All questions of Chemical Coordination and Integration for NEET Exam

All correct

Thyroxine

Function of Calcitonin:
Calcitonin is a hormone produced by the parafollicular or C cells of the thyroid gland. Its main function is to regulate calcium levels in the blood by decreasing the levels when they are too high.

Decrease Calcium Level in Blood:
- Calcitonin works to decrease blood calcium levels by inhibiting the activity of osteoclasts, which are cells responsible for breaking down bone tissue. By reducing the activity of osteoclasts, calcitonin helps to prevent the release of calcium from bones into the bloodstream.
- In addition to inhibiting osteoclast activity, calcitonin also promotes the uptake of calcium by the bones, further reducing the amount of calcium in the blood.
- Overall, the action of calcitonin helps to maintain a balance of calcium in the body by preventing excessive levels of calcium in the blood.
- It is important to note that calcitonin's role in calcium regulation is complementary to the action of another hormone, parathyroid hormone (PTH), which works to increase blood calcium levels when they are too low.
In conclusion, the main function of calcitonin is to decrease blood calcium levels by inhibiting the activity of osteoclasts and promoting calcium uptake by bones. This helps to maintain a balance of calcium in the body and prevent harmful effects of excessive calcium levels in the blood.

Hormone that never reaches cytoplasm

FSH (Follicle-stimulating hormone) is the hormone that never reaches the cytoplasm. Let's understand this in detail.

Introduction to Hormones

Hormones are chemical messengers that are secreted by various glands in the body. They travel through the bloodstream and act on specific target cells or organs to regulate various physiological processes. Hormones can be classified into different types, such as peptide hormones, steroid hormones, and amino acid-derived hormones.

Mechanism of Hormonal Action

Hormones act on target cells by binding to specific receptors on the cell membrane or inside the cell. Once the hormone binds to its receptor, it triggers a series of intracellular signaling pathways that ultimately lead to a specific physiological response. The response can be either short-term, such as muscle contraction, or long-term, such as growth and development.

Hormones that Reach Cytoplasm

Most hormones, such as estrogen, progesterone, and testosterone, are lipid-soluble and can diffuse through the cell membrane. Once inside the cell, they bind to specific receptors in the cytoplasm or nucleus. This binding activates gene expression and initiates the synthesis of new proteins, which ultimately lead to a physiological response.

Hormones that Never Reach Cytoplasm

In contrast, peptide hormones, such as FSH, are water-soluble and cannot diffuse through the cell membrane. Therefore, they bind to specific receptors on the cell membrane. This binding activates intracellular signaling pathways that ultimately lead to a physiological response. However, FSH never reaches the cytoplasm or nucleus of the cell.

Conclusion

In conclusion, FSH is a peptide hormone that binds to specific receptors on the cell membrane and activates intracellular signaling pathways. However, it never reaches the cytoplasm or nucleus of the cell.

FSH

False Statement about Steroid Hormones:




Steroid Hormones are Proteinaceous in Nature:
- This statement is false because steroid hormones are not proteinaceous in nature. They are actually derived from cholesterol and are lipid-based molecules.
- Steroid hormones are synthesized in the endocrine glands such as the adrenal glands, gonads, and placenta.
- These hormones are characterized by their ability to pass through cell membranes easily due to their lipid nature.

Correct Statements about Steroid Hormones:
- They act by affecting gene expression: Steroid hormones bind to specific receptors inside the cell and then move into the nucleus where they can affect gene expression.
- They can pass through nuclear membranes: Steroid hormones are lipid-soluble molecules that can easily pass through the nuclear membrane to bind to their receptors inside the cell.
- The steroid hormone-receptor complex binds to hormone response elements in DNA: Once the steroid hormone binds to its receptor, the complex can bind to specific hormone response elements in the DNA, leading to changes in gene expression.

Peptide Hypophysiotropic Hormones:

Hypophysiotropic hormones are hormones that regulate the release of other hormones from the anterior pituitary gland. These hormones are primarily peptides, with the exception of a few non-peptide hormones.

Explanation:

Corticotropin Releasing Hormone (CRH):
- CRH is a peptide hormone that stimulates the release of adrenocorticotropic hormone (ACTH) from the anterior pituitary gland, which in turn stimulates the adrenal glands to produce cortisol.

Growth Hormone Inhibitory Hormone:
- This is not a specific hormone but rather a general term used to describe hormones that inhibit the release of growth hormone from the pituitary gland. These hormones are typically peptides.

