Melanin functions

Melanin functions

Melanin is the brown black, non-haemoglobin-derived pigment
normally present in the hair, skin choroid of the eye, meninges and adrenal
medulla. It is synthesized in the melanocytes and dendritic cells, both of which
are present in the basal cells of the epidermis.

Melanin is stored in the form of cytoplasmic granules in the phagocytic cells called the melanophore, present in the under lying dermis. Melanocytes possess the enzyme tyrosinase necessary for the synthesis of melanin from the amino acid called tyrosine Tyrosine tyrosinase Melanin

Various disorders of melanin pigmentation cause generalized and
localized hyperpigmentation and hypopigmentation.

Generalized hyperpigmentation

a) In Addison’s disease, there is generalized hyperpigmentation of the skin,
especially in areas exposed to light and buccal mucosa.
b) Hyper pigmentation on skin of face, nipples and genitalia during pregnancy
under the influence of oestrogen.
c) In chronic arsenical poisoning, there is characteristic rain-drop pigmentation
of the skin.

Generalized hypopigmentation

Albinism is an extreme degree of generalized hypo pigmentation in
which tyrosinase activity of the melanocytes is genetically defective and no
melanin is formed. Albinoes have blonde hair, poor vision and severe
photophobia. They are highly sensitive to sunlight. Chronic sun exposure
may lead to pre-cancerous lesions, squamous and basal cell cancers of the
skin.

Localised hypopigmentation

a) Leucoderma is a form of partial albinism and is an inherited disorder.
b) Vitiligo is local hypopigmentation in the skin.
c) Acquired local hypopigmentation can result from various causes such as
leprosy, healing of wounds, radiation dermatitis, etc.

Related Topics in Zoology:

Bio Zoology All Important Topics

  1. Human Physiology Introduction
  2. Nutrition
  3. Carbohydrates Poly hydroxyaldehydes (or) ketones
  4. Proteins (Polypeptides)
  5. Lipids
  6. Vitamins – Functions Of Vitamins
  7. Deficiency of Vitamin
  8. Minerals – Water – Role of water
  9. Balanced diet
  10. Obesity
  11. Digestive System
  12. Dental Caries (Tooth decay)
  13. Root Canal Treatment
  14. Peptic ulcer
  15. Hernia and Types
  16. Appendicitis (Appendix)
  17. Gall Stones
  18. Hepatitis
  19. Fractures – Types of fractures
  20. Mechanism of fracture
  21. Dislocation of joints
  22. Arthiritis
  23. Rickets and Osteomalacia – Orthopedics
  24. Muscles
  25. Mechanism of muscle contraction
  26. Types of muscle contraction
  27. Myasthenia Gravis
  28. Respiration – Process of pulmonary respiration
  29. Mechanism of Breathing
  30. Regulation of Respiration
  31. Pneumonia Tuberculosis Symptoms Treatment
  32. Bronchitis – Acute bronchitis, Chronic Bronchitis Causes
  33. Circulatory System – Functioning of Human heart
  34. Cardiac Cycle
  35. Coronary blood vessel and its significance
  36. Myocardial infarction
  37. Angina pectoris
  38. Angiogram – Angioplasty
  39. Atherosclerosis
  40. Heart block Echo cardiography Heart Valves
  41. Rheumatic Heart Disease (RHD), ICCU – (Intensive Coronary Care Unit)
  42. Blood Pressure
  43. Heart transplantation
  44. Pulse rate
  45. Cardio Pulmonary Resuscitation (CPR)
  46. Blood – Composition of plasma – Blood cells
  47. Clotting of Blood or Haemostasis
  48. Thrombosis
  49. Nervous system Co-ordination systems
  50. The Brain – Fore Brain, Midbrain, Hindbrain
  51. Memory
  52. Sleep – Types of sleep
  53. Stroke – Brain haemorrhage
  54. Alzheimer – Meningitis (Brain fever)
  55. Conditioned reflex
  56. Electroencephalography EEG
  57. Right and Left brain concept
  58. Spinal cord functioning
  59. Chemical co-ordination – Functions of Endocrine glands
  60. Hypothalamus
  61. Pituitary gland – hormone
  62. Hormones of Neurohypophysis – vasopressin
  63. Thyroid gland
  64. Parathyroid Gland
  65. Pancreas
  66. Adrenal gland
  67. Gonads
  68. Receptor Organs – Eye
  69. Photochemistry of Retinal visual Pigments
  70. Errors of refraction
  71. Optometry – Retinopathy
  72. Cataract – Lens Replacement – Glaucoma – Nyctalopia
  73. Eye Infections and Eye Care
  74. Ear
  75. Mechanism of hearing
  76. Defects of the ear
  77. Hearing Aid – Noise pollution
  78. Skin and functions of skin
  79. Melanin functions
  80. Effects of solar radiation / UV radiation – Skin grafting
  81. Dermatitis
  82. Tongue – Mechanism of Stimulation
  83. Excretion Ureotelism Nephron
  84. Mechanism of urine formation
  85. Renal Failure, Dialysis, Kidney Machines
  86. Kidney stone – Kidney transplantation
  87. Diabetes mellitus
  88. Functioning of male reproductive system
  89. Functioning of female reproductive system
  90. Ovulation and fate of the ovum – Menstrual cycle
  91. Fertilization
  92. Birth control

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