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PY352 > Adrenal Cortex > Flashcards

Adrenal Cortex Flashcards

1
Q

Where do the adrenal glands lie? What are they divided into?

A

The adrenal glands above the kidneys. They can be referred to suprarenal glands. They are retroperitoneal. The adrenal glands are divided into two portions; the adrenal cortex (90%) and the adrenal medulla (10%)

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2
Q

Which is essential for life? Adrenal medulla or adrenal cortex?

A

Unlike the adrenal medulla, a functioning adrenal cortex is essential for life

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3
Q

What are the adrenal (outer) cortex and adrenal (inner) medulla concerned with?

A

Inner medulla - stress response

Outer cortex - stress, sodium and glucose homeostasis.

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4
Q

Comment on the adrenal cortex hormones structure and what they are called.

A

The hormones produced by the adrenal cortex are all very similar in chemical structure being derived from cholesterol from the diet or synthesised within the gland itself; these hormones are collectively known as adrenocortical steroid hormones or corticosteroids.

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5
Q

What are the three layers that the adrenal cortex is divided into?

A
  • zona glomerulosa (outer)
  • zona fasiculata (middle)
  • zona reticularis (innermost)
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6
Q

Which hormones does the zona glomerulosa produce?

A

mineralocorticoid e.g. aldosterone

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7
Q

Which hormones do the the zona fasiculata and zona reticularis produce?

A
  • glucocorticoids e.g. cortisol

- androgens (DHEA and androstenedione)

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8
Q

Why are different hormones produced in different places?

A

Cells in different areas posses a different range of enzymes and therefore are concerned with the synthesis of different adrenocortical hormones.

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9
Q

What are glucocorticoids e.g. cortisol concerned with?

A

the control of carbohydrate metabolism

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10
Q

What are mineralocorticoids e.g. aldosterone concerned with?

A

the control of sodium and potassium balance.

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11
Q

What are the major secretions of the adrenal cortex?

A

Glucocorticoids i.e. cortisol

mineralocorticoids i.e. aldosterone

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12
Q

Steroid hormones produce a variety of effects, but they are usually classified according to their _______ ______.

A

predominant action

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13
Q

The most important representative of the mineralocorticoid is?

A

aldosterone

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14
Q

The most important representative of the glucocorticoid is _________ and ________.

A

cortisol

corticosterone

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15
Q

Where, precisely, is cortisol made?

A

zona fasiculata

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16
Q

Where, precisely, are androgens made?

A

zona reticularis

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17
Q

What enzyme is present in the zona glomerulosa?

A

18-hydroxylase. This synthesises aldosterone.

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18
Q

What enzyme is present in the zona fasiculata and zona reticularis?

A

17-a-hydroxylase. This synthesises 17-a-hydroxypregnenolone and 17-a-hydroxyprogesterone and thus hormones are derived from this.

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19
Q

A similar pathway exists for the synthesis of the ___ hormones within the ____ and _____

A

sex
testes
ovaries.

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20
Q

What are androgens? Give an example.

Is this significant?

A

Male sex hormones.
DHEA, androstenedione and testosterone, and female oestrogens e.g oestradiol.

Only in adrenal disorders.

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21
Q

What is controlled INDEPENDENTLY in regards to mineralocorticoids and glucocorticoids.

A

The synthesis, secretion and actions of them

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22
Q

Outline the control of glucocorticoid secretion.

What mechanism is present to control it?

A

Hypothalamus releases CRH
Pituitary gland is stimulated and releases ACTH. This causes the Adrenal gland to synthesis Cortisol.

Negative feedback. This can lead to cyclical variation.

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23
Q

OTHER THAN CONTROLLING CARBOHYDRATE METABOLISM, what is cortisol important for?

A

regulates or modulates many of the changes that occur in the body in response to stress e.g. glucose levels, protein, fat and carb metabolism to maintain blood glucose

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24
Q

Describe the manner in which ACTH is released.

What is the pattern related to?

A

In a pulsatile pattern,
Peaks in the early morning/ time of waking
Nadir (lowest) in the middle of the night.

The pattern is related to sleep-wake patterns: it is disrupted by shift work and long haul travel i.e jet-lag.

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25
Q

When is secretion of ACTH increased?

A

During times of prolonged stress.

