Tag: mechanism of hormone action

Questions Related to mechanism of hormone action

Which of the following hormones triggers the release of androgens?

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. FSH

  2. ACTH

  3. LH

  4. None of the above

Show answer
Correct Option: C
Explanation:

  • The hypothalamus secretes gonadotropin-releasing hormone (GnRH) which stimulates the pituitary gland into secreting luteinizing hormone (LH) and follicle-stimulating hormone (FSH). 
  • LH stimulates testicular Leydig cell secretion of Testosterone whereas FSH stimulates spermatogenesis in Sertoli cells of the seminiferous tubules. 
  • An androgen is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. 
  • The major androgen in males is testosterone. Hence,  LH hormones trigger the release of androgens.
So, the correct answer is 'LH'.

The cause of hyperprolactinemia in males may be

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. Dehydration

  2. Tumors

  3. Excessive intake of salts

  4. None of the above

Show answer
Correct Option: B
Explanation:

  • Prolactin levels may be elevated for any number of reasons. One of the more common cause is the formation of a benign tumour on the pituitary gland. 
  • This noncancerous growth, known as a prolactinoma, directly secretes excessive prolactin while decreasing the levels of other sex hormones. Hence, The cause of hyperprolactinemia in males may be Tumors
So, the correct answer is 'Tumors'.

Which of the following is responsible for steroid production?

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. Salt

  2. Lipids

  3. Cholesterol

  4. None of the above

Show answer
Correct Option: B
Explanation:

  • Cholesterol also plays a role in synthesizing the steroid hormones aldosterone, which is used for osmoregulation, and cortisol, which plays a role in metabolism. 
  • Cholesterol is also the precursor to bile salts, which help in the emulsification of fats and their absorption by cells. Hence,  Lipids is responsible for steroid production.
So, the correct answer is 'Lipids'.

Pacinian corpuscles of skin are receptors of.

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. Movement

  2. Pressure

  3. Temperature

  4. Pain

Show answer
Correct Option: B

Which of the following is not involved as $2^{nd}$ messenger?

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. cAMP

  2. DAG

  3. Phospholipase

  4. $IP _{3}$

Show answer
Correct Option: C

As per accepted concept of hormone action, if receptor molecules are removed from target organs, the target organs will

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. Continue to respond to hormone but in opposite way

  2. Continue to respond to hormone without any difference

  3. Continue to respond to hormone but will require higher concentration

  4. Stop responding to hormone

Show answer
Correct Option: D
Explanation:
Hormones bind to specific proteins known as hormone receptors to produce their effects. These receptors are present on target tissues only. There are two types of receptors in target tissues:
  • Membrane bound receptors : These are present on the cell membrane of target cells.
  • Intracellular receptors: These are present inside the target cell.
When a hormone binds to its receptor, hormone receptor complex is formed. This complex leads to some biochemical changes in target tissue. Hormones regulate metabolism and physiological functions of target tissue.
Hence, if receptor molecules are removed from target organs, the target organs will stop responding to hormones.
So, the correct answer is 'Stop responding to hormone'.

Receptors for protein hormones are found

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. Inside nucleus

  2. Inside cytoplasm

  3. On surface of ER

  4. On the plasma membrane of the cell

Show answer
Correct Option: D
Explanation:
Protein hormones are peptide hormones which are derived from amino acids. These are insoluble in lipids and hence can't enter the target cell (cell membrane is a lipid bilayer). These act as primary messengers at the surface of target cell by binding to cell surface receptors and this results in the formation of a hormone-receptor complex.
So, the correct answer is 'On the plasma membrane of the cell'.

In hormone action, if receptor molecules are removed from target organ, the target organ will 

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. Continue to respond to hormone

  2. Not respond to hormone

  3. Continue to respond but requires higher concentration

  4. Continue to respond but in the opposite way

Show answer
Correct Option: B
Explanation:
Hormones bind to specific proteins known as hormone receptors to produce their effects. These receptors are present on target tissues only. There are two types of receptors in target tissues:
  • Membrane bound receptors : These are present on the cell membrane of target cells.
  • Intracellular receptors: These are present inside the target cell.
When a hormone binds to its receptor, hormone receptor complex is formed. This complex leads to some biochemical changes in target tissue. Hormones regulate metabolism and physiological functions of target tissue.
Hence, if receptor molecules are removed from target organ, the target organ will not respond to hormone.
So, the correct answer is 'Not respond to hormone'.

Steroid hormones, estrogen and testosterone bind to

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. Membrane ion channels

  2. Enzyme-linked membrane receptors

  3. G-Protein linked membrane receptors

  4. Cytoplasmic receptors

Show answer
Correct Option: D
Explanation:

Hormones are of 2 types based on their chemical composition. 

  1. Protein hormones: They are build up of amino acids and are soluble in water. 
  2. Steroid hormones: They are build up of fats and are not soluble in water. 
  3. Since the steroid hormones are not soluble in water they can pass through the plasma membrane and bind to the receptors in the cytoplasm.  
So the answer is Cytoplasmic receptors. 

In heart cells, which one a second messenger that speeds up muscle contraction in response to adrenaline 

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. cAMP

  2. cGMP

  3. GTP

  4. ATP

  5. AMP

Show answer
Correct Option: A
Explanation:
Adrenaline binds to its receptors present on the cell surface i.e. plasma membrane. In heart muscles, cAMP (cyclic adenosine monophosphate) acts as a second messenger. It increases muscle contraction in response to adrenaline which is a neurotransmitter secreted from adrenal medulla. cGMP (cyclic guanosine monophosphate) also acts as a second messenger but it decreases muscle contraction in response to acetylcholine.
So, the correct answer is 'cAMP'.