Adrenal Hormones Flashcards
What does the adrenal gland consist of?
- Cortex.
- Medulla.
What does the cortex of the adrenal gland secrete?
Adrenocorticoids and adrenal androgens.
What does the medulla of the adrenal gland secrete?
Epinephrine (adrenaline).
Into how many zones is the adrenal cortex divided?
Three zones.
From what does the adrenal cortex’s three zones synthesize various steroids?
Cholesterol.
What does the outer layer of the adrenal cortex produce?
Mineralocorticoids (e.g., aldosterone).
What does the middle layer of the adrenal cortex synthesize?
Glucocorticoids (e.g., cortisol also known as hydrocortisone).
What does the inner layer of the adrenal cortex secrete?
Adrenal androgens (e.g., dehydroepiandrosterone).
What controls the secretion of the two inner zones and the outer zone of the adrenal cortex?
Pituitary ACTH.
What serves as feedback inhibitors of ACTH and CRH secretion?
Glucocorticoids.
List four therapeutic uses of adrenal cortex hormones.
Replacement therapy, treatment and management of asthma and other inflammatory diseases (e.g., rheumatoid arthritis), treatment of severe allergic reactions, and treatment of some cancers.
Where do adrenocorticoids bind in target tissues?
To specific intracellular cytoplasmic receptors. (They are lipophilic and can penetrate cell membranes)
How is the distribution of glucocorticoid receptors different from mineralocorticoid receptors?
Glucocorticoid receptors are widely distributed throughout the body, whereas mineralocorticoid receptors are mainly confined to excretory organs like the kidney, colon, and salivary and sweat glands.
Which type of receptor has a wider spectrum of activity, glucocorticoid or mineralocorticoid?
Glucocorticoid.
What is the principal glucocorticoid?
Cortisol.
How is glucocorticoid production characterized diurnally?
Peak early in the morning, followed by a decline, then a smaller peak in the late afternoon.
What factors influence glucocorticoid secretion?
Stress.
How do glucocorticoids favor gluconeogenesis?
By stimulating protein catabolism (except in the liver) and lipolysis, providing building blocks for glucose synthesis, leading to hyperglycemia.
How do glucocorticoids increase resistance to stress?
By raising plasma glucose levels, providing the body with energy to combat stress.
How do glucocorticoids affect blood pressure?
They can cause a modest rise by enhancing vasoconstrictor action of adrenergic stimuli on small vessels.
How do glucocorticoids alter blood cell levels in plasma?
Decrease eosinophils, basophils, monocytes, and lymphocytes; increase hemoglobin, erythrocytes, platelets, and neutrophils.
What are the anti-inflammatory actions of glucocorticoids?
Reduce the inflammatory response and suppress immunity by lowering and inhibiting peripheral lymphocytes and macrophages, inhibiting phospholipase A2, reducing COX-2 synthesis, and decreasing histamine release.
How do glucocorticoids affect other components of the endocrine system?
Feedback inhibition of ACTH and TSH production, and increased GH production.
Why is adequate cortisol essential?
For normal renal glomerular filtration (GF).
How can high doses of glucocorticoids affect the stomach?
They stimulate gastric acid and pepsin production, which may exacerbate ulcers.
How do glucocorticoids influence the CNS?
They influence mental status.
What are the long-term effects of chronic glucocorticoid therapy?
Severe bone loss, myopathy, and weakness.
What do mineralocorticoids help control in the body?
Water volume and concentration of electrolytes, especially sodium and potassium.
How does aldosterone affect the kidneys?
It acts on kidney tubules and collecting ducts, causing reabsorption of sodium, bicarbonate, and water.
What effect does aldosterone have on potassium reabsorption?
It decreases reabsorption of potassium, which, with H+, is lost in the urine.
What can elevated aldosterone levels cause?
Alkalosis and hypokalemia.
How does the retention of sodium and water affect blood volume and pressure?
It leads to an increase in blood volume and blood pressure.
What are the classifications of corticosteroids?
Glucocorticoids:
- Short-acting (1-12 hours):
- Hydrocortisone.
- Cortisone. - Intermediate-acting (12-36 hours):
- Prednisone.
- Prednisolone.
- Methylprednisolone.
- Triamcinolone. - Long-acting (36-55 hours):
- Betamethasone.
- Dexamethasone.
Mineralocorticoids:
- Fludrocortisone.
- Deoxycorticosterone.
What is the purpose of hydrocortisone in primary adrenocortical insufficiency (Addison’s disease)?
To correct the deficiency.
How is the daily dose of hydrocortisone divided for Addison’s disease treatment?
Two-thirds in the morning and one-third in the afternoon.
What might be administered in addition to hydrocortisone to raise mineralocorticoid activity to normal levels?
Fludrocortisone.
What is used for replacement therapy in secondary or tertiary adrenocortical insufficiency?
Hydrocortisone.
What test is used to diagnose Cushing’s syndrome?
Dexamethasone suppression test.
How is congenital adrenal hyperplasia treated with corticosteroids?
By normalizing hormone levels through suppressing CRH and ACTH release.
How do glucocorticoids relieve inflammatory symptoms?
By reducing rheumatoid and osteoarthritic inflammations and inflammatory conditions of the skin.
In what conditions are glucocorticoids beneficial for treating allergies?
Asthma, allergic rhinitis, and allergic reactions.
How do glucocorticoids accelerate lung maturation in premature infants?
Cortisol enhances lung maturation; betamethasone or dexamethasone is administered intramuscularly before delivery.
Which glucocorticoid has no effect on the fetus during pregnancy?
Prednisone.
Why is prednisone safe for the fetus?
It is not converted to the active compound prednisolone in the fetal liver.
What occurs with long-term use of large doses of glucocorticoids?
Suppression of the hypothalamic-pituitary-adrenal (HPA) axis.
How can the suppression of the HPA axis be prevented?
By using an alternate-day administration regimen of the adrenocortical steroid.
Why is withdrawal from corticosteroids a serious problem?
Because the patient may have experienced HPA suppression.
What can abrupt removal of corticosteroids cause?
Acute adrenal insufficiency syndrome, which can be lethal.
How should the dose of corticosteroids be adjusted when discontinuing therapy?
The dose must be tapered gradually.
What is a major side effect of long-term corticosteroid therapy related to bones?
Osteoporosis.
Why do glucocorticoids cause osteoporosis?
They suppress intestinal Ca2+ absorption, inhibit bone formation, and decrease sex hormone synthesis.
Can alternate-day dosing prevent osteoporosis in long-term corticosteroid therapy?
No, patients are advised to take calcium and vitamin D supplements.
What syndrome can long-term corticosteroid therapy induce that mimics another disease?
Cushing-like syndrome.
What effect do long-term corticosteroids have on the eyes?
Increased frequency of cataracts.
What is a potential metabolic side effect of long-term corticosteroid therapy?
Hyperglycemia, which may lead to diabetes mellitus.
How do glucocorticoids affect potassium levels?
They can cause hypokalemia.
What effect can long-term corticosteroid use have on children’s growth?
Decreased growth in children.
What is a common appetite-related side effect of long-term corticosteroid therapy?
Increased appetite.
How do corticosteroids affect infection risk?
They increase the risk of infection.
What is a potential fluid-related side effect of long-term corticosteroid use?
Peripheral edema.
Why might the glucocorticoid dose need adjustment when coadministered with certain medications?
Because they are metabolized by liver P450s, and medications that induce or inhibit hepatic mixed-function oxidases may require dose adjustment.