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26
Q

Cortisol secretion has the _____ pattern as ACTH but the peak and nadir occurs ____ hours later than those of ACTH

A

same

two

27
Q

Tell me about the availability of cortisol in the blood.

A

only 10% of cortisol in the blood is in it’s free, active form.
the remain is bound to plasma proteins:
-75% corticosteroid binding globulin (CBG)
-15% albumin
The same proteins also transport other glucocorticoids and progesterone.

28
Q

During pregnancy, what happens to the levels of cortisol in the blood?

A

During pregnancy, the amount of CBG increase, causing the compensatory increase in circulating plasma cortisol concentration, BUT the amount of free cortisol remains stable.

29
Q

Where are adrenal steroids metabolised?

A

In the liver where they are glucoronidated into a water soluble form; which is excreted in the urine.

30
Q

What are the 4 physiological actions of glucocorticoids?

A

1 - stress
2 - metabolism
3 - cardiovascular
4 - immunological (immunosuppressive/anti-inflammatory

31
Q

Like all other steroid hormones, how do glucocorticoids produce their action?
MOA?
delays?
types of receptors?

A

They produce their action by binding on intracellular receptors and alteration in gene expression. This MOA inevitably results n a delay, in the order of hours or days

32
Q

How many types of steroid receptors are there?

A

Two.
Type 1 receptors a.k.a. MR (mineralocorticoid receptor; aldosterone receptor)
Type 2 receptors a.k.a glucocorticoid receptor.

33
Q

In some cases, the effects of cortisol is rapid. How is this?

A

The inhibition of ACTH secretion negative feedback.

34
Q

Glucocorticoids can stimulate mineralocorticoid receptors. How can this be overcome?

A

aldosterone sensitive tissues have an enzyme 11-b-HSD2, which converts cortisol to inactive cortisone. Therefore, mineralocorticoid actions of glucocorticoids are only apparent at high concentrations.

35
Q

At normal physiological concentrations, what is the most important action of cortisol?

A

carbohydrate metabolism.

36
Q

How does cortisol oppose insulin?

A
  • Antagonises effects of insulin on cellular uptake of glucose
  • stimulates glycogenesis
  • stimulates hepatic gluconeogenesis
37
Q

In the liver, cortisol

A

stimulates amino acid uptake, leading to enhanced gluconeogenesis

38
Q

In the periphery, cortisol does what to amino acids?

A

inhibits amino acid uptake and protein synthesis, resulting in a net loss of skeletal protein

39
Q

How does cortisol stimulate lipolysis and mobilisation of fatty acids?

A

partially by potentiating the effects of growth hormone and the catecholamines.

40
Q

What happens in excessive concentrations of cortisol?

A

In excessive concentrations cortisol causes fat synthesis and deposition in novel anatomical sites, most notably the face, the trunk and the intrascapular region of the shoulders.

41
Q

What are the immunological actions of glucocorticoids?

A

Glucocorticoids have a broad range of inhibitory actions on the immune system. This includes:

  • They suppress the lymphoid tissue. This will result in a reduced antibody production and so it will inhibit the cellular immune system.
  • They stabilise the leukotriene membrane. This reduces the amount proteolytic enzymes.
  • They inhibit phospholipase A2, which is responsible for producing inflammatory mediators.
42
Q

What are the cardiovascular actions of glucocorticoids?

A

Another effect of excess glucocorticoids is an enhanced vasoconstrictor responses to catecholamines which results in increased blood pressure.

43
Q

What are the two psychological effects with possible feelings that glucocorticoids can cause?

A

Elation and sedation

44
Q

Facts glucocorticoid actions on stress?

A
  • In the absence of corticosteroids, even mild stress can be fatal.
  • In response to psychological and physiological stress; infection, trauma and hypoglycaemia, there is a rapid secretion of ACTH and corticosteroids
  • At these raised concentrations, the additional effects of these hormones become apparent.
45
Q

What happens during stress/ pain? How does glucocorticoids play a role?

