Endocrine Glands

The endocrine system consist of gland that are locate at various part of the body and which secrete substance called HORMONES. Other glands like salivary glands is called EXOCRINE gland. They release their secretions through ducts to where they are needed. An endocrine glands have no ducts, they are referred to as ductless glands and their secretions are delivered straight into the blood stream.

Diagram of  endocrine system

HORMONES

Hormones are chemical substances produce in small quantity by the cells of one part of the body and carried to all or some part of the body by the blood stream in animals or vascular system in plant where they produces a response.

The activities of the various part of the bodies in higher animals are controlled and coordinated by two coordinating system, these are nervous and endocrine system , the nervous system act swiftly, instantly and electrically while the endocrine system act slowly and chemically.

In animals hormones are manufactured in ductless (endocrine glands) and poured straight into the blood stream. Hence, hormone can coordinate the body functions in a place far away from where they are produce.

1. PITUITARY GLAND : This glad is located below the hypothalamus in the fore brain, it consists of the anterior lobe of pituitary gland produce no less than six hormones . They are made up of four tropic hormones, a growth hormone and prolactin .The pituitary gland is considered as master gland because  it controls other glands.

The tropic hormones are

a.Thyroid stimulating hormone ( TSH) which stimulates the thyroid gland to produce is hormone .

follicle stimulating hormone ( FSH) which causes follicle in the ovary to open mature taste to initiate sperm function.

Luteinizing hormone (LH) which causes the release of mature egg (ovulation into fallopian tube and secretion of testosterone in the testes.

The growth hormone ( somatotropin) this hormone stimulates the grow of long bones, it increase the metabolic rate and promotes protein synthesis, over secretion of this hormone in children cause GIGANTISM while under secretion causes DWARFISM

prolactin– this induces milk production in pregnant woman from the mammary gland

Note–   over secretion of somatotropin in adult leads to a condition called ACROMEGALY a situation leading increase in size of head, hand ,body, legs thick lips etc The posterior part of pituitary gland produces two hormones

f.Anti- Diuretic Hormone (ADH) It raises blood pressure by constriction of the arterioles and increasing the reabsorption of water in the kidney tubules

oxytocin  this hormone induces milk secretion from the nipples and the contraction of the uterine wall.

2.THYRIOD GLAND –it is located in the neck rust in front of the larynx . it provides three hormones but the most important is the thyroxin, .second hormone being calcitonin which lower the level of calcium  in the blood by contracting effect of parathyroid hormone . The thyroxin is formed from amino acid and iodine .It regulates the growth and development of all body cells by increasing basal metabolic rate .

Under secretion if thyroxin is secreted at a level less than normal before maturity it causes CRETINISM .A cretin is a dwarf who is physically, mentally and sexually underdeveloped. The under secretion or deficiency of this may lead to GOITRE if under sec is after maturity the person is physically obese and mentally dull with a reduced heart beat and lowered body temperature.

Over secretion  of thyroxin may result to HYPERTHYROIDISM i.e.  increase in metabolic rate these are four tiny glands attaché to thyroid gland of the neck region. The secretion produces by this gland is called PARATHORMONE which raises the level of calcium in the blood .

OVERSECRETION

-it cause the softening of bones

-it brings about increase los of phosphate .

Under secretion – it lead to tetany ( muscle spasm and possible death).

PANCREAS OR PANCREATIC GLAND

The gland is located in the loop of duodenum and pancreas is an organ that produces both enzyme and hormone .A group or cell which are scattered throughout the pancreas are called islet of Langerhans which secrete hormones called INSULIN from the B- cells and  GLUGAGON from the. A- cell

Functions

i)The insulin causes the conversion of excess glucose to glycogen for storage in the liver

ii).Glucagon is also responsible for reconversion of glycogen to glucose

iii).It also aids or stimulates the of absorption of glucose by tissue cells.

DEFFIENCY OR UNSECRETION

-deficiency  of insulin bring about a disorder called diabetes mellitus in which excess‘ blood  sugar cannot be converted  to glycogen, it may also lead to high blood pressure

 oversecretion

– falls in the blood sugar level .

– it may lead to hypoglycemia

ADRENAL GLAND

These glands are located on top of each kidney . They secrete two main hormones, each gland is made up of an outer adrenal cortex and inner adrenal medulla . The outer cortex produces a group of hormones called the corticoids .the inner medullar produces adrenaline and noradrenalin.

Functions: the corticoids regulates the level of potassium and sodium ions in the body fluids

little adrenaline and noradrenalin are hormones produced at emergency that is when terrified

oversecretions         

i           increases excitement and anxiety

ii          increases blood pressure and heart beat

iii         it leads to profuse sweating.

iv         it lead to heavy breathing on under secretion

i           it brings about slow response to emergency

ii          it leads to low heartbeat

iii         it leads to low blood pressure