Endocrinology Practice Questions

Q: Which of the following inhibits appetite by counteracting the effects of neuropeptide Y?

Leptin. ***Leptin*** - **Leptin** is a hormone primarily produced by **adipose tissue** that signals satiety to the brain, effectively counteracting the appetite-stimulating effects of neuropeptide Y. - It acts on receptors in the **hypothalamus** to reduce food intake and increase energy expenditure, thereby inhibiting appetite. *Orexins* - **Orexins** (also known as hypocretins) are **neurotransmitters** involved in regulating **wakefulness** and appetite. - Their primary role related to appetite is typically to **stimulate hunger** and food seeking behavior, rather than inhibiting it. *Neuropeptide Y* - **Neuropeptide Y (NPY)** is a potent **orexigenic peptide**, meaning it **stimulates appetite** and food intake. - It promotes the consumption of carbohydrates and is a key mediator of hunger signals in the brain through its action on the **hypothalamus**. *Ghrelin* - **Ghrelin** is a hormone produced mainly in the **stomach** that acts as a strong **appetite stimulant**. - It is often referred to as the "**hunger hormone**" and its levels rise before meals, signaling the brain to initiate food seeking.

Q: Stress induced hyperglycemia is mediated through which hormone:

Cortisol. ***Cortisol*** - **Cortisol** is the **primary mediator** of stress-induced hyperglycemia among the counter-regulatory hormones - It promotes **gluconeogenesis** (formation of new glucose from amino acids and glycerol) in the liver - Stimulates **protein catabolism** in muscles, providing substrates for gluconeogenesis - Induces **insulin resistance** in peripheral tissues, reducing glucose uptake - Released as part of the **HPA axis response** to stress, with sustained elevation during prolonged stress - This is the **correct answer** for stress-induced hyperglycemia mediation *Epinephrine* - **Epinephrine** (adrenaline) is a potent hyperglycemic hormone but acts as an **acute, immediate response** to stress - Rapidly increases blood glucose through **glycogenolysis** (breakdown of glycogen) in liver and muscles - Stimulates **gluconeogenesis** and inhibits insulin secretion - Effects are **rapid but short-lived**, making it more of an emergency response rather than the sustained mediator - Works synergistically with cortisol but is not the primary sustained mediator *Growth hormone* - **Growth hormone** does contribute to hyperglycemia through **anti-insulin effects** and promoting lipolysis - Its hyperglycemic effects are **slower and less pronounced** compared to cortisol and epinephrine - Plays a role in **chronic stress** but is not the primary acute mediator - More important for **long-term metabolic adaptation** rather than immediate stress response *Insulin* - **Insulin** is a **glucose-lowering hormone** that facilitates glucose uptake into cells - During stress, insulin secretion is **suppressed** and tissues become **insulin-resistant** due to counter-regulatory hormones - It does **not mediate** stress-induced hyperglycemia; rather, its action is **opposed** by stress hormones - Decreased insulin action contributes to hyperglycemia but insulin itself is not the mediator

Q: Calcium absorption is affected by-

All of the options. ***All of the options*** - **Calcitriol**, **parathyroid hormone (PTH)**, and **proteins** all play crucial roles in regulating calcium absorption and metabolism. - While calcitriol directly enhances intestinal calcium absorption, PTH indirectly influences it via calcitriol synthesis, and proteins are necessary for calcium transport and binding. *Calcitriol* - **Calcitriol** (1,25-dihydroxyvitamin D3) is the hormonally active form of vitamin D, which is essential for stimulating calcium absorption in the intestine. - It increases the synthesis of **calcium-binding proteins (calbindins)** in enterocytes, facilitating calcium uptake. *PTH* - **Parathyroid hormone (PTH)** primarily regulates calcium levels by stimulating its release from bone and increasing reabsorption in the kidneys. - It also indirectly enhances intestinal calcium absorption by stimulating the **renal conversion of 25-hydroxyvitamin D to calcitriol**. *Proteins* - Various **proteins** are involved in calcium transport and absorption, including calcium-binding proteins (e.g., calbindin) in the gut. - Dietary protein intake can also influence calcium balance; however, specific mechanisms regarding direct absorption are more complex and indirect compared to calcitriol.

Q: In trauma, which of the following hormones is/are increased? a) Epinephrine b) ACTH c) Glucagon d) Parathormone

abc. ***abc*** - Trauma is a significant stressor that triggers the release of **epinephrine** (a), **ACTH** (b), and **glucagon** (c) as part of the body's **fight-or-flight response** and metabolic adaptation. - **Epinephrine** increases heart rate, blood pressure, and mobilizes energy stores; **ACTH** stimulates cortisol release to manage stress and inflammation; **glucagon** mobilizes glucose to provide energy for tissues. - **Parathormone** (d) is NOT significantly increased in acute trauma as it primarily regulates calcium homeostasis, not the acute stress response. *bc* - This option is incomplete as **epinephrine** (a) is also significantly increased during trauma due to the activation of the sympathetic nervous system. - While **ACTH** and **glucagon** are elevated, failing to include epinephrine underestimates the full hormonal response to trauma. *acd* - This option incorrectly includes **parathormone** (d) as a primary hormone elevated in acute trauma. While calcium regulation is important, parathormone's immediate increase is not a hallmark of the acute stress response. - It also omits **ACTH** (b), which is a key hormone in the stress axis response. *bcd* - This option incorrectly includes **parathormone** (d) which does not typically show a significant immediate increase during acute trauma. - It also omits **epinephrine** (a), a crucial component of the acute stress response mediated by sympathetic activation.

Q: Mineralocorticoid receptors are present in all of the following sites, Except:

Liver. ***Liver*** - Among the options listed, the liver has the **least prominent and least classical expression** of mineralocorticoid receptors (MRs) compared to the other sites. - While hepatocytes do express MRs, the liver is primarily known for **metabolizing aldosterone and other steroids** rather than being a primary classical target organ for mineralocorticoid action. - The physiological significance of hepatic MRs is an area of ongoing research, with roles in gluconeogenesis and metabolic regulation being explored. *Colon* - The colon is a **classical target organ** with prominent expression of **mineralocorticoid receptors (MRs)** in epithelial cells. - MRs in the colon mediate **sodium and water absorption**, particularly in the distal colon, contributing to fluid and electrolyte balance. *Kidney* - The kidney is the **primary and most well-established target organ** for mineralocorticoids, with abundant **MRs** in the distal tubules and collecting ducts. - These receptors mediate **sodium reabsorption** and **potassium/hydrogen ion excretion**, playing a central role in blood pressure regulation and electrolyte homeostasis. *Hippocampus* - The hippocampus contains a **high concentration of mineralocorticoid receptors (MRs)**, making it an important extrarenal target. - Hippocampal MRs are involved in **cognitive functions**, **stress response**, **mood regulation**, and neuroplasticity, modulating the effects of corticosteroids on the central nervous system.

Q: Insulin increases the entry of glucose into which tissue primarily?

Skeletal muscle. ***Skeletal muscle*** - Insulin significantly increases glucose uptake into **skeletal muscle** and adipose tissue by triggering the translocation of **GLUT4 transporters** to the cell membrane. - Skeletal muscle is the **primary site** for insulin-mediated glucose disposal, accounting for approximately **80% of postprandial glucose uptake** due to its large mass. - This is a key mechanism for **glucose disposal** from the blood, especially after a meal. *The mucosa of the small intestine* - Glucose absorption in the small intestine occurs via **SGLT1** and **GLUT2 transporters**, processes that are largely **insulin-independent**. - Small intestinal mucosal cells are responsible for absorbing dietary glucose, not for insulin-stimulated glucose uptake from the bloodstream. *Renal tubular cells* - Glucose reabsorption in renal tubules occurs primarily through **SGLT1** and **SGLT2 transporters** in the kidneys. - These processes are **insulin-independent** and are responsible for recovering glucose from the filtrate back into the blood. *All tissues* - While many tissues use glucose, not all of them rely on insulin to facilitate its entry. For example, the **brain**, liver, and **red blood cells** have insulin-independent glucose uptake mechanisms. - Only tissues like skeletal muscle and adipose tissue are **insulin-sensitive**, meaning their glucose uptake is directly stimulated by insulin via GLUT4 translocation.

Q: Insulin dependent glucose uptake occurs in:

Muscle. ***Muscle*** - **Insulin** stimulates glucose uptake in **muscle cells** by promoting the translocation of **GLUT4 transporters** to the cell surface. - This process is crucial for removing glucose from the blood and storing it as **glycogen** in muscle tissue. - Along with **adipose tissue**, muscle is one of the **primary sites of insulin-dependent glucose uptake** in the body. *Brain* - The brain primarily uses **GLUT1** and **GLUT3 transporters** for glucose uptake, which are **insulin-independent**. - These transporters are always active, ensuring a continuous supply of glucose to the brain, regardless of insulin levels. *Epithelial cells of small intestine* - Glucose absorption in the small intestine initially occurs via **SGLT1** (sodium-glucose co-transporter 1) at the apical membrane and then exits into the bloodstream via **GLUT2** at the basolateral membrane. - This process is mainly regulated by the concentration gradient of glucose and sodium, not directly by **insulin**. *Kidney* - The kidneys reabsorb glucose from the filtrate primarily via **SGLT1** and **SGLT2** transporters in the renal tubules. - This reabsorption mechanism is **insulin-independent** and aims to conserve glucose, preventing its loss in urine.