A
  • Pain, which alerts the sufferer to the damage
  • Oedema, which dilutes any toxic substances that may be present and immobilises and stabilises the joint
  • Infiltration of leukocytes, which destroy invading cells and the antibodies inactivate the foreign proteins
  • Tissue repair which is enhanced by prostaglandins

STEROIDS APPEAR TO BE ACTING CONTRARY TO INDIVIDUAL’S BEST INTEREST (by adverse effects of injury and and retarding tissue repair)

BUT the adrenocortical stress response decreases the inflammatory response which:

  • removes the pain and decreases immobilisation by oedema
  • allows for steroid-induced sedation to occur so that the severity of situation is not as noticed, due to lack of awareness
  • Overall effect is to allow individual to perform despite the presence of infection or injury.
46
Q

What are the physiologically important mineralocorticoids?

A

Aldosterone and 11-deoxycorticosterone

47
Q

What is the major controlling factor in the release of aldosterone? Does ACTH have an affect?

What else directly stimulates aldosterone stimulation? (4things) What inhibits it?

A

Renin-angiotension system.
ACTH does not have much affect on aldosterone although it does stimulate the initial conversion of cholesterol to pregnenolone

  1. Trauma
  2. Anxiety
  3. Hyperkalaemia
  4. Hyponatraemia
    - Aldosterone is inhibited by ATP (atrial natriuretic peptide)
48
Q

How much is aldosterone protein bound within the circulation?

A

50%

49
Q

Aldosterone has specific receptors which cause the expression of ___ _______ that transport ________ and _________ ions across the cell.

A

ion channels
sodium
potassium

50
Q

Aldosterone stimulates the reabsorption of what, where?

A

Na+
into the distal convoluted tubule of the kidney, and some lesser effects in the CD, PT, LoH, sweat glands, salivary glands and colon.
The Na+ reabsorption occurs in exchange of K+ or of H+ ions.
By controlling the reabsorption of Na+, aldosterone influences plasma Na+ conc. This, in turn, influences water reabsorption in the CD, via an effect on ADH secretion
The interaction of the renin-angiotension system, aldosterone and ADH therefore, controls blood volume and influences blood pressure.

51
Q

The interaction of the renin-angiotension system, aldosterone and ADH controls:

A

blood volume and influences blood pressure.

52
Q

Glucocorticoid hypersecretion causes

A

Cushing’s Disease and Cushing Syndrome

53
Q

Difference between Cushing’s syndrome and Cushing’s disease?

A

Cushing’s disease is a TYPE of Cushing’s syndrome. Cushing’s disease is when there is a tumour in the pituitary gland, leading to an overproduction of ACTH. Excessive ACTH stimulates the adrenal cortex to produce high levels of cortisol, producing the disease state.
Cushing’s syndrom has LOW ACTH production?

54
Q

Cushing’s Disease ration from male: female

A

1:5

age is between 25-40 years

55
Q

Some signs and symptoms of Cushing’s Disease and Syndrome?

A 
Buffalo bump
Moon face (with red cheeks)
Easily bruised
Poor wound healing
Hypertension
Thinning of skin
Thin arms and legs; muscle wasting
Increased abdominal fat
Obesity
Osteoporosis
Euphoria
56
Q

Glucocorticoid hyposecretion causes

A

Addison’s disease

57
Q

What is Addison’s disease due to? What is affected?

A

Due to destruction of entire adrenal cortex therefore, glucocorticoid, mineralocorticoid and sex steroid production are all affected.

58
Q

Symptoms of Addison’s disease?

A 
Fatigue
weight loss
weakness
pigmentation changes
postural hypotension (due to Na+ loss)
59
Q

Mineralocorticoid hypersecretion causes

A

Conn’s syndrome

60
Q

what is excess mineralocorticoid production due to?

A

adrenal adenoma mainly

61
Q

Symptoms of Conn’s syndrome?

A 
Hypertension
Polyuria
Polydipsia
Weakness and muscle cramps
Headaches and lethargy
Nocturia
62
Q

cortisol deficiency with our without aldosterone deficiency and androgen excess causes:

A

Congenital Adrenal Hyperplasia

63
Q

Second most cause of Congenital Adrenal Hyperplasia?

A

deficiency of 11b-hydroxylase

64
Q

Symptoms of Congenital Adrenal Hyperplasia

A

Symptoms:
Female infants : ambiguous genitalia
Male: no signs at birth except subtle hyperpigmentation and possible penile enlargement

PY352 (25 decks)

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