Tag: endocrine system in humans

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

Tyrosine act as a precursor for which of the following hormones?

  1. Thyroid

  2. Adrenal

  3. Prolactin

  4. FSH
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Thyroxine (3,5,3',5'-tetraiodothyronine) is the thyroid hormone produced by follicular cells of the thyroid gland.
  • Thyroxine hormone is produced in the thyroid gland from tyrosine and iodine.
  • Hence the precursor for the synthesis of thyroid hormone is amino acid Throne.
  • Tyrosine (symbol Tyr or Y) or 4-dihydroxyphenylalanine is one of the 20 standard amino acids.
  • So, the correct answer is 'Thyroid'.
Multiple choice zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

The stomach pain impulses are received by receptors known as

  1. Proprioreceptors

  2. Exteroreceptors

  3. Visceral receptors

  4. Chemoreceptors
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

a) Proprioceptors are the mechanoceptors which are activated by changes in pressure or movement and are involved in maintaining muscle tone, body equilibrium and posture. 

b) Exteroreceptors are the one that is activated by stimulus from external environments. This includes photoreceptors of eye and mechanoreceptors of inner ear. Stomach pain is an internal stimulus. 
c) Receptors which are present in internal organs and are activated by internal stimuli are known as visceral receptors. 
d) Chemoceptors are the specialized receptors for taste and smell which are activated by changes in the chemical concentration of the substances. 

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

The signal transduction of steroid hormone across cell is through

  1. Binding of hormone to the cytoplasmic receptor and the complex binds to hormone response element on DNA with promoter DNA

  2. Binding of hormone to the transmembrane receptor which initiates the production of second messenger that activates enzymes which further activates transcription factors

  3. Binding of hormone to the transmembrane receptor which diffuse inside the cell cytoplasm and then activates the enzyme necessary for the activation of transcription factors

  4. Binding of hormone to the cytoplasmic receptor that initiates the production of second messenger which activates enzymes that further activates transcription factors
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Steroid hormones, i.e., androgens, estrogens, glucocorticoids, mineralocorticoids, and progestins, bind with high affinity to their respective steroid hormone receptors (SR).


Steroid hormone receptors are found in the nucleus, cytosol, and also on the plasma membrane of target cells. They are generally intracellular receptors (typically cytoplasmic or nuclear) and initiate signal transduction for steroid hormone which leads to changes in gene expression over a time period of hours to days.

So the correct answer is ' binding of hormone to the transmembrane receptor which diffuse inside the cell cytoplasm and then activates the enzyme necessary for the activation of transcription factors'.

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

The elevated concentrations of cAMP indicates

  1. The activation of a cAMP-dependent protein kinase called protein Kinase A

  2. The activation of membrane receptors

  3. The splitting of ATP

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Elevated levels of cAMP act as a second messenger that activates protein kinase A, which then phosphorylates target proteins to produce a cellular response.

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

Which of the following hormones triggers the release of androgens?

  1. FSH

  2. ACTH

  3. LH

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
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'.

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

The cause of hyperprolactinemia in males may be

  1. Dehydration

  2. Tumors

  3. Excessive intake of salts

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
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'.

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

Which of the following is responsible for steroid production?

  1. Salt

  2. Lipids

  3. Cholesterol

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
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'.