Physiology of the Adrenal Gland

Question 1

what is the adrenal gland?

Answer 1

small triangular glands located craniomedially to each kidney

Question 2

retroperitoneal?

Answer 2

situated or occurring behind the peritoneum

Question 3

the adrenal gland is like the kidney in what respect?

Answer 3

it is retroperitoneal
only their ventral surface is in contact with parietal peritoneum

Question 4

why are they called adrenal glands?

Answer 4

ADrenal because of proximity to kidneys

Question 5

what are the two parts of the adrenal gland?

Answer 5

outer cortex - steroid hormones such as cortisol and aldosterone
inner medulla - catecholamines such as adrenaline (epinephrine) and noradrenaline (norepinephine)

Question 6

cortex development origins of the adrenal gland?

Answer 6

cortex develops from mesodermal tissue and secretes steroid hormones, primarily under control of the anterior pituitary gland

Question 7

medulla development of the adrenal gland?

Answer 7

medulla develops from neuronal tissue and is functionally part of the sympathetic nervous system
it releases the catecholamine hormones adrenaline (epinephrine) and noradrenaline (norepinephrine)

Question 8

the adrenal cortex can be further divided into three zones - what are these?

Answer 8

Zona glomerulosa - synthesis mineralocorticoids
Zona fasciculata - synthesises glucocorticoids
Zona reticularis - synthesises androgens

Question 9

what are the hormones of the adrenal cortex called?

Answer 9

adrenocortical hormones

Question 10

all steroid hormones are derived from?

Answer 10

from cholesterol

Question 11

what is the end product hormone of each region of the cortex?

Answer 11

Zona glomerulosa - aldosterone
Zona fasciculata - cortisol
Zona reticularis - androstenedione and testosterone

Question 12

structure of the hormones of the adrenal cortex?

Answer 12

all have the basic steroid carbon skeleton

Question 13

what is the starting point of the structure of the hormones of the adrenal cortex?

Answer 13

cholesterol is the starting point - derived from cholesterol

Question 14

first step of synthesis of the hormones of the adrenal cortex?

Answer 14

first step is removal of the cholesterol side chain (C22-C27)

Question 15

hormones of the adrenal cortex are…

Answer 15

lipid soluble

Question 16

hormones of th eadrenal cortex having cholesterol side chain forms?

Answer 16

pregnenolon

Question 17

wherwe does th eformation of pregnenolon occur?

Answer 17

in the mitochondria of adrenocortical cells

Question 18

what is the first step regulated by for the fomration of pregnenolone?

Answer 18

by the pituitary hormone 0 adrenocorticotropic hormones (ACTH) in the inner zones
Angiotensin Ii in outermost xone

Question 19

ACTH is part of what axis?

Answer 19

hypothalamic-pituitary-adrenal axis
includes hypothalamus pituitary and adrenal glands

Question 20

what si the primary stimulua of hypothalamic - pituitary-adrenal axis?

Answer 20

stress

Question 21

rejun?

Answer 21

produced and released by the juxtaglomerular cells

Question 22

what is rejun?

Answer 22

enzyme that converts the precursor angiotensinogen to angiotensin I

Question 23

mineralocorticoids have crucial effects on what?

Answer 23

on the homeostasis of important inorganic ions (Na+ K+ Cl-)

Question 24

aldesterone?

Answer 24

the most active hormone that is produced by the zona glomerulosa

Question 25

what is ACTH necessary for?

Answer 25

for aldosterone secretion. howeber it has minor importance for the regulation of the rate of secretion

Question 26

regulation of aldosterone secretion is mainly under control of what?

Answer 26

of the renin-angiotensin system (angiotensin II) and the extracellular conc of K+

Question 27

aldosterone is produced and secrteed where?

Answer 27

from the zona glomerulosa of the adrenal gland

Question 28

why is aldosterone produced?

Answer 28

in response to activation of the renin-angiotensin-aldosterone system

Question 29

what does angiotensin II stimulate?

Answer 29

stimulates the release of aldosterone from the adrenal cortex

Question 30

action of aldosterone stimulated by?

Answer 30

by systemic hypotension or high K+ intake

Question 31

what membrane does aldosterone cross?

Answer 31

basolateral membrane of renal tubule cells and binds to mineralocorticoid nuclear receptor

Question 32

activation of aldosterone activates the transcription and synthesis of?

Answer 32

of new Na+ channels New K+ channels New Na+/K+ pumps

Question 33

why does aldosterone act?

Answer 33

to increase reabsorption of Na+ and secretion of K+

Question 34

Glucocorticoids?

Answer 34

the most important glucocorticoid in most domestic mammals in cortisol (corticosterone in birds and rodents)

Question 35

how is glucocorticoids transported?

Answer 35

it is tightly bound to cortisol-binding-globulin (CBG) so lasts longer - longer half-life

Question 36

what is the release of glucocorticoids related to?

Answer 36

to circadian rhythms, particularly in humans - less so in domestic species

Question 37

what is the main stimulus for release of glucocoticoids?

Answer 37

stress

Question 38

what are the actions of glucocorticoids?

Answer 38

all nucleated cells in the body have cortisol receptors

Question 39

describe cortisol molecules?

Answer 39

these are lipid soluble which can diffuse across the cell membrane and bind to cortisol receptors

Question 40

what does the cortisol-receptor complex do?

Answer 40

it then binds to DNA and stimulates or inhibits the transcription of different genes

Question 41

cortisol is an important stress hormone - explain why?

Answer 41

plasma levels increase greatly when sustained/high levels of stress affecting digestion, BP, and body's energy resources it also has a permissive action for catecholamines to induce vasoconstriction

Question 42

immunomodulatory effects of glucocorticoids?

Answer 42

high levels of cortisol can reduced/reverse inflammatory and allergic responses (immunosuppression)