Pharos university Faculty of Allied Medical SCIENCE Biochemistry 1 (MLBC-201)

1. Pharos universityFaculty of Allied Medical SCIENCEBiochemistry 1(MLBC-201) Dr. Dr Hewaida Fadel & Dr. Tarek El Sewedy Department of Medical Laboratory Technology Faculty of Allied Medical Sciences

2. Lecture22/12/2013 Hormones , Vitamins and minerals Structure and function

3. Intended Learning Outcomes • By the end of this lecture, students will learn: • Recognize The structure, function and classification of hormones, Biomedical importance of hormones and pathophysiology conditions related to disturbance in the hormonal levels. • Learn major functions and diseases related with vitamins and minerals.

4. Lecture Content • Hormone classification and types. • Hormone structure and functions. • Vitamins • Minerals • Deseases related to vitamin deficiency.

5. The endocrine system • The survival of multicellular organisms depends on their ability to adapt to a constantly changing environment. • Intercellular communication mechanisms are necessary requirements for this adaptation. • The nervous system and the endocrine system provide this intercellular, organism-wide communication. • The nervous system was originally viewed as providing a fixed communication system, whereas the endocrine system supplies hormones, which are mobile messages.

6. Hormones • The word “hormone” is derived from a Greek term that means to arouse to activity. • As classically defined: • A hormone is a substance that is synthesized in one organ and transported by the circulatory system to act on another distant tissue (endocrine action). • However, this original description is too restrictive because hormones can act also on adjacent cells (paracrine action) and on the cell in which they were synthesized (autocrine action) without entering the systemic circulation

7. There are about 200 types of differentiated cells in humans. • Only a few produce hormones, but virtually all of the 75 trillion cells in a human are targets of one or more of the over 50 known hormones. • The presenceof a specific receptor defines the target cells for a given hormone. • Receptors are proteins that bind specific hormones and generate an intracellular signal. • Hormones work by binding to receptors on or withinthe cell and changing the activity of that particular cell).

8. General features of hormone classes

9. Hormones classification • Hormones can be classified according to: • Chemical structure. • Solubility properties. • Location of receptors. • Nature of the signal used to mediate hormonal action.

10. 1. Structural Classifications • Under this method of classification, there are four groups: • steroid hormones. • peptides derived. • amino acid derived. • fatty acid derived.

11. 1. Steroid Hormones • Steroid hormonesare derived from cholesterol The sex hormones (androgens, estrogens and progesterone) and hormones produced in the adrenal glands.

12. Cholesterol derived Hormones

13. 2. Amino acid derivative hormones • They are derived from tyrosineand tryptophan. • There are two types of tyrosine derived hormones: • 1. Thyroid hormones (T3 and T4): regulates the development of organs and metabolism • 2. Catecholamines (Norepinephrine and epinephrine ) stress hormones. Both increase heart rate, dilate blood vessels and cause the release of glucose during times of stress. Thyroxin T4 T3

14. Tyrosin Derived hormones

15. Thyroxin Pathophysiology • Goiter (enlargement of thyroid gland iodine deficiency). • Hyperthyroidism (Graves disease); increase apetite, rapid heart rate. • Hypothyroidism; (hypertension, slow heart rate, sleepiness, sensitivity to cold, dry skin).

16. Tryptophan derived hormones • Tryptophan is a precursor to serotonin and melatonin. • 1. Serotonin is mostly found in our gastro-intestinal tract and regulates movement in our intestines. • Serotonin is associated with moodand low levels often result in depression. • Serotonin is also part of appetite and can make you sleepy. • 2. Melatoninsignal forms part of the system that regulates the sleep-wake cycle by chemically causing drowsiness and lowering the body temperature

17. 3. Peptide derived hormones • These are hormones derived from polypeptides. They need to be activated

18. 1. Insulin (Hetero-dimeric polypeptide) Biological importance • Decrease blood glucose level. • Promote the entry of glucose and amino acids into cells. • Promote the utilization of glucose. • Has anabolic effect. • Stimulate protein synthesis. • Stimulate the cell replication. Pathophysiology Diabetes mellitus

19. 2.Glucagon Biological importance • Single polypeptide chain • It opposes the insulin action Pathophysiology Diabetes mellitus

20. 4. Fatty Acid derived hormones • Hormones that are arrived from fatty acids are calledeicosanoids. • hey are synthesized from a 20-carbon amino acid called arachidonicacid. • they are produced and secreted by nearly every cell in the body instead of just one gland. • Eicosanoids have various important roles in the body including inflammation, blood pressure and blood clotting. • Prostaglandins are classified as eicosanoids.

