Hormone: Definition, Mechanism, mechanism of influence their role

In this article, we tell you about hormones, their  Definition, Mechanism, mechanism of influence & their role. these questions are in the type of questions in which we describe to you some main questions regarding hormone. These answers are written by me so maybe here having some mistakes but all these data are chosen from the internet. so if you have some problem here, don’t forget to write in the comment section or contact us.

 

The Hormone

A hormone is a chemical organic substance that is made by a particular special cell and secretes or produce by some endocrine glands in a small amount. It is secreted into the bloodstream and controls their activities like metabolic and biological activities and is also known as a chemical messenger because they work as a transmission of information between the tissues and cells.
Firstly this process, Means synthesis of hormone starts in the nucleus where DNA Convert into pre-mRNA by transcription. And Then Pre-mRNA is converting into mRNA with the help of Post-transcriptional processing and mRNA where goes to ribosome which is present in the cytosol and makes Pre-Pro-hormone by the translation. After that Pre-Pro-hormone converts into Pro-hormone by the post-translational processing at endoplasmic reticulum which is converted into Proper hormone in Golgi apparatus And in the cytosol, there are so many kinds of organelles which is complete this process in which the main process is completed by the ribosome and endoplasmic reticulum. Synthesized and then stored in secretory vesicles until endocrine cells are stimulated.

Hormone - Definition and Mechanism - 2

For example – Parathyroid hormone is synthesized and stored in chief cells of the parathyroid gland which is stimulus by a low concentration of extracellular calcium. When low concentration calcium is detected by the sensor of the parathyroid gland after that translocated of secretory vesicles to the cell membrane and release parathyroid hormone in the blood and regulate the calcium level.

They have some kind of properties: –

  • Secreted by specialized glands and directly in the bloodstream.
  • Serve as chemical nature and transported by the bloodstream to the targeted cell or tissue and regulate their rates of specific metabolic reaction
  • Require in very small amount and according to the concentration and physiological condition they can work as an excitatory and inhibitory.

Different type of chemical nature: –

    • Steroid hormone derived from cholesterol. e. glucocorticoids, mineralocorticoids, sex hormone
    • Protein or peptide hormones derived from Amino Acid i.e. insulin, glucagon, antidiuretic hormone, oxytocin
    • In amino acid made up from mostly tyrosin i.e. epinephrine, norepinephrine, thyroxin (T4), triiodothyronine (T3)
    • Eicosanoid made up of lipid i.e. prostaglandin, thromboxane

Neuro Endocrine regulation system: – in this mechanism, the hypothalamus maintain the other hormonal activity which helps to regulate some function in our body i.e. homeostasis, reproduction, metabolism, eating, and other all things.

There are some Neuro Endocrine Systems: –

  • HPA means Hypothalamus – Pituitary – adrenal axis
  • HPT means Hypothalamus – Pituitary – thyroid axis
  • HPG means Hypothalamus – Pituitary – gonadal axis
  • Hypothalamus – Neurohypophyseal system

The neuroendocrine system`s Neuron is the large system known as factories of secretory products. Their Produce product can be easily measured in blood. And then give stimuli for the opening of the hypothalamus.


Question 1): – How is the necessary concentration of the hormone in the blood maintained (describe the mechanism as detailed as possible).

Feedback mechanism
It is controlled by the feedback inhibition mechanism. Hormones are control so many types of activity in our body. These are most important in homeostasis. A higher concentration of hormones in the blood can cause so many types of deficiency. So it is controlled by a feedback mechanism. Feedback mechanism means the product of reaction inhibits the own production for control the mechanism.

  • Negative Feedback: – It occurs when the product inhibits or stops its own production. When they go to higher concentration or becomes extreme, they do negative feedback. For example – the thyroid gland, when the hypothalamus secretes the thyrotropin-releasing hormone, stimulates the pituitary gland for secreting TSH, and stimulates the thyroid to secrete thyroid hormone. When the level of thyroid hormone getting high, the hormone doing a negative feedback work on the hypothalamus to stop producing TRH and also to the pituitary gland for producing TSH.
  • Positive feedback: – it occurs when a product increase or starting own production. When the concentration goes too low or becomes increasingly extreme, this feedback started. For example: – Milk production in mother for baby. When the baby shucks the nipple of the mother, the nervous system is activated and nerve massage goes to the pituitary gland for releasing prolactin to secrete or produce more milk.

My conclusion: – Most of the hormonal activities are controlled by negative feedback. This process occurs when they become too extremely condition, they decrease or stop their own production for back to normal.

For Hormone production of the endocrine gland, there are three types: –

  • Neural Stimuli: – Sometimes nervous system stimulating the endocrine gland and the produced hormone. i.e. On the stress response, epinephrine and norepinephrine are produced for the regulation of energy and body response. In this neural signaling, SNS activates the Adrenal medulla to releasing of hormone epinephrine and norepinephrine.
  • Humoral Stimuli: – Humoral means Body fluid like the blood which can control or regulate the releasing of the hormone on any kind of changes in blood like conc of ions. i.e. increase the blood glucose level in the blood stimulate the pancreatic gland to secrete insulin.
  • Hormonal Stimuli: – Hormones are responsible for release another hormone. i.e. TRH is responsible for secrete TSH and Then TSH is responsible for release Thyroid hormones which on the excess level, feedback inhibits the TRH and TSH.

Question 2).  Describe the mechanism of influence of thyroid hormones in the regulation of heat transfer.

Thyroid Hormone
regulation of energy in homeostasis, thermoregulation, maintaining body temperature help by thyroid hormone. There are two types of diseases or deficiency have which cause because of irregularity or abnormality in thyroid hormone regulation. 1) hypothyroidism 2) hyperthyroidism
In both cases, these are the same changes to observed- when it’s regulated by the fasting or cold condition.
Thermogenesis can be regulated by CNS and also thyroid hormone directly acts on the metabolic activity and thermogenesis of the body.
The heat regulation being in the brain with the help of the hypothalamus which secrets the Thyroid Releasing hormone known as TRH. It travels to the pituitary gland to produce a Thyroid-stimulating hormone known as TSH. It enters the bloodstream and goes to the thyroid gland for help to produce T4 (thyroxin) then it converts into T3 by 5’-deiodinase enzyme. T3 works on the cell nuclear receptor. T3 Start a cascade of reactions in each cell and affect the cell`s metabolic rate.

T3 and T4 transport in blood and enter into cell

The thyroid hormone is doing great work at the nuclear receptor which is known as thyroid hormone receptor and these all are bound with DNA and make Thyroid hormone response elements which are also known as (TREs). This receptor corepressor DNA complex can stop gene transcription. T3 is the active form of T4. When T3 binds to the receptor it does conformational changes and displacing the co-repressor from the complex. This is activating the transcription of the gene and regulates the metabolic rate.
Thermal regulation known as the calorigenic effect means an increase in metabolic rate and oxygen consumption in the cell. Due to this situation, Body Heat or temperature rises.
Oxygen consumption by the increasing of T4 and T3. Thyroid hormones increase in activity of the membrane boundedNa, K ATPase in many tissues. In increased metabolic activity it increases Thermogenesis.
Thyroid hormones are regulated by feedback inhibition. In this TH-feedback loop is the activation by the Thyroid receptors and make a beta dependent signaling for the decreasing of Thyroid stimulation and releasing hormone.
In cold situation: – Thyroid releasing hormone activates and changing these conditions by the HPT axis. And release to heat and increase metabolic pathway.

Production-and-action-of-thyroid-hormone-The-key-components-required-for-thyroid-hormone


Question 3). Describe the role of pancreatic hormone in the metabolism of proteins and lipids.

role of pancreatic hormones in the metabolism of proteins and lipids.
Answer – Homeostasis regulates the internal cell’s condition and other things like – temperature, water, sugar level, Blood pressure. In this Two kinds of hormones used – insulin and glucagon where both are controlled by the Pancreas.

  • Imbalance of Blood glucocorticoids: – where the low concentration of glucocorticoids in blood and in hypothalamic blood sensors they catch signals by the sensors in blood vessels and perceive Hypothalamus for maintaining glucocorticoids.
  • After that Signals Where goes to the hypothalamus and then the hypothalamus releases Corticotrophin-releasing-hormone (CRH).
  • CRH releases a starting hormone cascade that triggers the adrenal gland for releasing Glucocorticoids in the blood.
  • When glucocorticoids starting a release to blood. When blood concentration of glucocorticoids getting high.
  • Hypothalamus receives a normal concentration of glucocorticoids and stops releasing CRH which knows as negative feedback of feedback inhibition.

From this situation, it maintains the blood sugar concentration.

  • When blood glucose is getting low in their concentration in blood: –

When blood glucose is getting low in concentration in blood or decreases glucose level in the blood, the hormone glucagon is start released by the pancreas. By the stimuli of glucagon, stimulate hepatic Glycogenolysis and Gluconeogenesis in which the liver breaks down glycogen and releases glucose in the blood. On the normal concentration of blood glucose level, the glucagon releasing will be reduced.
Glucagon is synthesized from alpha cells. When glucagon is released, it binds with the glucagon receptor which is known as the G protein-coupled receptor and present in the plasma membrane. Where G protein bind with the receptor and starts conformational changes and GTP convert into GDP and replacement of alpha subunit from beta and gamma subunits where alpha subunits activate another enzyme known as adenylate cyclase which makes cAMP or cyclic adenosine monophosphate for activating cAMP-dependent Protein Kinase A (PKA) which activates phosphorylase kinase to phosphorylates phosphorylase kinase (PPK)by the convert of ATP to ADP and one phosphate group attached to phosphorylase kinase to activate this enzyme which Converting phosphorylates glycogen phosphorylase b (PYG b) to activate form phosphorylase a (PYG a).
PYG is an enzyme that is helping to release another enzyme called Glucose-1-phosphate by glycogen polymers. And then the synthesis of glucose where start.

  • When blood glucose is getting high in their concentration in the blood

When blood glucose gets high, the pancreas release insulin to maintain blood glucose level. Insulin mainly sends signals to the muscle, adipose tissue, and liver for works on the target cells to take up glucose and the liver starts to convert glucose to glycogen.
Insulin bind to the alpha receptors and starts auto-phosphorylation of beta receptors. This helps to activate the tyrosine kinase enzyme and start phosphorylation of (IRS) means insulin receptor substrate. After that multiple intracellular are translocated to the cell membrane in which glucose uptake by glucose transport facilitates. The cell membrane, more permeable to AA, K+, and phosphate ion, and then it will be showing the effect on translation and transcription.