adrenal cortex and medulla, lect 18/19

Question 1

where is the adrenal glands located

Answer 1

sits on the kidneys

Question 2

function of mineralocorticoids

Answer 2

regulate salt and water retention at the kidney

Question 3

function of glucocorticoids

Answer 3

increase plasma glucose levels

Question 4

the adrenal gland is actually composed of what two glands

Answer 4

• adrenal cortex
• adrenal medulla

Question 5

the adrenal cortex is composed of what three layers? What hormone does each layer secrete

Answer 5

• zoma glomerulosa (outmost layer): aldosterone
• zona fasciculata: cortisol
• zona reticularis: sex steroids (androgens)

Question 6

what hormones does the adrenal medulla secrete

Answer 6

epinephrine and norepinephrine

Question 7

hormones secreted from the cortex are derived from what compound

Answer 7

cholesterol

Question 8

List the regulation steps that cause the release of adrenal cortex hormones

Answer 8

• hypothalamus secretes corticotropin-releasing hormone (CRH) which acts on corticotrophs of AP
• anterior pituitary releases adrenocorticotropic hormone (ACTH)
• adrenal cortex secretes cortisol, aldosterone, and adrenal androgens

Question 9

corticotropin releasing hormone acts on what cells types in the anterior pituitary

Answer 9

corticotrophs -> cause secretion of ACTH

Question 10

ACTH has what two functions

Answer 10

1. activates cholesterol desmolase which acts on cholesterol to form pregnenolone, a product that then can differentiate into hormones
2. stimulates adrenal gland growth

Question 11

function of cholesterol desmolase

Answer 11

• precursor for all adrenocortical steriods is cholesterol
• first step in synthesis is conversion of cholesterol to pregnenolone by desmolase
• all 3 layers contain cholesterol desmolase which is stimulated by ACTH

Question 12

cortisol has what negative feedback mechanisms

Answer 12

1. directly inhibits CRH at hypothalamus
2. inhibits action of CRH on corticotrophs decreasing ACTH release

Question 13

CRH released from hypothalamus reaches the corticotrophs in the anterior pituitary and activates what messenger cascade

Answer 13

• G protein
• adenylyl cyclase/cAMP/PKA
• activation of L-type Ca2+ channels leads to an increase in Ca2+ that rapidly leads to the release of preformed ACTH

Question 14

cortisol secretion follows what pattern

Answer 14

• a diurnal rhythm
• levels begin to increase during sleep, reach highest levels in the am

Question 15

cortisol is released in response to what? What is the primary function?

Answer 15

• Stress
• effect of cortisol is to increase the availability of glucose which would protect the CNS from malnutrition or extreme fasting

Question 16

cortisol increases synthesis of what

Answer 16

• gluconeogenesis -> increased blood glucose
• increased protein catabolism
• increases lipolysis, providing glycerol
• decreases glucose uptake by tissues

Question 17

aldosterone is a mineralocorticoids that is synthesized in what layer

Answer 17

z. glomerulosa

Question 18

what two enzymes are necessary in production of aldosterone from cholesterol

Answer 18

1. cholesterol desmolase
2. aldosterone synthase

Question 19

why can’t z. glomerulosa produce glucocorticoids and androgens

Answer 19

• zone lacks 17a hydroxylase

Question 20

what causes release of aldosterone

Answer 20

• a drop in ECF and blood pressure
• a rise in plasma K+

Question 21

ACE is present in which organ

Answer 21

lung

Question 22

function of aldosterone

Answer 22

• stimulates
  
  • sodium reabsorption
  • potassium secretion
  • net effect: expansion of extracellular fluid

Question 23

what adrenal cortex layer produces androgens

Answer 23

Z. reticularis

Question 24

What enzymes are necessary in the production of androgens from cholesterol

Answer 24

• 17 a-hydroxylase
• 17,20 desmolase (lyase)

Question 25

adrenal androgens are more significant in males or females

Answer 25

* in females, the cortex is the major source of androgens * responsible for the development of pubic and axillary hair and for libido * little signifance in males

Question 26

adrogens produced from adrenal cortex is converted to testosterone in males in what organ

Answer 26

testes

Question 27

primary dysregulation: disorders of adrenal cortex

Answer 27

disorder resides in the actual endocrine gland

Question 28

secondary dysregulation: disorders of adrenal cortex

Answer 28

* dysfunction resides in pituitary

Question 29

tertiary dysregulation: disorders of adrenal cortex

Answer 29

disturbance is explained by a hypothalamic defect

Question 30

Differentiate between cushings syndrome and cushings disease

Answer 30

* **cushings syndrome**: primary adrenal hyperplasia -\> **ACTH levels are low** * **cushings disease**: defect caused by overactive anterior pituitary -\> **excess ACTH**

Question 31

clinical presentation * hyperglycemia * thin skin * muscle wasting * central obesity * round face * buffalo hump * HTN

Answer 31

* cushing's * excess glucocorticoids and androgens

Question 32

What is addison's disease

Answer 32

* primary adrenocortical insufficiency: autoimmune destruction of gland * decreased synthesis in all adrenocorticol hormones * loss of cortisol * loss of aldosterone * loss of androgens

Question 33

clinical presentation * hypoglycemia during stress, anorexia, weight loss, weakness * hyperkalemia, hypotension, mtabolic acidosis * in females: decreased pubic and axillary hair, decreased libido

Answer 33

addisons disease

Question 34

what is secondary adrenocortical insufficiency

Answer 34

* insufficient CRH or failure of corticotrophs to adequately secrete ACTH * plasma ACTH levels are low * clinical features relate to cortisol and androgen deficiency * aldosterone levels are usually normal

Question 35

what is conn's syndrome

Answer 35

* aldosterone secreting tumor -\> aldosterone hypersection * increased Na+ reabsorption -\> HTN * increased K+ secretion -\> hypokalemia * increased H+ secretion -\> metabolic alkalsosis * low renin levels

Question 36

what is adrenogenital syndrome

Answer 36

* hypersecretion of **adrenal androgens** * masculinizing conditions in females * deepened voice * increased muscle mass * amenorrhea * hirsutism * cliotral enlargement * acne

Question 37

what does 21 B-hydroxylase deficiency cause

Answer 37

* cortex does not produce glucocorticoids or mineralocorticoids * steroid intermediates build up and are converted to androgens -\> **androgenital syndrome** * **ACTH levels are high**, because of lack of feedback control or cortisol on the pituitary

Question 38

what does 17a-hydroxylase deficiency cause

Answer 38

* glucocorticoids and androgens are not produced * steroid intermediates build up -\> promote mineralocorticoids production -\> overproduction of mineralocorticoids * **HTN inhibits renin secretion** * **​aldosterone levels are low** because of the symptoms of corticosterone excess

Question 39

synthesis of epi and NE is regulated by

Answer 39

* sympathetic stimulation

Question 40

cortisol activates what molecule that converts NE into epi

Answer 40

phenylethanolamine-N-methyltransferase

Question 41

catecholamine effects on metabolism

Answer 41

* epi mobilizes fuels in times of STRESS to sustain glucose production for use by CNS * skeletal muscle -\> increased glycogenolysis * liver -\> increased glycogenolysis * adipose tissue -\> increased lipolysis