Module 3A Flashcards
What is the role of the adrenal gland in the endocrine system?
response to stress maintain salt/water equilibrium maintain BP Sympathetic function (extension of ANS)
What are the two regions of the adrenal gland?
Medulla and cortex
What does the adrenal cortex produce
Aldosterone, cortison, and DHEA
What does the adrenal medulla produce?
releases catecholamines - epinephrine and NE
What are the three layers of the adrenal cortex?
Zona glomerulosa (outer), Fasiculatat (middle), and zona reticularis (inner)
What is the difference between outer, middle and inner adrenal cortex?
Zona glomerulosa (outer) produces/secretes: Mineralcorticoid (aldosterone Zona Fasiculata (middle) and Zona reticularis (inner) both produce/secrete: Glucocorticoids (cortisol) and Adrenal androgen (DHEA)
What is the precursor for adrenal cortex
Cholesterol
What is step 1 in adrenal cortex hormone synthesis?
Cholesterol is converted to prenenolone
What is required to initiate the first tep of AC hormone synthesis?
ACTH and enzyme desmolase
What is the rate limiting step in AC hormone synthesis?
Cholesterol transportation across cell membrane is rate limiting step
What is the cascade pathway for AC hormone synthesis?
Stimulate, synthesize, release
What are the end products of AC hormone synthesis?
aldosterone, cortisol of DHEA
t/f hormones are not stored they are synthesized dependent on rate of demand (circadian rhythm)
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What is the stimulus for production of AC hormones?
hypothalamus releases CRH
CRH stims anterior pituitary to release ACTH
ACTH stimulates desmolase to convert cholesterol to pregnenolone.
What inhibits the production of AC hormones?
Increased levels of cortisol.
What makes cortisol an ideal negative feedback mechanism?
Initial steps of each AC hormone pathway are capable of producing cortisol. So very efficient
what is the stimulus for cortisol secretion?
ACTH released from anterior pituitary
Normal circadian rhythm
Stress stimulates release of ACTH
What inhibits the release of cortisol secretion?
elevated levels of cortisol inhibit ACTH and CRH
Negative feedback loop
What is the function of cortisol
a. in regards to glucose?
b. in regards to mineral corticoid receptors?
c. Pharmaceutically?
a. Elevates blood glucose
b. maintains fluid volume
c. Modulates immune system
What tissues does cortisol adversely effect?
Bone Muscle CT/Tendon Immune system CNS
What tissue does cortisol positively effect?
Fat cells liver decreased inflammation fetal lung development stress
Where is aldosterone produced?
Zona glomerulosa (outer)
What is the primary function of aldosterone?
Increase blood volume/BP by increasing renal sodium resorption (primary)
Decrease plasma potassium
Increase plasma pH (more alkaline)
What are the three actions of aldosterone?
- Increase sodium resorption in distal nephron
- Sodium resorption leads to cascade of other events : potassium excretion, and hydrogen excretion
- Vasoconstriction
What do you need besides aldosterone to keep the pathway going?
Angiotensin II (need both stimuli to keep cascade going on outer cortex).
What triggers the cascade for production of Angiotensin II?
Renin
Describe the renin-angiotensin system
BP and fluid volume decrease-we need more blood volume so the kidney releases Renin and liver releases precursor for angio I. Precursor + renin=angio I, Then Angio I + ACE=Angio II which results in vasoconstriction and production of aldosterone.
What factors inhibit aldosterone?
Negative feedback from Angio II, Hypokalemia, and ACTH
Where are the adrenal androgens produced?
Zona Fasciculata (middle) and Zona reticularis (inner)
What are considered the adrenal androgens?
DHEA and androstenedione
T/F the major role of androgens is in females?
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What is the role of androgens in females?
Maintaining muscle mass, bone density, sexual desire, and sense of well being, estrogen production (testosterone converts to estrogen)
What is the role of androgens in males, and where are they primarily produced?
deep voice, beard, male pattern baldness: But most testosterone in a male is produced in the testes so the adrenal androgens do not have as big of a role in males.
Where are androgens produced in the female? and what is their role?
Ovaries, and adrenal cortex. Adrenal androgens have a much more significant role in females.
Which is produced in higher quantities? DHEA or androstenedione? and what are they a precursor to?
DHEA is produced in larger quantity. DHEA and androstenedione are precursors to testosterone
What are the two fates of circulating DHEA?
- Converted to more potent androgen-testosterone
2. inactivated and degraded
What is more concerning: A female with increased androgen function of adrenal gland, or a male?
A female: Females will develop male characteristics. In males this wouldn’t be as obvious.
What is the effect in an adult male with excessive adrenal androgens?
No effect
What effect do excessive adrenal androgens have on pre-puberty males?
isosexual, precocious puberty. Onset < 9yo
What is the effect of excessive adrenal androgen in adult females?
Masculinization effects-male characteristics
What is the effect of excessive adrenal androgen in pre-pubescent females?
heterosexual precocious puberty (early secondary male characteristics)- < 8yo
What stimulates adrenal androgen secretion?
ACTH from the pituitary
What inhibits the release of adrenal androgen?
Cortisol (negative feedback)
What clinical diagnosis are under deficient secretion of adrenal cortex hormones?
Primary hypoadrenalism (Addison’s dz), and Secondary hypoadrenalism
What clinical diagnosis are under excessive secretion of adrenal cortex hormones?
Cushing’s dz, Cushings Syndrome, Excess androgens, and Primary hyperaldoseteronism
What occurs in Primary Hypoadrenalism?
Addison’s Dz: Adrenal cortex is damaged, Elevated ACTH attempts to stimulate adrenal cortex results in:
Hyperkalemia -K+ resorption in kidneys-bradycardia, cardiac arrhythmias
Hypoglycemia-Fatigue, weakness, wt loss
Decreased androgens - female loss of pubic/axillary hair
What occurs in Secondary hypoadrenalism?
Defficient secretion: Anterior pituitary is damaged ACTH levels decrease.
Hyperkalemia
Hypoglycmia
Decreased androgens
What occurs in Hypersecretion of adrenal cortex Cushings?
Cushing’s syndrome: excess cortisol, Cushings Dz: Excess ACTH (results in excess cortisol):
Increased aldosterone-hypertension
Hyperglycemia
Poor wound healing
muscle wasting
Increased Androgens-Acne Hirsutism, menstrual d/o
What occurs in Hypersecretion of adrenal cortex - Conn’s syndrome
Primary hyperaldosteronism (conn's syndrome): Tumor of adrenal cortex (outer layer) that secretes aldosterone. Increase aldosterone:-hypertension, hypokalmeia, metabolic alkalosis Production of cortisol and Androgens unchanged.
