Anatomy
5 questionsWhere is the Bartholin gland situated?
The thyrocervical trunk is a branch of which part of subclavian artery?
Waldeyer's fascia lies?
Corpora arenacea is seen in?
Which of the following is a tributary of the coronary sinus?
NEET-PG 2012 - Anatomy NEET-PG Practice Questions and MCQs
Question 161: Where is the Bartholin gland situated?
- A. Superficial perineal pouch (Correct Answer)
- B. Deep perineal pouch
- C. Inguinal canal
- D. Ischiorectal fossa
Explanation: ***Superficial perineal pouch*** - The **Bartholin glands** are located posterolateral to the vaginal orifice within the boundaries of the **superficial perineal pouch** [1]. - They are covered by the **bulbospongiosus muscle** and their ducts open into the vestibule of the vagina [1]. *Deep perineal pouch* - This pouch contains structures like the **urethra**, part of the **vagina**, and the **deep transverse perineal muscle**, but not the Bartholin glands [2]. - It is located superior to the superficial perineal pouch and separated by the **perineal membrane**. *Inguinal canal* - The **inguinal canal** is a passage in the anterior abdominal wall that transmits the **round ligament of the uterus** in females and the **spermatic cord** in males. - It is anatomically distinct from the perineum and does not house the Bartholin glands. *Ischiorectal fossa* - The **ischiorectal fossae** are fat-filled spaces located lateral to the anal canal, inferior to the levator ani muscles. - They are known for their susceptibility to abscess formation but do not contain the Bartholin glands.
Question 162: The thyrocervical trunk is a branch of which part of subclavian artery?
- A. 1st part (Correct Answer)
- B. 2nd part
- C. 3rd part
- D. 4th part
Explanation: ***1st part*** - The **thyrocervical trunk** is one of the three primary branches arising from the **first part** of the subclavian artery. - The first part lies medial to the **anterior scalene muscle**. *2nd part* - The **second part** of the subclavian artery gives rise to the **costocervical trunk**. - This part lies posterior to the **anterior scalene muscle**. *3rd part* - The **third part** of the subclavian artery typically has no branches or may give off the **dorsal scapular artery**. - This part lies lateral to the **anterior scalene muscle**. *4th part* - This option is incorrect as the **subclavian artery has only three parts**, divided by their relationship to the anterior scalene muscle. - There is no anatomical fourth part of the subclavian artery.
Question 163: Waldeyer's fascia lies?
- A. In front of the bladder.
- B. Behind the rectum. (Correct Answer)
- C. Between the bladder and uterus.
- D. Between the uterus and rectum.
Explanation: ***Behind the rectum*** - **Waldeyer’s fascia**, also known as the **sacrorectal fascia**, is a retrorectal connective tissue sheet located between the **rectum** and the **sacrum**. - It plays a crucial role in supporting the rectum and forms part of the posterior rectosacral space, separating the rectum from the sacral bone and nerves. *In front of the bladder* - The space in front of the bladder is typically referred to as the **retropubic space of Retzius**, containing loose connective tissue and fat. - No specific fascial layer named Waldeyer's fascia is located in this anterior position relative to the bladder. *Between the bladder and uterus* - This space, known as the **vesicouterine pouch** or **anterior cul-de-sac**, is a peritoneal reflection between the bladder and the uterus [1]. - It does not contain a structure known as Waldeyer's fascia. *Between the uterus and rectum* - This space is the **rectouterine pouch** or **Pouch of Douglas**, which is the deepest part of the peritoneal cavity in females [2]. - While important surgically, it does not correspond to the location of Waldeyer's fascia.
Question 164: Corpora arenacea is seen in?
- A. Pineal (Correct Answer)
- B. Seminal vesicle
- C. Breast
- D. Prostate
Explanation: ***Pineal*** - **Corpora arenacea**, also known as **brain sand**, are calcium deposits found in the pineal gland. - Their presence is a normal, age-related finding and increases with age, though their exact physiological role is not fully understood. *Prostate* - The prostate gland contains **corpora amylacea**, which are concentric calcifications found within the glandular acini. - While similar in appearance to corpora arenacea, they are distinct structures specific to the prostate. *Seminal vesicle* - The seminal vesicles produce a fluid component of semen, and while they may occasionally show calcifications, these are typically due to stones or chronic inflammation, not the characteristic "brain sand" seen in the pineal gland. - They do not contain corpora arenacea as a normal physiological feature. *Breast* - Calcifications in the breast are common and can be either benign (e.g., **fibrocystic changes**, vascular calcifications) or malignant (e.g., **ductal carcinoma in situ**). - These calcifications are generally not referred to as corpora arenacea and have different clinical implications and microscopic appearances.
Question 165: Which of the following is a tributary of the coronary sinus?
- A. Anterior cardiac vein
- B. Smallest cardiac vein
- C. Thebesian vein
- D. Great cardiac vein (Correct Answer)
Explanation: ***Great cardiac vein*** - The **great cardiac vein** is a major tributary that drains into the **coronary sinus**, carrying deoxygenated blood from the anterior and left ventricular walls [1]. - It travels alongside the **anterior interventricular artery** (LAD) and then wraps around the left side of the heart to join the coronary sinus [1]. *Anterior cardiac vein* - The **anterior cardiac veins** typically collect blood directly into the **right atrium**, bypassing the coronary sinus [1]. - They primarily drain the anterior wall of the right ventricle. *Thebesian vein* - **Thebesian veins** (or venae cordis minimae) are small veins that drain blood from the **myocardium directly into the heart chambers**, predominantly the atria [1]. - They represent a direct communication between the myocardial capillaries and the heart chambers, not tributaries of the coronary sinus. *Smallest cardiac vein* - The term "smallest cardiac vein" is often used synonymously with **Thebesian veins** [1]. - These veins empty directly into the **heart chambers**, serving as an ancillary drainage system, rather than converging into the coronary sinus.
Biochemistry
3 questionsWhich isoenzyme of lactate dehydrogenase (LDH) is predominantly elevated in liver injury?
Which of the following pairs of compounds has the highest standard reduction potential?
Fluoroacetate inhibits?
NEET-PG 2012 - Biochemistry NEET-PG Practice Questions and MCQs
Question 161: Which isoenzyme of lactate dehydrogenase (LDH) is predominantly elevated in liver injury?
- A. LDH-3
- B. LDH-5 (Correct Answer)
- C. LDH-1
- D. LDH-2
Explanation: ***LDH-5 isoenzyme most significant in hepatic conditions*** - **LDH-5** is the predominant isoenzyme found in the **liver** and skeletal muscle. - An elevation of **LDH-5** is highly indicative of **hepatocellular damage** or injury. *LDH-1 isoenzyme associated with cardiac tissue* - **LDH-1** is primarily present in the **heart** and red blood cells. - Its elevation suggests conditions like **myocardial infarction** or hemolytic anemia, not liver injury. *LDH-3 isoenzyme typical in respiratory system* - **LDH-3** is found in the **lungs**, kidneys, and other tissues. - While it can be elevated in **pulmonary embolism** or renal disease, it is not specific for liver injury. *LDH-2 isoenzyme linked to erythrocyte metabolism* - **LDH-2** is abundant in **red blood cells** and also found in the heart and kidneys. - Elevations are often seen in conditions involving **hemolysis** or myocardial damage, similar to LDH-1.
Question 162: Which of the following pairs of compounds has the highest standard reduction potential?
- A. NADH/NAD+
- B. Succinate/Fumarate
- C. Ubiquinone/Ubiquinol
- D. Fe³⁺/Fe²⁺ (Correct Answer)
Explanation: ***Fe³⁺/Fe²⁺*** - The **Fe³⁺/Fe²⁺ couple** has a **standard reduction potential (E'0)** of **+0.77 V**, making it the highest among the given options. - A higher positive E'0 indicates a stronger tendency for the oxidized form to accept electrons and be reduced. *NADH/NAD+* - The **NADH/NAD+ couple** has a **standard reduction potential** of **-0.32 V**, indicating it is a strong reducing agent. - Its negative reduction potential means it readily donates electrons during metabolic processes. *Succinate/Fumarate* - The **succinate/fumarate couple** has a **standard reduction potential** of **+0.03 V**. - This pair is involved in the **TCA cycle**, where succinate is oxidized to fumarate, releasing electrons. *Ubiquinone/Ubiquinol* - The **ubiquinone/ubiquinol couple** has a **standard reduction potential** varying around **+0.05 to +0.10 V**, depending on the specific state. - It acts as a mobile electron carrier in the **electron transport chain**, accepting electrons from NADH and FADH2.
