LOCOMOTION AND MOVEMENT

 

Oxytocin :

• Acts on smooth muscles of out body and stimulates their contraction.
• In females it stimulates a vigorous contraction of the uterus at the time of child birth.
• Stimulates contraction of smooth muscles of mammary gland causes milk ejection.

Vasopressin :

• Acts mainly on kidney and stimulates active reabsorption of water and electrolytes leads to concentration of urine and reduce loss of water. It is also known as Anti-diuretic hormone (ADH)

The pineal gland :

• Located on the dorsal side of the forebrain.
• Secretes one hormone called melatonin.
• Melatonin plays important role in sleep awakening cycle
• Regulate body metabolism.
• Control pigmentation.
• Influence on menstrual cycle.
• Influence body defense capability.

Thyroid gland :

• The thyroid gland is composed of two lobes which are located on either side of the trachea below larynx.
• Both lobes are connected by isthmus.
• The thyroid gland is composed of follicles and stromal tissues.
• Each thyroid follicle is lined by Cuboidal follicular cells, enclosing a cavity filled with a colloid called thyrocolloid.
• Follicular cells  synthesise two hormones –
  • Tetraiodothyronine or thyroxine (T4).
  • Triiodothyronine (T3)
  
  
• These hormones are synthesized due to iodination of amino acid called tyrosine.
• In dietary deficiency of Iodine leads to enlargements of thyroid gland called goitre.
• Hypothyroidism during pregnancy causes defective development and maturation of the growing baby leading to a condition called cretinism.

• Cretinism is characterized by –
  • Stunted growth
  • Mental retardation.
  • Low intelligence quotient.
  • Abnormal skin.
  • Deaf mutism.
  • Pot bellied.
  • Dribbling saliva.
  
  
• In adult woman hypothyroidism may cause irregular menstrual cycle.
• Over secretion of thyroid hormone is called hyperthyroidism.

Function of thyroid hormone :

• Regulates basal metabolic rates.
• Support formation of red blood cells.
• Control metabolism of carbohydrates, protein and fat
• Maintain water and electrolyte balance.
• Hormone secreted by parafollicular cells called thyrocalcitonin (TCT).
• Thyrocalcitonin regulates blood calcium level (hypocalcemia).

Parathyroid gland :

• Four parathyroid glands are present on the back side of the thyroid gland.
• Parathyroid secretes a peptide hormone called parathyroid hormone (PTH).
• The secretion of PTH is regulated by blood calcium level by feed back regulation.
• PTH increases the blood calcium level (hypercalcemia).
• Stimulates resorption of bone (demineralization)
• Stimulates reabsorption of Ca2+ from the renal tubule.
• Increases absorption of Ca2+ from the digested food.
• Along with thyrocalcitonin it regulates blood calcium level.

Thymus gland :

• A lobular structure located on the dorsal side of the heart and the aorta.
• Plays important role in development of immune system.
• Secretes a hormone called thymosin.
• Thymosin play important role in differentiation of T-lymphocytes which provide cell-mediated immunity.
• Promotes production of antibodies to provide humoral immunity.
• It is commonly known as the throne of immunity.
• Thymus atrophies in old age decreasing body immune power.

Adrenal gland :

• One pair of adrenal glands located on the top of each kidney.
• Each adrenal gland composed of two types of tissues –
  • Centrally located tissue called adrenal medulla.
  • Peripheral tissue called adrenal cortex.
  
  
• Adrenal medulla secretes two hormones called –
  • Adrenaline or epinephrine
  • Non-adrenaline or nor epinephrine.
  
  
• Hormones of adrenal medulla are commonly known as catecholamine.
• Adrenaline and nor-adrenaline are rapidly secreted in response to stress of any kind during emergency situations and are called emergency hormones.
• Catecholamine are also known as 3’F’ hormone because they play a great role in manage stress full condition like Fight, Flight and Fright.

CBSE Biology (Chapter Wise) Class XI ( By Mr. Hare Krushna Giri ) 
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