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MEDSCI 142 > Section 2: Autonomic and Endocrine System > Flashcards

Section 2: Autonomic and Endocrine System Flashcards

1
Q

Organisation of nervous sytems: CNS and PNS

A

CNS:
Brain
Spinal cord

PNS:
Cranial nerves
Spinal nerves
Ganglia
Peripheral nerves
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2
Q

Sensory vs motor neurons

A

Sensory neurons: afferent, carry into body
Motor neurons: efferent, carry away from body. Multi-polar in structure

Via cranial and spinal nerves

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3
Q

Types of motor (efferent) neurons

A

Somatic (voluntary) –> Skeletal muscle

Autonomic (involuntary) –> Sympathetic or parasympathetic –> cardiac muscle, smooth muscle, glands

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4
Q

The alarm response

A

Increased heart rate and force of contraction
Dilation of pupils
Decreased salivation
Dilation of bronchi –> breathe faster
Contraction of arrector pili muscles and increased secretion from sweat glands (skin)
Constriction of blood vessels, especially in skin
Decreased digestion (gut)
Increased blood sugar, blood pressure (liver) and water retention (kidneys)

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5
Q

The relaxation response

A

Decreased heart rate and force of contraction
Contraction of pupils
Increased salivation
Constriction of bronchi –> breathe slower
Dilation of peripheral blood vessels (skin)
Increased digestion (gut)

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6
Q

Autonomic Nervous System (ANS)

A

Controls body’s internal response

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7
Q

ANS - Sympathetic division

A

Responses associated with exercise, emotion, excitement

Alarm response

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8
Q

ANS - Parasympathetic division

A

Responses associated with repletion, rest, relaxation

Relaxation response

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9
Q

ANS: Autonomic vs somatic - sensory input

A

Autonomic: Mainly interoceptors (internal sensing)

Somatic: Special senses and somatic senses

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10
Q

ANS: Autonomic vs somatic - control of output

A

Autonomic: Involuntary from limbic system, hypothalamus, brain stem and spinal cord

Somatic: Voluntary from cerebral cortex (outer cortical brain)

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11
Q

ANS: Autonomic vs somatic - motor neuron pathway

A

Autonomic: Two-neuron pathway (pre-ganglionic and post-ganglionic)

Somatic: One-neuron pathway

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12
Q

ANS: Autonomic vs somatic - neurotransmitters

A

Autonomic: Acetylcholine
- Pre-ganglionic axons
- Post-ganglionic parasympathetic
- Post-ganglionic sympathetic to sweat glands
Autonomic: Norepinephrine
- Post-ganglionic sympathetic fibres other than to sweat glands

Somatic: Acetylcholine

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13
Q

ANS: Autonomic vs somatic - effectors

A

Autonomic: Smooth muscle, cardiac muscles, glands

Somatic: Skeletal muscle

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14
Q

Raynaud disease

A

Excessive stimulation following emotion stress/exposure to cold
Chronic vasoconstriction
Fingers and toes become ischemic –> could kill cells in long term
Therefore important for responses to be inducible

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15
Q

Hypothalamus - functions

A

Control internal organs via ANS and pituitary gland
Regulates behavioural patterns, circadian rhythms and sleep/wake cycles
Controls body temp
Regulates eating and drinking behaviour

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16
Q

Endocrine system - main organs

A

Hypothalamus
Pituitary
Adrenal glands

HPA axis - controls other organs in endocrine system

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17
Q

Types of hormones

A

Circulating hormones - distant target cells

Local hormones (paracrines and autocrimes)

  • Paracrine hormones - nearby target cell
  • Autocrine hormones - same target cell
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18
Q

Mechanism of action of lipid-soluble hormones

A
  1. Lipid soluble hormone diffuses into cell
  2. Activated receptor-hormone complex alters gene expression
  3. Newly formed mRNA directs synthesis of specific proteins on ribosomes
  4. New protein alters cell’s activity
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19
Q

