Mechanism of Hormone Action – Notes CBSE Class 11

Mechanisms of Hormone Action are seen in the protein hormones such as Insulin, Adrenaline, TSH, and so on. These protein hormones are water soluble and they cannot pass through the cell membrane as it is made up of a lipid layer therefore this is known as a fixed membrane receptor mechanism whereas steroid hormones are made up of fats and are insoluble in water. These receptors are intracellular and can float in the cytoplasm on the nuclear membrane or inside the cell and due to this they are mobile receptor mechanisms.

Hormones Action

The chemical messengers which are produced by the endocrine glands and released into the bloodstream directly are known as Hormones. Hormones are used for regulating many body functions such as digestion, reproduction, and so on. There are two types of hormones which are:

• Protein Hormones: The Hormones which are soluble in water are known as Protein Hormones. Example- Adrenaline, Noradrenaline. These hormones can be easily transported in the blood.
• Steroid Hormones: The Hormones which are not soluble in water are known as Steroid Hormones. Example- Thyroid Hormones. These hormones are only transported to their target organs because they are not water soluble and bind to plasma proteins.

Each and every hormones consists of a receptors which are found on the cell membrane of the target organs. When the hormones are bind to its receptor it forms a series of action which are used to release secondary messengers inside the cells and these messengers are responsible for the relaying the information to the nucleus. There are two different types of receptors which are as follows:

1. Internal receptor: These type of receptor are for steroid hormones. They can be nuclear receptor or cytoplasmic receptor. Nuclear receptor are found in the nuclear membrane whereas cytoplasmic receptor are found in the cytoplasm of the cell.
2. External receptor: These type of receptor are for the protein hormones. They are the transmembrane receptor which are embedded in the lipid layer of cell membrane.

Mechanism of Hormone Action

The mechanism of hormone action is grouped into two classes:

• Fixed membrane receptor mechanism – The water soluble hormones that are proteins shows this type of mechanism. The hormones cannot pass through the lipid membrane. They are having their target receptor which the hormones binds. When the hormone binds on target receptor, the enzyme known as adenyl cyclase in the cell membrane gets activated which helps in the production of cyclic AMP (cAMP).
• Mobile receptor mechanism – The fatty acids and the steroids shows this type of mechanism which consists of intracellular receptor where the hormones bind in the target receptor which activates the enzymatic activity of the cells to bring biochemical changes.

Mechanism of Action hormone are seen in the protein hormones such as Insulin, Adrenaline, TSH and so on. These protein hormones are water soluble therefore they cannot pass through the cell membrane as it is made up of lipid layer. The protein hormone binds to the receptor, series of reactions occurs in the starting with the production of adenyl cyclase enzyme. These enzyme leads in the production of cyclic cAMP or AMP. The steroid hormones are made up of fats and are insoluble in water. There receptor are intracellular which can float in the cytoplasm on the nuclear membrane or inside the cell and due to this they are mobile receptor.

Hormones as Regulators

The inner environment of the body is maintained by the hormones. Therefore, when secretion of the hormones are under control of the other hormones it is known as feedback control. It is of two types:

• Positive Feedback control: It is defined as a process in which end products of action cause more of action which occur in a feedback loop. Example – menstrual cycle, blood clotting.
• Negative Feedback control: This is a type of process in which the regulation of the end product reduces the stimulus. Example – blood sugar regulation, temperature regulation.

Hormones as Messengers

Neurohormones is defined as the neurosecretory cells of the hypothalamus secrete hormones. Neurohormones carries pituitary glands and stimulates it to release hormones and that’s why they are called as releasing factors.

Hormone Imbalance in the Human Body

The hormonal imbalance in the human body is caused due to several health conditions. Some of the diseases are thyroid disorders, diabetes, polycystic ovary syndrome and menstrual syndromes. Some of the common condition are ovarian tumors and ovarian cysts.

FAQs on Mechanism of Hormone Action

1. What do you mean by Mechanism of Hormone action?

Answer:

Mechanism of Action hormone are seen in the protein hormones such as Insulin, Adrenaline, TSH and so on. These protein hormones are water soluble therefore they cannot pass through the cell membrane as it is made up of lipid layer.

2. What are the three mechanisms of hormone control?

Answer:

The three mechanisms in which the endocrine glands stimulates and releases hormones are:

• Hormonal stimuli
• Humoral stimuli
• Neural stimuli

3. What are the 5 major processes that are in hormones control?

Answer:

The 5 major processes that are in hormones control are:

• Reproduction
• Growth and development of body
• Metabolism
• Sexual function
• Homeostasis

4. Name the types of mechanism of hormone action ?

Answer:

The mechanism of hormone action is grouped into two classes:

• Fixed membrane receptor mechanism
• Mobile receptor mechanism