21. 2. Classification according to solubilityLipid Soluble vs Water Soluble Hormones • Lipid soluble hormones are able to pass right through the target cell’s membrane. • They work by binding to receptors inside the cell. This binding activates certain proteins, which then binds to a portion of DNA inside the cell’s nucleus causinggenes to turn enzyme activity on or off, which alters the activity of the target cell. • Steroid derived hormones are lipid soluble.

22. 2. Classification according to solubilityLipid Soluble vs Water Soluble Hormones • Water soluble hormones, actindirectly on target cells. Since the cell membrane has a lipid bi-layer, it is hydrophobic, or water fearing. This simply means that anything that is water soluble is not getting through. Unlike lipid soluble hormones, • water soluble hormones have to bind to receptors on the surface of the target cell. • Once the hormone is bound to the receptor, enzyme activity inside the cell is altered. Depending on the hormone, enzyme activity is increased or decreased. • Water soluble hormones include those that are derived from amino acids and polypeptide hormones.

23. Vitamins & Minerals

24. BIOMEDICAL IMPORTANCE OF VITAMINSA. Lipid Soluble vitamins • Vitamins are defined as a group of organic nutrients required in small quantities for a variety of biochemical functions and which, generally, cannot be synthesized by the body and must therefore be supplied in the diet. • However, vitamin D, which can be made in the skin after exposure to sunlight, and niacin, which can be formed from the essential amino acid tryptophan, do not strictly conform to this definition. • The lipid-soluble vitamins are apolar hydrophobic compounds that can only be absorbed efficiently when there is normal fat absorption. They are transported in the blood, like any other apolar lipid, in lipoproteins or attached to specific binding proteins. • Lipid-soluble Vitamins have diverse functions: • vitamin A, vision; • vitamin D, calcium and phosphate metabolism; • vitamin E, antioxidant; • vitamin K, blood clotting.

25. Biological importance of lipid-soluble vitamins • dietary inadequacy or conditions affecting the digestion and absorption of the lipid-soluble vitamins can all lead to deficiency syndromes, including: • Night blindness and xerophthalmia (vitamin A); • Rickets in young children and osteomalacia in adults (vitamin D); • Neurologic disorders and anemia of the newborn (vitamin E); • Hemorrhage of the newborn (vitamin K). • Vitamin A as well as vitamin E, are antioxidants and have possible roles in atherosclerosis and cancer prevention. • Toxicity can result from excessive intake of vitamins A and D.

26. B. Water-Soluble vitamins • Water-soluble vitamins comprise the B complex and vitamin C and function as enzyme cofactors. • Folic acid acts as a carrier of one-carbon units. • Deficiency of a single vitamin of the B complex is rare, since poor diets are most often associated with multiple deficiency states. Nevertheless, specific syndromes are characteristic of deficiencies of individual vitamins: • Beriberi (thiamin); • Glossitis (riboflavin); • Pellagra (niacin); • Peripheralneuritis (pyridoxine); • Megaloblastic anemia and pernicious anemia (vitamin B12); • Megaloblastic anemia (folic acid). • Vitamin C deficiency leads to scurvy

28. Night Blindness and Xerophthalmia (Retinol Vit A)

29. Rickets (Vit D)

30. Beriberi (Thiamin , B1)

31. Pellagra (Niacin)

32. Anemia (Vit B, Folic acid and B12)

33. Dermatitis (Biotin Vit H)

34. Scurvy (Ascorbic Acid, Vit C)

35. Inorganic Minerals • Inorganic minerals must be provided in the diet. When the intake is insufficient, deficiency symptoms may arise, eg, anemia (iron), goiter (iodine). • If present in excess as with selenium, toxicity symptoms may occur. • For any nutrient, particularly minerals and vitamins, there is a range of intakes between that which is clearly inadequate, leading to clinical deficiency disease, and that which is so much in excess of the body’s metabolic capacity that there may be signs of toxicity. • Between these two extremes is a level of intake that is adequate for normal health and the maintenance of metabolic integrity.

36. Assignments • Any student who did not deliver an assignment should deliver an assignment on the “Physiological importance of vitamins” before 24 /12/2013 or will not be accepted anymore.

38. Write the actions of insulin and glucagon. • Mention the difference between Water soluble and insoluble hormones. Study Question

39. Principles of Biochemistry, Donald J. Voet, Judith G. Voet, Charlotte W. pratt; Willey, 3rd ed. Suggested readings: