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Z OLD ESA 1- Metabolism > Pituitary and Adrenals > Flashcards

Pituitary and Adrenals Flashcards

1
Q

Where is the pituitary gland located?

A

In the base of brain

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2
Q

How is the pituitary gland associated with the hypothalamus?

A

It’s suspended from the hypothalamus by a stalk

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3
Q

What surrounds the pituitary gland?

A

Lies in a deep recess of sphenoid bone (the pituitary fossa), surrounded by a small bony cavity (sella turcia)

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4
Q

How much does the pituitary gland weigh?

A

0.5-0.9g

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5
Q

Who is the pituitary gland larger in?

A

Females

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6
Q

Why is the pituitary gland larger in females?

A

Due to the effect of oestrogen on Lactotropes

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7
Q

Why is the blood flow to the pituitary gland unusual?

A

It has a portal system

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8
Q

What is meant by a portal system?

A

A vessel connecting to capillary beds located in separate tissues

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9
Q

Where do the capillary beds making up the pituitary glands portal system lie?

A

One in hypothalamus, one in anterior pathway

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10
Q

Where does the pituitary get its arterial blood supply from?

A

The superior and inferior hypothyseal arteries arising from internal carotid arteries

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11
Q

What do pituitary glands develop as?

A

A fusion between up growth of ectodermal cells from the roof of the primitive pharynx (buccal cavity), and a down growth of neural tissue from the hypothalamus

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12
Q

What is formed from the up growth of ectodermal cells from the roof of the buccal cavity?

A

The anterior lobe

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13
Q

What is the anterior lobe of the pituitary gland also known as?

A

Adenohypophysis

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14
Q

What is formed from the down-growth of neural tissue from the hypothalamus?

A

The posterior lobe

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15
Q

What is the posterior lobe of the pituitary gland also known as?

A

Neurohypophysis

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16
Q

How are the posterior and anterior lobes of the pituitary gland different?

A

Histologically different, have different functins

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17
Q

Where are hormones produced in the anterior pituitary?

A

In distinct cell types

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18
Q

What hormones are produced in the anterior pituitary?

A
  • TSH
  • ACTH
  • Growth hormone
  • LH and FSH
  • Prolactin
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19
Q

Where is TSH produced?

A

Thyrotropes

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20
Q

Where is ACTH produced?

A

Corticotropes

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21
Q

Where is growth hormone produced?

A

Somatotropes

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22
Q

What do somatotropes constitute?

A

The largest cell group in the anterior pituitary

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23
Q

Where is LH and FSH produced?

A

Gonadotropes

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24
Q

Where is prolactin produced?

A

Lactotropes

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25
Q

What are the adrenal glands?

A

A pair of multifunctional endocrine glands

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26
Q

Where are the adrenal glands found?

A

Capping the upper roles of the kidneys, and lie against the diaphragm

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27
Q

How much to the adrenal glands weigh?

A

6-8kg

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28
Q

How do the adrenal glands differ in females?

A

They weigh slightly less

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29
Q

What do the adrenal glands consist of?

A

2 regions

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30
Q

What are the 2 regions of the adrenal glands?

A

NAME?

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31
Q

What hormones does the adrenal cortex produce?

A
  • Mineralocorticoids
  • Glucocorticoids
  • Androgens
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32
Q

Give an example of of a mineralocorticoid

A

Aldosterone

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33
Q

Give 2 examples of glucocorticoids

A
  • Cortisol

- Costerone

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34
Q

Give an example of an androgen

A

Dehydroepiandrosterone

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35
Q

How much androgen is produced by the adrenal gland?

A

Only small amounts

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36
Q

What hormone does the adrenal medulla produce?

A

Adrenaline

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37
Q

What can be recognised in the adrenal cortex?

A

3 zones

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38
Q

What do the 3 zones of the adrenal cortex lie under?

A

A connective tissue capsule

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39
Q

What does the connective tissue capsule of the adrenal cortex have?

A

A plexus of blood vessel

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40
Q

How can the 3 zones of the adrenal cortex be identified?

A

By the different arrangement of the secretory cells

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41
Q

What does each zone of the adrenal cortex have?

A

An associated network of capillaries and sinusoids

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42
Q

What are the 3 zones of the adrenal cortex?

A
  • Zona Glomerulosa
  • Zona Fasciculata
  • Zona Reticularis
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43
Q

What do the cells of the zona glomerulosa do?

A

Secrete mineralocorticoids

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44
Q

What is the purpose of the zona glomerulosa’s secretions?

A

Regulate body Na + and K + levels

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45
Q

What do the cells in the zona fasciculata do?

A

Produce glucocorticoids

46
Q

What is the purpose of the secretions of the zona fasciculata?

A

Number of functions, including regulation of carbohydrate metabolism

47
Q

What do the cells of the zona reticularis do?

A

Secrete glucocorticoids and small amount of androgens

48
Q

What is cortisol a member of?

A

The C 21 steroid family

49
Q

How does cortisol differ form other steroids?

A
  • The number of C atoms
  • Presence of functional groups
  • Distribution of C=C double bonds
50
Q

What is true of all steroid hormones?

A

NAME?

51
Q

How are steroid hormones synthesised from cholesterol?

A

Via progesterone, in a series of enzyme catalysed reactions

52
Q

What is the main factor in controlling the release of cortisol?

A

ACTH (or corticotropin)

53
Q

What is ACTH secreted by?

A

The cortiotropes of the anterior pituitary

54
Q

How is secretion of ACTH controlled by?

A

Corticotropin releasing factor (CRF)

55
Q

What is CRF?

A

A 41 amino acid polypeptide

56
Q

Where is CRF produced?

A

In hypothalamus

57
Q

What is CRF secreted in response to?

A

Physical, chemical and emotional stressors

58
Q

Give 2 examples of physical stressors?

A
  • Temperature

- Pain

59
Q

Give an example of a chemical stressor

A

Hypoglycaemia

60
Q

How do glucocorticoids have an impact on cortisol secretion?

A

They exert negative feedback on both the hypothalamus and pituitary

61
Q

What is ACTH?

A

A 39 amino acid, single chain polypeptide hormone

62
Q

What is the initial biosynthetic precursor of ACTH?

A

A large protein, of ~250 amino acids, called proopiomelanocortin (POMC)

63
Q

What happens to POMC?

A

Post-translational processing of POMC at different sites

64
Q

What does post-translational processing of POMC produce?

A

A range of biologically active peptides

65
Q

Give 3 peptides produced by POMC?

A

NAME?

66
Q

What is α-MSH?

A

Melanocyte stimulating hormone

67
Q

Where is the α-MSH sequence contained?

A

Within the ACTH sequence

68
Q

What is the result of the α-MSH sequence being contained within the ACTH sequence?

A

It gives ACTH some α-MSH-like activity when present in excess

69
Q

How long is the ACTH half life in circulation?

A

Short- ~8mins

70
Q

In what manner in ACTH released into the circulation?

A

In pulses that follow a cardiac rhythm

71
Q

When do peak plasma levels of ACTH occur?

A

Early morning

72
Q

Is ACTH hydrophilic or hydrophobic?

A

Hydrophilic

73
Q

What does ACTH interact with?

A

High affinity receptors on the surface of the cells in zona fasciculata and reticularis

74
Q

What does the binding of ACTH to receptors lead to?

A

Activation of cholesterol esterase

75
Q

What does the activation of cholesterol esterase do?

A

NAME?

76
Q

What do the clinical consequences of over-secretion of ACTH relate to?

A

Direct effects of ACTH on tissues and the adrenal cortex

77
Q

What are the effects of over-secretion of ACTH on the tissues?

A

Increased pigmentation

78
Q

What causes increased pigmentation?