Mechanism of action of water-soluble hormones

A
  1. Binding to receptor activates G protein which activates adenylate cyclase
  2. Activated adenyl cyclase converts ATP to cAMP
  3. cAMP serves as a second messenger to activate protein kinases
  4. Activated protein kinases phosphorylate other enzymes
  5. Phosphorylated enzymes catalyse reactions that produce physiological responses
  6. Phosphodiesterase inactivates cAMP
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20
Q

Parts of the adrenal gland

A

From superior to inferior:
Capsule
Adrenal cortex
Adrenal medulla

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21
Q

Enhancing the alarm response

A

Pre-ganglionic neuron joins to post-ganglionic neurons
Modified post-ganglionic neurons act as secretory cells - secretes epinephrine and norepinephrine into bloodstream when stimulated

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22
Q

Adrenal medulla - hormones, stimulated by, principal actions

A

Hormones: Epinephrine (adrenaline) and norepinephrine
Stimulated by: ACh from sympathetic pre-ganglionic neurons
Principal actions: Enhance sympathetic autonomic alarm response

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23
Q

Adrenal cortex - hormones, stimulated by, principal actions

A

A:
Hormone: Mineralo-corticoids (e.g. aldosterone)
Stimulated by: Increased K+ and angiotensin II in blood
Principal action: Increase blood Na+ and water and decrease blood K+ –> increased blood V and pressure

B:
Hormone: Glucocorticoids (e.g. cortisol)
Stimulated by: ACTH from pituitary, which is stimulated by CRH from hypothalamus
Principal actions: Resistance reaction to stress, dampens inflammation and depresses immune responses

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24
Q

What do the hypothalamus and pituitary gland regulate

A

Development
Metabolism
Homeostasis

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25
Q

Portal system between hypothalamus and pituitary gland

A

Capillaries - portal vein - capillaries

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26
Q

Negative feedback effects on pituitary gland

A

Elevated cortisol inhibits release of ACTH by anterior pituitary corticotrophs (cortisol –> anterior pituitary)

Elevated cortisol inhibits release of CRH by hypothalamic neurosecretory cells (cortisol –> hypothalamus)

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27
Q

Resistance reaction: Actions and consequences of glucocorticoids - Protein breakdown

A

Increase protein breakdown mainly in muscle fibres

Amino acids released into bloodstream may be used for synthesis of new proteins and ATP production

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28
Q

Resistance reaction: Actions of glucocorticoids - Gluconeogenesis

A

Liver cells convert some amino acids or lactic acid to glucose, which neurons and other cells can use for ATP production

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29
Q

Resistance reaction: Actions of glucocorticoids - Lipolysis

A

Breakdown of triglycerides and release of fatty acids from adipose tissue into blood

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30
Q

Resistance reaction: Actions of glucocorticoids - Resistance to stress

A

Increased glucose and ATP combat stresses, e.g. exercise, fasting, fright, temp extreme

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31
Q

Resistance reaction: Actions of glucocorticoids - Vasoconstriction

A

Blood vessels become more sensitive to hormones that cause vasoconstriction –> rise in blood pressure

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32
Q

Resistance reaction: Actions of glucocorticoids - Anti-inflammatory

A

Inhibit white blood cells that participate in inflammatory responses (to limit tissue damage by them)
Retards tissue repair and slow wound healing

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33
Q

Resistance reaction: Actions of glucocorticoids - Immune depression

A

High glucocorticoid conc depress immune responses

Used therapeutically following organ transplants to retard graft rejection

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34
Q

Fight-or-flight response vs resistance reaction

A

Fight-or-flight is a faster response and only lasts a short while, whereas resistance reaction is slower and lasts longer (stage 2)

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35
Q

Fight-or-flight response

A

Immediate burst
Initiated by nerve impulses from hypothalamus to sympathetic division of ANS
Adrenal medulla involvements (epinephrine and NE)

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36
Q

Resistance reaction

A

Slower, longer lasting
Associated with hypothalamus - pituitary - adrenal cortex
Initiated in large part by hypothalamic releasing hormones
Corticosteroid (cortisol) production

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37
Q

The stress response

A

Sympathetic autonomic activation (stage 1)
Mobilise resources for immediate physical activity
Glucose and oxygen consumption
Alertness and activity
Reduce tissue damage (stage 2)
Ward off danger or flee!

