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ENDOCRINOLOGY - BRS > 1a The Adrenal Gland > Flashcards

1a The Adrenal Gland Flashcards

1
Q

What does the left adrenal gland drain into?

A

The renal vein

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2
Q

What does the right adrenal gland drain into?

A

The inferior vena cava

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3
Q

How many arteries and veins are there in the adrenal glands?

A

One central vein, many arteries

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4
Q

Where are the adrenal glands located?

A

Above the kidneys

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5
Q

What is the adrenal cortex composed of?

A

The zona glomerulosa
The zona fasciculata
The zona reticularis

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6
Q

What does the adrenal cortex secrete?

A

Corticosteroids

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7
Q

What is secreted in the zona glomerulosa?

A

Aldosterone

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8
Q

What is secreted in the zona fasciculata?

A

Cortisol

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9
Q

What are catecholamines?

A

Adrenaline and noradrenaline

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10
Q

Where are catecholamines secreted from?

A

The adrenal medulla

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11
Q

What is the relative percentages of adrenaline and nor-adrenaline produced?

A

80% ADRENALINE
20% NORADRENALINE

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12
Q

What is the precursor for all steroid hormones?

A

Cholesterol

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13
Q

How many carbons do cholesterol molecules have?

A

27

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14
Q

How is cholesterol turned into pregnenolone?

A

Side chain cleavage

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15
Q

What enzyme converst pregnenolone into progesterone?

A

3-Beta Hydroxy Steroid dehydrogenase

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16
Q

Which enzymes are specifically found in the zona glomerulosa?

A

Those involved in the synthesis of steroids like aldosterone and corticol from cholesterol

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17
Q

What are the numbers of Hydroxylases that eventually take Progestone to Aldosterone?

A

21 Hydroxylase
11 Hydroxylase
18 Hydroxylase

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18
Q

What do the hydroxylase enzymes do?

A

Add an OH group to that position on the molecule

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19
Q

What are the numbers of hydroxylases that are required to take Progestone and convert it into Cortisol?

A

17 Hydroxylase
21 Hydroxylase
11 Hydroxylase

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20
Q

What is the function of aldosterone?

A

The major net effect is to conserve body sodium by stimulating its reabsorption into the blood

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21
Q

Explain how aldosterone works to increase sodium reabsorption

A
  1. Aldosterone binds to receptors on nucleus
  2. Causes the transcription of certain genes which results in Sodium ion channels and Na+/K+ Pumps being opened
  3. This results in an influx of Na+ from the urine, and more Na+ being pumped into blood
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22
Q

What affect does increase sodium reabsoprtion have on the blood pressure?

A

Increased Na+ into the blood, sets up a high concentration gradient for water, meaning water is reabsorbed into the blood also by osmosis

This water reabsorption raises blood volume and therefore raises blood pressure as well

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23
Q

What is the name of the renin secreting cells?

A

Juxtaglomerular cells

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24
Q

Which cells detect changes in blood pressure?

A

Cells in the macula densa

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25
Q

What is released and from where when the blood pressure drops?

A

Renin released from the juxtaglomerular apparatus

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26
Q

What regulates the release of aldosterone?

A

Angiotensin II

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27
Q

What effect does renin have on Angioteninogen?

A

Renin cleaves angiotensinogen to form angiotensin I

28
Q

What enzyme is used to convert Angiotensin I to Angiotensin II?

A

Angiotensin converting enzyme ACE

29
Q

What does angiotensin II do?

A

Acts on the zona glomerulosaof the adrenal cortex to stimulate the release of aldosterone

30
Q

How is cortisol regulated?

A

ACTH = Adrenocorticotrophic hormone

31
Q

What does cortisol do?

A

Prepares the body for stress

32
Q

What are some of the metabolic effects of stress?

A
  1. Gluceoneogenesis
  2. Increased blood glucose concentration
  3. Increased lipolysis (fat metabolism)
  4. Enhanced effects of glucagon and catecholamines
33
Q

What is the rhythm of cortisol release?

A

Diurnal release

34
Q

Describe the hypothalamo-pituitary-adrenal axis?

