Adrenal medulla, Biology

Assignment Help:

ADRENAL MEDULLA

The adrenal medulla develops from the neuroectoderm of the embryo.

Medulla consists of chromaffin cells or phaeochromocytes. These cells are connected with the preganglionic motor fibres of the sympathetic nervous system.

Hormones : The medulla of the adrenal glands secretes two hormones: norepinephrine (noradrenaline) and epinephrine

(adrenaline). Norepinephrine and epinephrine are derived from the aminoacid tyrosine.

(i) Norepinephrine (Noradrenaline). It regulates the blood pressure under normal condition. It causes constriction of essentially all the blood vessels of the body. It causes increased activity of the heart, inhibition of gastrointestinal tract, dilation of the pupils of the eyes and so furth.

(ii) Epinephrine (Adrenaline). It is secreted at the time of emergency. Hence it is also called emergency hormone. It causes almost the same effects as those caused by norepinephrine, but the effects differ in the following respects.

  • First, epinephrine has a greater effect on cardiac activity than norepinephrine.
  • Second, epinephrine causes only weak constriction of the blood vessels of the muscles in comparison with a much stronger constriction that results from norepinephrine.
  • A third difference between the action of epinephrine and norepinephrine relates to their effects on tissue metabolism.
  • Epinephrine probably has several times as great a metabolic effect as norepinephrine.

Target Cells. Both adrenaline and noradrenaline acts on the cells of skeletal, cardiac and smooth muscles and blood vessels and fat cells.

Because of the role of their hormones, the adrenal glands are also called 'glands of emergency'.


Related Discussions:- Adrenal medulla

Objectives of the nutritional care process, Thus, the objectives of the nut...

Thus, the objectives of the nutritional care process should include the following points: 1. Restoration of good nutritional status with dietary modifications and counseling.

How sugar is used in meringues, How sugar is used in Meringues? Egg whi...

How sugar is used in Meringues? Egg whites beaten for a meringue hold air bubbles as the mechanical action of the beaters partly coagulates the egg protein. Sugars make the pro

Etiologic factor of atherosclerosis, Q. Etiologic factor of atherosclerosis...

Q. Etiologic factor of atherosclerosis? Various factors are responsible for atherosclerosis. These include: 1. Hyperlipidemin: Excess circulating fats in blood especially th

Determine the term mentalis, Mentalis The mental tubercles on either si...

Mentalis The mental tubercles on either side of mental protruberance(in midline) gives origin to the mentalis muscle. Above the mentalis origin, the incisivus muscle takes orig

Mechanism of respiration in cockroach, MECHANIS M - Tergo-sternal m...

MECHANIS M - Tergo-sternal muscles are relaxed. Volume of cavity is increased and pressure is decreased. To full fill the pressure air comes through the passage & mixed

Bovine spongiform encephalopathy (bse), Normal 0 false fal...

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4

Prevention strategy for diverticular disease, Q. Prevention strategy for di...

Q. Prevention strategy for diverticular disease? The prevention strategy for the disease involves the following: • Eat a high-fiber diet (more than 15 g/day of crude fiber)

Procedure for define percentage of reducing and total sugar, Procedure For ...

Procedure For Define Percentage of reducing and total sugar by fehling soxhlet? 1. Standard titration (Standardization of Fehling's solution) - Titrate 10 ml of Fehling's solut

Define mechanism for copper absorption, Define Mechanism for Copper Absorpt...

Define Mechanism for Copper Absorption? As in the case of other minerals, copper absorption appears to occur by two mechanisms: i) Saturable active mechanism, which operates

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd