CONTROL OF RESPONSES IN MAMMALS

CONTROL OF RESPONSES IN MAMMALS

Coordination in mammals can be divided into two

  1. 1.      THE ENDOCRINE SYSTEM

This is a system of ductless glands in which hormones are produced

The release of their secretion is stimulated by either the central nervous system or a

hormone from another gland

A hormone is an organic substance which is produced in small quantities and transported by blood to target organs where it exerts its effects.

  1. 2.      EXOCRINE GLANDS

These are glands which have ducts through which their secretions are transported together with the nervous system ,the endocrine system is very important for the integration of body functions and Coordination .

A TABLE SHOWING THE HORMONES PRODUCED BY THE ENDOCRINE SYSTEM AND THEIR EFFECTS

 Glands Hormone produced Effects/ functions
Anterior pituitary gland Thyroid stimulating hormone (TSH)
  • It stimulates the thyroid gland to produce the thyroxine hormones
Follicle stimulating hormone.(FSH)
  • It stimulates egg development in the females and sperm development in the males.
  • Stimulates the ovaries to produce oestrogen
  • Stimulates release of progesterone by the ovary
  • Stimulates testosterone secretion in testes
Luteinizing hormone (LH)
  • It causes ovulation in the females,
  • It causes conversion of the grafian follicle into corpus luteum in ovaries.
  • It stimulates testosterone secretion in the testes
 Growth hormone (GH)
  • It stimulates growth especially bones, excess in children results into gigantism and under secretion in children results into stunted growth (dwarfism)
Andrenocoticotrophic hormone (ACTH)
  • It causes the adreno cortex to produce/secrete its hormones.
  • Stimulates lipid breakdown and release of fatty acids from fat cells
Posterior pituitary glandNB. Pituitary gland is the master gland. Anti-duirectic hormone(A.D.H) vasopresin
  • It causes reabsorption of water in the kidney nephrones. i.e.  osmoregulation
  • Under secretion results in diabetes inspidus
Oxytocin
  • It brings about parturition(contraction of the uterus during birth)
  • Stimulates milk flow from the mammary glands
Thyroid gland (neck region) Thyroxine
  • Controls metabolic activity, raises body metabolic rate (BMR)
  •  Excess results into an increased metabolic rate which leads to protrusion of eye balls. Under secretion leads to goiter.
 Parathyroid glands. Parathyroid hormone
  • It increases iron calicium absorption
stomach gastrin
  • Stimulates secretion of gastric juice
Duodenum Secretin
  • Controls secretion of bile and pancreatic juices
 Pancreas (Islets of langerhans) Insulin,
  • It controls the balance of sugar in blood by converting glucose to glycogen in case there is an excess.
  • Under secretion results into diabetes mellitus.
glucogon
  • It converts glycogen in to glucose
Adrenal gland adrenalin
  • For flight and fight actions, by increasing heart rate and metabolic rate.
 Ovary (lower abdomen) Oestrogen hormone
  • It brings about healing and repair of the uterus wall after menstruation.
  • It brings about development of female reproductive organs.
  • It brings about development of secondary sexual characteristics.
  • Deficiency causes delay in the development of secondary sexual characteristics.
 Progesterone
  • It promotes proliferation of uterus wall
  • Controls the menstrual cycle
  • It maintains pregnancy.
 Testis (produced on scrotum) Testosterone (male sex hormone)
  • Development of male sexual characters
  • Deficiency causes delay in the development of secondary characters.
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