HORMONES

AND

THE ENDOCRINE

SYSTEM

Animal hormone Is a chemical signal that is secreted into

the circulatory system and communicates regulatory messages within the body.

Hormones may reach all parts of the body

But only certain types of cells, target cells, are equipped to respond

Endocrine Glands

Hypothalamus Gland

It mainly secretes two hormones :• Releasing Hormones• Inhibiting Hormones

Hypothalamus provides connection between nervous and endocrine system.

It is also called as control centre or Supreme commander of endocrine system.

Pituitary Gland

The Anterior Pituitary or Adenohypophysis It secrets various hormones :

Growth Hormone : It promotes growth and

development of bones and muscles.

Thyroid stimulating hormone(TSH) : It stimulates

the Thyroid Gland to secrete thyroxin.

Gigantism- Over secretion of somatotropin before puberty.

Dwarfism- Under secretion of somatotropin. Cause: tumor, injury, infection, genetics.

Follicle Stimulating Hormone (FSH) : It

stimulates the production of gametes.

Luteinizing Hormone : It stimulates the

production Hormones.

The Posterior Pituitary or Neurohypophysis

It secrets various hormones :

Oxytocin: It is also known as birth

hormones. It stimulates the contraction

and relaxation of muscles during child

birth.

Vasopressin : it regulates water

and electrolyte balance in the

body by promoting reabsorption of

water in the kidneys.

Thyroid Gland Position : In the neck region

It secretes two hormones : Thyroxin Calcitonin

Thyroxin contains iodine and controls the metabolism of carbohydrates, fats and protein. Calcitonin lowers the calcium levels in bones.

Hyperthyroidism, excessive secretion of thyroid hormones

Can cause Graves’ disease in humans

Goiter – Lack of Iodine

Position : Roof of the brainHormone : Melatonin Functions : Lightens Color, regulates working of Gonads.It regulates the

Biological Clock

Pineal Gland

Pancreas It is the only hetrocrine gland.

It mainly secretes two hormones : Glucagon

Is produced by alpha cells Insulin

Is produced by beta cells

Over secretion : Hypoglycemia

Under secretion: Diabetes mellitus

The Adrenal Gland Position : Top of the kidneys Are actually made up of two glands: the adrenal

medulla and the adrenal cortex

The adrenal medulla secretes epinephrine

or adrenaline and nor epinephrine or

noradrenaline

Adrenaline is a emergency hormone.

Adrenal Cortex secretes :1) Mineralocorticoids2) Glucocorticoids

The Gonads – Testes and Ovaries

Testes• Position : In scrotal

Sacs• Hormones :

Testosterone stimulate the development of secondary sexual characters in males.

OVARIES Position : Lower

Abdomen Hormones : 1. Oestrogen2. Progesterone 3. Relaxin

Functions :1. Oestrogen : Develop female reproductive organs

and secondary sexual characters.2. Progesterone : It stop egg production and attach

foetus to uterine wall.3. Relaxin : Widening of pelvis at birth.

THANKYOU