NEET-PG 2012 Practice Questions

Q: Blastocyst makes contact with endometrium on ?

5 - 7 days. ***5-7 days*** - The **blastocyst makes initial contact** (apposition) with the **endometrium** around **day 5-6 after fertilization**. - **Implantation**, which includes adhesion and invasion, typically begins around day 6 and is complete by day 10. - This timeframe allows the blastocyst to travel from the fallopian tube to the uterus and for the uterine lining to be optimally prepared. *< 3 days* - Within the first few days after fertilization, the zygote is still undergoing **cleavage** and development into a **morula**, then a young blastocyst, while traveling down the fallopian tube. - It has not yet reached the uterus or developed sufficiently to interact with the endometrium. *8-11 days* - By 8-11 days, the process of implantation is usually **well underway or completed**, with the blastocyst already invading the endometrial wall. - Initial contact and attachment occur prior to this period. *15-16 days* - This timeframe is well beyond the typical window for initial blastocyst contact and implantation. - By 15-16 days post-fertilization, the embryo would be undergoing **gastrulation** and early organogenesis, assuming successful implantation.

Q: Which is derived from Wolffian duct?

Appendix of epididymis. The **appendix of the epididymis** is a vestigial structure directly derived from the mesonephric (Wolffian) duct in males. It is an embryological remnant of this duct, located at the head of the epididymis. *Appendix of the testis* - The **appendix of the testis** (hydatid of Morgagni) is a remnant of the paramesonephric (Müllerian) duct, not the Wolffian duct. - It is usually found on the upper pole of the testis, typically near the epididymis. *Uterine structure* - **Uterine structures** (uterus, fallopian tubes, and upper vagina) are derived from the paramesonephric (Müllerian) ducts in females [1]. - The Wolffian ducts largely regress in females due to the absence of testosterone. *Hydatid of Morgagni* - The term **hydatid of Morgagni** can refer to the appendix of the testis (Müllerian duct remnant) or, less commonly, to the appendix of the epididymis (Wolffian duct remnant). - However, in common clinical and anatomical usage, it almost exclusively refers to the **appendix of the testis**, which is a Müllerian duct derivative.

Q: What is the preferred site for intramuscular injection in the gluteus muscle?

Superolateral. ***Superolateral*** - This quadrant is preferred because it avoids the **sciatic nerve** and major **blood vessels**, minimizing the risk of injury. - The muscle mass in this region, primarily the **gluteus medius**, is sufficient for medication absorption. *Inferomedial* - This area carries a high risk of damaging the **sciatic nerve**, which runs through the lower, medial part of the gluteus. - Injecting here can also hit major **blood vessels**, leading to bleeding or hematoma. *Superomedial* - While somewhat safer than the inferomedial quadrant, this area is still closer to the **sciatic nerve** exit point and major vessels compared to the superolateral region. - The muscle bulk is also less prominent here compared to the superolateral aspect. *Inferolateral* - This quadrant is still in the vicinity of the **sciatic nerve** and major blood vessels, making it riskier than the superolateral site. - There is less muscle mass here compared to the superior quadrants, which can lead to improper drug absorption.

Q: Sympathetic supply to the heart arises from which of the following spinal segments?

T1 to T5. The preganglionic sympathetic fibers that innervate the heart originate from the lateral horns of the thoracic spinal segments T1 to T5. These fibers synapse in the cervical and upper thoracic sympathetic ganglia, from which postganglionic fibers extend to the heart. While there is some overlap, the primary and most significant sympathetic innervation to the heart stems predominantly from T1 to T5, making T2 to T6 a less precise answer. Including T6 would extend past the typical primary cardiac sympathetic innervation, which largely concludes at T5. This range is too caudal and largely beyond the principal segments providing sympathetic innervation to the heart. Segments T6-T8 are more involved in sympathetic supply to abdominal organs and other structures rather than direct cardiac control.

Q: Which structure is located immediately posterior to the head of the pancreas?

Portal vein. ***Portal vein*** - The **portal vein** is formed by the union of the **splenic vein** and the **superior mesenteric vein** (SMV) posterior to the **neck** of the pancreas [1]. - It then runs in a **groove on the posterior surface** of the head of the pancreas, lying anterior to the **inferior vena cava** (IVC). - Among the given options, the portal vein has the most direct posterior relationship to the head of the pancreas. *Splenic artery* - The **splenic artery** runs along the **superior border** of the pancreas, following its body and tail. - It does not lie posterior to the head of the pancreas. - It is a branch of the **celiac trunk** and supplies the spleen. *Inferior mesenteric vein* - The **inferior mesenteric vein** typically drains into the **splenic vein** or the junction of the splenic and superior mesenteric veins. - It ascends **anterior** to the left kidney and does not lie immediately posterior to the head of the pancreas. *Coeliac trunk* - The **celiac trunk** originates from the **abdominal aorta** at the level of T12-L1 vertebra. - It lies **superior and anterior** to the pancreas, giving off the splenic artery, common hepatic artery, and left gastric artery. - It is not located posterior to the head of the pancreas.

