The endocrine system

The endocrine system
We will discuss:
Neurohypophysis
Pituitary
Thyroid. Parathyroid and endocrine pancreas
Adrenal medulla. Sex hormones and adrenal cortex


It is the combination of parts which are certain chemicals that pass into the bloodstream, are distributed throughout the body and modify the activity of other cells specifically sensitive. Endocrine organs are ductless by pouring their secretion into the blood. The substances produced by these bodies are called hormones. The major endocrine organs are: neurohypophysis, adenohypophysis, thyroid, parathyroid, islets of Langerhans in the pancreas, gastrointestinal epithelium, adrenal cortex, adrenal medulla, interstitial cells of testis and ovary.

Neurohypophysis

It is the posterior pituitary lobe. Their role is reduced to a storage organ that receives the material produced by certain neurons and distributed throughout the body via the blood. Hence we have isolated two hormones occitocina and antiduretina. The first stimulates the contractile activity of uterine muscle and the mammary gland, and the second promotes water reabsorption in renal tubules.

Pituitary

It is the anterior pituitary lobe. It is connected with the hypothalamus through the blood vessels. The anterior pituitary secretes at least six hormones: growth hormone or comatotrofina (STH) Thyrotrophs hormone (TSH), adrenocorticotropic hormone (ACTH), follicle stimulating hormone (FSH), luteinizing hormone (L) or interstitial cell stimulating (ICSH); lactogenic hormone or prolactin.

Thyroid. Parathyroid and endocrine pancreas
The thyroid is formed from the ventral wall of the pharynx and is situated on the sides of the trachea. Thyroid cells taken from the blood circulating amino acids and iodine and produce thyroglobulin. The hydrolysis of this protein provides specific gland hormones: thyroxine and triiodothyronine. Thyroid hormones stimulate the body's overall metabolic activity and influence the morphogenesis and growth. In hypothyroidism there is a sharp drop in basal metabolism. By contrast, hyperthyroidism causes a significant increase in metabolism. The parathyroids are four small oval masses placed at the edges of the thyroid. Its function is to regulate the concentration of calcium in the blood. The endocrine pancreas in the islets of Langerhans secrete insulin (B cells) and glucagon (A cells). Insulin lowers glucose levels in the blood. Glucagon increases the concentration of blood glucose by stimulating the liver enzyme system, which determines the conversion of glycogen into glucose. Degeneration of pancreatic B cells causes a disease known as diabetes mellitus

Adrenal medulla. Sex hormones and adrenal cortex
Next to the upper pole of the kidney is a small triangular structure are the adrenals. The hormones produced by the adrenal medulla are epinephrine and norepinephrine. These hormones influence the metabolism of carbohydrates. Modify the operation of most visceral organs: stimulate the heart, inhibit intestinal peristalsis, relaxes the bronchial muscle, etc.. Its effects are similar to the sympathetic system. On the other hand the adrenal cortex secretes many substances of steroid nature. Among these are: aldosterone, a regulator of metabolism of sodium and potassium, as it stimulates sodium reabsorption in renal tubules while increasing the excretion of potassium through the urine cortisol, which influences the metabolism of carbohydrates , also activates the protein metabolism and mobilize fatty deposits.

Among the sex hormones are: tetosterona androgens secreted by the testicular interstitial cells, this is a male sex hormone which develops sex organs (penis, prostate, etc.). And estrogen estradiol produced by cells growing ovarian follicles, which stimulates the development of sex organs of the female (uterus, vagina, etc.).. After ovulation the follicle secretes another hormone, progesterone, whose function is to prepare the uterus for implantation of the fertilized egg.

*Automatic Translation