Inorganic Substances Biochemistry Essay Questions And Answers

Inorganic Substances

Question 1. What is the normal serum calcium level? How is it regulated? Enumerate the physiological functions of calcium. (or) What is the normal blood calcium level? What are the factors which maintain this level? (or) Functions of calcium (or) Regulation of serum calcium (or) Calcium homeostasis (or) The normal level of serum calcium Four functions of calcium
Answer:

Normal serum calcium level:

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Regulation of calcium/ hemostasis

• Calcium level is regulated by

1. Calcitriol
   1. It is the active form of the vitamin D

Mechanism

1. • Induces synthesis of calcium-binding protein
   • This increases calcium absorption by the intestine
   • This increases calcium level
   • It also promotes calcification & remodeling of bone
2. Parathyroid hormones
   • Secreted by Parathyroid glands

Mechanism

1. • Binds to a membrane receptor protein
   • Activates adenylate cyclase
   • Liberates cAMP
   • Increases intracellular calcium
     1. Action on bone
        • Stimulates pyrophosphatase & collagenase
        • Causes decalcification of bone
        • Results in bone resorption
     2. Action on the kidney
        • Stimulates 1-Hydroxylation of 25-hydroxy cholecalciferol
        • Promotes production of Calcitriol
     3. Action on intestine
        • Promotes synthesis of Calcitriol
        • Increases calcium absorption
2. Calcitonin
   • Secreted by parafollicular cells of thyroid gland Mechanism
     • Increases osteoblastic activity
     • Promotes calcification
     • Decreases bone resorption
     • Increases calcium excretion
     • This decreases blood calcium level

Functions of calcium:

1. Development of bone & teeth
   • Calcium is required for the formation of hydroxyapatite
   • Bones serve as a reservoir of calcium
2. Muscle contraction
   • Calcium ions react with troponin C & trigger muscle contraction
   • Activates ATPase
   • Increases interaction between actin & myosin
3. Blood coagulation
   • Calcium is coagulation factor IV
4. Nerve transmission
   • It is involved in the transmission of nerve impulse
5. Membrane integrity & permeability
   • It influences the membrane structure
6. Activation of enzymes
   • It activates ATPase, lipase & succinate dehydrogenase
7. Binds with calmodulin to activate certain enzymes
8. It acts as a second messenger for certain hormonal actions
9. Causes release of insulin, PTH, calcitonin
10. Involved in endocytosis, exocytosis & cell motility
11. Involved in cell contact & cell adhesion
12. Acts on the myocardium & prolongs systole

Question 2. Write the dietary sources, factors influencing absorption, biochemical functions & daily requirements of calcium. (or)  Factors affecting calcium absorption
Answer:
Answer:

Dietary sources:

1. Milk & milk products are regarded as the best sources of calcium
2. Other good sources of calcium are:

• Beans, leafy vegetables, fish, cabbage, egg yolk.

Factors influencing absorption:

Daily Requirements: