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Membranes > MacDonald > Flashcards

MacDonald Flashcards

1
Q

What speed do hormones act?

A

Slow response, low acting

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2
Q

Where are hormones produced?

A

In endocrine glands

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3
Q

What are the 3 classes of hormones?

A

Peptides
Amines
Steriods

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4
Q

How do nuclear hormones cross the plasma membrane?

A

Hydrophobic diffusion

Carrier proteins

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5
Q

What type of targets do steroid hormones have?

A

Nuclear

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6
Q

What are the types of steroid hormones?

A 
Glucocorticoids
Mineralocorticoids
Androgens
Oestrogens
Progestogenss
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7
Q

What are the 2 vague classifications of steriod hormones?

A

Adrenal

Gonadal

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8
Q

Where are the corticosteroids produced?

A

Adrenal cortex

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9
Q

How are the corticosteroids synthesised?

A

Dervived from cholesterol via pregenelone by the action of dehydroxylation and dehydrogenation

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10
Q

Which enzymes catalyse the synthesis of corticosteroids?

A

Cytochrome P450s

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11
Q

How is the synthesis of corticosteroids stimulated?

A

7 releasing hormones from hypothalamus
anterior pituitary releases secondary hormone
Adrenal cortex stimulated

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12
Q

How many hormones do the adrenal glands produce?

A

36

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13
Q

What are the 3 regions of the adrenal cortex?

A

Glomerulosa
Fasiculata
Reticularis

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14
Q

What class of steroid hormones does the glomerulosa region of the adrenal cortex produce?

A

mineralocorticoids

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15
Q

What region of the adrenal cortex is responsible for the synthesis of glucocorticoids?

A

Fasiculata

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16
Q

What region of the adrenal cortex is responsible for the synthesis of androgens?

A

reticularis

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17
Q

What is the main glucocorticoid?

A

Cortisol

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18
Q

What is the main mineralocorticoid?

A

Aldosterone

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19
Q

What are the main roles of cortisol?

A

Increase gluconeogenesis
Mobilisation of fatty acids and amino acids
Inhibition of glucose uptake in muscle and adipose tissues

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20
Q

How is cortisol released?

A 
Stress
Hypothalamus
CRH
Anterior Pituitary
ATCH
Adrenal gland
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21
Q

What are the gonadal steroids?

A

testosterone

oestrogen

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22
Q

Where is testosterone synthesised?

A

Leydig cells in the testes
Transported by ABP
Activated in Sertolli cells

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23
Q

What is the active form of testosterone?

A

dihydrotestosterone

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24
Q

What is the synthesis pathway for steroid hormones?

A

Cholesterol
Pregenelone
Progesterone
Mineralo/Gluco/testosterone

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25
Q

How is oestrogen derived?

A

From testosterone using aromatase enzyme in ovaries

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26
Q

Where is oestrogen produced in post-menopausal women?

A

Adrenal glands

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27
Q

Where is progesterone produced?

A

in corpus luteum

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28
Q

What effects does progesterone have?

A

Changes in luteral phase of menstrual cycle

A differentiation factor for mammary glands

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29
Q

What is the releasing hormone for oestrogen?

A

FSH

30
Q

What is LH the releasing hormone for?

A

Progesterone and testosterone

31
Q

What is angiotensin the releasing hormone for?

A

Aldosterone

32
Q

How are most steroid hormones found?

A

Inactive forms bound to carrier proteins in blood

33
Q

What structure do steroid receptors have?

A

Modular transcription factors with

(N)variable-zinc finger-ligand binding

34
Q

What are orphan receptors?

A

No identified ligand

35
Q

How does ligand binding activate receptors?

A

Conformational change exposes DBD

36
Q

Are steroid receptors ubiquitous?

A

No, none in yeast or plants

37
Q

What are the 2 classes of steroid receptors?

A 
Classical class 1
RXR class 2
38
Q

How are Class 1 receptors activated?

