Tag: mechanism of hormone action

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Multiple choice biology chemical coordination and integration mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

Most of the endocrine hormone is controlled by

  1. Negative feedback inhibition

  2. Positive feedback inhibition

  3. Competitive inhibition

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Most of the hormones, especially the hormones of the pituitary gland are controlled by the negative feedback inhibition. This system operates between endocrine gland secreting the hormone and the target cells. For example ACTH secreted by the anterior lobe of pituitary stimulates the target cells present in the adrenal gland to produce cortisol. As soon as the concentration of cortisol rises above the set point in the blood stream it acts on pituitary gland to inhibit the secretion of ACTH. Thus option A is the correct answer.

Multiple choice biology chemical coordination and integration mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

A major regulatory mechanism for multistep reactions is

  1. Presence of inhibitors

  2. Availability of activators

  3. Feed-back mechanism

  4. All the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • A feedback mechanism for multistep reactions is a biological occurrence wherein the output of a system amplifies the system (positive feedback) or inhibits the system (negative feedback).
  • For example, a positive feedback system is childbirth. During labour, a hormone called oxytocin is released that intensifies and speeds up contractions and facilitates childbirth.
  • Hence A major regulatory mechanism for multistep reactions is the feedback mechanism.
  • So, the correct answer is 'Feed-back mechanism'.
Multiple choice biology chemical coordination and integration mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

Complex fatty acids that function as intercellular messengers are

  1. Prostaglandins

  2. Catecholamines

  3. Sphingolipids

  4. Steroids
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

  • The prostaglandins are a group of physiologically active lipid compounds called eicosanoids having diverse hormone-like effects in animals.
  • Prostaglandins have been found in almost every tissue in humans and other animals. 
  • They are derived enzymatically from the fatty acid arachidonic acid. Every prostaglandin contains 20 carbon atoms, including a 5-carbon ring. 
  • They are a subclass of eicosanoids and of the prostanoid class of fatty acid derivatives. Hence, Prostaglandins are complex fatty acids that function as intercellular messengers.
So, the correct answer is 'prostaglandin'.

Multiple choice biology chemical coordination and integration mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

Choose the correct answer from the alternatives givens.
In a negative feedback mechanism:

  1. the output cancels the input

  2. there is a fluctuation above and below the average

  3. there is self-regulation

  4. a regulatory center communicates with other body parts
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Negative feedback, a self-regulated process occurs when some function of the output of a system process, or mechanism is fed back in a manner that tends to reduce the fluctuation in the output whether caused by the changes in the input or by other disturbance.

So, the correct answer is 'there is self-regulation'

Multiple choice biology chemical coordination and integration mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

How does chemical coordination take place in animals?

  1. Endocrine glands----> hormones-----> blood----> organs / tissues----> biochemical / physiological activity.

  2. Endocrine glands----> hormones----> biochemical / physiological activity-----> blood----> organs / tissues.

  3. Hormones----> biochemical / physiological activity-----> blood----> organs / tissues----> endocrine glands.

  4. Hormones----> biochemical / physiological activity-----> endocrine glands----> blood----> organs / tissues
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Endocrine glands----> hormones-----> blood----> organs / tissues----> biochemical / physiological activity.

Chemical coordination in multicellular organisms take place through the special chemical substances called hormones, which are produced in endocrine glands. These chemicals unlike nerve cells, reach all the cells of the body and bring about desirable changes as instructed by the brain and spinal cord. This is done by using a hormone named adrenaline. It is directly secreted into the blood and carried to different parts of the body. The heart, beats faster to supply more oxygen to our muscles. The breathing rate also increases. All these responses enable the animal body to be ready to face the situation. Such hormones constitute a second way of control and coordination.

Multiple choice biology chemical coordination and integration mechanism of hormone action coordination in human beings- chemical control endocrine system in humans
Feed back inhibition of an enzyme is influenced by

  1. Enzyme itself

  2. External factors

  3. End product

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

In feed back inhibition product of a reaction inhibits the enzyme catalysing that reaction. It is a type of control mechanism at the enzyme level. If the product is produced in sufficient amount, it inhibits the enzyme to stop the further production. So, the correct answer is 'End product'.

Multiple choice biology chemical coordination and integration mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

In feedback inhibition, a metabolic pathway is switched off by the accumulation of end products.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Accumulation of end products triggers an inhibiting action as a feedback inhibition of the metabolic pathway causing its inhibition. as a result, the metabolic pathway is switched off or halted. For example, the absence of the suckling stimulus leads to inhibition of the milk secretion.

Hence, the correct answer is 'true'.

Multiple choice biology chemical coordination and integration mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

Feed back mechanism controls

  1. Nervous system

  2. Enzyme production

  3. Time and amount of hormones released by endocrine glands

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

Most hormones are regulated by feedback mechanisms. A feedback mechanism is a loop in which a product feeds back to control its own productions. Most negative feedback loops get involved from hormone feedback mechanisms. Here the time delay occurs and hormones are released.

So, the correct option is 'Time and amount of hormones released by endocrine glands'.

Multiple choice biology chemical coordination and integration mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

Group of hormones which is released with cytoplasmic bounded receptors?

  1. Hypothalamic hormones and epinephrine

  2. Thyroid hormone and estradiol

  3. Insulin and glucagon

  4. GH and MSH
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

There are two sets of nerve cells in the hypothalamus that produce hormones.

One set sends the hormones they produce down through the pituitary stalk to the posterior lobe of the pituitary gland where these hormones are released directly into the bloodstream. These hormones are anti-diuretic hormone and oxytocin.
So, the correct option is 'Hypothalamic hormones and epinephrine.

Multiple choice biology chemical coordination and integration mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

A feedback mechanism regulates the action of the 

  1. Hormones

  2. Lipids

  3. Cell division

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

The feedback mechanism is the process wherein the upregulation and downregulation of genes, hormones, homoeostasis and other factors are controlled. For example, if the level of sugar concentration in blood has increased feedback mechanism upregulates the hormone insulin which helps to stabilise the sugar in the blood. 

So, the correct answer is option A.