A

Partial MSH activity

79
Q

What is the result of over-secretion of ACTH on the adrenal cortex?

A

Adrenal hyperplasia and over-production of cortisol

80
Q

What are the clinical consequences of under-secretion of ACTH related to?

A

Lack of glucocorticoids

81
Q

Why is under-secretion of ACTH not related to lack of lack of mineralocorticoids?

A

As aldosterone secretion is normal, because it’s not controlled by ACTH

82
Q

What kind of hormone is ACTH?

A

Peptide

83
Q

What does ACTH act on?

A

G-protein coupled receptors on plasma membrane of target cells

84
Q

What is the specific GPCR for ACTH?

A

A type of melanocortin receptor (type 2), known as MC 2

85
Q

What does the MC 2 receptor use?

A

cAMP

86
Q

What does the MC 2 receptor use cAMP for?

A

As the second messenger

87
Q

How must cortisol be transported?

A

Bound to plasma proteins

88
Q

What is the major transport protein for cortisol?

A

Transcortin

89
Q

What is transcortin also known as?

A

Corticosteroid binding globulin (CBG)

90
Q

How much of the plasma cortisol is carried by transcortin?

A

90%

91
Q

What happens to the 10% or cortisol not bound to transcortin?

A

It is free and biologically active

92
Q

What is cortisol an important component of?

A

The stress response

93
Q

When do the major metabolic effects of cortisol act?

A

In the stressed/starved states

94
Q

What does cortisol affect regarding metabolism?

A

The availability of all major metabolic substrates

95
Q

How does cortisol affect the availability of major metabolic substrates?

A

Increasing proteolysis, gluconeogenesis and lipolysis

96
Q

What do the metabolic actions of cortisol include?

A
  • Decreased amino acid uptake
  • Decreased protein synthesis
  • Increased proteolysis in most tissues
  • Increased hepatic gluconeogenesis and glycogenolysis
  • Increased lipolysis in adipose tissue
  • Decreased peripheral uptake of glucose
97
Q

Where does cortisol not increase proteolysis?

A

In the liver

98
Q

What is the effect of high cortisol levels in adipose tissue?

A

Increases lipogenesis

99
Q

What does cortisol do in additional to its metabolic actions?

A

Has direct effects on cardiac muscle, bone and immune system

100
Q

What is the adrenal medulla in essence?

A

A modified sympathetic ganglia

101
Q

What does the adrenal medulla do?

A

Synthesises catecholamines, including the hormone adrenaline and the neurotransmitters noradrenaline and dopamine

102
Q

How are catecholamines synthesised?

A
  • In a series of enzyme catalysed steps that convert the amino acid tyrosine into dopamine.
  • Dopamine then converted to noradrenaline
  • Noradrenaline converted to adrenaline
103
Q

Where are the catecholamines stored?

A

In the medullary cells in membrane-limited vesicles

104
Q

What is adrenaline released as part of?

A

The fright, flight or fight response

105
Q

What is adrenaline released in response to?

A

Stressful situations

106
Q

What does adrenaline have effects on?

A
  • Cardiovascular system
  • CNS
  • Carbohydrate metabolism
  • Lipid metabolism
107
Q

What is the effect of adrenaline on the cardiovascular system?

A

NAME?

108
Q

What is the effect of adrenaline on the CNS?

A

Increased mental alertness

109
Q

What is the effect of adrenaline on carbohydrate metabolism?

A

Increased gluconeogenesis in liver and muscle

110
Q

What is the effect of adrenaline on lipid metabolism?

A

Increased lipolysis in adipose tissue

111
Q

What usually causes overproduction of adrenaline?

A

A tumour- pheochromocytoma

112
Q

What are the clinical consequences of over-secretion of adrenaline?

A
  • Hypertension
  • Anxiety
  • Palpitations
  • Pallor
  • Sweating
  • Glucose intolerance

Z OLD ESA 1- Metabolism (17 decks)

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