ENDOCRINE SYSTEM
A gland is an organ whose function is to produce and secrete chemical substances.
There are two types of glands:
Exocrine glands and endocrine glands.
The exocrine gland:
It pours its secretions outside, through an excretory canal. The gland is called "external secretion or open gland.
The main exocrine glands are:
salivary glands present in the mouth, which secrete saliva
-the sebaceous glands of the skin that secrete sebum
-the mammary glands that secrete milk
-the sweat glands of the skin that excrete sweat
- all the digestive glands of the pancreas, intestine and stomach.
The endocrine gland:
It pours its secretion, called hormone, directly into the blood.
The gland is called "internal secretion"
Endocrine glands include:
-thyroid
-the parathyroids
-l'hypophyse
-l'épiphyse
-the pancreas (cells of the islets of langerhans)
the adrenal glands (cortico- and adrenal medulla)
the gonads (ovaries and testicles)
-the thymus
SALIVARY GLANDS
2 parotid glands,
2 submaxillary glands
2 sublingual glands
They secrete saliva (about 1 L per day) composed of:
99.5% water, mineral salts, an enzyme (amylase)
saliva permeates food, the first chemical step in digestion.
it protects against caries by neutralizing acids.
GASTRIC GLANDS:
lining the wall of the stomach, secrete a digestive juice:
gastric juice, 2nd chemical step of digestion.
THE PANCREAS :
exocrine function:
by the secretion of the pancreatic juice dumped into the duodenum.
the pancreatic juice contains:
- electrolytes: the role of which is to neutralize the acidity of the stomach chyme
- enzymes: which act on proteins, lipids, starch, nucleic acids.
the secretion of pancreatic juice depends on:
- the nervous system (neurovegetative)
- Hormones: the secretin released by the duodenum at the arrival of the acidic stomach chyme.
endocrine function:
secretes 2 types of hormones that regulate the blood glucose level:
- insulin: hormone that lowers blood sugar (hypoglycemic)
- glucagon: hormone that raises glucose levels (hyperglycemic)
LIVER :
the largest of the glands (1.5 kg)
it secretes bile, intervenes in the metabolism of carbohydrates, lipids, proteins and iron.
- the bile flows through the hepatic ducts and accumulates in the gallbladder, before being excreted in the duodenum by the common bile duct.
bile facilitates the digestion of lipids. - the liver synthesizes proteins whose role is essential when blood clotting (fibrinogen, prothrombin)
- under the action of insulin, the liver stores excess glucose in the form of glucogen.
many diseases cause impaired liver functions:
- cirrhosis
- hepatic colic
- hepatitis (A.B.C.D.E.F.G)
- jaundice or jaundice
ENDOCRINE GLANDS
THYROID :
the largest of the endocrine glands, located on the anterior aspect of the neck, below the larynx and directly applied against the trachea.
it consists of 2 side lobes united by a narrowed part called the isthmus.
a) thyroid hormones:
- Di-iodo thyronine = T2
- Tri-ioda thyronine = T3
- Tetra-iodo-thyronine = T4 (75% of circulating hormones)
- Thyrocalcitonin (calcium metabolism)
the essential fact is the iodine richness of the thyroid hormones.
b) physiology:
- the thyroid activates the combustion processes at the cell level. it acts on:
the use by the cells of carbohydrates, proteins, lipids, - on thermal regulation and in the metabolism of iodine.
she has an action on: - the growth,
- causes thyroid dwarfism, if ablation or insufflation.
- on the cartilages, prepares the ossification.
- on the genital system: stimulates the appearance of puberty
