structure and activity of endocrine glands is studying a science, as endocrinology.Discipline also explores the different types of hormones and their interaction, the way of their education and impact on the body.
What is a hormone?
This compound enters the blood stream and through it enters the different organs.Due to the activity of these substances is reduced or increased activity of other cells, called targets.Hormones through their influence on almost all have a vital function of the human body.The concentration of the compounds produced depends on various factors.In particular, the value has the time of day, age, physical and emotional condition.The hormones penetrate the blood as needed, and are excreted unchanged in small volumes through the bile or urine.There are different types of compounds, which have a greater or lesser degree of influence on the human condition.Some of them are neurohormones.These compounds are produced in a particular area of the brain.What are these substances?As a way of neurohormones?What impact do they have on the system in the body?This was on.
General
Before you figure out where and how to form neurohormones should understand what these substances at all.The definition itself has Greek roots.Literally translated as the neuron (nerve) + hormaino (to encourage, to set in motion).What neurohormones?This biologically active peptide compound.They come in the pituitary gland and regulate its activity.Neurohormones produced by the hypothalamus.Thanks to the activity of the compounds in question communicates endocrine and nervous systems with each other.This is due to the fact that neurosecretory cells have a special sensitivity to the activity of mediators - compounds, which transmit the pulse to the actuator with the nerve ending.Therefore, their participation in the regulation extends endocrine glands activity during development and growth of the organism.
Classification
In this category two groups of compounds.The first is the liberiny.These substances have a stimulating effect on the production of pituitary tropic secrets.In this group, in particular, include corticotropin and thyroliberin, folliberin, lyuliberin, somatoliberin, melanoliberin, prolaktoliberin.The second group netsyrogormonov - statins.These products soednieniya slow tropic pituitary secrets.In this group, in particular, include somatostatin, and melanostatin prolaktostatin.According to the results of the research activities of neurohormones of the hypothalamus is not limited only to the stimulation or inhibition of production of biologically active compounds tropic.The substances have the ability to influence the process of biosynthesis.
In what areas is carried out to develop?
We have said that the production of such compounds in humans is carried out in a particular area of the brain.Formation of these materials occurs in both vertebrates and invertebrates.Where and how neurohormones are produced in other organisms?In vertebrates, involved in the secretion of the pineal gland pinealocytes elements chromaffin tissue in the adrenal medulla, ganglia and nerve trunks paraganglia autonomic and peripheral nervous system.The secretory granules neurohormones usually bind to carrier proteins.
Some features
Unlike the classical type of nerve cells that produce the chemical transmitters nerve impulse - neurotransmitters, neurosecretory cells produce in the cytoplasm (in rare cases in the nucleus) special connection.These substances are distinguished primarily by the nerve endings (terminals) in the blood, the hemolymph, cerebrospinal fluid and tissue.Neurohormones have a regulating influence on the activities of visceral organs (endocrine glands, in particular) and the central nervous system.
What are the functions of neurosecretory cells?The activities of these elements is controlled by classical neurons.Their axons form synapses on numerous body and processes of neurosecretory cells that have the ability to generate action potentials, and to spread the momentum along the axon.
location and concentration
find out where and how neurohormones are formed, consider their distribution in the nervous system.In invertebrates lower organisms connections are distributed diffusely.The phylogeny indicated concentration neurosecretory cell bodies in their respective centers.So, there is accumulation of shellfish in the X-body, and in insects, for example, in prototserebrume.At the same time there neyrogemalnye bodies and neurosecretory way.In vertebrates, the latest focus in a particular area of the diencephalon (and also fish in the caudal region of the spinal cord - urofize).As a result, formed are two main neurosecretory system: caudal (exclusively in fishes) and hypothalamic-pituitary.
stages of development
Where is formed neurohormones?Synthesis of compounds related to carrier proteins, is carried out on the ribosome.Accumulation occurs in the tubules of the endoplasmic reticulum.Elementary granules are finally formed in the Golgi.These components, whose diameter is from 50 to 500 nm have lipoprotein envelope.It is separated from the electron-dense center.It, in turn, consists of a carrier protein and neurohormone.Moving the granules is carried toward the axons.Some axons in contact with the capillaries in the neurohypophysis.Others - with glandular cells in the adenohypophysis (mainly its interim shares).In fish, the axons of the caudal neurosecretory system creates aksoventrikulyarnye contacts.Direct selection of content from the pellets is performed in the data contacts by exocytosis or derivatives neyrogemalnyh bodies, precapillary space and intercellular gap at the molecular level.
Possible pathology
Neurohormones participate in the maintenance of hemostasis (water and salt, etc.), various aspects of metabolism, regulation of smooth muscle tone.In addition, due to their activity provides a stable operation of the elements of the endocrine glands.It is also considered the operation of peptide compounds contributes to the protective-adaptive reactions of the organism.Proceeding into the hemolymph, the cerebrospinal fluid or tissue, they have a long distant regulatory influence.In the case of serious violations of the hypothalamus and produce, respectively, hypothalamic neurohormones, there are irregularities in the production of hormones in the pituitary and endocrine glands other.The man began to develop a variety of diseases of the endocrine system.In particular, these include hypothalamic-pituitary insufficiency, Cushing's disease, acromegaly, hypothyroidism, and other ailments.
