12th Zoology

Functioning of male reproductive system

Reproduction (Functioning of male reproductive system)

All living organism maintain their populations by reproduction. Most
simple organisms such as bacteria reproduce asexually by cell division
resulting in offspring’s that are genetically identical.

In human beings, reproduction is sexual, involving the fusion of two
reproductive cells, namely a sperm (male gamete) and an egg (female gamete).
If a sperm succeeds in fertilizing an egg, DNA (genetic material) from
each parent combines to create a unique individual. Sexual reproduction results
in an infinite variety of offsprings.

Functioning of male reproductive system

The central role of the male reproductive system is carried out by the
testes, which produce sex cells called spermatozoa or sperms containing
genetic material. The testes produce sperms continuously from puberty onward.

Men remain fertile for a much longer period than women. In addition, the testes
manufactures male sex hormones or androgens which influence sperm
production, fertility and sex drive. Male sex hormones also promote the
secondary sexual characters.

Gametogenic function of testes (male reproductive system)

Factors controlling spermatogenesis: FSH of pituitary gland
stimulates and controls spermatogenesis. It acts on sertoli cells to facilitate
last stages of maturation of spermatids. It further stimulates the production of
androgens such as testosterone.

The LH of the pituitary acts on the Leydig’s cells of the testes that
releases testosterone. The temperature of testes should be maintained at
32oC for an effective production of spermatozoa.

Spermatozoa (male reproductive system)

Each mature spermatozoan is a motile cell . It has an oval flat head
having an acrosome and a large nucleus containing chromosomal material. The
head is followed by a short neck, a body (middle piece) and a long tail.

The middle piece contains spiral mitochondrial sheaths which are the site of energy production. The tail has a main piece and an end piece. The energy for movement is provided by ATP molecule.

Puberty (male reproductive system)

Puberty is a process in sexual development. Once puberty is reached
sperms are manufactured continuously in the two testes at a rate of about 125
million each day.

Puberty occurs between age 12-15 Hormones secreted by the pituitary cause levels of the male sex hormone testosterone to increase, stimulating changes such as general growth, and the development of secondary sexual characters.

Transport of spermatozoa. For reproduction to take place, the sperm must be
transported to the female reproductive system. The mature spermatozoa that are
formed leave each testis through an epididymis, a long coiled tube that lies above and behind each testis.

The sperms are stored in the epididymis and periodically pushed into the vasdeferens the tube that connects an epididymis to an ejaculatory duct.

During sexual activity each vas deferens, contracts and pushes the sperm toward urethra, the tube that connects the bladder to the outside of the body. The sperms are carried in a fluid consisting of secretions from various glands forming a thick seminal fluid or semen.

Semen is a milky mucoid fluid which contains sperms (50 million in single
ejaculate) plus seminal plasma made up of secretions of the seminal vesicles,
prostate, Cowper’s gland and bulbo – urethral glands. Semen provides nutrient
that help to keep the sperm healthy and also serves as a medium for the
spermatozoa to swim.

During arousal, the penis gets enlarged and becomes firm. Muscular
contraction at the have of the penis then forces the sperm through the male
urethra into the vagina during male orgasm.

Hormonal control (male reproductive system)

Male reproductive function is controlled by several hormones.

1. The hypothalamus of the brain controls the release of FSH and LH through
its releasing factors.

2. FSH and LH stimulate the gonads. Hence the gonads produce sperms
and secrete the hormone, testosterone.

3. Testosterone controls further male reproductive functions. It also helps to
develop and maintain secondary sexual characters, such as enlargement of
larynx, deepening of voice, growth of hair and other adolescent changes.
Regulation of testicular function

The hypothalamus, anterior pituitary and testes are interrelated in
testicular functions. FSH from the pituitary stimulates spermatogenesis in the
presence of testosterone. High concentration of testosterone is maintained due
to the presence of androgen binding protein which is secreted by the sertoli cells.
These cells also secrete another hormone called inhibitin which inhibits the action
of testosterone.

Testosterone secretion by Leydig cells is stimulated by LH. The
testosterone has its action on different target cells. It diffuses into the seminiferous tubules and stimulates spermatogenesis and suppresses secretion of LH by acting on hypothalamus and anterior pituitary.

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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