The endocrine system
Introduction :
The endocrine system is the set of organs whose secretions or hormones pours
directly into the circulation, without the intermediary of an excretory duct.
It is a regulator and coordinator of many functions of the body system.
This device similar to the nervous system through its role, is closely linked to it.
A hormone is a chemical produced by the endocrine glands,
Released into the blood and transported into the bloodstream.
It exercises action at a distance on an organ or target cells.
Endocrine glands are glands structural members, they include:
-L'hypophyse (Or pituitary gland)
-the Body pineal
-the Thyroid gland
-The Parathyroid glands
-The Thymus
-The Adrenals
- Para nodes
-The pancreas
-L'ovaire And testicular
1-The pituitary:
The pituitary gland is a small gland at the base of pendant brain and located in the sella,
cavity dug into the body of the sphenoid.
It has a regulating effect on other endocrine glands.
It consists of two lobes;
a / -L'adénohypophyse or anterior lobe: receiving hormonal stimulation of the hypothalamus
It is responsible for the secretion of many hormones (FSH, LH, TSH, ACTH, GH, MSH)
b / -The posterior pituitary or posterior lobe: hypothalamic hormones will be stored in this
lobe, eg oxytocin and antidiuretic hormone (ADH) or vasopressin.
2-The pineal gland:
The pineal gland is a small gland located deep in the brain between the brain, trunk
cerebral and cerebellum.
It secretes melanotonine and hormones that appear to regulate hormone synthesis
hypothalamus and anterior pituitary.
3-The thyroid gland:
The thyroid gland is located at the front of the base of the neck by joining the larynx.
It consists of two lobes, right and left united in the thyroid isthmus.
The volume increase is known as goiter.
It secretes hormones responsible in particular basal metabolism (thyrixineT4 hormone,
triiodothyronineT3, calcitonin).
Role of thyroid hormones T3 and T4
* Regulation of metabolism.
* Regulation of growth.
* Regulation of development.
4-The parathyroid glands:
The parathyroid glands are four small glands located on the posterior surface of the gland
thyroid.
There are two upper and two lower parathyroid glands.
They produce hormones that regulate the metabolism of calcium and phosphorus
(parothormonePTH).
Role of parathyroid hormone
* Increased blood calcium levels.
* Lowering blood phosphate levels.
* Activation of the production of vitamin D
5-The adrenal glands
Pyramidal, adrenal glands are located above the upper pole of the kidney
.Each Adrenal gland consists of two parts.
* A core or medulla: secreting hormones called, catecholamines: Adrenaline
Norepinephrine
Dopamine
These hormones act on the metabolism of the cardiovascular system and to prepare the body
respond to stress.
* A device or part cortex: producing hormones that regulate the metabolism of sodium,
potassium and male sexual hormones.
Hormones of the adrenal cortex
* And mineral corticoids (aldosterone):
-increased Sodium and water levels in the blood.
-Reduced Potassium levels.
* Gluco-corticoids (cortisol):
-Métabolisme Normal.
-Stress resistance.
-Combat Of the inflammatory reaction.
* Gonado-steroids:
-Quantity Low and negligible effects.
6-T thymus:
Odd organ, located behind the manubrium, the thymus consists of two lobes and right
left.
It is functional during fetal life and gradually atrophy after puberty.
It is a center of production of lymphocytes before puberty.
7-T pancreas:
This gland is mixed, flattened and spread in length, located deep within the abdomen.
T pancreas has three parts; head, body and tail.
Its exocrine secretions drain into the duodenum through the pancreatic duct and the duct
Pancreatic accessory.
Its hormonal secretions are glucagon and insulin; are produced by respectively
α and β Langerhans cells.
8 T-testis:
The testicle is a gland pair, mixed, producing sperm and sex hormones
(testosterone, inhibin).
D e ovoid shape, it is located in the scrotum, and partially covered by a serous training;
the tunica vaginalis.
9-Ovarian
It is a pair gland, producing eggs and sex hormones (estrogen, progesterone)
It is located against the pelvic wall, between the uterus and tubal fringes.
Note
Endocrine organs can be classified into two groups:
* The glandular endocrine organs or endocrine glands, and
* Non glandular endocrine organs.
-The Non glandular endocrine organs:
Many polymorphic and these non-glandular organs have a secondary function
Endocrine.
The digestive tract
The brain
Kidney
The placenta
Para-nodes (dissiminees structures, similar to the medulla of the adrenal gland point
functional view and appear to be related to the parasympathetic ganglia include
friendly, carotid, jugular, coccygeal, para-aortic and pulmonary body
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