A
  1. Hypothalamus releases CRH = corticotrophin releasing hormone
  2. This acts on the corticotrophs in the anterior pituitary to release ACTH = adrenocorticotrophic hormone
  3. This ATCH acts on adrenal cortex to stimulate cortisol release
35
Q

How many levels does cortisol negatively feed back on and where?

A

The hypothalamus and the pituitary

36
Q

What happens when cortisol levels are high?

A

The negative feedback loops are engaged, so the pituitary and hypothlamus stop producting CRH and ACTH

37
Q

What affect does ACTH have on the adrenal gland?

A

Increases the activation of the enzymes needed to produce cortisol (17, 21 and 11)

38
Q

At what time are cortisol levels the highest?

A

8:30 am in the morning

39
Q

If you wanted to measure a patients highest possible cortisol level, what time would be the best to test it?

A

8:30 am in the morning

40
Q

What is Addisons disease?

A

A disorder where the endocrine system does not produce enough steroid hormones

41
Q

What is primary adrenal failure?

A

An autoimmune disease where the immune system decides to destroy the adrenal cortex

42
Q

What is the most common cause of primary adrenal failure?

A

TB

43
Q

What happens to ACTH levels when a patient has primary adrenal failure?

A

The raise - this is because the body is not producting enough cortisol, therefore via negative feedback loops, the body works to increase ACTH production so it accumulates

44
Q

What is MSH?

A

Melanin Stimulating Hormone

45
Q

What affect does CRH have on MSH?

A

Increases the release of MSH

46
Q

What happens to patients blood pressure when they have primary adrenal failure?

A

Low blood pressure as no aldosterone to regulate it

47
Q

Why do patients with Addisons disease have a good tan?

A

POMC - proopiomelanocortin is a large precursor protein which is cleaved to form a number of smaller peptides, including ACTH, MSH and endorphins

48
Q

What is the urgent treatment for Addisons crisis?

A

rehydrate with normal saline, give dextrose to prevent hypoglyceamia and hydrocortisone

49
Q

What are some symptoms of Addisons disease?

A

Weight loss
Hyperpigmentation due to MSH
Autoimmune vitiligo
Constipating, vomiting, nausea, diarrhoea
Low Blood Pressure

50
Q

What is cushings syndrome?

A

When you have an excess of cortisol

51
Q

What happens to your weight in Cushing syndrome?

A

Weight increases - put on weight

52
Q

What can cause too much cortisol?

A

A tumour of the adrenal = too much cortisol
pituitary tumour = excess ACTH

53
Q

What happens to blood pressure in Cushings syndrome?

A

Blood pressure increases

54
Q

What are some clinical signs of Cushing syndrome?

A

Thin skin, centripetal obesity, Red Stretch Marks, Easy bruising, high blood pressure, impaired glucose tolerance

55
Q

What does the adrenal medulla produce?

A

Catecholamines eg Adrenaline and Noradrenaline

56
Q

What is the medulla derived from?

A

The ectodermal neural crest

57
Q

What is a precursor for Adr and NA synthesis?

A

Tyrosine

58
Q

What are catecholamines stored in?

A

Cytoplasmic granules

59
Q

When is adrenaline and noradrenaline released?

A

In respnose to ACh from preganglionic sympathetic neurones

60
Q

Describe how adrenaline and nor adrenaline are produced?

A

Tyrosoine -> DOPA -> Dopamine -> Noradrenaline -> Adrenaline

61
Q

What is the role ofcatecholamines?

A

mediate the fight or flight response

62
Q

How do NA and Adrenaline circulate?

A

Bound to albumin

63
Q

Which enzymes degrade NA and Adrenaline?

A

Monoamine oxidase and catechol-O-methyl transferase

64
Q

Why are the adrenal androgens more important for women?

A

Women do not have Leydig cells which are found in the testes to produce testosterone, so rely heavily on the production of testosterone from the adrenal gland

65
Q

What is DHEA?

A

Dehydroepiandrosterone - A hormone which is made by the adrenal gland

66
Q

What happens to DHEA in peripheral tissues?

A

It is converted into Testosterone / Dihydrotestosterone using the enzyme 5-alpha reductase

67
Q

Under what conditions would renin be released from the juxtaglomerular cells of the macula densa?

A

Low blood pressure, hyperkalaemia and hypoatrenemia

ENDOCRINOLOGY - BRS (21 decks)

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