Module 3A Flashcards
What role does the adrenal gland have in the endocrine system?
- response to stress (fight or flight)
- maintain water/salt equilibrium
- maintain BP
- sympathetic function (“extension of ANS”)
What are the two regions of the adrenal gland?
- medulla
- cortex
What hormones does the adrenal medulla release?
- catecholamines (E, NE)
What hormones does the adrenal cortex release?
- aldosterone
- cortisol
- dehydroepiandosterone (DHEA)
What are the steps to hormone release from the adrenal medulla?
- stressor stimulates CNS/hypothalamus which stimulates brainstem & SC to sympathetic trunk which affects the adrenal medulla to release E & NE
What are the responses of systemic sympathetic activation?
- increase CV response (increase HR, BP, TPR)
- increase BMR
- increase ventilation response
- decrease GI fxn
- increase CNS “alertness”
- mobilize fuel via glycogenolysis and lipolysis)
What are the layers of the adrenal cortex?
- zona glomerulosa (outer)
- zona fasiculata (middle)
- zona reticularis (inner)
What is produced/secreted by the zona glomerulosa?
- mieralcorticoid (aldosterone)
What is produced/secreted by the zona fasiculata?
- gluocorticoids (cortisol)
- adrenal androgen (DHEA)
In general, what does the adrenal cortex produce/stimulate?
- all steroids but subtly different
Why do the different layers of the adrenal cortex produce/secrete different hormones?
- different layers contain different enzymes
What is the precursor for all adrenal cortex hormones?
- cholesterol
What is the first step(s) in adrenal cortex hormone synthesis?
- cholesterol transported from blood stream to cortex
- once in cortex: cholesterol w/ desolase –> pregnenolone
What stimulates the first chemical step in adrenal cortex hormone synthesis?
- ACTH
What happens to pregnenolone in the adrenal cortex?
- based on which layer it is in, converted to aldosterone, cortisol, or DHEA via specific pathway enzymes
What occurs if there are deficiencies in the pathway specific enzymes?
- deficiency in that hormone ==> adrenal pathology
T/F: Hormones are stored in the adrenal cortex for secretion as needed.
- False, synthesized at rate of demand
What pattern do hormones tend to be secreted from the adrenal cortex?
- circadian rhythmn
What are the signaling steps in the stimulus of hormone release from the adrenal cortex?
- hypothalamus releases CRH
- CRH stimulates ant. pit to release ACTH
- ACTH stimulates desmolase in adrenal cortex to convert cholesterol to pregnenolone
What can also influence aldosterone?
- angiotensin II
- ECF K+
What inhibits hormone release from the adrenal cortex?
- increase levels of cortisol inhibit release of ACTH and CRH (neg. feedback loop)
Why does cortisol inhibit hormone release from the adrenal cortex?
- the initial step of each pathway is capable of producing cortisol
What is the ideal neg. feedback hormone to affect hormone release from the adrenal cortex?
- cortisol
What is the more secondary inhibitory hormone of hormone release from the adrenal cortex?
- aldosterone
Where is cortisol produced?
- zona fasiculata (middle) & reticularis (inner)
What is the stimulus for cortisol secretion?
- ACTH from ant. pit
What factors influence cortisol secretion?
- normal circadian rhythm
- stress
What inhibits cortisol secretion?
- elevated cortisol (inhibits ACTH & CRH from ant. pit and hypothalamus, respectively)
- elevated ACTH inhibits hypothalamus
(negative feedback loop)
What is the function of gluocorticoids (cortisol)?
- catabolic to produce/mobilize/store glucose
- maintains fluid volume
- modulates immune system (anti-inflam response)
What are target tissues of cortisol?
- bone
- adipose
- muscle
- tendon/ligament/connective tissue
- immune system
- CNS
- metabolic
What is the effect of cortisol on bone?
- stimulate osteoclast/Ca2+ resportion
What is the adverse effect of cortisol on bone?
- decrease bone density
What is the effect of cortisol on adipose?
- stimulate lipolysis (mobilize FFA and glycerol for fuel & production of new glucose
- synergistic with glucagon, GH, catecholamines
What is the adverse effect of cortisol on adipose?
- adipose loss/redistribution
What are the clinical descriptors of adipose redistribution?
- moon face
- buffalo hump
What is the effect of cortisol on muscle?
- stimulate proteolysis (mobilize a.a. for fuel & production of new glucose)
What is the adverse effect of cortisol on muscle?
- muscle wasting/weakness
- loss of lean body mass
What is the effect of cortisol on tendon/ligament/connective tissue?
- catabolic effect (inhibits fibroblasts/collagen production)
What is the adverse effect of cortisol on tendon/ligament/connective tissue?
- ligament/tendon failure
What is the effect of cortisol on immune system?
- anti-inflam
What is the adverse effect of cortisol on immune system?
