[Biology Class Notes] on Mechanism of Hormone Action Pdf for EXAM

The endocrine system is a complex system of organs that work together to release any chemical messengers located inside our body called hormones. The endocrine system works in coordination with the nervous system to regulate different body functions such as metabolism, growth, and reproduction hormones secreted by endocrine glands that together make up the endocrine system. 

The endocrine glands are also called ductless glands because they do not have any ducts and therefore their secretions are called hormones in the bloodstream vessels, through which they reach the organs the hormones flow inside the bloodstream. Blood carries hormones to the needed sites where they carry the further process.

Types of Hormones

To regulate various functions, different types of hormones are produced in the body. They are classified as follows:

• Peptide Hormones

• Steroid Hormones

• Peptide Hormones

What Is The Mechanism of Hormone Action?

A hormone is a chemical messenger secreted to enable communication between cells and tissues throughout the body. They flow through the bloodline. The mechanism of hormone action begins at the endocrine system. A hormone action regulates various other systems including the excretory and reproductive systems. 

Hormone action activities exit their respective cells of origin by the means of membrane transport. Hormones are chemical messengers of the human body that affect different tissues of the human body. The site of the hormone action is usually far away from its site of origin. In the human body, there are numerous hormones performing various functions for different purposes.

What Is The Mechanism of Peptide Hormone Action?

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Peptide hormones find their functional value in the plasma membrane of different target cells. The hormone action of peptide hormones is the so-called second messenger function that takes place within the cell.  The mechanism of peptide hormone action leads to the generation of secondary messenger hormones. These secondary messengers are also similar to hormones that are chemical messengers. The structure of the cell surface receptors has three underlying domains that form an integral part of the membrane structure of the proteins. The three structural domains are namely:

• Extracellular domain

• Transmembrane domain

• Intracellular domain

Except for the receptors of the thyroid hormone, all other amino acid receptors and peptide hormones are located in the plasma membrane. At the target cells, the hormones undergo various unique biological activities. 

Hormonal Imbalance in the Human Body

Hormonal imbalance in the human body is caused due to several health conditions. Some major diseases caused by hormonal dis functionalities are diabetes, thyroid disorders, polycystic ovary syndrome (PCOS), and various other menstrual syndromes. Ovarian tumors and ovarian cysts are common conditions caused as a result of excess Androgen in the human body.

Endocrine Glands and the Hormones Secretion

As stated before, hormones are released by the endocrine glands. These are very different from other glands of the human body.

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The Different Hormones Performing Different Functions are as follows:

• Thyroid: Heartbeat regulation and maintains calorie intake.

• Pancreas: produces insulin and regulates blood sugar level.

• Ovaries: The ovaries secrete sex hormones that are essential for reproductive cycles. Pituitary Gland: The pituitary gland is the major hormone-releasing organ of the body. The gland releases all of the major hormones of the human body.

• Adrenal Gland: The adrenal gland releases stress hormones. There are two mechanisms of hormone action that are required for the proper functioning of the human body.

Feedback Mechanism – Thyroid

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The thyroid gland produces a hormone called thyroxine. When the level of thyroxine in the blood reduces, the hypothalamus stimulates thyroxine secretion by stimulating TSH secretion. This represents a positive feedback mechanism.

If the hypothalamus continues to produce thyroxine, blood levels of thyroxine can increase. This sends negative feedback to the hypothalamus.  Hormones are aimed at specific functions of the target tissue. It will be eliminated when you arrive at your destination. 

Solved Examples

1. Explain the Two Mechanisms of Hormone Action in The Human Body. 

The two mechanisms of hormone action in the human body are broadly divided into two groups:

• Mobile receptor mechanism

• Fixed membrane mechanism

• Mobile Receptor Mechanism: In this form of hormone action the steroids and fatty acids can pass through the lipid membranes easily. The hormones bind to the target receptor and enzymatic activates.

• Fixed Membrane Mechanism: In the fixed membrane mechanism the hormones can’t pass through the lipid membranes. This type of mechanism is generally shown by water-soluble hormones such as amines or proteins. 

2. What are The Features of Hormones? 

Hormones are the chemical messengers of the human body. Different hormones have different effects on the functioning of the human body. The hormones help in the growth, metabolism, development, reproduction, and secretion of fluids. The mechanism of hormone action will start at a certain time and keep working over a continuous period of time. A few important hormones of the human body are Insulin, thyroid hormones, estrogen, progesterone, testosterone, and serotonin.

Functions of Hormones

Following are some important functions of hormones:

1. Food metabolism.

2. Growth and development.

3. Controlling thirst and hunger.

4. Maintaining body temperature.

5. Regulating mood and cognitive functions.

6. Initiating and maintaining sexual development and reproduction

Fun Facts About The Hormone Action In The Human Body

• Although estrogen is a female or one and testosterone is a male hormone, both male and female bodies need these two hormones.

• The hormone action in the human body performs the following functions. Progesterone helps maintain body balance.

• Our memory, learning, and motor control activities need testosterone and estrogen.

• Women become hormonal during their menstrual cycle as the rate of secretion of progesterone increases during a very short span.

• Oxytocin is an essential hormone and is important during childbirth.

Conclusion

This is all about hormones, their sources – endocrine glands, and their functions. Learn how these biochemical compounds hold their importance in human physiological functions. Concentrate on how the hormones act on the different organs and tissues of a human body to promote another function.