Q: Hyperthyroid state is characterized by -

Lipolysis. ***Lipolysis (Correct)*** - **Thyroid hormones** have potent **lipolytic effects**, stimulating the breakdown of **triglycerides** into free fatty acids and glycerol - This increased fat catabolism is a key metabolic feature of hyperthyroidism and contributes to the **weight loss** commonly observed despite increased appetite - Enhanced lipolysis also explains the increased free fatty acid levels seen in hyperthyroid patients *Decreased glycolysis (Incorrect)* - **Thyroid hormones** increase overall metabolic rate, including **carbohydrate metabolism** - **Glycolysis** (glucose breakdown) is typically **increased**, not decreased, in hyperthyroid states - This increased glucose utilization contributes to the hypermetabolic state *Increased cholesterol (Incorrect)* - **Thyroid hormones** accelerate both the synthesis and catabolism of cholesterol, with a net effect of **increased cholesterol degradation and excretion** - **Serum cholesterol levels** are typically **decreased** in hyperthyroidism (often used as a metabolic marker) - Conversely, hypothyroidism is associated with hypercholesterolemia *Increased protein synthesis (Incorrect)* - While physiological levels of thyroid hormones support anabolic processes, **excessive thyroid hormone levels** in hyperthyroidism create a net **catabolic state** - This results in increased **protein breakdown (proteolysis)** exceeding synthesis - Clinical manifestations include **muscle weakness, muscle wasting**, and negative nitrogen balance

Q: Which gland secretes calcitonin for regulation of calcium metabolism?

Thyroid gland. ***Thyroid gland*** - The **thyroid gland** contains specialized cells called **parafollicular cells** or C cells, which are responsible for secreting **calcitonin**. - **Calcitonin** plays a role in calcium metabolism by **lowering blood calcium levels** when they are too high, primarily by inhibiting osteoclast activity and stimulating calcium excretion by the kidneys. *Parathyroid gland* - The **parathyroid glands** secrete **parathyroid hormone (PTH)**, which has the opposite effect of calcitonin. - **PTH** acts to **raise blood calcium levels** by promoting bone resorption, increasing calcium reabsorption in the kidneys, and stimulating vitamin D activation. *None of the glands* - This option is incorrect because the **thyroid gland** is directly involved in producing calcitonin, a key hormone for calcium regulation. - Hormonal regulation of calcium is a vital physiological process orchestrated by specific endocrine glands. *Both glands* - While both the thyroid and parathyroid glands are crucial for **calcium homeostasis**, they secrete different hormones with opposing functions. - The thyroid secretes **calcitonin**, while the parathyroid secretes **parathyroid hormone**; they do not both secrete calcitonin.

Q: Melatonin is secreted from which cells of pineal gland?

Pinealocytes. ***Pinealocytes*** - **Pinealocytes** are the primary secretory cells within the **pineal gland** responsible for synthesizing and secreting **melatonin**. - These cells exhibit rhythmic activity, secreting more melatonin during periods of **darkness** to regulate the **sleep-wake cycle**. *Glial cells* - **Glial cells** (specifically astroglial cells and microglial cells) are present in the pineal gland but primarily provide **structural support** and **immune surveillance**, not melatonin synthesis. - Their main function is to maintain the **neural environment** and respond to injury or infection. *Zymogen cells* - **Zymogen cells** are typically found in glands like the pancreas or stomach, where they secrete **inactive enzyme precursors**. - They are not associated with the pineal gland or **melatonin production**. *Oncocytes* - **Oncocytes** are cells characterized by abundant **mitochondria** and are typically found in endocrine glands like the thyroid or parathyroid, often in **neoplastic conditions**. - They are not the **normal secretory cells** of the pineal gland.

Question 1

Which of the following inhibits appetite by counteracting the effects of neuropeptide Y?

Accepted Answer

Leptin

Answer

Orexins

Answer

Neuropeptide Y

Answer

Ghrelin

Question 2

Stress induced hyperglycemia is mediated through which hormone:

Accepted Answer

Cortisol

Answer

Epinephrine

Answer

Insulin

Answer

Growth hormone

Question 3

Calcium absorption is affected by-

Accepted Answer

All of the options

Answer

Calcitriol

Answer

PTH

Answer

Proteins

Question 4

In trauma, which of the following hormones is/are increased?
a) Epinephrine
b) ACTH
c) Glucagon
d) Parathormone

Accepted Answer

abc

Answer

bc

Answer

acd

Answer

bcd

Question 5

Mineralocorticoid receptors are present in all of the following sites, Except:

Accepted Answer

Liver

Answer

Colon

Answer

Kidney

Answer

Hippocampus

Question 6

Insulin increases the entry of glucose into which tissue primarily?

Accepted Answer

Skeletal muscle

Answer

The mucosa of the small intestine

Answer

Renal tubular cells

Answer

All tissues

Question 7

Insulin dependent glucose uptake occurs in:

Accepted Answer

Muscle

Answer

Brain

Answer

Epithelial cells of small intestine

Answer

Kidney

Question 8

Hyperthyroid state is characterized by -

Accepted Answer

Lipolysis

Answer

Decreased glycolysis

Answer

Increased cholesterol

Answer

Increased protein synthesis

Question 9

Which gland secretes calcitonin for regulation of calcium metabolism?

Accepted Answer

Thyroid gland

Answer

Parathyroid gland

Answer

None of the glands

Answer

Both glands

Question 10

Melatonin is secreted from which cells of pineal gland?

Accepted Answer

Pinealocytes

Answer

Glial cells

Answer

Zymogen cells

Answer

Oncocytes

Endocrinology — MCQs

Endocrinology — MCQs

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