Midterm 2 - Importance of Adrenal Hormones Flashcards
what are adrenals
paired organs capping the kidneys
what do the adrenals consist of
2 layers
what are the 2 layers of the adrenals
outer cortex and inner medulla
what is the outer cortex derived from
mesoderm
what is the inner medulla derived from
neural crest
what is the medulla a part of
ANS
what is the medulla equivalent to
a ganglion, but with postganglionic cells secreting catecholamines that diffuse in blood
catecholamines
epinephrine, norepinephrine
what are the 3 zones that compose the cortex
zona glomerulosa
zona fasciculata
zona reticularis
what does the zone glomerulosa secrete
mineralcorticoids
what does the zone fasciculata secrete
glucocorticoids
what does the zone reticularis secrete
androgens
what percentage of the adrenal glands mass is the cortex
90%
what hormones does the cortex produce
steroid hormones (adrenocortical hormones) required for survival
how are hormones from the cortex produced
by a stepwise conversion of cholesterol perviously absorbed from blood lipoproteins
what are major enzymes in the conversion of cholesterol
cytochrome-p450
what do cells from each zone of the cortex have
different enzymes while allows formation of different hormones
what is the most potent mineralcorticoid
aldosterone
what happens to mineralocorticoids after diffusion
they circulate loosely bound to cortisol binding globulin (CBG)
what is synthesis and secretion of mineralocorticoids stimulated by
angiotensin
direct actin of K+ concentration on cortical cells
does ACTH from pituitary have an impact on aldosterone production
minimal
what doe mineralocorticoids regulate
metabolism of important inorganic ions
what do mineralocorticoids stimulate
the reabsorption of Na+ and the secretion of K+ in the distal kidney tubules and collecting ducts
what does aldosterone do in target cells
binds to its receptor to modulate gene transcription
what does aldosterone do to gene transcription in Na+ and K+ pumps in basolateral membrane
increase
what does aldosterone do to gene transcription in Na+ channels in apical membrane
increase
what do glucocorticoids regulate
glucose metabolism
what is the most potent glucocorticoids
cortisol
what glucocorticoid has weaker activity
corticosterone
what does cortisol do after diffusing into blood
binds to CBG
what does the free hormone portion of cortisol do
enters target cells, binds to its receptors and stimulates or inhibits gene transcription
what cells are potential targets of cortisol
all
what is permissive action
activates transcription of several enzymes that facilitate the action of other hormones
what happens to cortisol levels during stress
increase –> enhances the effect of norepinephrine on blood pressure
what does cortisol stimulate
gluconeogensis
what does cortisol inhibit
tissue glucose utilisation
what is the result of cortisol activity during stress
increase in plasma glucose concentration
what does cortisol stimulate at high level
the deflation of fat and protein therefore increasing plasma amino acids and fatty acids concentrations
what is another thing that cortisol inhibits in many tissues
gene transcription
what is the growth inhibition effect
combined with the degradation of fat and protein –> energy conserved for survival during high stress
what are anti-inflammatory effects of cortisol
inhibits formation of prostaglandins and cytokines
reduces number of lymphocytes migration
another name glucocorticoid deficiency
Addison’s disease
where is glucocorticoid deficiency most common
in dogs
what is the consequence of glucocorticoid deficiency
life threatening
what is a major cause of glucocorticoid deficiency
autoimmune disorders that destroy adrenal cortex cells
symptoms of glucocorticoid deficiency
reduced blood pressure –>dizziness
reduced appetite, sluggish, depression, vomiting
what is the symptom of loss of negative feedback associated with glucocorticoid deficiency
a measurable increase in ACTH secretion
what is another name for glucocorticoid (cortisol) overproduction
Cushing’s disease
which animals is cortisol overproduction common
mostly dogs, can occur in cats and horses
what is cortisol overproduction primarily due to
pituitary and adrenal cortex tumours
symptoms of when cortisol is continuously high
dogs eat and drink a lot, lose hair, muscles weaken
anti-insulin effects can lead to diabetes
what are androgens similar to
testosterone
how do androgens circulate
partly bound to SHBG and albumin
iare androgens or testosterone more potentate
testosterone
is the role of androgens known in males
no
what is the role of androgens in females
transformed to estrogen in adipose tissue
what is the only source of estrogen after menopause in females
androgens
what type of hormones does the adrenal medulla secrete
catecholamines (epinephrine, norepinephrine)
what does the ratio of epinephrine/norepinephrine depend on
species
what is the ratio of epinephrine/norepinephrine in humans
4/1
what is secretion of catecholamines partly under the control of
preganglionic sympathetic nerves that release Ach
what does Ash do to cells from the medulla
depolarizes the cells
induces Ca2+ entry and exocytosis of hormones
what is the effect of medulla compared to sympathetic system
slower but longer
what is the issue with the normal blood level of catecholamines
it is too low to exert an action
where do catecholamines bind to
adrenergic receptors in target cells
what are the 2 types of receptors that catecholamines bind to
alpha and beta both G-protein coupled receptors
what is the effect of alpha receptors for catecholamines
increase Ca2+
what is the effect of beta receptors for catecholamines
increase cAMP
what catecholamine receptors are most common in target cells from the sympathetic
alpha
what effect does stimulation of catecholamine alpha receptors have in arterioles and sphincters of GI tract
constriction of smooth muscle
what is the result of activation of B1 catecholamine receptors in heart
increase in heart rate and contractility
where are B2 catecholamine receptors present
in muscles from bronchioles –> inhibition of contraction
where does epinephrine have a dual effect on alpha and beta receptors
in arterioles of skeletal muscles
what is the effect that epinephrine has in arterioles of skeletal muscles
low levels active beta receptors (relaxation)
high levels activate alpha receptors (small contraction)
what is stress
factors that alter or might alter the body internal envrionemtn
what are 2 types of stress
internal
external
examples of external stress
cold
exercise
injury
examples of internal stress
pain
physiological factors
