Pituitary and Adrenals Flashcards Preview

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

Flashcards in Pituitary and Adrenals Deck (112):
1

Where is the pituitary gland located?

In the base of brain

2

How is the pituitary gland associated with the hypothalamus?

It’s suspended from the hypothalamus by a stalk

3

What surrounds the pituitary gland?

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

4

How much does the pituitary gland weigh?

0.5-0.9g

5

Who is the pituitary gland larger in?

Females

6

Why is the pituitary gland larger in females?

Due to the effect of oestrogen on Lactotropes

7

Why is the blood flow to the pituitary gland unusual?

It has a portal system

8

What is meant by a portal system?

A vessel connecting to capillary beds located in separate tissues

9

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

One in hypothalamus, one in anterior pathway

10

Where does the pituitary get its arterial blood supply from?

The superior and inferior hypothyseal arteries arising from internal carotid arteries

11

What do pituitary glands develop as?

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

12

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

The anterior lobe

13

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

Adenohypophysis

14

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

The posterior lobe

15

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

Neurohypophysis

16

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

Histologically different, have different functins

17

Where are hormones produced in the anterior pituitary?

In distinct cell types

18

What hormones are produced in the anterior pituitary?

- TSH
- ACTH
- Growth hormone 
- LH and FSH
- Prolactin

19

Where is TSH produced?

Thyrotropes

20

Where is ACTH produced?

Corticotropes

21

Where is growth hormone produced?

Somatotropes

22

What do somatotropes constitute?

The largest cell group in the anterior pituitary

23

Where is LH and FSH produced?

Gonadotropes

24

Where is prolactin produced?

Lactotropes

25

What are the adrenal glands?

A pair of multifunctional endocrine glands

26

Where are the adrenal glands found?

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

27

How much to the adrenal glands weigh?

6-8kg

28

How do the adrenal glands differ in females?

They weigh slightly less

29

What do the adrenal glands consist of?

2 regions

30

What are the 2 regions of the adrenal glands?

#NAME?

31

What hormones does the adrenal cortex produce?

- Mineralocorticoids 
- Glucocorticoids 
- Androgens

32

Give an example of of a mineralocorticoid

Aldosterone

33

Give 2 examples of glucocorticoids

- Cortisol 
- Costerone

34

Give an example of an androgen

Dehydroepiandrosterone

35

How much androgen is produced by the adrenal gland?

Only small amounts

36

What hormone does the adrenal medulla produce?

Adrenaline

37

What can be recognised in the adrenal cortex?

3 zones

38

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

A connective tissue capsule

39

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

A plexus of blood vessel

40

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

By the different arrangement of the secretory cells

41

What does each zone of the adrenal cortex have?

An associated network of capillaries and sinusoids

42

What are the 3 zones of the adrenal cortex?

- Zona Glomerulosa 
- Zona Fasciculata 
- Zona Reticularis

43

What do the cells of the zona glomerulosa do?

Secrete mineralocorticoids

44

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

Regulate body Na +  and K + levels

45

What do the cells in the zona fasciculata do?

Produce glucocorticoids

46

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

Number of functions, including regulation of carbohydrate metabolism

47

What do the cells of the zona reticularis do?

Secrete glucocorticoids and small amount of androgens

48

What is cortisol a member of?

The C 21  steroid family

49

How does cortisol differ form other steroids?

- The number of C atoms 
- Presence of functional groups 
- Distribution of C=C double bonds

50

What is true of all steroid hormones?

#NAME?

51

How are steroid hormones synthesised from cholesterol?

Via progesterone, in a series of enzyme catalysed reactions

52

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

ACTH  (or corticotropin)

53

What is ACTH secreted by?

The cortiotropes of the anterior pituitary

54

How is secretion of ACTH controlled by?

Corticotropin releasing factor (CRF)

55

What is CRF?

A 41 amino acid polypeptide

56

Where is CRF produced?

