Supra Renal Glands.mansfans.com

Adrenal glands There are 2 adrenal (= suprarenal) glands, one at the superior pole of each kidney. Each gland consists of two parts: an outer adrenal cortex and an inner adrenal medulla Adrenal cortex The adrenal cortex is essential for life. It secretes steroid hormones '' Corticosteroids'' which are derivatives of cholesterol. Functional histology www.MansFans.com The adrenal cortex is formed of three zones. These zones are: 6. Zona glomerulosa: '' outer zone '‘ • Groups of cells arranged in oval or arched pattern (glomeruli). • Secretes Mineralocorticoids: Aldosterone mainly and deoxycorticosterone. • Mineralocorticoids hormones control Na+, K+ and H2O metabolism.

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Adrenal glands - Continued 1. 

Zona Fasciculata: '' Middle zone '' Large cells arranged in columns or cords (fascicles), widest zones rich in lipid and Vitamin C.  Secretes Glucocorticoids hormones: Cortisol mainly and Corticosterone.  Glucocorticoids control carbohydrates, proteins and fat metabolism. 3. Zona reticularis '' Inner zone ''.  Columns of cells arranged in a reticular manner.  Secretes sex hormones: Mainly androgens (hormones produce musculinizing ''male'' effects e.g. dihydroepiandrosterone = DHEA) & very small amount of estrogen and progesterone.

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I. Mineralocorticoids Mineralocorticoids include Aldosterone and deoxycorticosterone (DOC) hormone, they are secreted from the Zona glomerulosa of adrenal cortex. Action of Aldosterone hormone: 1- On kidney '' main action '': Aldosterone hormone stimulates Na+ and H2O reabsorption and K+ secretion by distal convoluted tubules and collecting tubules of the kidneys. This results in:  Increased Na+ level in blood and extra cellular fluid (ECF).  Decreased K+ level in blood and ECF. Increased ECF volume due to Na+ and H2O retention.  2. Other effects:  Aldosterone decreases Na+ content in the sweat, saliva, gastric juice and milk.  Aldosterone increases Na+ re-absorption and K+ excretion by intestine and colon.

II. Glucocorticoids Glucocorticoids include Cortisol (hydrocortisone) and corticosterone hormones secreted from Zona fasciculata of adrenal cortex. Action of Glucocorticoids: 1- Metabolic effects: A. Protein metabolism: o In extra hepatic tissues; Cortisol stimulates protein catabolism (i.e. mobilization of amino acids from extra-hepatic tissues (mainly skeletal muscles). B. Carbohydrate metabolism:  Cortisol increases blood glucose level (hyperglycemic effect).  Cortisol stimulates liver glycogenesis. C. Fat metabolism:  Cortisol causes lipolysis (breakdown of fat molecules), ketogenesis (formation of ketone bodies) and deposition of fat in face, cervical and trunk regions.

Action of Glucocorticoids- Continued 2. Water and electrolyte balance:  Cortisol increases the excretion of water in urine by accelerating the inactivation of ADH in the liver and inhibiting its secretion.  Cortisol has a weak Mineralocorticoids activity. They help Na+ retention and K+ secretion (excretion) in urine. 3. Blood cells and lymphatic tissues: Cortisol resulted in: * Polycythaemia, neutrophillia and thrombocytosis. * Decease the output of T- lymphocytes and antibodies. * Decrease the size of lymph glands, spleen and thymus gland by inhibiting mitotic division of lymphocytes and increase their destruction.

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Action of Glucocorticoids - Continued 4. Anti inflammatory effect: Cortisol in large pharmacological dose Inhibit inflammatory reaction because it:  Stabilizes lysozymes membrane.  Inhibit the release of vasodilator substances e.g. Kinins.  Decreases capillary permeability and edema formation.  Suppresses immune system especially the T – lymphocytes. 5. Anti-allergic effect: Cortisol in pharmacological doses: o Inhibit histamine release from mast cells. o Decreases the Eosinophile and lymphocytes. 6. Resistance to stress: Cortisol increases the body resistance to stress through: • Increasing vascular reactivity to circulating Catecholamine. • Mobilization of fatty acids as a source of energy during stress. • Maintenance of plasma volume.