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38
Q

Links between neuroendocrine and immune systems

A

Neuroendocrine —hormones (e.g. cortisol)—> immune
Neuroendocrine —autonomic nerves—> immune
Immune —cytokines (immune hormones)—> neuroendocrine

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39
Q

Short-term remedial action

A

Threat system arousal:

  • Blood (energy)
  • Muscle (motor)
  • Vigilance (sensory)

Dampen unnecessary:

  • Digestion
  • Immunity
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40
Q

Types of stresses

A

Eustress (acute):

  • Prepares us to meet certain challenges
  • Helpful, beneficial

Distress (chronic):

  • Associated with undesirable events
  • Potentially harmful
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41
Q

How is the spinal cord connected to the brain

A

Through the foramen magnum of the occipital bone

Encircled by bones of vertebral column

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42
Q

What does PNS consist of

A

All nervous tissue outside the CNS

e.g. nerves, ganglia, sensory receptors

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43
Q

What is a nerve

A

A bundle of hundreds to thousands of axons plus associated CT and blood vessels that lie outside the brain and spinal cord

44
Q

Number of cranial and spinal cords

A

12 pairs of cranial nerves emerge from brain

31 pairs of spinal nerves emerge from spinal cord

45
Q

What are ganglia

A

Small masses of nervous tissue, consisting primarily of neuron cell bodies located outside of the brain and spinal cord
Closely associated with cranial and spinal nerves

46
Q

What are enteric plexuses

A

Extensive networks of neurons located in walls of organs of GI tract

47
Q

What is a sensory receptor

A

A structure of the nervous system that monitors changes in internal or external environment

48
Q

Nervous system - functions (3)

A

Sensory function
Integrative function
Motor function

49
Q

Nervous system - sensory function

A

Sensory receptors detect internal or external stimuli

This sensory info is then carried into the brain and spinal cord through cranial and spinal nerves

50
Q

Nervous system - integrative function

A

Processes sensory info by analysing it and making decisions for appropriate responses - known as integration

51
Q

Nervous system - motor function

A

Once sensory info is integrated, the nervous system may elicit an appropriate motor response by activating effectors through cranial and spinal nerves

52
Q

Nervous tissue is comprised of what types of cells

A

Neurons and neuroglia, which combine in a variety of ways in diff regions of the nervous system

53
Q

Neurons - electrical excitability

A

The ability to respond to a stimulus and convert it into an AP

54
Q

What is a stimulus

A

Any change in the environment that is strong enough to initiate an AP

55
Q

What is an AP

A

An electrical signal that propagates along the surface of the membrane of a neuron

56
Q

Parts of a neuron

A

Cell body
Dendrites
An axon

57
Q

Types of neurons

A

Multipolar neurons (most common neuron in brain and spinal cord)
Bipolar neurons
Unipolar neurons

58
Q

Dual innervation

A

Most organs have dual innervation - receive impulses from both sympathetic and parasympathetic neurons

59
Q

Cholingergic neurons

A

Release ACh

60
Q

Where is ACh stored

A

Stored in synaptic vesicles, released by exocytosis

61
Q

Adrenergic neurons

A

Release NE

62
Q

Where is norepinephrine stored

A

Stored in synaptic vesicles, released by exocytosis

63
Q

Receptor agonist

A

A substance that binds to and activates a receptor, in the process mimicking the effect of a natural neurotransmitter / hormone

64
Q

Receptor antagonist

A

A substance that binds to and blocks a receptor –> prevents a natural neurotrasmitter or hormone from exerting its effect

65
Q

Hypothalamus - composed of a dozen or so nuclei in which four major regions?