Q: Ophthalmic artery is a branch of:

Cerebral part of ICA. ***Cerebral part of ICA*** - The **ophthalmic artery** is typically the first major branch off the **internal carotid artery (ICA)** once it exits the cavernous sinus and enters the cranial cavity. - This segment of the ICA is also known as the supraclinoid or **cerebral part**, underscoring its proximity to the brain. *Cavernous part of ICA* - The **cavernous part of the ICA** is located within the cavernous sinus and typically gives off smaller branches such as the **meningohypophyseal trunk** and the **inferolateral trunk**, which supply structures within and around the sinus. - The ophthalmic artery emerges after the ICA exits the cavernous sinus, not from within it. *MCA* - The **middle cerebral artery (MCA)** is a major terminal branch of the internal carotid artery, supplying large parts of the cerebrum. - It does not give rise to the ophthalmic artery, which branches off the ICA before the ICA bifurcates into the MCA and anterior cerebral artery. *Facial artery* - The **facial artery** is a branch of the **external carotid artery**, supplying structures of the face. - The ophthalmic artery is a primary supply to the orbit and is derived from the internal carotid artery, a completely separate vascular system.

Q: In walking, gravity tends to tilt pelvis and trunk to the unsupported side, the major factor in preventing this unwanted movement is?

Gluteus medius and minimus. ***Gluteus medius and minimus*** - The **gluteus medius** and **gluteus minimus** are essential **abductors** of the hip, primarily responsible for stabilizing the pelvis during the **single-limb support phase of gait**. - When one leg is lifted during walking, these muscles on the **stance leg side** contract to prevent the pelvis from tilting downwards on the unsupported swing leg side. *Adductor muscles* - **Adductor muscles** (adductor longus, brevis, magnus, pectineus, gracilis) primarily function to bring the thigh toward the midline of the body. - While they play a role in gait stability, their main action is not to prevent the lateral pelvic tilt described. *Quadriceps* - The quadriceps femoris group (rectus femoris, vastus lateralis, medialis, intermedius) are powerful **extensors of the knee**. - They are crucial for weight acceptance and propulsion during walking but do not directly prevent lateral pelvic tilt [1]. *Gluteus maximus* - The **gluteus maximus** is the largest and most powerful muscle of the hip, primarily responsible for **hip extension** and **external rotation**. - It is crucial for activities like climbing stairs or running, but its main role in normal walking is not to prevent lateral pelvic tilt; that function is more specific to the gluteus medius and minimus.

Q: Nonshivering thermogenesis in adults is due to:

Brown fat between the shoulders. ***Brown fat between the shoulders*** - In adults, the primary **effector tissue** for **non-shivering thermogenesis** is **brown adipose tissue (BAT)**, with major depots located between the shoulders, around the neck, and along the spine. - **BAT** contains specialized mitochondria with **uncoupling protein 1 (UCP1)** that uncouples oxidative phosphorylation, generating heat instead of ATP. - This is the tissue where non-shivering thermogenesis actually occurs, making it the direct answer to what non-shivering thermogenesis is "due to." *Noradrenaline* - **Noradrenaline** is the key neurotransmitter that **activates brown fat** via **β3-adrenergic receptors** to initiate non-shivering thermogenesis. - While noradrenaline is the **trigger/stimulus**, the actual heat production occurs in brown adipose tissue. - Noradrenaline itself does not produce heat directly; it acts as the signal that activates the thermogenic machinery in BAT. *Thyroid hormone* - **Thyroid hormone** increases **basal metabolic rate** and can potentiate the thermogenic response by upregulating UCP1 expression in brown fat. - Its role is **permissive and long-term** rather than being the immediate effector of acute non-shivering thermogenesis. - It modulates overall cellular metabolism but is not the primary mechanism for rapid heat generation in cold exposure. *Muscle metabolism* - **Muscle contraction** during shivering generates heat through increased ATP hydrolysis, which is **shivering thermogenesis**. - **Non-shivering thermogenesis** specifically refers to heat production **without muscle contraction**, making muscle metabolism the mechanism for shivering, not non-shivering, thermogenesis.

Q: Which of the following is NOT a location where multi-unit smooth muscle is present?

