NEET-PG 2013 Practice Questions

Q: What is the approximate ratio of connective tissue to smooth muscle in the cervix?

Approximately 8:1. ***Approximately 8:1*** - The **cervix** is predominantly composed of **fibrous connective tissue**, which provides its structural integrity and rigidity [1]. - This high ratio of **collagenous connective tissue** to smooth muscle is crucial for maintaining pregnancy and undergoing significant remodeling during parturition [1]. - The approximate ratio is **8:1 to 10:1**, with connective tissue forming about 85-90% of cervical tissue [1]. *2:1* - This ratio would imply a significantly higher proportion of **smooth muscle** (33%), making the cervix much more muscular and less fibrous than it actually is. - Such a composition would compromise the cervical function of maintaining a **closed uterine orifice** during pregnancy. *5:1* - While higher than 2:1, this ratio still underestimates the true dominance of **connective tissue** in the cervical structure. - The **cervix's mechanical properties**, including its ability to resist stretching, are primarily due to its abundant collagen content. *15:1* - This ratio overestimates the proportion of connective tissue, suggesting less than 7% smooth muscle. - While the cervix is indeed fibrous, it does contain a modest amount of **smooth muscle** (10-15%) particularly in the internal os region, making this ratio too extreme [1].

Q: Which organ is primarily supplied by the portal vein?

Liver. ***Liver*** - The **portal vein** is unique in that it carries **nutrient-rich, deoxygenated blood** from the gastrointestinal tract and spleen directly to the liver [1], [2]. - This specialized circulation allows the liver to **process absorbed nutrients** and detoxify harmful substances before they enter the systemic circulation [1], [3]. *Spleen* - The spleen is supplied by the **splenic artery**, a branch of the **celiac trunk**, which carries oxygenated arterial blood to the organ. - While the splenic vein drains into the portal vein, the portal vein itself does not primarily supply the spleen [2]. *Pancreas* - The pancreas receives its blood supply from branches of the **celiac artery** and the **superior mesenteric artery**, specifically the splenic, gastroduodenal, and superior mesenteric arteries [1]. - While pancreatic veins drain into the portal system, the portal vein is not the primary arterial supply to the pancreas [1]. *Colon* - The colon is supplied by the **superior mesenteric artery** and the **inferior mesenteric artery**, which provide oxygenated arterial blood to different segments of the large intestine. - The venous drainage from the colon primarily collects into the superior and inferior mesenteric veins, which then merge to form part of the portal venous system, but the portal vein does not primarily supply the colon with blood [2].

Q: Helicine arteries are branches of which artery?

Internal pudendal artery. ***Internal pudendal artery*** - The **internal pudendal artery** is the primary arterial supply to the external genitalia, and its branches, including the **helicine arteries**, are crucial for erectile function. - In males, these arteries supply the **corpus cavernosa** of the penis, and in females, they supply the **clitoris**, playing a key role in sexual arousal. *Femoral artery* - The **femoral artery** is a large artery in the thigh that supplies blood to the lower limb, but it does not directly branch into the helicine arteries of the genitalia. - Its main branches include the **deep femoral artery** and the **superficial femoral artery**, which are involved in blood supply to the muscles and skin of the thigh. *External pudendal artery* - The **external pudendal artery** branches off the femoral artery and supplies the skin of the external genitalia and the perineum, but not the deeper erectile tissues via helicine arteries. - It primarily provides superficial blood supply, such as to the **scrotum** or **labia majora**, and is distinct from the internal pudendal artery's deeper distribution. *None of the options* - This option is incorrect because the **internal pudendal artery** is indeed the origin of the helicine arteries. - The other options provided are incorrect as they do not directly give rise to the helicine arteries.

Q: Which testis is typically positioned higher?

Right testis. ***Right testis*** - The **right testis** is commonly positioned slightly higher than the left testis in most males [1]. - This anatomical variation is due to the **left spermatic cord** being inherently longer, which allows the left testis to hang lower. *Left testis* - The **left testis** is typically positioned lower than the right testis. - Its lower position is attributed to the generally **longer left spermatic cord**. *It varies between individuals* - While minor individual variations exist, a consistent pattern of the **right testis** being higher is observed in the majority of males. - The differences in cord length lead to a general trend, not complete randomness in height. *Both are at the same level* - It is uncommon for both testes to be at precisely the **same level**. - The **asymmetrical length** of the spermatic cords makes equal positioning rare.

Q: Carbonic anhydrase activity is found in all of the following except?

