The Adrenal Gland And Adrenal Hormones (week3)

Question 1

Function of aldosterone

Answer 1

It governs the extra cellular volume (ECV) due to its action on Na retention/ absorption by the kidney. Arginine vasopressin (AVP) - also known as anti diuretic hormone (ADH) - regulates osmolality because of its effect on free water balance (indirectly affects Na concentration)

Question 2

Osmolality meaning

Answer 2

Osmolality is the measure of solute particles in a solution.
It quantifies the number of osmoles ( a unit of measurement for the concentration for the solute particles.

Question 3

Osmolarity meaning

Answer 3

Concentration of solute particles in a solution per 1L of solvent

Question 4

Where is aldosterone synthesised and what from

Answer 4

The adrenal gland. Zona glomerulosa

Cortisol

Question 5

What are the only cells that contain aldosterone synthase

Answer 5

Glomerulosa cells, these cells are exclusive site of aldosterone synthesis

Question 6

How quickly is aldosterone released

Answer 6

Secretion of aldosterone is limited by the rate at which the glomerulosa cells can synthesise the hormone

Question 7

What stimulates the production of aldosterone in the glomerulosa

Answer 7

ACTH, extracellular [K+][Na+] and the peptide hormone ANG II

Question 8

How does ACTH, K+, and ANG II enhance secretion

Answer 8

By increasing the activity of enzymes acting as rate-limiting steps in aldosterone synthesis.
These include the SCC enzyme (common to all steroid-producing cells) and aldosterone synthase (unique to glomerulosa cells and involved in the final stops of formation)

Question 9

What is the major action of aldosterone

Answer 9

To stimulate the kidney to reabsorb Na+ and water and to enhance K+ secretion. Aldosterone has similar actions in the colon, salivary glands and sweat glands.

Question 10

Is aldosterone hydrophobic or hydrophilic

Answer 10

Hydrophobic so transported in the blood with albumin

Question 11

aldosterone class and location of synthesis

Answer 11

class: mineral corticoids
location of synethesis: synthesised and released by the outer layer (the zona glomerulosa) of the adrenal cortex

Question 12

epinephrine(adrenaline) class and location of synthesis

Answer 12

class: catecholamine
location of synethesis: synthesised and released by the adrenal medulla, inner part of the adrenal gland

Question 13

norepinephrine(noradrenaline) class and location of synthesis

Answer 13

class: catecholamine adrenergic hormone
location of synthesis: synthesised and released by the adrenal medulla, inner part of the adrenal gland

Question 14

regulation of aldosterone synethesis

Answer 14

Na and water levels feedback through the RAS
Ang II binds to receptor
Gaq to PLC to DAG anf IP3
Ca increase, Ca-dependent enzymes increase
Depolarises glomerulosa cells, voltage-gated Ca channels open
Ca rises, stimulants

Question 15

what is the stimulus for the release of renin

Answer 15

renin is released from juxtaglomerular cells in the kidney
low blood pressure
decreased blood volume
low sodium levels in the distal tubules of the kidneys

Question 16

how is angiotensinogen converted to angiotensin I

Answer 16

Renin acts on a plasma protein called angiotensinogen, which is produced by the liver, to convert it into angiotensin I.

Question 17

how is angiotensin II converted to angiotension II

Answer 17

through angiotensin converting enzyme(ACE) primarily found in the lungs, this conversion occurs in the blood stream

Question 18

stimulation of aldosterone

Answer 18

angiotensin II acts directly on the adrenal cortex, primarily the zona glomerulosa

Question 19

negative feed back

Answer 19

as blood pressure and blood volume increase in response to aldosterones actions, there is a negative feedback loop that inhibits further release of renin. This helps prevent excessive sodium retention and fluid accumulation

Question 20

what does the adrenal cortex develop from

Answer 20

mesmodermal cells into steroidogenic cells that produce mineralocorticoids, glucocorticoids, and adrenal androgens.

Question 21

what is the influence of cortisol

Answer 21

chromaffin cells have the potential of developing into post ganglionic sympathetic neurons and synthesize the norepinphrine from tyrosine, however the cells of the adrenal medulla are exposed to high local concentrations

Question 22

what are the hormones secreted by catechlomines

Answer 22

dopamine
epinephrine
norepinephrine

Question 23

synthesis of catechlomines

Answer 23

epinephrine and some norepinphrine stored in chromaffin granule complex with ATP.

70-80% of the cells of the adrenal medulla secrete epinephrine and the remaining 20-30% secrete norpinephrine.

Question 24

regulation of catechlomines

Answer 24

autonomic centers that initiate sympathetic responses reside in the hypothalamus and the brain steam and they receive inputs from the cerebral cortex, the limbic system, and other regions of the hypothalamus and brain steam.

ACh increases the activity of the rate-limiting enzyme, tyrosine hydroxylase, and of dopamine beta-hydroxylase and stimulates exocytosis of the chromaffin granules.

Question 25

degradation of catechlomines

Answer 25

the biological response if very brief, approximatley 10 seconds, circulating catehlomines degraded.

Question 26

what are the twp primary enzymes involved in the degradation of catechlomines.

Answer 26

monoamine oxidase (MAO) - the predominant enzyme in neuronal mitochodria
catechol-O- methyltansferase -(COMT)

Question 27

physiologic actions of catechlomines

Answer 27

Because the adrenal medulla is directly innervated by the autonomic nervous system, adrenomedullary responses are very rapid

Because of the involvement of several centers in the CNS adrenomedullary responses canprecede onset of the actual stress (i.e., responses can be anticipated

increased blood flow to muscles
increased glucose availability
decreased energy demand by visceral smooth muscle

Question 28

what is Pheochromocytoma

Answer 28

An uncommon tumor caused by hyperplasia of adrenal medulla or other chromaffin tissue.
Excessive, unregulated production of catecholamines

Question 29

what are some symptoms of Pheochromocytoma

Answer 29

Sudden outburst of hypertension,
headaches,
episodes of sweating,
anxiousness,
tremor and glucose intolerance