Adrenal Gland Hormones Flashcards
(20 cards)
What is functions of mineralocorticoids
Function of Mineralocorticoids (Aldosterone)
They increase Na* concentration in the ECF and consequently increasing ECF volume, which is important in the long-term regulation of blood pressure
Aldosterone is imp for long term regulation of BP through
Actions on the kidney: The kidneys are the major site of action of these hormones, where they act mainly at the late distal convoluted tubules and the collecting ducts, increasing Na” reabsorption in exchange with secretion of either K or H*.
Actions outside the kidney Mineralocorticoids increase Na* absorption from other body fluids e.g sweat and saliva as well as from the GIT mucosa, especially at the colon,
What is mechanism of action of aldesterone
Aldosterone is a lipophilic hormone, diffuses readily to the inside of target cells. In the cytoplasm, it combines with a specific receptor forming aldosterone-receptor complex which diffuses into the nucleus. increases the transcription of mRNA..new proteins formation
The new proteins may be sodium channels or enzymes such as sodium-potassium dependent ATPase (Na-K+ ATPase enzyme), which pumps 3 sodium out of the target cells into the interstitium and 2 potassium to the inside of the target cell.
Describe regulation of aldesterone secretion
1️⃣Potassium ion concentration in ECF:
Aldosterone secretion varies directly with serum K+ level. A small percentage increase in potassium concentration can cause a severalfold increase in aldosterone secretion.
2️⃣Angiotensin II
It stimulates aldosterone secretion,
It is formed through the renin-angiotensin system.
🌷In addition, angiotensin II promotes growth of the zona glomerulosa.
3️⃣- Reduced sodium ion concentration, blood pressure, and blood volume:
Via the renin-angiotensin-aldosterone system stimulates aldosterone secretion.
4️⃣ Although aldosterone secretion is independent of the anterior pituitary control, ACTH has a small stimulant effect (supportive role) on the release of aldosterone.
……..and ……. Are the most potent factors in regulating aldosterone secretion
K &Ang11
Mention causes of aldesterone hypersecretion
1️⃣Primary hyperaldosteronism (Conn’s disease): due to hypersecreting tumor of the zona glomerulosa cells.
2️⃣Secondary hyperaldosteronism: due to inappropriate high activity of renin- angiotensin system (may be due to decreased renal blood flow).
Mention electrolytes disturbance in hyperaldosteronism
★-Hypernatremia → ECF volume → hypertension. Despite that, no (or slight) edema occurs because of the phenomenon of aldosterone escape.
★Hypokalemia → severe muscle weakness, renal damage (hypokalemic nephropathy) as well as many cardiac effects.
★Increased H secretion → alkalosis→ decreased ionized calcium → tetany.
Define aldosterone escape phenomenon
High doses of aldosterone cause sodium and water retention and increase ECF volume. However, after few days this effect disappears and the kidneys escape from the effect of aldosterone, so the excretion of sodium and water increases again although the aldosterone blood level is maintained high.
why only slight edema occurs in hyperaldosteronism
It is due to the increase of the ECF volume itself which leads to:
1️⃣Rise of the ABP and this leads to pressure diuresis
2️⃣ Secretion of ANP, which causes both natriuresis as well as water diuresis.
Complete
1/……………. (95% of all glucocorticoid activity).
2/……. (less potent 4% of glucocorticoid activity).
3)…. of cortisol circulates bound to corticosteroid binding globulin (transcortin), 4)…. bound to albumin and 5) …… free.
1/Cortisol (hydrocortisone)
2/ Corticosterone
3/ 75%
4/ 15%
5/ 10%
Mention Physiological functions of cortisol
🍁Metabolism
Cortisol increases blood glucose, amino acids and fatty acids
🍁Permissive action
Cortisol must be in adequate
amount to permit catecholamine to induce 1️⃣ vasoconstriction 2️⃣bronchodilation3️⃣lipolysis
★NSV BL WATER★ 🌊⛈️
N==⟩effect on nervous system
S==⟩ adaptation to stress 😬
V==⟩ vascular smooth muscle responsiveness to epinephrine
B==⟩ ↑↑ RBCs platlet and neutrophils
↓↓basophils , eosinophils and lymphocytes
L==⟩. Lung maturation
Maturation of surfactant in the lungs 🫁
W==⟩ effect on water and electrolyte metabolism 🌻 promotes water excretion by 1️⃣–ADH2️⃣↑GFR3️⃣Weak mineralocorticoid effect
Cortisol depress the formation of RNA , Proteins in many extrahepatic tissue especially……&…….