Plasma. ***Plasma*** - **Carbonic anhydrase** is an intracellular enzyme that catalyzes the rapid interconversion of carbon dioxide and water to carbonic acid, **bicarbonate**, and protons. - It is notably **absent in plasma** in healthy individuals, as it is primarily found within cells where its function is crucial for pH regulation and CO2 transport. *Brain* - Carbonic anhydrase is found in various brain cells, including **neurons**, **oligodendrocytes**, and **astrocytes**. - It plays a vital role in pH regulation, fluid balance, and the production of cerebrospinal fluid (CSF) within the **central nervous system**. *Kidney* - The kidney is rich in carbonic anhydrase, particularly in the **proximal tubules** and collecting ducts. - It is critical for **bicarbonate reabsorption** and proton excretion, essential processes for maintaining acid-base balance. *RBC* - **Red blood cells (RBCs)** contain a high concentration of carbonic anhydrase (specifically CA-I and CA-II isoforms). - This enzyme facilitates the rapid conversion of CO2 to bicarbonate for transport to the lungs and the reverse reaction for **CO2 exhalation**.

Q: What does spermiogenesis refer to?

Formation of spermatozoa from spermatids. ***Formation of spermatozoa from spermatids*** - **Spermiogenesis** is the final stage of spermatogenesis, involving the remarkable transformation of a round **spermatid** into a motile, mature **spermatozoon**. - This process includes crucial morphological changes such as the formation of the **acrosome**, condensation of the nucleus, development of the flagellum, and shedding of excess cytoplasm. *Formation of spermatozoa from spermatogonia* - This describes the entire process of **spermatogenesis**, which begins with **spermatogonia** and encompasses multiple stages including mitosis, meiosis, and spermiogenesis. - While it's the ultimate outcome, it doesn't specifically define the detailed transformation from spermatid to sperm. *Formation of spermatids from spermatocytes* - This stage refers to **meiosis II**, where **secondary spermatocytes** undergo division to produce **spermatids**. - Spermatids are precursors to spermatozoa and still require significant morphological changes to become mature sperm. *Formation of secondary spermatocytes from primary spermatocytes* - This describes **meiosis I**, where a **primary spermatocyte** divides to form two **secondary spermatocytes**. - This step reduces the chromosome number by half but doesn't involve the final morphological changes seen in spermiogenesis.

Q: Which of the following does not stimulate growth hormone (GH) release?

Free fatty acids. ***Free fatty acids*** - High levels of **free fatty acids** in the bloodstream inhibit growth hormone (GH) secretion. - This occurs through a **negative feedback loop** at the level of the hypothalamus and pituitary gland. *Fasting* - **Fasting** (especially prolonged) is a potent stimulus for GH release, helping to mobilize fat stores and maintain **glucose homeostasis**. - During fasting, ghrelin levels increase, which further promotes GH secretion. *Exercise* - **Physical exercise** is a well-known physiological stimulus for GH release, contributing to muscle growth and repair. - The intensity and duration of exercise can influence the magnitude of GH secretion. *Stress* - Various forms of **stress**, including physical (e.g., trauma, surgery) and psychological stress, stimulate GH release. - This response is mediated in part by the **sympathetic nervous system** and increased cortisol levels.

Q: Most common type of calcium channels of skeletal muscles is?

L-type. ***L type*** - **L-type calcium channels**, also known as **dihydropyridine receptors (DHPRs)**, are the predominant type of calcium channel found in skeletal muscle. - In skeletal muscle, they serve as voltage sensors that **mechanically link** to ryanodine receptors (RyRs) on the sarcoplasmic reticulum to trigger calcium release without significant calcium influx from the extracellular space. *N-type* - **N-type calcium channels** are primarily found in **neurons** and play a crucial role in neurotransmitter release at synapses. - They are not the primary calcium channels involved in skeletal muscle excitation-contraction coupling. *T-type* - **T-type calcium channels** are low-voltage activated channels found in various excitable cells, including cardiac muscle and neurons, where they contribute to **pacemaker activity** and repetitive firing. - They are not the main calcium channels responsible for excitation-contraction coupling in skeletal muscle. *R-type* - **R-type calcium channels** are found in various neural cells and are involved in diverse functions, including **synaptic transmission**, but their precise physiological role is less clearly defined compared to other types. - These channels are not the primary calcium entry pathways in skeletal muscle and do not play a significant role in its contraction.

Q: What is the effect of moderate exercise on cerebral blood flow?

Increases. ***Increases*** - Moderate exercise leads to an **increase in systemic arterial pressure** and an increase in **cardiac output**, which often results in a moderate increase in cerebral blood flow. - This increase is also attributed to **vasodilation of cerebral arteries** in response to metabolic demands and changes in blood gas levels during exercise. *Decreases* - A decrease in cerebral blood flow is generally associated with conditions leading to **hypoperfusion** or **severe vasoconstriction**, which are not typical effects of moderate exercise. - While extreme exercise could potentially cause some transient vasoconstriction, moderate exercise typically has the opposite effect due to compensatory mechanisms. *Initially decreases then increases* - There is generally no physiological mechanism by which moderate exercise would cause an initial decrease in cerebral blood flow followed by an increase. - Cerebral autoregulation usually maintains a stable blood flow, and the overall trend with moderate exercise is an increase. *Does not change* - While **cerebral autoregulation** aims to keep cerebral blood flow stable over a range of blood pressures, moderate exercise often pushes parameters (like CO2 levels and systemic pressure) enough to cause a measurable, albeit modest, **increase in blood flow**. - The brain's metabolic demand also increases during exercise, necessitating an increased blood supply.

Q: What is the role of gap junctions in cardiac muscle function?

Facilitate impulse transmission between cardiac myocytes. ***Facilitate impulse transmission between cardiac myocytes*** - **Gap junctions** are specialized channels between adjacent cells that allow for direct communication and rapid movement of **ions** and small molecules. - In cardiac muscle, they form an essential part of **intercalated discs**, enabling the heart to function as a **syncytium** by allowing electrical impulses to spread quickly from one myocyte to another. *Are not found in cardiac muscles* - This statement is incorrect; **gap junctions** are a defining feature of **cardiac muscle** and are crucial for its coordinated contraction. - They are located within the **intercalated discs** that connect individual cardiac muscle cells. *Are not found in smooth muscles* - This statement is incorrect; **gap junctions** are indeed found in **smooth muscle**, particularly in single-unit smooth muscle, where they contribute to synchronized contractions, such as in the **gastrointestinal tract**. - They allow for the rapid propagation of electrical signals, leading to coordinated muscle activity. *Have no significant role in cardiac muscle function* - This statement is incorrect; **gap junctions** play a critically significant role in cardiac muscle function by ensuring the **rapid and synchronized spread of electrical impulses**. - Without functional gap junctions, the heart would not be able to contract efficiently or effectively as a pump.

Question 1

What is the approximate ratio of connective tissue to smooth muscle in the cervix?

Accepted Answer

Approximately 8:1

Answer

2:1

Answer

5:1

Answer

15:1

Question 2

Which organ is primarily supplied by the portal vein?

Accepted Answer

Liver

Answer

Spleen

Answer

Pancreas

Answer

Colon

Question 3

Helicine arteries are branches of which artery?

Accepted Answer

Internal pudendal artery

Answer

None of the options

Answer

Femoral artery

Answer

External pudendal artery

Question 4

Which testis is typically positioned higher?

Accepted Answer

Right testis

Answer

It varies between individuals

Answer

Left testis

Answer

Both are at the same level

Question 5

Carbonic anhydrase activity is found in all of the following except?

Accepted Answer

Plasma

Answer

Brain

Answer

Kidney

Answer

RBC

Question 6

What does spermiogenesis refer to?

Accepted Answer

Formation of spermatozoa from spermatids

Answer

Formation of spermatozoa from spermatogonia

Answer

Formation of spermatids from spermatocytes

Answer

Formation of secondary spermatocytes from primary spermatocytes

Question 7

Which of the following does not stimulate growth hormone (GH) release?

Accepted Answer

Free fatty acids

Answer

Exercise

Answer

Fasting

Answer

Stress

Question 8

Most common type of calcium channels of skeletal muscles is?

Accepted Answer

L-type

Answer

N-type

Answer

T-type

Answer

R-type

Question 9

What is the effect of moderate exercise on cerebral blood flow?

Accepted Answer

Increases

Answer

Decreases

Answer

Initially decreases then increases

Answer

Does not change

Question 10

What is the role of gap junctions in cardiac muscle function?

Accepted Answer

Facilitate impulse transmission between cardiac myocytes

Answer

Are not found in cardiac muscles

Answer

Are not found in smooth muscles

Answer

Have no significant role in cardiac muscle function

NEET-PG 2013

Anatomy

Biochemistry

Physiology