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Biology Form 5 Science

Chapter 4: MOVEMENT AND SUPPPORT IN ANIMALS

THE ENDOCRINE GLAND

The endocrine system carrries out hormonal coordination in animals. It is made up of a number of gland called endocrine like other gland, they secrete useful substances.

NB: glands like pancreas, liver and salivery gland are known as non-endocrine gland because they secrete their product through tips and ducts which goes directly to the place were this substances carry oput their functions. Hence such glands are called exocrine glands. Endocrine gland or ductless gland have no ducts. They secrete their product called normones directly into the blood  stream which carry them all around the body were the affect organ sensitive to them. Cell that responds to hormones are called target cells.

 

FUNCTIONS OF ENDOCRIME GLAND

  1. PITUITARY GLAND: it is located in the brain below the hypothalamus. It is known as the master gland. It is called the master gland because some of its hormone stimulate or inhibit other endocrine gland the pituitary is divided into two lobes: anterior and posterior
  2. PROLACTIN: it stimulate milk production by the breast and growth of the breast.
  3. THYROID STIMULATING HORMONES: it stimulate the thyroid to release thyroid hormone
  4. FOLICLE STIMULATING HORMONES: it stimulate the primary follicles in the ovary grow to maturity.
  5. LUTEINIZING HORMONE: it triggers ovulation.

The posterior pituitary secrete the following

Antiduiretic hormone(ADH):  it help to constrict blood vessels and also function asmoregulation

Oxytocine: it is responsible for the involuntary contraction of  uterine smooth muscle during birth

THE THYROID GLAND: it is situated in the neck infront of the trachea. It produces thynoixine. Thyroixine controls growth and development and also control the metabolic rate.

PANCREAS: the pancreas has both the exocrine and endocrine function. They produce and secrete enzmes of the pancreatic juice into the pancreatic duct . they also secrete insulin and glycagon. Which helps to regulate blood glucose level.

THE ADRENAL GLAND it secrete the adrenaline adrenaline is produce under the condition of stress, fright etc.

The GONADS:  

THE TESTIS:  the testis produces testosterone which stimulate the development of male sex organ and the secondary sexual characteristics.

THE OVARY:  it is produces oestrogen which stimulates the development of female sex organ and the development of feminine sexual characteristics.

par Claude Foumtum