Muscle 💪
Lymphoid tissue
How cortisol increases the liver proteins but not in most other tissues
↑ protein degradation
↓protein synthesis
Also it enhance amino acids transport into the liver also enhance liver enzymes required for protein synthesis
What is the effect of cortisol on carbohydrate metabolism
- Stimulation of gluconeogenesis by the liver, increasing glucose release from the liver. Decrease the utilization of glucose by muscle and adipose tissue (anti-insulin effect)
- Both, the increased rate of gluconeogenesis and the reduction of glucose utilization by the cells lead to rise in blood glucose level and may lead to adrenal diabetes.
Pharmacological actions of cortisol include…………
…………
Antiinflammatory action
Immunosuppressive action
Describe the antiinflammatory effect of cortisol
🌻1. Stabilizes the lysosomal membranes: and le This is one of its most important anti-inflammatory effects.
Most of the proteolytic enzymes that are released by damaged cells to cause inflammation, which are mainly stored in the lysosomes, are released in greatly decreased quantity.
🌻 2 .Decreases the permeability of the capillaries:
Probably as a secondary effect of the reduced release of proteolytic enzymes.
🌻 3. Decreases both migration of white blood cells into the inflamed area and phagocytosis of the damaged cells:
🌻4.suppresses the immune system
These effects probably result from the fact that cortisol diminishes the formation of prostaglandins and leukotrienes in damaged cell membranes that increase vasodilation, capillary permeability, and mobility of white blood cells. Suppresses the immune system:
⚫ Causing marked decrease of lymphocyte reproduction, in turn, reduced amounts of T cells and antibodies in the inflamed area lessen tissue reactions that would otherwise promote inflammation.
🌻5. Attenuates fever:
Mainly because it reduces the release of interleukin-1 from the white blood cells, which is one of the principal excitants to the hypothalamic temperature control system. • The decreased temperature in turn reduces the degree of vasodilation.
Explain immunosuppressive action of cortisol
Cortisol exerts multiple inhibitory effects on the overall immune process: 1. Decreased number of circulating eosinophils and basophils.
- Decreased the circulating lymphocyte count and the size of the lymph nodes and thymus
by inhibiting lymphocytic mitotic activity.
-
Cortisol reduces secretion of cytokines by inhibiting the effect of NF-kB on the nucleus. The reduced secretion of the cytokine IL-2 leads to reduced proliferation of lymphocytes,and these cells undergo apoptosis. As a result of decreasing the output of T cells and antibodies from the lymphoid tissue, the level
of immunity for almost all foreign invaders of the body is decreased. 🌻Cortisol provides to be useful in the management of various inflammatory, allergic disorders
and in prevention of organ transplant rejections
Cortisol…. gastric acid secretion
…. growth
…… TSH secretion
True or false
Cortisol delays wound healing
⬆️
Inhibit..⬇️GH
⬇️
True
Control of cortisol secretion
1.
Hypothalamic control: Corticotropin releasing hormone (CRH) is secreted by the hypothalamus into hypophyseal - portal blood.
of CRH binds to receptors on anterior pituitary to secrete ACTH through the formation of CAMP (acts as 2nd messenger).
2. Pituitary control:
- ACTH enhances many steps in the synthesis of cortisol. - ACTH is secreted in irregular bursts through the day.
Negative feedback: 3. - Cortisol inhibits secretion of CRH from hypothalamus and inhibits secretion of ACTH from anterior pituitary through a long loop negative feedback mechanism
4. Stress:
Causes dramatic increase in cortisol secretion.
-Stressful stimuli act on hypothalamus to increase CRH that stimulates ACTH secretion.
ACTH increases cortisol secretion.
5. Circadian rhythm:
The levels of CRH, ACTH and cortisol in plasma are not constant but show a diurnal fluctuation. The high rate of secretion occurs in early morning and is lowest in the evening.
Mention Causes of hypercortisolism Cushing $
a. Primary: adrenocortical tumors that secretes cortisol.
Secondary:
- Hypersecretion of ACTH from anterior pituitary which stimulates oversecretion of cortisol from adrenal cortex (ACTH-dependent Cushing syndrome).
2) ACTH-secreting tumors located in places other than the pituitary gland, most commonly
in the lungs.
c. Most often results from the clinical administration of pharmacological (very high) doses
of cortisol drugs.