Question 163: Fluoroacetate inhibits?
- A. Citrate synthase
- B. Succinate dehydrogenase
- C. Alpha-ketoglutarate dehydrogenase
- D. Aconitase (Correct Answer)
Explanation: ***Aconitase*** - **Fluoroacetate** is metabolically converted to **fluorocitrate**, which is a potent competitive inhibitor of **aconitase**. - **Aconitase** is the enzyme responsible for converting **citrate to isocitrate** in the **Krebs cycle**, and its inhibition blocks the cycle. *Citrate synthase* - This enzyme is responsible for the formation of **citrate** from **acetyl-CoA** and **oxaloacetate**. - While fluoroacetate indirectly affects the cycle, it does not directly inhibit **citrate synthase**. *Succinate dehydrogenase* - This enzyme is part of the **Krebs cycle** and the **electron transport chain**, converting **succinate to fumarate**. - **Malonate** is a competitive inhibitor of succinate dehydrogenase, not **fluoroacetate**. *Alpha-ketoglutarate dehydrogenase* - This enzyme catalyzes the conversion of **alpha-ketoglutarate to succinyl-CoA** in the **Krebs cycle**. - Specific inhibitors of this enzyme include **arsenite** and **mercury compounds**, but not fluoroacetate.
Physiology
2 questionsWhat is the process by which water moves from the extracellular space to the intracellular space?
What is the effect of acetylcholine on the Lower Esophageal Sphincter (LES)?
NEET-PG 2012 - Physiology NEET-PG Practice Questions and MCQs
Question 161: What is the process by which water moves from the extracellular space to the intracellular space?
- A. Osmosis (Correct Answer)
- B. Diffusion
- C. Filtration
- D. Active transport
Explanation: ***Osmosis*** - **Osmosis** is the movement of water across a **semipermeable membrane** from an area of higher water concentration (lower solute concentration) to an area of lower water concentration (higher solute concentration). - In the context of fluid shifts, if the **extracellular fluid** becomes hypotonic relative to the **intracellular fluid**, water will move into the cells to equalize the solute concentration. *Diffusion* - **Diffusion** refers to the net movement of particles from an area of higher concentration to an area of lower concentration, down their **concentration gradient**. - While water molecules can diffuse, **osmosis** specifically describes the net movement of water across a membrane due to **solute concentration differences**, which is the precise mechanism for water moving between fluid compartments. *Filtration* - **Filtration** is the process by which water and solutes move across a membrane due to a **pressure gradient**, typically a **hydrostatic pressure gradient**. - This process is crucial in the kidneys for forming filtrate, but it is not the primary mechanism for water movement between the intra- and extracellular spaces based on solute concentration. *Active transport* - **Active transport** involves the movement of molecules across a membrane against their **concentration gradient**, requiring **energy expenditure** (e.g., ATP). - Water movement between fluid compartments is generally a passive process, relying on **osmotic gradients** rather than direct energy input to pump water molecules.
Question 162: What is the effect of acetylcholine on the Lower Esophageal Sphincter (LES)?
- A. Causes contraction (Correct Answer)
- B. Causes relaxation
- C. No effect on LES
- D. Contraction followed by relaxation
Explanation: ***Correct Option: Causes contraction*** - Acetylcholine acts on **M3 muscarinic receptors** on LES smooth muscle cells to cause **contraction** - This is part of the **excitatory cholinergic pathway** that maintains LES tone and prevents gastroesophageal reflux - Acetylcholine is released from **excitatory motor neurons** in the myenteric plexus *Incorrect: Causes relaxation* - LES relaxation during swallowing is mediated by **nitric oxide (NO)** and **vasoactive intestinal peptide (VIP)**, NOT acetylcholine - These inhibitory neurotransmitters are released from separate **inhibitory motor neurons** - The relaxation response during swallowing is due to activation of the inhibitory pathway, which suppresses cholinergic tone *Incorrect: No effect on LES* - Acetylcholine has a significant effect on the LES - It is one of the key neurotransmitters maintaining basal LES tone - Loss of cholinergic input can lead to decreased LES pressure *Incorrect: Contraction followed by relaxation* - Acetylcholine itself causes only contraction - The swallowing reflex involves coordinated activation of inhibitory (NO/VIP) and suppression of excitatory (acetylcholine) pathways - The sequence of events is neural, not a biphasic response to acetylcholine alone