Adrenal Hormones Flashcards
What NS innervates the adrenal medulla?
sympathetic innervation
What cells are included in the adrenal medulla?
Chromaffin cells
What does the adrenal medulla secrete?
Catecholamines
90% cells produce epi, 10% produce NE
What does the adrenal cortex secrete?
Corticosteroids
Bulk of the gland
What is the adrenal cortex stimulated by?
Stimulated by the ACTH
True/False: Adrenal cortex is key to survival?
- True
A. Vital to survival
B. Trauma to or removal of the adrenal glands requires corticosteroid supplementation throughout life
What is the function of the adrenal cortex?
- Different functional categories of steroid hormones are synthesized and secreted in three separate zones
A. Regulates salt, sugar, and sex
What are the 3 zones of the adrenal cortex and what do they produce?
1. Zona glomerulosa A. Aldosterone 2. Zona fasiculata B. Cortisol and Androgens 3. Zona reticularis A. androgen precursors
What are the general characteristicsof the zona glomerulosa?
- Produces mineralcorticoids
A. Principal mineralcorticoid is aldosterone
What is the function of aldosterone?
Outer layer
1. Affects Na metabolism
A. Increases tubular transport Na
B. Causes re-absorption Na, Cl, HCO3, & water
C. Causes excretion K
2. Secretion of these cells controlled by extracellular fluid concentrations of angiotensin II & K
A. Increase in either of above increases aldosterone secretion
What are the general characteristics of the zona fasciulata?
- Middle Layer
2. Produces glucocorticoids
What is the function of the glucocorticoids?
- Cortisol is the principal glucocorticoid
- Stimulates metabolism of lipids, proteins, glucose
- Anti-inflammatory effects
A. Inhibit WBC’s & other components of immune system - Also secretes small amounts androgens & estrogens
- Secretion of glucocorticoids is controlled by hypothalamic-pituitary axis via ACTH
What are the characteristics of the zona reticularis?
- Inner most layer
- Produces sex hormones
A. Androgens - Can also produce small amounts of cortisol
- Regulated by ACTH
A. Physiology not well understood
What are the actions of cortisol?
- muscle wasting
- gluconeogenesis
- hyperglycemia
- anti-inflammatory
- anti-immune effects
- insulin resistance
- It also has mineralocorticoid-like effects on the kidney at high concentrations.
How are glucocorticoids involved in carbohydrate metabolism?
- Stimulate gluconeogenesis
A. Formation of carbohydrates from proteins & other substances by liver - Cause decrease in rate of glucose utilization by most cells in body
- Cause increased insulin
A. Leads to insulin resistance
How are glucocorticoids involved in protein metabolism?
- Stimulates protein catabolism
A. Promotes amino acid mobilization from muscle to provide amino acids for gluconeogenesis - Increased protein catabolism and decreased protein synthesis leads to reduced protein stores (except liver)
- Increased liver proteins and plasma proteins
A. Inc liver & plasma proteins
B. Results from transport of proteins via plasma to liver for gluconeogenes
How are glucocorticoids involved in fat metabolism?
- Promotes mobilization fatty acids from adipose tissue
2. Shifts primary energy source to fatty acids
How are glucocorticoids involved with stress/inflammation?
- Stress causes increase ACTH which causes increase in cortisol secretion
- Different types of stress
A. Trauma
B. Infection
C. Surgery
D. Emotional
What are the anti-inflammatory effects of cortisol?
- Decreases permeability of capillaries
- Decreases migration of WBC’s into inflammed area
- Suppresses immune system
- Attenuates fever
A. Reduces Interleukin I which affects hypothalamic temperature control system
What is the neg feedback mechanism for the adrenal cortex?
1. Hypothalamus A. CRF 2. Anterior Pit A. ACTH 3. Adrenal Cortex A. Glucocorticoids, levels feed back to hypothalamus and anterior pituitary
When is Melanocyte Stimulating hormone (MSH) released?
- When ACTH secreted, MSH is secreted
- When ACTH is produced in excess, excessive amounts of MSH are produced
A. Results in darkening of skin
What is the function of MSH?