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Disorders of adrenal cortex A) Hypo function of adrenal cortex

- ''''ADDISION' DISEASE

Addison's disease is an autoimmune disease in which antibodies are formed against adrenal cortex causing its damage and atrophy. Manifestations: • Hypotension: Due to Aldosterone deficiency Na+ and water loss in urine Hypovolemia decreased arterial blood pressure. • Hypoglycemia. (i.e. decreased blood glucose level) due to Cortisol deficiency • Hyperkalemia (i.e. increased Blood K+ level) due to Aldosterone deficiency diminished K+ excretion in urine. • Hyper pigmentation: Bronze skin pigmentation especially occurs in the face, groins, axilla, nipples, and exposed area to sun light and scars as umbilicus. • Asthenia (i.e. generalized muscle weakness) due to tissue hypoxia, Hyperkalemia and hypoglycemia. • Loss of appetite (anorexia), vomiting and diarrhea. • Resistance to stress is decreased. • Sexual disturbances; e.g. amenorrhea in females. Treatment:  Adrenocortical hormones: Aldosterone and Cortisol are given.  Diet rich in NaCl and glucose but poor in K+.

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B- Hyper function of adrenal cortex ''Cushing's syndrome'' It is due to excessive secretion or administration of Glucocorticoids (Cortisol and corticosterone) Manifestations: 1- Increased protein catabolism; this leads to:  Muscle wasting and weakness.  Thin skin, hair and subcutaneous tissues.  Osteoporosis; loss of bone mass due to decreased protein content with bone demineralization leading to: o Deformity and fractures of bone o Collapse of vertebrae leading to Kyphosis (i.e. arching of the back). 2- Abnormal fat distribution; fat is deposited in:  Face becomes rounded (moon face)  Supra-clavicle region and back of the neck and inter-scapular region.  Trunk and abdominal wall (trunk obesity); while extremities are thin (Buffalo hump appearance) .

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.Manifestations of Cushing- Cont 3- Hyperglycemia, glucosuria (i.e. presence of glucose in urine). 4- Hypertension: Due to Na+ and H2O retention. 5- Androgenic manifestations; as acne, Hairsutism (abnormal appearance of hairs). 6- Increased basal metabolic rate (BMR). 7- Mental abnormalities as insomnia, euphoria and psychosis.

Adrenal medulla a)

b) c)

The adrenal medulla secretes Catecholamines: Adrenaline or Epinphrine (80%) and noradrenaline or Norepinephrine (20%) hormones. The gland is not essential for life. Adreno-medullary hormones help the activity of sympathetic system when generalized sympathetic stimulation occurs (stress response or flight and fight response)

Action of Catecholamines Catecholamine act on: • Metabolism: Adrenaline stimulates basal metabolic rate, liver glycogenolysis, muscle glycogenolysis and lipolysis. • The heart: Catecholamine stimulates all cardiac properties and dilates coronary vessels. So, it produces:  Increased heart rate (tachycardia), increased force of contraction, increased excitability & enhanced conductivity, increased metabolism and O2 consumption and coronary vasodilatation. III- On blood vessels & blood pressure: o Noradrenalin causes generalized vasoconstriction increase in the peripheral resistance increase of blood pressure with concomitant decrease in cardiac output. o Adrenaline causes vasoconstriction of skin, renal and splanchnic blood vessels whilst vasodilatation occurs in skeletal muscles blood vessels. Cardiac output is increased. IV-Central nervous system: Catecholamine increases the excitabilities of CNS and shortens the response time. Adrenaline increases the alertness, awareness and mental activity. V- Respiration: Catecholamine increases the rate and depth of respiration. VII- Skin: adrenaline causes pallor of the skin due to cutaneous vasoconstriction

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