3.1.3 Adrenal Cortex Physiology

Question 1

What is the objective of this lecture?

Answer 1

Steroidogenesis

Question 2

What protein is important in the transport of cholesterol into the mitochondria?

Answer 2

Steroidogenic acute regulatory protein (StAR)

Question 3

Where is CBG synthesized?

Answer 3

Liver

Question 4

The fasiculata and reticularis express what protein and are responsible for the synthesis of what?

Answer 4

Express CYP17

Responsible for DHEA and cortisol production

Has a role in adrenarche

Question 5

What are the secretion rates and plasma concentrations of andrenocortical hormones?

Answer 5

Question 6

Cortisol binding globulin (CBG) binds to what?

Answer 6

Glucocorticoids, aldosterone and progesterone

Question 7

What are the 3 mechanisms by which hormones are inactivated?

Answer 7

Question 8

What is the pathway by which 21-hydroxylase deficiency will lead to elevated androgens?

Answer 8

This will also lead to no feedback on ACTH by cortisol

Question 9

The glomerulosa in the adrenal cortex expresses what?

Answer 9

Aldosterone synthase

Question 10

What is cortisol’s function in metabolism?

Answer 10

Question 11

What is cortisol’s function in inflammation and circulation?

Answer 11

Question 12

What are two tests that can assess adrenal function?

Answer 12

Question 13

What is Cushing’s Disease?

Answer 13

This is a hypersecretion of ACTH from a pituitary adenoma

Question 14

The glomerulosa lacks what enzyme?

Answer 14

CYP17

Question 15

What are the important anatomical parts of the adrenal gland?

Answer 15

Question 16

How is aldosterone regulated?

Answer 16

Question 17

What does epinephrine do?

Answer 17

Come on you know this

Question 18

What genetic defects could lead to adrenal disorders?

Answer 18

Question 19

What are the effects excess cortisol in metabolism?

Answer 19

Question 20

What is the treatment of glucocorticoid excess?

Answer 20

Pituitary surgery or remove exogeneous ACTH

Adrenalectomy

Administration of glucocorticoids

Question 21

What are the main products of the adrenal gland?

Answer 21

Focus on squarred ones

Question 22

How do serum concentrations of ACTH change throughout the day?

Answer 22

Question 23

What is the rhythm and peak of cortisol secretion?

Answer 23

ACTH secretion is episodic and has a circadian rhythm (peaks in the morning). Cortisol exerts a negative feedback on the CRH-ACTH system.

Question 24

Describe the regulation of glucocorticoid and androgen synthesis.

Answer 24

Question 25

What are the functions of cortisol?

Answer 25

Question 26

All steroids are derived from?

Answer 26

Cholesterol

Question 27

Albumin binds to?

Answer 27

glucocorticoids

Question 28

What is Addison's disease?

Answer 28

Primary hypoadrenalism ## Footnote Primary hypofunction (Addison’s disease) of the adrenal gland can be caused by autoimmune disease, destruction of the gland by tuberculosis, or an unknown origin

Question 29

Cortisol binds to?

Answer 29

CBG and albumin

Question 30

Describe the renin-angiotensin and it's role on the adrenals.

Answer 30

Question 31

What are two sources of steroids?

Answer 31

Diet and de novo

Question 32

What is Cushing's syndrome?

Answer 32

Hypersecretion of ATCH from non-pituitary tumor

Question 33

The glomerulosa is important in the production of what?

Answer 33

Aldosterone

Question 34

The glomerulosa layer of the adrenal gland is primarily regulated by? (Creepy endocrine guy slide)

Answer 34

Renin/angiotensin (Na+ levels) also responsive to K+ and ACTH

Question 35

What is the reaction that is stimulated in the adrenal medulla by ACTH?

Answer 35

Tyrosine ⇒ DOPA via tyrosine hydroxylase

Question 36

What are the different layers of the adrenal

Answer 36

Adrenal Cortical layers 1) **Zona glomerulosa** - This is the outer most layer of the cortex. It is composed of small clumps of cells that synthesize and secrete the mineralocorticoid - aldosterone. These cells are distinct from the underlying layers in that they lack the steroidogenic enzyme P450c17 (17a hydroxylase and 17,20 desmolase), but uniquely express the aldosterone synthase enzyme complex. This explains why aldosterone is only produced within this layer of the adrenal cortex. 2) **Zona fasciculata** - This layer lies just underneath the glomerulosa. 3) **Zona reticularis** - This layer lies just underneath the fasciculata. Both the fasciculata and reticularis layers of the adrenal have the 17a hydroxylase and 17,20 desmolase enzymes and produce glucocorticoids (cortisol and lesser amounts of corticosterone) and androgens (primarily dehydroepiandrosterone).

Question 37

What is the primary function of the adrenals?

Answer 37

The primary function of the adrenal glands is to protect the organism against acute and chronic stress

Question 38

What is the rate limiting step in steroid synth?

Answer 38

The initial step in this enzymatic cascade is the rate limiting step: conversion of cholesterol to pregnenolone by P450 side chain cleavage enzyme and Transport of cholesterol into the mitochondria

Question 39

What is a dexamethasone test?

Answer 39

Measurement of glucocorticoids following administration of dexamethasone the night before. This can detect an ectopic source of ACTH

Question 40

The fasiculata and reticularis layers of the adrenal cortex lack expression of what?

Answer 40

Aldosterone synthase

Question 41

What type of effect does ACTH have on fasciculata and reticularis and what can occur in the absence of ACTH?

Answer 41

Question 42

What are the symptoms of glucocorticoid excess?

Answer 42

Question 43

Glucocorticoid deficiency can lead to what symptoms?

Answer 43

Question 44

What is this an image of and what are the characteristics?

Answer 44

EM of cells within the zona fasiculata - characterized by abundant mitochondria, lipid droplets, and smooth endoplasmic reticulum

Question 45

What is the role of ACTH on the adrenal cortex?

Answer 45

ACTH stimulates the growth of the adrenal cortex especially the machinery necessary for glucocorticoid and androgen biosynthesis. ACTH's actions at the adrenal cortex are mediated by cyclic AMP. Secondary actions of ACTH include: stimulation of lipolysis, stimulation of insulin secretion, and increased skin pigmentation (often a pathological sign). The secondary actions of ACTH are largely related to the structural homologies of ACTH with the other proopiomelanocortin peptides.

Question 46

Cortisol induces what reaction in the adrenal medulla?

Answer 46

Norepi ⇒ Epi Cortisol activated the enzyme that catalyzes the reaction (PNMT)