- poor wound healing/immune defenses
- only a concern with long or large doses
What is the effect of cortisol on CNS?
- alters perception and mood
- neg. feedback to hypothalamus & ant. pit
What is the effect of cortisol on metabolic function?
- alters intermediary metabolism to produce, mobilize, and store glucose (trying to save glucose for CNS survival)
- optimizes/enhances effect of glucagon
What is the effect of cortisol on the liver?
- gluconeogenosis
- glycogenesis
What is the effect of cortisol on catecholamines?
- optimizes/enhances effect
i. e. vasoconstriction & bronchodilation
What is the effect of cortisol on fetus lungs?
- surfactant production
- lung development
T/F: Cortisol enhances the body’s ability to tolerate stress
- True
Where are mineralcorticoids (aldosterone) produced?
- zona glomerulosa (outer)
What is the primary function of aldosterone?
- increase blood volume/BP by increasing renal Na+ resoprtion
What are the secondary functions of aldosterone?
- decrease plasma K+
- increase plasma pH
What are the actions of aldosterone?
- increase Na+ resorption in distal nephron (fine tuning)
- vasoconstriction
What does Na+ resorption lead to?
- increased H20 absorption (gradient follows Na+)
- facilitates K+ & H+ excretion
What stimulates aldosterone secretion?
- ACTH
- angiotenstin II
- hyperkalemia
T/F: ACTH is not as influential on aldosterone release as angiotensin II & K+ levels.
- True
What inhibits aldosterone secretion?
- hypernatrimia
- ANP (atrial natriuretic peptide)
- elevated ACTH levels
- hypokalemiea
Where are adrenal androgens produced?
- zona fasiculata (middle) & zona reticularis (inner)
What are adrenal androgens?
- sex hormones associated with the development/maintenance of male sexual characteristics
What are the responses in the female to adrenal androgens?
- maintaining muscle mass, bone density, sexual desire, & sense of well being
- estrogen production
What will low levels of adrenal androgens in female lead to?
- low libido
- muscle/bone mass loss
- fatigue
Describe androgen production in males
- primarily produced in testes
- adrenal cortex produces androgens that are converted to T in the periphery but NOT in significant amounts
Describe androgen production in females
- produced in ovaries & adrenal cortex
T/F: Adrenal androgens have amore significant role in males.
- False, females
Which is produced in a higher quantity: DHEA or androstenedione?
- DHEA
Where can DHEA/androstenedione converted to T?
- peripheral tissues
Conversion of DHEA/androstenedione to T is contributes more significantly to circulating levels of T in males or females?
- females
What is the most abundant circulating hormone in the body?
- DHEA
What is a weak androgen with poor binding affinity to androgen receptors?
- DHEA
What are the two fates of circulating DHEA?
- converted to more potent androgen = testosterone (T)
- inactivated and degraded
What is the androgen function of the adrenal gland?
- weak androgen function (masculinization)
- excessive adrenal androgens will promote inappropriate masculinization effects
T/F: Gonadal androgens (T) have a much more significant role in development of male characteristics
- True
Define isosexual precocious puberty
- < 9y/o inappropriate masculinization in males
Define heterosexual precocious puberty
- < 8y/o inappropriate masculinization in females
What is the stimulus for adrenal androgen secretion?
- ACTH
What is the inhibitor for adrenal androgen release?
- cortisol
What is Addison’s Dz?
- adrenalcortical insufficiency
- destruction of adrenal cortex so loss of all adrenal cortex hormones
What will labs demonstrate in Addison’s Dz?
- elevated ACTH
- decreased adrenal hormones
What is the effect of Addison’s on the zona glomberulosa?
~decreased mineralcorticoid (aldosterone) secretion~
- dehydration with polyuria
- hypotension
- hyponatremia
- hyperkalemia
- metabolic acidosis
- decreased blood vol.
What is the effect of Addison’s on the zona reticularis & fasiculata?
~decreased mineralcorticoid (aldosterone) secretion~
- hypoglycemia
- hyperpigmentation
- weakness
- anorexia
- wt loss
- nausea
- decrease in pubic/axillary hair in females
What is the difference b/t Cushing’s Syndrome & Dz?
- syndrome = excess cortisol of any pathology
- dz = excessive ACTH which results in excess cortisol
What is a clinical example of hyperadrenalism?
- Cushing’s Syndrome/Dz
What are the effects of increased glucocorticoids (cortisol)
- poor wound healing
- hyperglycemia
- muscle wasting
- osteoperosis
- central obesity
What are the effects of increased mineralcorticoids?
- HTN
What are the effects of increased adrenal androgens?
- virilization
- menstrual disorders
What is a clinical example of primary hyperaldosteronism?
- Conn’s Syndrome
What is the result of Conn’s Syndrome?
- HTN
- hyperkalemia
- metabolic alkalosis