Gut. ***Gut*** - The gut primarily contains **unitary (single-unit) smooth muscle**, characterized by cells connected by **gap junctions** that allow for synchronized contractions (e.g., peristalsis). - This type of smooth muscle exhibits **spontaneous rhythmic contractions** due to pacemaker cells, and its activity is modulated by neural and hormonal inputs rather than requiring individual innervation of each cell. - Multi-unit smooth muscle is **NOT present** in the gut. *Blood vessels* - Many larger blood vessels (e.g., large arteries) contain **multi-unit smooth muscle**, which allows for **fine, graded control** over vascular tone and blood flow. - Each muscle cell is typically **innervated individually**, enabling precise regulation of contraction strength. *Iris* - The iris contains **multi-unit smooth muscle** (e.g., sphincter pupillae and dilator pupillae muscles) which control pupil size. - These muscles require **individual innervation** to allow for very fine and precise movements in response to light intensity changes. *Ciliary muscle* - The ciliary muscle of the eye contains **multi-unit smooth muscle**, which controls the shape of the lens for accommodation (focusing). - These muscle fibers are **individually innervated** to allow precise control of lens curvature for near and far vision.

Q: What is the primary mechanism of heat loss in a modern X-ray tube?

Radiation. ***Radiation*** - The **primary mechanism** of heat loss in a modern X-ray tube is **radiation** (infrared emission). - The anode surface reaches extremely high temperatures (>1000°C) during X-ray production, causing it to emit significant **infrared radiation**. - Modern X-ray tubes use **high-emissivity materials** (tungsten-rhenium alloys) on the anode to maximize radiative heat transfer. - Since the tube operates in a **vacuum**, radiation is the only effective mechanism for heat dissipation from the anode itself. *Evaporation* - **Evaporation** requires a liquid-to-gas phase change, which is not applicable in the solid-state environment of an X-ray tube anode. - The **vacuum environment** inside the tube prevents any evaporative cooling. - This mechanism is irrelevant for heat loss from the anode. *Conduction* - **Conduction** does transfer heat from the focal spot through the anode body to the rotor bearings. - However, this is heat transfer *within* the tube components, not the primary mechanism for heat loss *from the tube*. - Heat conducted through components must ultimately be dissipated by **radiation** (from anode) or **convection** (from housing via cooling oil). *Convection* - **Convection** requires fluid movement (liquid or gas), which cannot occur in the **vacuum** inside the X-ray tube envelope. - While cooling oil outside the tube uses convection to remove heat from the housing, this is secondary heat removal, not the primary mechanism of heat loss from the anode. - The anode loses heat primarily via **radiation** first, then that heat may be further managed by convection in the cooling system.

Question 1

Blastocyst makes contact with endometrium on ?

Accepted Answer

5 - 7 days

Answer

< 3 days

Answer

8 - 11 days

Answer

15-16 days

Question 2

Which is derived from Wolffian duct?

Accepted Answer

Appendix of epididymis

Answer

Appendix of the testis

Answer

Uterine structure

Answer

Hydatid of Morgagni

Question 3

What is the preferred site for intramuscular injection in the gluteus muscle?

Accepted Answer

Superolateral

Answer

Inferolateral

Answer

Superomedial

Answer

Inferomedial

Question 4

Sympathetic supply to the heart arises from which of the following spinal segments?

Accepted Answer

T1 to T5

Answer

T2 to T6

Answer

T3 to T7

Answer

T4 to T8

Question 5

Which structure is located immediately posterior to the head of the pancreas?

Accepted Answer

Portal vein

Answer

Splenic artery

Answer

Inferior mesenteric vein

Answer

Coeliac trunk

Question 6

Ophthalmic artery is a branch of:

Accepted Answer

Cerebral part of ICA

Answer

Cavernous part of ICA

Answer

MCA

Answer

Facial artery

Question 7

In walking, gravity tends to tilt pelvis and trunk to the unsupported side, the major factor in preventing this unwanted movement is?

Accepted Answer

Gluteus medius and minimus

Answer

Adductor muscles

Answer

Quadriceps

Answer

Gluteus maximus

Question 8

Nonshivering thermogenesis in adults is due to:

Accepted Answer

Brown fat between the shoulders

Answer

Muscle metabolism

Answer

Thyroid hormone

Answer

Noradrenaline

Question 9

Which of the following is NOT a location where multi-unit smooth muscle is present?

Accepted Answer

Gut

Answer

Blood vessels

Answer

Iris

Answer

Ciliary muscle

Question 10

What is the primary mechanism of heat loss in a modern X-ray tube?

Accepted Answer

Radiation

Answer

Evaporation

Answer

Conduction

Answer

Convection

NEET-PG 2012

Anatomy

Physiology

Radiology