Derived Lipids Lecture Notes PDF

Lipid Chemistry Lecture 3 derived lipids  Prof / Ayman El Baz Professor of Medical Biochemistry & Molecular Biology Dr/ Sara El Derbaly Assistant Professor of Medical Biochemistry& Molecular Biology 1. Identify different types of derived lipids, t...

Lipid Chemistry Lecture 3 derived lipids  Prof / Ayman El Baz Professor of Medical Biochemistry & Molecular Biology Dr/ Sara El Derbaly Assistant Professor of Medical Biochemistry& Molecular Biology 1. Identify different types of derived lipids, their structure and function. 2. Correlate the knowledge to the clinical situation. Derived lipid  Derived lipids Definition: They are compounds derived from simple and or compound lipids by hydrolysis or substances related to lipids as steroids 1. Fatty acids 2. Glycerol Y Both are derived from To - Steroids are derived lipids because : To 3. Steroids: a. Sterols -- dycerol fatty Acids b. Steroid hormones c. Vitamin D d. Bile acids and salts I/ foxidation Acetyl CoA per Steroids Lipids 1. STEROLS: CHOLESTEROL The precursor of all steroids is cholesterol. All of them have steroid nucleus. Functions of cholesterol: 1. It is a major constituent of the plasma membrane and of plasma lipoproteins 2. It is the precursor of all other steroids as: Steroid hormones Vit D3 Bile acids and salts Sterols · 2. Steroid hormones A. Sex hormones: Estrogens, progesterone and androgens (produced by sex organs and adrenal cortex). Corticoids : means it's from B. Glucocorticoids : cortisone (by adrenal cortex) * the adrenal cortex. C. Mineralocorticoids : aldosterone (by adrenal cortex) Both glucocorticoids and mineralocorticoids are called corticosteroids. A. SEX HORMONES Male sex hormones: In humans, testosterone (one of androgens) is the major male hormone The Leydig cells (interstitial cells) of testis secrete testosterone under the influence of LH Zona reticularis of adrenal cortex synthesizes and secretes DHEA (the precursor of testosterone) Testosterone is responsible for maturation and function of male secondary sex organs (virilization) Female sex hormones: Estrogen and progesterone are the major female sex hormones. They are produced in response to LH and FSH hormones Estrogen is produced by ovarian follicular cells and adrenal cortex (zona reticularis). It is responsible for maturation and function of female secondary sex organs (feminization) Progesterone is produced by the ovaries, adrenal cortex and by the placenta during pregnancy. It is responsible for implantation of ovum and maintenance of pregnancy B. GLUCOCORTICOIDS (CORTISOL) They are synthesized and produced by zona fasciculata of adrenal cortex under the influence of adrenocorticotrophic hormone (ACTH) The glucocorticoids, as the name suggests, mainly affect metabolism of glucose They have diverse effects on inflammation, immunity, and protein, lipid & carbohydrate metabolism C. MINERALOCORTICOIDS (ALDOSTERONE) They are synthesized and produced by zona glomerulosa of adrenal cortex under the control of renin angiotensin aldosterone system (RAAS) Aldosterone increases sodium reabsorption from renal tubules, leading to sodium and water retention. The sodium potassium exchange at the renal tubules lead to increased potassium excretion. 3. Vit D3 It is a fat- soluble vitamin synthesized in the skin from 7- dehydrocholesterol by the effect of ultraviolet rays to produce cholecalciferol. Cholecalciferol is activated in liver and kidney through enzymatic reactions to produce active form of vit D3 (calcitriol or 1,25 (OH)2 D) Vit D3 has a major role in calcium and phosphorus homeostasis. 4. BILE ACIDS These are synthesized in the liver from cholesterol by hydroxylation. Bile acids as cholic acid are conjugated with glycine or taurine and secreted with bile in the form of their sodium salt (the bile salts). They have important role in the digestion and absorption of fats through formation of Micelles and they aid in fat emulsification. References  Vasudevan's Textbook of Biochemistry For Medical Students, 7th Edition.  Chatterjea’s Textbook of Medical Biochemistry, 8th edition.  Lippincott’s Illustrated Reviews: Biochemistry, 8th edition