Adrenal Gland Physiology

Question 1

where are the adrenal glands located

Answer 1

retroperitoneal space

cranial and medial to the kidneys

Question 2

what are the layers of the adrenal gland

Answer 2

zona glomerulosa
zona fasciculata
zona reticularis
medulla

Question 3

what does the zona glomerulosa produce

Answer 3

mineralocorticoids (aldosterone)

Question 4

what does the zona fasciculata produce

Answer 4

glucocorticoids (cortisol)

Question 5

what does the zona reticularis produce

Answer 5

androgens

Question 6

what does the medulla produce

Answer 6

catecholamines (epi/NE)

Question 7

what type of hormones are produced in the cortex

Answer 7

steroids (derivatives of cholesterol)

Question 8

what is the function of aldosterone

Answer 8

maintain sodium and potassium balance and ECF volume

Question 9

what is the main target of aldosterone

Answer 9

kidneys

promotes sodium reabsorption and potassium excretion

Question 10

what are the main regulators of aldosterone secretion

Answer 10

• RAAS system
• Na/K concentration
• ACTH

Question 11

what is the main stimuli for the RAAS system

Answer 11

low renal blood flow
low Na/Cl delivery
SNS innervation

Question 12

RAAS overview

Answer 12

1. JGA senses stimuli and secrete renin
2. renin converts angiotensinogen –> ANG I
3. ACE (lungs) converts ANG I –> ANG II
4. ANG II stimulates aldosterone secretion, vasoconstriction, and NE/epi/ADH secretion

Question 13

hyperaldosteronism

Answer 13

Conn’s syndrome; RARE

caused by a primary aldosterone secreting tumor in the adrenal cortex (glomerulosa)

Question 14

what electrolyte imbalances are caused by hyperaldosteronism

Answer 14

hypokalemia
hypernatremia

Question 15

what is the main clinical sign of hyperaldosteronism

Answer 15

hypertension

Question 16

hypoadrenocorticism

Answer 16

Addison’s disease

caused by immune mediated destruction of all adrenal cortical layers

Question 17

what electrolyte imbalances are caused by hypoadrenocorticism

Answer 17

hyponatremia
hyperkalemia

can get hypoglycemia

Question 18

what are the main clinical signs of hypoadrenocorticism

Answer 18

hypovolemia
cardiac arrhythmias

Question 19

what test can be used to diagnose hypoadrenocorticism

Answer 19

ACTH stimulation test

cortisol levels will NOT increase following exogenous ACTH administration

Question 20

function of cortisol

Answer 20

many functions (metabolic, immune, cardiovascular, renal)

Question 21

what are the targets of cortisol in the body

Answer 21

all tissues express cortisol receptors

Question 22

what receptor type does cortisol use

Answer 22

cytosolic

Question 23

pituitary dependent hyperadrenocorticism (PDH)

Answer 23

Cushing’s disease caused by a primary pituitary tumor that secretes excess ACTH

leads to overstimulation of the adrenal cortex (zona fasciculata) with loss of negative feedback on ACTH

Question 24

what lesion is associated with pituitary dependent hyperadrenocorticism

Answer 24

bilateral adrenal gland enlargement

Question 25

adrenal dependent hyperadrenocorticism

Answer 25

Cushing's caused by a primary adrenal tumor that secretes excess cortisol

Question 26

what lesion is associated with adrenal dependent hyperadrenocorticism

Answer 26

unilateral adrenal mass contralateral adrenal atrophy

Question 27

what is the difference in serum ACTH levels in pituitary dependent and adrenal dependent hyperadrenocorticism

Answer 27

pituitary dependent: HIGH ACTH from lack of negative feedback adrenal dependent: LOW ACTH from negative feedback

Question 28

what cell type is found in the adrenal medulla

Answer 28

chromaffin cells

Question 29

chromaffin cells

Answer 29

synthesize and secrete catecholamines extension of SNS - acts as a postganglionic sympathetic neuron w/o axons

Question 30

what controls catecholamine secretion from chromaffin cells

Answer 30

sympathetic innervation

Question 31

what is the primary stimuli for catecholamine release

Answer 31

stress hemorrhage, hypoxia, hypotension, hypoglycemia, low perfusion, anesthesia, surgery, fear

Question 32

function of catecholamines

Answer 32

regulate cardiovascular and metabolic processes

Question 33

what are the targets of catecholamines

Answer 33

many - the action depends on the receptor type

Question 34

what are the cardiovascular receptors and effects of catecholamines

Answer 34

a1: vasoconstriction a2: inhibits NE reuptake, decreases BP B1: increase HR/contractility, stimulates renin B2: vasodilation and bronchodilation

Question 35

what are the metabolic receptors and effects of catecholamines

Answer 35

a and B receptors - main goal is to increase blood glucose liver: stimulate gluconeogenesis and glycogenolysis adipose: stimulate lipolysis pancreas: inhibits insulin secretion and stimulates glucagon secretion

Question 36

pheochromocytoma

Answer 36

adrenal medulla tumor that episodically secretes excess catecholamines

Question 37

what are the clinical signs of a pheochromocytoma

Answer 37

episodic: weakness, collapse, panting, tachypnea, tachycardia, arrhythmias, systemic hypertension, hyperglycemia