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Adrenal Medullary hormones (Epinephrine and Nor-Epinephrine)

Adrenal Medullary Hormones 1. Chemistry Belong to the catecholamine group (derived from the amino acid tyrosine ). Water-soluble hormones. Stored in secretory vesicles (chromaffin granules) inside adrenal medulla. Act via adrenergic receptors (α and β receptors) on target tissues. 2. Secretion Secreted by chromaffin cells of the adrenal medulla . Stimulated by sympathetic nervous system (fight-or-flight response). Normal ratio: about 80% epinephrine, 20% norepinephrine . Triggered by stress (fear, anger, hypoglycemia, exercise, trauma, pain). 3. Functions Epinephrine (Adrenaline) Acts mainly on β-adrenergic receptors . Metabolic effects : ↑ Blood glucose (stimulates glycogen breakdown in liver and muscle). ↑ Lipolysis (fat breakdown). Cardiovascular effects : ↑ Heart rate (positive chronotropic effect). ↑ Cardiac output. Dilates skeletal muscle blood vessels (β₂ effect). Respiratory effects : Bronchodilation (helps...
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Adrenal gland hormones-Chemistry, Secretion, Functions and Regulations of Adrenal Cortex hormones (glucocorticoids and mineralocorticoids)

1. Adrenal Cortex – Overview The adrenal gland has two main parts: Adrenal cortex → produces steroid hormones (glucocorticoids, mineralocorticoids, and androgens). Adrenal medulla → produces catecholamines (epinephrine and norepinephrine). We’ll focus on cortical hormones : Glucocorticoids (mainly cortisol in humans) Mineralocorticoids (mainly aldosterone) 2. Chemistry Both glucocorticoids and mineralocorticoids are steroid hormones . Derived from cholesterol through a series of enzymatic reactions. Lipid-soluble, so they can easily cross cell membranes and bind to intracellular receptors . 3. Secretion Glucocorticoids (cortisol) → secreted mainly by the zona fasciculata of the adrenal cortex. Mineralocorticoids (aldosterone) → secreted mainly by the zona glomerulosa of the adrenal cortex. Secretion pattern: Cortisol → shows diurnal rhythm (high in early morning, low at midnight). Aldosterone → secretion depends on renin-angiotens...
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Ovarian cycle and its regulation.

  The ovarian cycle has follicular (FSH, estrogen), ovulation (LH flow), and luteal (progesterone) phases, regulated by the hypothalamic–pituitary–ovarian axis through a delicate balance of feedback mechanisms. 1. Ovarian Cycle – Phases The ovarian cycle lasts about 28 days (average) and has three main phases: A. Follicular Phase (Day 1–14, variable) Begins with menstruation . FSH stimulates growth of several ovarian follicles. One follicle becomes dominant (Graafian follicle) → secretes estrogen . Rising estrogen → proliferation of endometrium (preparing for implantation). B. Ovulation (Around Day 14) High estrogen levels (positive feedback) → LH surge . LH surge causes: Final maturation of oocyte. Rupture of Graafian follicle → release of ovum. C. Luteal Phase (Day 15–28, fixed ~14 days) Remaining follicle forms corpus luteum . Corpus luteum secretes progesterone (main) + estrogen . Progesterone prepares endometrium (se...
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Chemistry, Secretion, Functions and Regulations of Gonadal hormones: Progesterone

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  1. Chemistry Progesterone is a C-21 steroid hormone , belonging to the progestogen group. Chemical formula: C₂₁H₃₀O₂ . Derived from cholesterol via the steroidogenesis pathway. It is a lipid-soluble hormone and acts via intracellular nuclear receptors (Progesterone Receptors: PR-A and PR-B) . 2. Secretion • Progesterone is synthesized in the ovaries mainly from cholesterol. • Normal secretions level  • Female pre ovulation/male/post-menopausal=1ng/ml • Female mid cycle=5-20ng/ml • Pregnancy   1st trimester=11 to 90ng/ml  2nd trimester=25 to 89ng/ml  3rd trimester=48 to 150/300ng/ml. In Females Secreted mainly by the corpus luteum after ovulation. Also produced by the placenta during pregnancy (from ~8–12 weeks onward). Minor secretion by adrenal cortex . In Males Secreted in small amounts by testes (Leydig cells) and adrenal cortex. 3. Functions Reproductive Functions Prepares the endometrium for imp...
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Chemistry, Secretion, Functions and Regulations of Gonadal hormones: Estrogen

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Estrogen – Chemistry, Secretion, Functions, and Regulation 1. Chemistry Estrogen is a steroid hormone, derived from cholesterol. Belongs to the female sex hormone group. Three main natural estrogens in humans: Estradiol (E2) → most active, dominant in reproductive years. Estrone (E1) → present after menopause. Estriol (E3) → major estrogen in pregnancy. Lipid-soluble and acts through intracellular receptors (nuclear receptors). 2. Site of Secretion Females: Mainly from ovarian follicles (granulosa cells). Also secreted by corpus luteum and placenta (during pregnancy). Males: Very small amounts secreted by testes and adrenal cortex. In blood, estrogens are bound to sex hormone-binding globulin (SHBG) and albumin; only a small free fraction is active. 3. Normal Secretion Adult Women: Blood estradiol levels: 50–350 pg/mL (varies with menstrual cycle). Peaks just before ovulation. During Pregnancy: Very high levels (estriol predominates). After Menopause: Levels fall drastically. 4. Functi...
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Chemistry, Secretion, Functions and Regulations of Gonadal hormones: Testosterone

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Testosterone – Chemistry, Secretion, Functions, and Regulation 1. Chemistry Testosterone is a steroid hormone. It belongs to the group of androgens (male sex hormones). Derived from cholesterol in the Leydig cells of testes. It is lipid-soluble and easily passes through cell membranes. 2. Site of Secretion Males: Mainly secreted by Leydig (interstitial) cells in testes. Females: Secreted in very small amounts by the ovaries and adrenal cortex. In blood, testosterone is mostly bound to sex hormone-binding globulin (SHBG) and albumin; only 2–3% is free and biologically active. 3. Normal Secretion In Males: Average adult production: 6–7 mg/day. Blood levels: about 300–1000 ng/dL. Secretion starts during fetal life (for male sex differentiation), decreases after birth, rises again at puberty, and gradually declines after 40–50 years (andropause). In Females: Much lower levels (20–70 ng/dL). Contributes to libido, bone health, and muscle strength. 4. Functions of Testosterone ✅ ...
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PANCREAS & ITS HORMONES

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PANCREAS & ITS HORMONES PANCREAS ·      Pancreas in an organ that lies at the upper left abdomen. ·      Pancreas is made up of two major types of cells. ü Acini-which secretes digestive juice into the duodenum. ü Islets of Langerhans –which secretes hormones. (25%)α Islets of Langerhans – Glucagon. (60%)β Islets of Langerhans – Insulin. (15%)δ Islets of Langerhans – Somatostatin.        INSULIN: v Insulin is a protein hormone secreted by β cells of islets of Langerhans of pancreas.    Chemistry: v Molecular weight around 6000 Daltons. v It consist of 2 polypeptide chains-A chain & B chain. v A chain has 21 amino acids & B chain has 30 amino acids. v A chain & B chain are connected by 2 inter disulphide bridges at cysteine 7 of A chain and cysteine 7 of B chain and cysteine 20 of A chain and 19 of B chain. v ‘A’ chain has intra disulphide bridge between cys...
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