Test: Hormones and their Mechanism of Action - NEET MCQ

The hormone responsible for converting glucose into glycogen is produced by the pancreas.

This process is vital for regulating blood sugar levels. Here are some key points:

• The pancreas secretes insulin, a hormone that facilitates the uptake of glucose by cells.
• Once inside the liver, glucose is transformed into glycogen for storage.
• When blood sugar levels drop, glycogen can be converted back into glucose, ensuring a steady energy supply.

In summary, the pancreas plays a crucial role in managing energy by producing insulin, which helps maintain healthy blood sugar levels.

Topic in NCERT: Pancreas

Line in NCERT: "glucagon acts mainly on the liver cells (hepatocytes) and stimulates glycogenolysis resulting in an increased blood sugar (hyperglycemia)."

Epinephrine, commonly known as adrenaline, is a hormone that is released rapidly during stressful situations, such as when someone is being chased by a dog. This hormone plays a crucial role in the body's 'fight or flight' response. Here are some key points about epinephrine:

• Quick Release: Epinephrine is released swiftly from the adrenal glands in response to stress.
• Increases Heart Rate: It elevates heart rate and blood pressure, preparing the body for immediate action.
• Boosts Energy: It increases the availability of energy by breaking down glycogen into glucose.
• Enhances Alertness: Epinephrine sharpens focus and awareness, which can be vital in dangerous situations.

Other hormones mentioned, such as somatostatin, somatotropin, and prolactin, do not respond as quickly to immediate stressors and are associated with different physiological functions:

• Somatostatin: Primarily regulates hormone secretion and slows down bodily processes.
• Somatotropin: Also known as growth hormone, it is involved in growth and metabolism.
• Prolactin: Mainly related to milk production and reproductive functions.

In conclusion, during a stressful encounter like being chased by a dog, epinephrine is the hormone that acts rapidly to prepare the body for action.

Topic in NCERT: Adrenal gland

Line in NCERT: "the adrenal medulla secretes two hormones called adrenaline or epinephrine and noradrenaline or norepinephrine. these are commonly called as catecholamines. adrenaline and noradrenaline are rapidly secreted in response to stress of any kind and during emergency situations and are called emergency hormones or hormones of fight or flight."

Immediate cause of induction of ovulation in human females is a significant surge in plasma levels of certain hormones. The hormone primarily responsible for triggering ovulation is:

• LH (Luteinising Hormone) - This hormone plays a crucial role in the final maturation of ovarian follicles and the subsequent release of an egg.
• Other hormones such as FSH (Follicle-Stimulating Hormone), Estradiol, and Progesterone are involved in the menstrual cycle but do not directly induce ovulation.

During the ovulation phase, the surge in LH levels indicates that the ovary is ready to release an egg, marking a key point in the reproductive cycle.

Topic in NCERT: Hormones of the ovary

Line in NCERT: "in females, lh induces ovulation of fully mature follicles (graafian follicles) and maintains the corpus luteum, formed from the remnants of the graafian follicles."

Assertion: Diabetes insipidus is characterised by excessive urination and a strong thirst for water.

Reason: The anti-diuretic hormone is secreted by the posterior lobe of the pituitary gland.

• Both the Assertion and Reason are true.
• The Reason is a correct explanation of the Assertion.

In summary:

• Diabetes insipidus leads to significant fluid loss due to poor regulation of water retention.
• The anti-diuretic hormone plays a crucial role in controlling water balance in the body.
• When this hormone is insufficiently produced, it results in increased urination and thirst.

Topic in NCERT: Diabetes insipidus

Line in NCERT: "an impairment affecting synthesis or release of adh results in a diminished ability of the kidney to conserve water leading to water loss and dehydration. this condition is known as diabetes insipidus."

