Adrenal Gland Flashcards
Embryological origin of adrenal cortex vs. adrenal medulla
Adrenal cortex is of mesodermal origin
Adrenal medulla is of ectodermal origin
What types of hormones are secreted by adrenal cortex vs. adrenal medulla?
Adrenal cortex = corticoids and androgens
Adrenal medulla = catecholamines (NE and E)
What are the zones of the adrenal cortex?
[capsule] Zona glomerulosa Zona fasciculata Zona reticularis [adrenal medulla]
What is the primary hormone secreted from zona glomerulosa of adrenal cortex?
Mineralocorticoid = aldosterone
What is the primary hormone secreted from zona fasciculata of adrenal cortex?
Gluococorticoid = cortisol
[also some androgen secretion]
What is the primary hormone secreted from zona reticularis of adrenal cortex?
Androgens
[some cortisol as well]
What is the most common adrenal enzyme deficiency?
21-hydroxylase deficiency
A deficiency in 21-hydroxylase results in what changes in hormone production?
Decreased cortisol
Decreased mineralocorticoid
Increased sex hormones
What are signs/symptoms of 21-hydroxylase deficiency?
Hypotension (decreased aldosterone)
Sodium and volume loss
Hyperkalemia
Elevated renin
Female = virilization of fetus and sexual ambiguity at birth
Male = phenotypically normal, precocious pseudopuberty, premature growth plate closure
Tx for 21-hydroxylase deficiency
Replace glucocorticoids and mineralocorticoids
A deficiency in what adrenal enzyme leads to increased androgens, virilization of female features, and increased 11-deoxycorticosterone?
11b-hydroxylase deficiency
Signs and symptoms of 11b-hydroxylase deficiency
Hypertension
Hypokalemia
Suppressed renin secretion
A 17-alpha hydroxylase deficiency is extremely rare. What changes in hormone secretion occur with this deficiency?
Decreased androgens and cortisol
Excess mineralocorticoids
[patients typically diagnosed at puberty]
Signs/symptoms of 17-alpha hydroxylase deficiency
Hypertension
Hypokalemia
Hypogonadism
Do the following increase or decrease in a 17-alpha hydroxylase deficiency?
Mineralocorticoids Cortisol Sex hormones Blood pressure Plasma [K]
Mineralocorticoids increase Cortisol decrease Sex hormones decrease Blood pressure increase Plasma [K] decrease
Do the following increase or decrease in a 21-beta hydroxylase deficiency?
Mineralocorticoids Cortisol Sex hormones Blood pressure Plasma [K]
Mineralocorticoids decrease Cortisol decrease Sex hormones increase Blood pressuredecrease Plasma [K] increase
Do the following increase or decrease in an 11-beta-hydroxylase deficiency?
Mineralocorticoids Cortisol Sex hormones Blood pressure Plasma [K]
Mineralocorticoids decrease (aldosterone) Cortisol decrease Sex hormones increase Blood pressure increase Plasma [K] decrease
The target tissues of cortisol are body wide and the actions numerous. Genomic actions occur via ______, and non-genomic actions occur via _____
Glucocorticoid response elements (GREs)
Endocannabinoids
What conditions occur with glucocorticoid excess?
Cushing syndrome or cushing disease
What conditions occur with glucocorticoid deficiency?
Addison disease
What effect does cortisol have on the liver?
Increased gluconeogenesis
What effect does cortisol have on the muscle?
Breakdown of muscle protein
What effect does cortisol have on fat?
Promotes lipolysis in extremities, promotes central fat deposition
What effect does cortisol have on skin?
Skin thins, fragile blood vessels
What effect does cortisol have on the immune system?
Increased risk of infection (diminished immune response)
What effect does cortisol have on the endocrine system?
Insulin resistance or glucose intolerance
[also decreased LH, FSH release, decreased TSH release, decreased GH secretion
What effect does cortisol have on the GI system?
Increased risk of osteoporosis d/t interference with calcium absorption
Cortisol release begins with stimulationg by ____ from the ______ nucleus in the hypothalamus
This binds the CRF1 receptor (GPCR) and stimulates the release of ______, which acts on the adrenals and stimulates release of cortisol
CRF aka CRH; paraventricular
ACTH
ACTH is produced in the anterior pituitary and is the principle hormone that stimulates adrenal glucocorticoids
The precursor to ACTH is ______; it also contains ____ activity responsible for stimulation of melanocytes
POMC; MSH
Excess ACTH can lead to ______ due to increased alpha-MSH activity
Hyperpigmentation
Differentiate between long, short, and ultrashort HPA axis feedback loops
Long = from adrenal glands back up to anterior pituitary and hypothalamus
Short = from anterior pituitary back to hypothalamus
Ultrashort = hormone from hypothalamus inhibits itself
When do we experience the largest spike in cortisol release? How does this compare to the rhythm of ACTH?
Largest spike in cortisol upon awakening, around sun-up
ACTH tends to stay around the same levels with a slight drop off in early evening
Glucocorticoids exert negative feedback onto CRH and ACTH
What is the mechanism for this?
GCs inhibit POMC transcription
GCs also inhibit mRNA synthesis of CRH and ACTH