A

Mammilary region - most posterior part of hypothalamus
Tuberal region - widest part of hypothalamus
Supraoptic region - superior to optic chiasm
Preoptic region - anterior to supra optic region

66
Q

Hormones: Down-regulation and up-regulation

A

Down-regulation: If hormone is present in excess, number of target-cell receptors may decrease. Makes target cell less sensitive to a hormone
Up-regulation: If hormone is deficient, number of target-cell receptors may increase. Makes target cell more sensitive to a hormone

67
Q

Most common type of endocrine hormone

A

Circulating hormones - pass from secretory cells that make them into interstitial fluid and then into blood

68
Q

Local hormones

A

Act locally on neighbouring cells or on the same cell that secreted them without first entering the bloodstream
Usually inactivated quickly

69
Q

Types of lipid-soluble hormones

A 
Steroid hormones - derived from cholesterol
Thyroid hormones (T3 and T4) - synthesised by attaching iodine to tyrosine
Nitric oxide (NO) - hormone and neutransmitter
70
Q

Types of water-soluble hormones

A

Amino hormones - synthesized by decarboxylating and modifying certain amino acids
Peptide hormones and protein hormones - amino acid polymers
Eicosanoid hormones - derived from arachidonic acid (fatty acid)

71
Q

Water-soluble vs lipid-soluble hormones - free?

A

Most water-soluble hormones circulate in watery blood plasma in a ‘free’ form
Most lipid-soluble hormone molecules are bound to transport proteins

72
Q

Lipid-soluble hormones: Transport proteins - functions

A

Make lipid-soluble hormones temporarily water-soluble –> increases solubility in blood
Retard passage of small hormone molecules through filtering mechanism in kidneys –> slows rate of hormone loss in urine
Provide a ready reserve of hormone, already present in bloodstream

73
Q

The responsiveness of a target cell to a hormone depends on…

A

Hormone’s conc in blood
Abundance of target cell’s hormone receptors
Influences exerted by other hormones

74
Q

Hormones - permissive effect

A

Where actions of some hormones on target cells require a simultaneous or recent exposure to a second hormone

75
Q

Hormones - synergistic effect

A

Where effect of two hormones acting tgt is greater or more extensive than effect of each hormone acting alone

76
Q

Hormones - antogonistic effect

A

Where one hormone opposes actions of another hormone

77
Q

The release of most hormones occur in…

A

Short bursts, with little or no secretion between bursts

78
Q

Hormone secretion is regulated by…

A

Signals from nervous system
Chemical changes in blood
Other hormones

79
Q

Most hormones work via ____ feedback

A

Negative feedback, but a few operate via positive feedback

80
Q

Infundibulum

A

Attaches pituitary gland to hypothalamus

81
Q

Anterior vs posterior pituitary

A

Anterior: accounts for ~75% of weight of gland, composed of epithelial tissue
Posterior: composed of neural tissue

82
Q

Stressor

A

Any stimulus that produces a stress response

83
Q

Stress response is controlled by..

A

The hypothalamus

84
Q

Stages of the stress response

A
  1. An initial fight-or-flight response (alarm response)
  2. Extended alarm response
  3. A slower resistance reaction, and eventually
  4. Exhaustion
85
Q

Resistance stage and stressor

A

Resistance stage helps body continue fighting a stressor long after the fight-or-flight response
This is why heart continues to pound for several mins even after the stressor is removed

86
Q

Stress response - exhaustion

A

Due to resources of body eventually becoming depleted they can’t sustain the resistance stage
Prolonged exposure to high levels of cortisol and other hormones

87
Q

Adrenergic receptors

A

Bind both norepinephrine and epinephrine

88
Q

Autonomic tone

A

The balance between sympathetic and parasympathetic activity

89
Q

Autonomic tone - regulation

A

Regulated by hypothalamus, which typically turns up sympathetic tone at the same time it turns down parasympathetic tone and vice versa

90
Q

Why are effects of sympathetic stimulation longer lasting and more widespread than effects of parasympathetic stimulation

A

Sympathetic post-ganglionic axons diverge more extensively –> many tissues activated simultaneously
ACh esterase quickly inactivates ACh, but NE lingers in synaptic cleft for a longer period
Epinephrine and NE secreted into blood from adrenal medullae intensify and prolong responses caused by NE