Injection of insulin into an animal increases the glucose levels in various areas of the body. Here are the key points:

• Insulin primarily functions to facilitate the uptake of glucose by cells.
• This leads to a decrease in the concentration of glucose in the bloodstream.
• As a result, the glucose level within cells rises, enabling them to use glucose for energy.
• The overall effect is a controlled increase in cellular glucose levels, which is crucial for metabolism.

In summary, the injection of insulin is vital for managing glucose levels effectively, particularly within cells.

Topic in NCERT: Insulin and glucagon functions

Line in NCERT: "insulin stimulates cellular glucose uptake and utilisation, and glycogenesis resulting in hypoglycemia."

Hormones which interact with membrane-bound receptors normally do not enter the target cell, but generate second messengers (e.g., cyclic AMP, IP3 , Ca++ etc) which in turn regulate cellular metabolism (Figure 19.5a). Hormones which interact with intracellular receptors (e.g., steroid hormones, iodothyronines, etc.) mostly regulate gene expression or chromosome function by the interaction of hormone-receptor complex with the genome. Cumulative biochemical actions result in physiological and developmental effects

Glucagon is a hormone that has an anti-insulin effect, meaning it works to increase blood sugar levels. Here are some key points about glucagon:

• Produced by: The alpha cells of the pancreas.
• Function: Stimulates the liver to convert stored glycogen into glucose, releasing it into the bloodstream.
• Opposes insulin: While insulin lowers blood sugar levels, glucagon raises them, making it crucial for maintaining glucose balance in the body.
• Role in fasting: During periods of fasting, glucagon helps to provide energy by ensuring that glucose is available for use.

Understanding glucagon's role is essential for grasping how the body regulates blood sugar levels and maintains overall metabolic balance.

Topic in NCERT: Pancreas

Line in NCERT: "glucagon stimulates glycogenolysis and gluconeogenesis resulting in hyperglycemia."

The adrenal cortex can be divided into three layers, called zona reticularis (inner layer), zona fasciculata (middle layer) and zona glomerulosa (outer layer). The adrenal cortex secretes many hormones, commonly called as corticoids. The corticoids, which are involved in carbohydrate metabolism are called glucocorticoids. In our body, cortisol is the main glucocorticoid. Corticoids, which regulate the balance of water and electrolytes in our body are called mineralocorticoids. Aldosterone is the main mineralocorticoid in our body.

The adrenal medulla secretes two hormones called adrenaline or epinephrine and noradrenaline or norepinephrine. These are commonly called as catecholamines. Adrenaline and noradrenaline are rapidly secreted in response to stress of any kind and during emergency situations and are called emergency hormones or hormones of Fight or Flight.

In humans, four parathyroid glands are present on the back side of the thyroid gland, one pair each in the two lobes of the thyroid gland. The parathyroid glands secrete a peptide hormone called parathyroid hormone (PTH). The secretion of PTH is regulated by the circulating levels of calcium ions. Parathyroid hormone (PTH) increases the Ca2+ levels in the blood. PTH acts on bones and stimulates the process of bone resorption (dissolution/ demineralisation). PTH also stimulates reabsorption of Ca2+ by the renal tubules and increases Ca2+ absorption from the digested food. It is, thus, clear that PTH is a hypercalcemic hormone, i.e., it increases the blood Ca2+ levels. Along with TCT, it plays a significant role in calcium balance in the body.

Addison's disease is a condition caused by a deficiency of hormones produced by the adrenal cortex. This condition affects the body's ability to respond to stress and maintain various physiological functions.

• The adrenal cortex produces essential hormones, including cortisol and aldosterone.
• A lack of these hormones can lead to symptoms such as:
• Fatigue and weakness
• Weight loss
• Low blood pressure
• Darkening of the skin
• It is important to diagnose Addison's disease early to manage symptoms effectively.

Treatment typically involves hormone replacement therapy to restore the levels of adrenal hormones in the body.

Topic in NCERT: Adrenal cortex

Line in NCERT: "underproduction of hormones by the adrenal cortex alters carbohydrate metabolism causing acute weakness and fatigue leading to a disease called addison's disease."