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Year 2 - ENDO > 7 - Hypoadrenal disorders > Flashcards

7 - Hypoadrenal disorders Flashcards

1
Q

What is meant by ‘trophic’?

A

to grow

stimulating the activity of another endocrine gland

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2
Q

How many carbon atoms does cholesterol have?

A

27

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3
Q

What determines which steroids the different parts of the adrenal gland produce?

A

The combination of enzymes present in the different parts of the adrenal gland – hydroxylation in different positions of the cholesterol molecule gives different products

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4
Q

Which zones of the adrenal cortex produce what hormones?

A

zona glomerulosa - aldosterone (mineralocorticoid)
zona fasciculata - cortisol (glucocorticoid)
zona reticularis - sex hormones

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5
Q

Which enzyme converts cholesterol to pregnenolone?

A

Cytochrome P450 (short chain cleavage)

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6
Q

How is pregnenolone converted into progesterone?

A

oxidation (dehydrogenase enzymes)

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7
Q

Which sets of enzymes are switched on by ACTH?

A
  • Cortisol synthesis enzymes

- Sex steroid synthesis enzymes

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8
Q

The pituitary gland produces ACTH in response to what?

A

Stress

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9
Q

Structurally, how are testosterone and oestrodiol related?

A

they are isomers of each other

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10
Q

What is P450 scc?

A

P450 enzyme that that performs side chain cleavage

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11
Q

In what positions is pregnenolone hydroxylated in to become cortisol?

A

17, 21 and 11

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12
Q

In what positions is pregnenolone hydroxylated in to become aldosterone?

A

21, 11, 18

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13
Q

How is the aldosterone pathway regulated?

A

by the renin-angiotensin system

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14
Q

Draw out the simplified diagram of the enzymes and molecules involved in the production of hormones in the adrenal cortex

A

(see OneNote)

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15
Q

Which enzyme converts corticosterone to aldosterone?

A

Aldosterone synthase (includes 18-hydroxylase)

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16
Q

State three causes of adrenocortical failure.

A
  • Tuberculous Addison’s Disease – most common cause worldwide
  • Autoimmune Addison’s Disease – most common cause in the UK
  • Congenital Adrenal Hyperplasia
17
Q

State some consequences of adrenocortical failure

A

Hypotension (due to lack of aldosterone)
Hyperkalaemia
Loss of salt (sodium) in urine
Fall in blood glucose (due to lack of cortisol)
High ACTH —–> pigmentation
Vitiligo
Eventual death due to severe hypotension (Addisonian crisis)

18
Q

Why do Addison’s patients get vitiligo?

A

Vitiligo is an autoimmune disease where you have antibodies against melanin
(Autoimmune diseases tend to go hand-in-hand)

19
Q

Why does Addison’s cause skin pigmentation?

A

The lack of cortisol stimulates the production of huge amounts of ACTH.
ACTH is formed from the cleavage of POMC to ACTH and a-MSH
High ACTH also means high a-MSH —> skin pigmentation

20
Q

State some tests for Addison’s disease.

A
  • 9 am cortisol (this should be high in a normal person)
  • measure ACTH - should be high in Addison’s
  • Inject synthetic ACTH (synacthen) - if they have functioning adrenals, they should start to produce cortisol
    NOTE: 250 mg IM synacthem
21
Q

What is the most common cause of congenital adrenal hyperplasia (CAH)?

A

21-hydroxylase deficiency

22
Q

What are the two degrees of CAH?

A

Partial or Complete (absence of the enzyme)

23
Q

Why are foetuses with CAH normally fine in utero?

A

In utero, the foetus’ will have maternal cortisol and aldosterone so don’t need to rely on their own endogenous production.

24
Q

Which hormones are absent in complete 21-hydroxylase deficiency?

A

Cortisol and Aldosterone

25
Q

What effect does 21-hydroxylase deficiency have on sex steroid synthesis?

A

It funnels the precursors towards the steroid synthesis pathway so you get an increase in adrenal sex steroids.

26
Q

What will happen to a baby with complete 21-hydroxylase deficiency after they are born?

A

They will have a salt losing Addisonian crisis due to the lack of aldosterone.

27
Q

Which hormones will be in excess in complete 21-hydroxylase deficiency?

A

sex steroids and testosterone

28
Q

What are the two main features of 21-hydroxylase deficiency?

A

Hypotension

Virilisation (female babies will be born with ambiguous genitalia)

29
Q

Describe the presentation of partial 21-hydroxylase deficiency.

A
  • may present much later because they don’t have a salt losing Addisonian crisis.
  • will present once they start to see the effects of the excess adrenal sex steroids e.g. hirsuitism and precocious puberty
  • They will also be a little hypotensive
30
Q

What hormones are low/deficient in partial 21-hydroxylase deficiency?

A

cortisol and aldosterone

NOTE: not to the same extent as in complete - can survive for a long time

31
Q

What hormones are in excess in partial 21-hydroxylase deficiency?

A

sex steroid and testosterone

32
Q

What age does partial 21-hydroxylase deficiency present at?

A

any age as they can survive with no intervention

usually presents around the age of puberty e.g. hirsuitism and precocious puberty

33
Q

What steroid (intermediate) builds up in 11β hydroxylase deficiency? What impact does this have?

A

build up of 11-deoxycorticosterone, which is an active aldosterone receptor agonist
i.e. the person behaves as though they have a high level of aldosterone

34
Q

What hormones is there an excess of in 11β hydroxylase deficiency?

A

sex steroids and testosterone

35
Q

What are the clinical features of 11β hydroxylase deficiency?

A

hypertensive and hypokalaemic
children will be virilised because there is a high level of sex steroids (still be some funnelling towards the sex steroid synthesis pathway)

NOTE: boys may be missed because they tend to look normal

36
Q

What hormones will there be an excess of in 17β-hydroxylase deficiency?

A

aldosterone

37
Q

What hormones will be deficient in 17β-hydroxylase deficiency?

A

cortisol and sex steroids

38
Q

What are the problems associated with 17β-hydroxylase deficiency?

A

hypertension
hypokalaemia
sex steroid deficiency
glucocorticoid deficiency - borderline hypoglycaemia
have more infections because you require more cortisol to deal with the stress of infection

39
Q

When do people with 17β-hydroxylase deficiency usually present?

A

usually present around the pubertal age (the ovaries, testes and the adrenal glands are not producing sex steroids)

Year 2 - ENDO (20 decks)

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