91
Q

Parasympathetic responses (SLUDD and ‘three decreases’)

A 
Salivation
Lacrimnation
Urination
Digestion
Defecation

Decreased heart rate
Decreased diameter of airways
Decreased diameter of pupils

92
Q

Aldosterone

A

Major mineralocorticoid
Regulates homeostasis of Na+ and K+ (mineral ions)
Helps adjust blood pressure and volume
Promotes excretion of H+ in urine –> removes acids from body –> prevents acidosis

93
Q

Corticotropin-releasing hormone (CRH)

A

Promotes release of ACTH from anterior pituitary –> flows into blood –> stimulates glucocorticoid secretion

94
Q

Adrenal glands - vascular?

A

Highly vascularised

95
Q

Adrenal medulla

A

Modified sympathetic ganglion of ANS
Cells lack axons and form clusters around large blood vessels
Secrete hormones - epinephrine and NE

96
Q

Cytokines

A

Small protein hormones that stimulate or inhibit many normal cell functions, e.g. cell growth and differentiation

97
Q

Synaptic transmission - steps

A
  1. AP arrives at pre-synaptic axon terminal
  2. V-gated Ca2+ channels open on pre-synaptic terminal
  3. Ca2+ causes synaptic vesicles to fuse to the cell membrane and release neurotransmitters via exocytosis
  4. Neurotransmitter diffuses across synaptic cleft
  5. Neurotransmitter binds to receptors on post-synaptic cell membrane
  6. Ligand-gated ion channels open on post-synaptic membrane and Na+ flows into post-synaptic cell
  7. Post-synaptic potential reaches threshold and fires an AP
  8. Nerve impulses continue to propagate
98
Q

What is multiple sclerosis

A

A disease that occurs due to destruction of myelin sheaths –> slows down propagation of nerve impulses

99
Q

Multiple sclerosis - symptoms

A

Vary widely depending on amount of nerve damage and which nerve are affected
May experience long periods of remission without any new symptoms
Lose ability to walk independently or at all
Numbness or weakness in one of more limbs - usually occurs on one side of body at a time
Electric-shock sensations with certain neck movements
Tremor, lack of coordination or unsteady gait
Effects of visions - partial or complete loss, double vision
Slurred speech, fatigue, dizziness, tingling, pain in parts of body

100
Q

Connection of anterior and posterior pituitary to hypothalamus

A

Anterior: via hypophyseal portal system (vascular connection)
Posterior: via hypothalamic-hypophyseal tract (neural connection)

101
Q

Anterior and posterior pituitary - response to…

A

Anterior: releasing and inhibiting hormones from ventral hypothalamus
Posterior: directly to hypothalamic neurons

102
Q

Hypophyseal portal system

A

A vascular arrangement in which blood flows from one capillary bed in the hypothalamus to another capillary bed in the anterior pituitary without going through the heart in its journey

103
Q

Kidneys and sympathetic activation - steps

A
  1. Sympathetic nerve activation (as a result of fight/flight response)
  2. Increase in arteriole resistance –> pressure changes
  3. Baroreceptors sense change in pressure
  4. Juxtaglomerular cells in kidney release renin into blood
  5. Renin acts on angiotensin –> cleaved to angiotensin I via renin –> cleaved to angiotensin II via ACE
  6. Angiotensin II causes vasoconstriction, increases water retention and stimulates formation of aldosterone
104
Q

If cells in a particular organ don’t respond to water-soluble hormone prolactin, the most likely reason is…

A

The cells lack the prolactin surface receptor

105
Q

What occurs most rapidly when in a situation of immediate alarm

A

Sympathetic nerve signals affect various body functions

106
Q

What is produced by hypothalamus to control the anterior pituitary

A

Releasing and inhibiting hormones

107
Q

Resistance reaction: Responses

A

Increased glucose, fatty acids, amino acids
Sensitised vessels
Reduce inflammation
Immune suppression

MEDSCI 142 (9 decks)

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