In hypothalamus

57

What is CRF secreted in response to?

Physical, chemical and emotional stressors

58

Give 2 examples of physical stressors?

- Temperature 
- Pain

59

Give an example of a chemical stressor

Hypoglycaemia

60

How do glucocorticoids have an impact on cortisol secretion?

They exert negative feedback on both the hypothalamus and pituitary

61

What is ACTH?

A 39 amino acid, single chain polypeptide hormone

62

What is the initial biosynthetic precursor of ACTH?

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

63

What happens to POMC?

Post-translational processing of POMC at different sites

64

What does post-translational processing of POMC produce?

A range of biologically active peptides

65

Give 3 peptides produced by POMC?

#NAME?

66

What is α-MSH?

Melanocyte stimulating hormone

67

Where is the α-MSH sequence contained?

Within the ACTH sequence

68

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

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

69

How long is the ACTH half life in circulation?

Short- ~8mins

70

In what manner in ACTH released into the circulation?

In pulses that follow a cardiac rhythm

71

When do peak plasma levels of ACTH occur?

Early morning

72

Is ACTH hydrophilic or hydrophobic?

Hydrophilic

73

What does ACTH interact with?

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

74

What does the binding of ACTH to receptors lead to?

Activation of cholesterol esterase

75

What does the activation of cholesterol esterase do?

#NAME?

76

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

Direct effects of ACTH on tissues and the adrenal cortex

77

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

Increased pigmentation

78

What causes increased pigmentation?

Partial MSH activity

79

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

Adrenal hyperplasia and over-production of cortisol

80

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

Lack of glucocorticoids

81

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

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

82

What kind of hormone is ACTH?

Peptide

83

What does ACTH act on?

G-protein coupled receptors on plasma membrane of target cells

84

What is the specific GPCR for ACTH?

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

85

What does the MC 2  receptor use?

cAMP

86

What does the MC 2  receptor use cAMP for?

As the second messenger

87

How must cortisol be transported?

Bound to plasma proteins

88

What is the major transport protein for cortisol?

Transcortin

89

What is transcortin also known as?

Corticosteroid binding globulin (CBG)

90

How much of the plasma cortisol is carried by transcortin?

90%

91

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

It is free and biologically active

92

What is cortisol an important component of?

The stress response

93

When do the major metabolic effects of cortisol act?

In the stressed/starved states

94

What does cortisol affect regarding metabolism?

The availability of all major metabolic substrates

95

How does cortisol affect the availability of major metabolic substrates?

Increasing proteolysis, gluconeogenesis and lipolysis

96

What do the metabolic actions of cortisol include?

- 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

Where does cortisol not increase proteolysis?

In the liver

98

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

Increases lipogenesis

99

What does cortisol do in additional to its metabolic actions?

Has direct effects on cardiac muscle, bone and immune system

100

What is the adrenal medulla in essence?

A modified sympathetic ganglia

101

What does the adrenal medulla do?

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

102

How are catecholamines synthesised?

- 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

Where are the catecholamines stored?

In the medullary cells in membrane-limited vesicles

104

What is adrenaline released as part of?

The fright, flight or fight response

105

What is adrenaline released in response to?

Stressful situations

106

What does adrenaline have effects on?

- Cardiovascular system
- CNS
- Carbohydrate metabolism 
- Lipid metabolism

107

What is the effect of adrenaline on the cardiovascular system?

#NAME?

108

What is the effect of adrenaline on the CNS?

Increased mental alertness

109

What is the effect of adrenaline on carbohydrate metabolism?

Increased gluconeogenesis in liver and muscle

110

What is the effect of adrenaline on lipid metabolism?

Increased lipolysis in adipose tissue

111

What usually causes overproduction of adrenaline?

A tumour- pheochromocytoma

112

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

- Hypertension 
- Anxiety
- Palpitations 
- Pallor 
- Sweating
- Glucose intolerance