q

Aim of the SNS

A

To increase energy by increasing levels of glucose and oxygen

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11
Q

SNS receptors and messengers

A

Noradrenaline (neurotransmitter) binds to alpha 1 and 2
Adrenaline (hormone) binds to beta 2
Beta 1 binds noradrenaline and adrenaline equally

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12
Q

The heart and the SNS (3)

A

Mediated by the beta 1 receptor

  1. Increases SA node firing rate
  2. Increases AV node conduction velocity
  3. Increases contractility
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13
Q

Blood vessels and the SNS (2)

A

Beta 2 receptors - vascular smooth muscle relaxation causes vasodilation
Alpha 1 receptors - vascular smooth muscle contraction causes vasoconstriction

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14
Q

Drugs modulating blood vessels

A
  1. Beta blockers (beta 1 antagonists) reduce heart rate and contractility
  2. Beta agonists increase heart rate and contractility
  3. Alpha 1 receptor enhancer - synthetic noradrenaline
  4. Alpha 1 receptor blockers - hydrolazine
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15
Q

Lungs and the SNS

A

Beta 2 agonists (e.g. salbutamol) mimic effect of adrenaline - bronchodilation by relaxing smooth muscle

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16
Q

The kidneys and the SNS

A

Reduces urine formation

Increased adrenaline and noradrenaline release from adrenal medulla

17
Q

Adverse effects of beta antagonists (6)

A
Bradycardia
Hypotension
Depression
Impotence
Broncho-constriction
Elevated blood glucose
18
Q

Adverse effects of beta agonists (3)

A

Tachycardia
Anxiety
Problems with micturation

19
Q

Alpha agonists (3)

A

Increased heart rate
GI tract disturbances
Urinary retention

20
Q

Alpha antagonists (1)

A

Increased blood glucose

21
Q

The parasympathetic nervous system is largely controlled by…

A

the vagal nerve