Chapter 34 Adrenal glands Flashcards
What are the functional zones of the cortex?
Zone glomerulosa
Zone fasciculate
Zone reticularis
All together these zones are called Coricosteriods
What are the principal hormones secreted from each zone of the cortex?
Aldosterone is from glomerulosa
Cortisol is from fasciculate
DHEAS is from reticularis
Which part is both innervated and with blood supply ?
Adrenal medulla
What are the components of the neuroendocrine axis that control glucocorticoid secretion?
ACTH
What is the common precursor for the biosynthesis of the adrenal steroid hormones (glucocorticoids, mineralocorticoids, and androgens) and the key structural features that distinguish each class?
Common precursor is Cholesterol
after the precursor the first step for all the layers are generated by ACTH and the glomerulosa (outer layer) is then controlled by another hormone called Angiotensisn II
middle layer makes glucocorticoids
inner layer makes Androgen
What are the major actions of glucocorticoids on metabolism and the target organs?
-Stimulates protein breakdown to amino acids (especially muscles)
-Facilitates lipid breakdown in adipose tissues to fatty acids and glycerol
-Promotes hepatic gluconeogensis (synthesis of glucose) from amino acids glycerol and fatty acids
-Making glucose available to brain by inhibiting utilization by other tissues
What are the effect of glucocorticoids hormone in stress?
The hormone secretion increases
How do the adrenal cortical hormones act on target cells?
it causes the release of ACTH in pituitary which then goes on and acts on the target cells
What are the causes and consequences of
A)Over secretion
B)under secretion of glucocorticoids and adrenal androgens
Over secretion could lead to : neuron death, loss of memory
Under secretion : neuron death , abnormal neuronal development
What are the major mineralocorticoids and their biological actions and target organs or tissues?
-Aldosterone is the major form
-It targets the kidney
What are the physiological stimuli that cause increased mineralocorticoids secretion? Can you relate these stimuli to regulation of sodium and potassium excretion?
-Stimulates kidney reabsorb water and Na+
-Secretion stimulated by low blood pressure , low Na+ or high K+
What are the causes and consequences of ?
A)Over secretion
B)Under secretion of mineralocorticoids
A) Over secretion
Causes: Hypersecreting tumour of Z.Glomerulosa , High renin Angiotensin
Symptoms:
-Hypernatremia( Na+increase)
-Hypokalemia (K+ decrease)
-Hypertension
B) Under secretion
Causes : destruction atrophy or dysgenesis of adrenal cortex , or impaired steroidogenesis
Symptoms :
-Hyperkalemia(K+ increases)
-Hyponatremia (Na+ decreases)
-Hypotension
What is the negative feedback control of aldosterone secretion ?
when there is too much aldosterone it sends a feedback to the ACTH in the pituitary and the CRH in the Hypothalamus
What is the chemical nature of catecholamines and their biosynthesis, and how the structure of norepinephrine differs from epinephrine ?
Chemical nature :
-A benzene ring with two hydroxyl groups
Bio synthesis :
-The precursor tyrosine hydroxylaseses which then leads to Dopa Decarboxlyase then the Dopamine beta-hydroxylaseses which then allows norepinephrine to convert into epinephrine but that step is controlled bye PNMT and the PNMT is controlled by ACTH from the pituitary
Structure difference between norepinephrine and epinephrine:
-Epinephrine has a CH3 that norepinephrine doesn’t
What are the biological consequences of activation of the adrenal medulla and the target organs or tissues for catecholamines along with the receptor subtype that mediates the response?
-Effects in target organs are mediated by alpha or beta adrenergic receptors
-Tissues may have one ore more receptor types
