Tuesday, February 12, 2013

Endocrine system of animals, Hormones in animals

Endocrine system of animals, Hormones in animals

Endocrine system of animals, Hormones in animals,  Endocrine system of horse, Endocrine system of dog

Endocrine system is represented by a set of heterogeneous structure and origin of formations capable of internal secretion, ie the release of biologically active substances (hormones) that flow directly into the bloodstream.


 Endocrine system of horse  

Hormones have a number of properties:
1-dystantnoe action - hormones act on cells located far from where the hormone;
2-specificity of action - each hormone acts only on certain target cells;
3-high biological activity - hormones act in minimal concentrations and only in living cells.
Thus, hormones regulate growth, development and reproductive function of the body involved in the maintenance of homeostasis and adaptation. The chemical nature of hormones differ from each other and their structure affects the mechanism of action. There intracellular membrane and intracellular mechanisms of action of hormones. The first relates to the connection of the hormone and receptor enzyme located on the cell surface, resulting in stimulation of enzyme activity or synthesis. The second mechanism of action is associated with the penetration of the hormone into the cell and its connection with a special protein.This complex enters the nucleus and stimulates synthesizing activity (synthesis enzymes).

Endocrine glands

Endocrine system of dog
The most rational classification of endocrine formations based on their topography (location). In connection with this distinguished group of endocrine organs and glands:
1-bronhiohennye endocrine gland - the thyroid gland and okoloschitovidnye
2-adrenal endocrine organs - adrenals, paraganglia, interrenalovye bodies
3-neural endocrine glands - pineal and pituitary part; May endocrine glands: the island portion of the pancreas
4-sexual endocrine organs - interstitial tissue testes and ovaries, the corpus luteum.
However, in the body there are some agencies that perform endocrine functions but do not belong to the endocrine system (heart, kidney, placenta, etc.).

Pituitary gland

Pituitary gland, Endocrine system of animals
is part of the hypothalamus of the diencephalon and depending on the characteristics of the development is divided into two parts: the adenohypophysis and neurohypophysis.


adenohypophysis produces somatotropin (regulates the growth and development of animals through stimulation of protein synthesis), tirotropin (stimulates thyroid function), corticotropin (causing growth of the adrenal cortex and stimulates its activity), follicle-stimulating hormone (stimulates spermatogenesis in males and follicular development in females) , lyuteotropin (stimulates the growth and development of mammary and sebaceous glands, stimulates lactation in females also causes maturation of the follicle and corpus luteum formation), prolactin (contributes to the corpus luteum and stimulates the formation of milk), melanotropin (promotes redistribution of pigment in the integument may activate retina and improves visual acuity).


Neurohypophysis produces oxytocin (causes contraction of the smooth muscle ducts sexual apparatus in females and males, and females also reduce mioepitelialnyh cells of the breast and the milk-ejection) and adiuretin (reduces urine). These hormones also produces and hypothalamus of the diencephalon.Thus, between the hypothalamus and the pituitary gland are close functional connections - the hypothalamus produces releasing hormones that stimulate or inhibit hormone adenohypophysis.Adenohypophysis produces a group of tropic hormones that regulate the activity of the thyroid gland, gonads and adrenal glands. But between these glands, pituitary and hypothalamus is the feedback system: an increase in the number of hormone any of these glands leads to inhibition of the formation neyrosekretov hypothalamus and pituitary tropic hormones.

Pineal gland 

Pineal gland, Endocrine system of animals
is part of the epithalamus of the diencephalon, produces melatonin, which regulates the maturation of the gonads (inhibits their maturation) and participates in the regulation of biological rhythms.

Thyroid gland

thyroid gland, Endocrine system of animals
a small parenchymal organ dense, located behind the larynx Ventre-laterally on the second and third rings of the trachea, produces iodine-containing hormones (triiodothyronine and tetrayodtironin or thyroxine, which increase the intensity of metabolism and the formation of heat affect the growth and development of the skin, increase milk production, stimulate the development of conditioned reflexes) and tyreokaltsytonyn, which promotes the deposition of calcium in bone and reduces its concentration in plasma krovi.Okoloschitovidnye glands are very small education round or oval. They are arranged in pairs of two in the same thyroid gland (in or near it) and produce parathyroid hormone, which causes the release of calcium and phosphorus from bone and increases their concentration in blood plasma.The pancreas produces insulin (resulting in oxidation of glucose and convert it into glycogen and fat, stimulates protein synthesis) hlyukohon (promotes conversion of glycogen to glucose and increase its concentration in the blood, enhances lipolysis) and lypokayn (regulates the exchange of fat and its transition to fat depot).

Sex glands

sex glandsEndocrine system of animals
Male genital glands produce androgens (most importantly testosterone), which stimulate the growth and development of reproductive organs and secondary sexual characteristics, stimulates protein formation and growth of young animals, affecting the central nervous system, causing the development of sexual behavior and increased aggression.
Female sex glands produce estrogen (the ovaries), which stimulate the growth and development of reproductive organs and breasts, cyclic changes in the sexual apparatus, enhance the formation of protein and fat, as well as progesterone (synthesized in yellow body), which promotes pregnancy, parenchyma breast cancer, inhibits the expression of hunting and reduces the sensitivity of the uterus to oxytocin.

Adrenal glands

adrenal glands, Endocrine system of animals
The adrenal glands are small even uploschenno-learned education, wrong oval, dense with a rough surface. They are located in the cranial end corresponding kidney and related total fatty capsule, composed of cortical and medullary layers.Cork layer of the adrenal glands produce glucocorticoids (regulate carbohydrate metabolism, contribute to the formation of glucose and anti-inflammatory effect, involved in the regulation of stress), mineralocorticoids (regulate mineral and water metabolism, increase absorption in the kidneys of sodium, chloride, water and potassium excretion) and sex hormones .Brain layer of the adrenal glands produce adrenaline and nor-adrenaline (stimulate the sympathetic nervous system).
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