MSH causes melanocytes to produce melanin and disperse it to epidermis
What is the function of aldosterone?
- Affects Na metabolism
A. Increases tubular transport Na
B. Causes re-absorption Na, Cl, HCO3, & water
C. Causes excretion K
When is aldosterone secreted?
- Increase K in extracellular fluid
- Increase activity of renin-angiotensin system
A. Increase in angiotensin II - ACTH secretion
When is aldosterone secreted inhibited?
Plasma Na is increased
What is addison’s disease?
Adrenal hypofunction
What causes primary addison’s disease?
- Originates within adrenal gland
- Characterized by decreased secretion of mineralcorticoids, glucocorticoids and androgens
- Autoimmune destruction most common cause
A. cancer, adrenal hemorrhage, TB, bil adrenalectomy,
What causes secondary adison’s disease?
- Due to impaired pituitary secretion ACTH MC
A. less common: hypopituitarism, abrupt withdrawal of long term steroid Rx, removal of ACTH secreting tumor, autoimmune pituitary process. - Results in decreased cortisol secretion
What is the pathophys of addison’s disease?
- Cortisol deficiency
- Decreased liver gluconeogenesis
A. Makes it impossible to maintain normal glucose levels between meals
B. Glucose levels on pts on insulin can become dangerously low - Reduces mobilization of fats and proteins from tissues
A. Depresses other metabolic functions
What does the aldosterone deficiency in addison’s disease cause?
Increased Na loss, K reabsorption (cardiac toxicity), water volume loss
What does the androgen deficiency in addison’s disease cause?
Decreased hair growth in axilla and pubic area, ED, dec libido
What does the melanin production excess in addison’s disease cause?
- Increased melanin production
A. Leads to darkening of skin (bronze color)
B. Due to hypersecretion of melanocyte stimulating hormone
What is primary aldosteronism?
- Secretion of large amounts of aldosterone
2. Not that common but should be considered in pts with HTN
What is the etiology of primary aldosteronism?
Usually results from tumor in zona glomerulosa
What are the complications of primary aldosteronism?
- Hypokalemia
A. Can lead to muscle paralysis due to depressed action potential transmission - Increase in ECF volume
- HTN
What conditions can increase aldosterone?
1. Glucocorticoid Secretion Increased A. Surgery B. Anxiety C. Physical Trauma D. Hemorrhage 2. Glucocorticoid Secretion Unaffected A. High K+ B. Low Na+ C. Symptomatic when Standing
What is primary aldosterone deficiency?
Aldosterone deficiency
Rare
What are the complications from primary aldosterone deficiency?
- Severe hyponatremia, hyperkalemia
A. Hyponatremia ->low BP and low volume
B. Hyperkalemia -> cardiac toxicity - Low cardiac output follows which leads to circulatory shock
What are the plasma electrolyte levels in adrenal insufficiency?
- Na: 120
- K: 6.7
- Cl: 85
- CO2: 25
What are the plasma electrolyte levels in Primary hypoaldosteronism?
- Na: 155
- K: 2.4
- Cl: 96
- CO2: 41
What are the normal plasma electrolyte levels?
- Na: 142
- K: 4.5
- Cl: 105
- CO2: 25
What is cushing’s disease?
- Excess production ACTH
- Results in excess cortisol and androgen production
- In excess, cortisol is a catabolic hormone
What causes cushing’s disease?
- Pituitary tumor or ectopic ACTH producing tumor
- Long term high dose steroid use
- Adrenal tumor
What are the metabolic effects of excess glucocorticoids?
- Muscle wasting & thinning of skin
A. Results from protein catabolism and inhibition of protein synthesis - Bone resorption
A. Due to imbalance between osteoclastic and osteoblastic activity - Centripetal obesity
- Renal Na retention and K loss
A. Cortisol binds to mineralcorticoid receptors in addition to glucocorticoid receptors
What are the signs and symptoms of cushing’s disease?
- Mobilization of fats from lower body
- Extra deposition fat in thoracic region
A. “Buffalo hump” - Edematous appearance of face
A. “Moon facies” - Acne
- Hirsutism
- Striae