A

Release from HSP
Migration to nucleus
Homodimer TFs bind to inverted repeat

39
Q

What are examples of Class 1 receptors?

A

Androgens,
Corticosteroids
Progesterone

40
Q

Where are RXR receptors found?

A

Constitutively bound to DNA

41
Q

How do RXR receptors bind DNA?

A

As heterodimers with another TF

42
Q

How are nuclear hormones degraded?

A

Steroids are hydroxylated/sulphated/glycosylated in liver

Thyroids are de-iodinated

43
Q

How can steroid signalling be switched off?

A

Absence of stimulus
ligand degradation
Receptor dissociation

44
Q

How is secretion of cortisol regulated?

A

Negative feednack to CRH and ATCH

45
Q

What is Addisons disease?

A

Absence of cortisol

46
Q

What are the symptoms of lack of cortisol?

A 
hypotension, 
darkening of skin, 
weight loss
vomiting 
salt cravings
cardiac arrest in crisis
47
Q

How is addisons disease caused?

A

Autoimmune attack of adrenal glands

Infectious disease

48
Q

What does aldosterone do?

A

Raise blood volume and blood pressure,
Raise Na levels
Reduce K levels

49
Q

Where does aldosterone act?

A

In kidney and small intestine

50
Q

How is aldosterone produced?

A

Kidney senses stimuli
releases renin
Conversion of angiotensinogen (liver) to angiotensin 1
angiotensin 1 converted to angiotensin II by ACE
Angiotensin releases aldosterone

51
Q

What receptors does aldosterone act on?

A

glucocorticoid receptors

52
Q

How are cells selective for aldosterone over cortisol?

A

Cortisol converted to cortisone by 11-β-hydroxysteroid dehydrogenase
cortisone lower affinity

53
Q

What gene does aldosterone transcribe?

A

Na/K pump

54
Q

What is aldosteroidism also known as?

A

Conn’s syndrome

55
Q

What symtpoms does Conn’s syndrome have?

A

High Na/K pumps
Hypertension and cardiac failure
Depletion of K and muscle weakness

56
Q

What is congenital adrenal hyperplasia?

A

Absence of mineralocorticoids and overexpression of androgens

57
Q

What is congenital adrenal hyperplasia caused by?

A

90% caused by mutations of 21-hydrolase enzyme

58
Q

What symptoms does congenital adrenal hyperplasia have?

A

Lack of corticosteroids
Salt wasting
Mis-development of the sex characteristics

59
Q

Where does oestrogen bind?

A

ERE receptor in promoters of 600 genes

AP1 /ER independant pathways

60
Q

What function does oestrogen have?

A

Proliferation of cells

61
Q

How common is ER receptor overexpression?

A

70% of breast, ovarian, colon, prostate, endometrial cancers

62
Q

How does ER overexpression cause cancer?

A

Increased cell proliferation has more spontaneous DNA mutations
Metabolism of oestrogen produces genotoxic waste

63
Q

What ER receptor is found in differentiated tissue?

A

ERα

64
Q

What does tamoxifen do?

A

Neutralise ER overexpression
treats anvoluntary infertility
treats gynecomastia

65
Q

Where is vitamin D synthesised?

A

Skin, Kidney and liver

66
Q

How is Vitamin D transported?

A

carrier proteins in blood

67
Q

How is vitamin D synthesis stimulated?

A

By PT gland sensing low Ca
Secretes PTH
Stimulates liver activation of D3

68
Q

What effects does vitamin D have on a cell?

A

Binds RXR-LXR receptors
Mobilisation of Ca from bone
Kidney Ca retention
Intestinal calbindin Ca channel

69
Q

What do Vitamin D deficiencies cause?

A

Ricketts/osteomalacia

70
Q

How can vitamin D deficiencies be caused?

A

Hereditary mutations of receptor
Lack of sunlight
Kidney/Liver disease
Poor dietary intake of precursor

Membranes (7 decks)

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