Somatostatin:
- Somatostatin is a peptide hormone that inhibits the release of growth hormone, as well as other hormones such as insulin and glucagon. It acts as a negative regulator of hormone secretion.

Prolactin Release Inhibiting Hormone:
- Prolactin release inhibiting hormone, also known as dopamine, is a non-peptide hormone that inhibits the release of prolactin from the pituitary gland. It acts as a negative regulator of prolactin secretion.

Conclusion:

In conclusion, all hypophysiotropic hormones are peptides except for prolactin release inhibiting hormone, which is a non-peptide hormone. These hormones play crucial roles in regulating the endocrine system and maintaining homeostasis in the body.

Protein

Understanding Endocrine Glands
Endocrine glands are specialized organs that play a crucial role in the body's hormonal regulation. They differ significantly from exocrine glands, which utilize ducts to transport their secretions.
Characteristics of Endocrine Glands
- Ductless Nature: Endocrine glands do not possess ducts. Instead, they secrete hormones directly into the bloodstream. This allows for a more efficient and widespread distribution of hormones throughout the body.
- Hormonal Secretion: Hormones are chemical messengers that travel through the circulatory system to target organs or tissues. Each hormone has specific functions and effects, influencing various physiological processes.
Comparison with Exocrine Glands
- Exocrine Glands: In contrast, exocrine glands, such as sweat glands and salivary glands, have ducts that carry their secretions to specific sites. This means they deliver their products directly to the surface or into cavities of the body.
- Example of Endocrine Glands: Major endocrine glands include the pituitary gland, thyroid gland, adrenal glands, and pancreas. Each of these glands releases hormones that regulate metabolism, growth, stress response, and other vital functions.
Conclusion
- The absence of ducts in endocrine glands allows for the rapid and systemic effects of hormones. This ductless mechanism is fundamental to the endocrine system's ability to maintain homeostasis and coordinate complex bodily functions. Understanding this distinction is essential for comprehending human physiology, particularly in the context of examinations like NEET.

The pancreas.
b)It raises blood glucose levels.
c)It promotes glycogen breakdown in the liver.
d)It inhibits insulin secretion.
e)It is released in response to low blood glucose levels.

Adrenocorticotropic hormone secretion
Adrenocorticotropic hormone (ACTH) is secreted by the anterior pituitary gland in the brain. This hormone plays a crucial role in the regulation of the adrenal glands, which are located on top of the kidneys.

Stimulus for ACTH secretion
ACTH secretion is stimulated by the release of corticotropin-releasing hormone (CRH) from the hypothalamus. CRH triggers the anterior pituitary gland to release ACTH into the bloodstream.

Function of ACTH
ACTH acts on the adrenal glands to stimulate the production and release of cortisol, a stress hormone that helps the body respond to stress and regulate metabolism. It also plays a role in the production of other hormones, such as aldosterone and androgens.

Regulation of ACTH secretion
ACTH secretion is regulated by a negative feedback mechanism. When cortisol levels in the blood are high, they inhibit the release of CRH and ACTH, thereby reducing cortisol production. Conversely, when cortisol levels are low, the hypothalamus and pituitary gland increase the secretion of CRH and ACTH to stimulate cortisol production.
In conclusion, the secretion of adrenocorticotropic hormone is primarily regulated by the hypothalamus and the anterior pituitary gland, and it plays a crucial role in the regulation of adrenal gland function and cortisol production.

Understanding Ovulation in Females

Key Point: Ovulation in females is primarily under the control of LH.

Luteinizing Hormone (LH)
- LH is a hormone produced by the pituitary gland in the brain.
- It plays a crucial role in the menstrual cycle and ovulation in females.
- LH surge triggers the release of the mature egg from the ovary during ovulation.

Role of LH in Ovulation
- At the beginning of the menstrual cycle, LH levels are low.
- As the cycle progresses, LH levels rise, leading to a surge in LH around the middle of the cycle.
- This surge in LH triggers the release of the mature egg from the ovary, marking the peak of ovulation.

Other Hormones
- While other hormones such as estrogen and progesterone also play important roles in the menstrual cycle, LH is the primary hormone responsible for ovulation.
- ADH, TSH, LTH do not have a direct role in ovulation.

Conclusion:
- Ovulation in females is primarily controlled by LH, which triggers the release of the mature egg from the ovary. Other hormones like estrogen and progesterone also contribute to the menstrual cycle, but LH is the key player in ovulation.