ENT
1 questionsCone of light focuses on which quadrant of tympanic membrane?
NEET-PG 2013 - ENT NEET-PG Practice Questions and MCQs
Question 671: Cone of light focuses on which quadrant of tympanic membrane?
- A. Anteroinferior (Correct Answer)
- B. Posteroinferior
- C. Anterosuperior
- D. Posterosuperior
Explanation: ***Anteroinferior*** - The **cone of light** (or light reflex) is a characteristic triangular reflection of the otoscope's light, normally visible in the **anteroinferior quadrant** of a healthy tympanic membrane. - Its presence indicates a **healthy, intact eardrum** with normal tension and transparency; its absence or distortion can suggest pathology. *Posteroinferior* - While part of the tympanic membrane, the **posteroinferior quadrant** does not normally exhibit the focused cone of light. - This area is more often associated with the **round window niche** on its medial aspect in relation to the middle ear. *Anterosuperior* - The **anterosuperior quadrant** is located above the handle of the malleus and does not show the cone of light reflection. - This area contains the **anterior malleolar fold** and part of the **pars flaccida** (attic region). *Posterosuperior* - The **posterosuperior quadrant** is also not the usual site for the cone of light. - This area is relevant for the proximity to the **facial nerve** and structures like the **long process of the incus**.
Pharmacology
5 questionsWhich of the following conditions is not treated by penicillin G?
What is Hydroxyethyl starch?
Which of the following anticoagulants is given orally?
What is the mechanism of action of Warfarin?
Mechanism of action of tranexamic acid is
NEET-PG 2013 - Pharmacology NEET-PG Practice Questions and MCQs
Question 671: Which of the following conditions is not treated by penicillin G?
- A. Bacterial meningitis
- B. Syphilis
- C. Anthrax
- D. Rickettsial infection (Correct Answer)
Explanation: ***Rickettsial infection*** - **Rickettsial infections**, such as Rocky Mountain spotted fever or typhus, are caused by **obligate intracellular bacteria** that are not susceptible to penicillin G. - The primary treatment for rickettsial infections is **doxycycline**, due to its ability to penetrate host cells and inhibit bacterial protein synthesis. *Bacterial meningitis* - **Bacterial meningitis**, particularly caused by susceptible strains of *Neisseria meningitidis*, *Streptococcus pneumoniae*, and *Haemophilus influenzae*, can be effectively treated with **high-dose intravenous penicillin G** [1]. - Penicillin G's ability to cross the **blood-brain barrier** in inflamed meninges makes it a suitable option, though ceftriaxone is now more commonly used empirically due to resistance concerns [2]. *Syphilis* - **Penicillin G** remains the **drug of choice** for all stages of syphilis, caused by *Treponema pallidum*. - For primary, secondary, and early latent syphilis, a **single intramuscular dose of benzathine penicillin G** is curative. *Anthrax* - While **ciprofloxacin** and **doxycycline** are often considered first-line for anthrax, **penicillin G** can also be an effective treatment for susceptible strains of *Bacillus anthracis*. - It is particularly used in cases of less severe cutaneous anthrax or to de-escalate treatment once susceptibility is confirmed.
Question 672: What is Hydroxyethyl starch?
- A. Vasodilator
- B. Inotrope
- C. Plasma expander (Correct Answer)
- D. Diuretic
Explanation: ***Plasma expander*** - **Hydroxyethyl starch** is a **colloid solution** used intravenously to increase plasma volume and maintain oncotic pressure. - It is often used in situations of **hypovolemia** or shock to support circulation. *Vasodilator* - A **vasodilator** is a medication that widens blood vessels, typically used to lower blood pressure or improve blood flow. - Hydroxyethyl starch does not directly cause **vasodilation** as its primary mechanism of action. *Inotrope* - An **inotrope** is an agent that alters the force or energy of muscular contractions, mainly affecting the heart's contractility. - Hydroxyethyl starch has no direct effect on **myocardial contractility**. *Diuretic* - A **diuretic** is a substance that promotes increased production of urine, thereby increasing the excretion of water from the body. - While fluid administration can temporarily increase urine output, hydroxyethyl starch is not classified as a **diuretic agent** itself.
Question 673: Which of the following anticoagulants is given orally?
- A. Argatraban
- B. Alteplase
- C. Rivaroxaban (Correct Answer)
- D. Fondaparinux
Explanation: ***Rivaroxaban*** - Rivaroxaban is a **direct oral anticoagulant (DOAC)** that specifically inhibits **Factor Xa**. - It is administered orally and does not require routine coagulation monitoring. *Argatraban* - Argatroban is a **direct thrombin inhibitor (DTI)** primarily used intravenously, especially in patients with **heparin-induced thrombocytopenia (HIT)**. - It is not an orally administered anticoagulant. *Alteplase* - Alteplase is a **thrombolytic agent** (clot buster), not an anticoagulant, that works by converting **plasminogen to plasmin**. - It is administered intravenously to dissolve existing clots. *Fondaparinux* - Fondaparinux is a **synthetic pentasaccharide** that selectively inhibits **Factor Xa** by binding to antithrombin. - It is administered **subcutaneously**, not orally.
Question 674: What is the mechanism of action of Warfarin?
- A. Inhibition of Vitamin K epoxide reductase (Correct Answer)
- B. Inhibition of gamma glutamyl carboxylase
- C. Activation of Vitamin K epoxide reductase
- D. Activation of gamma glutamyl carboxylase
Explanation: ***Inhibition of Vitamin K epoxide reductase*** - Warfarin blocks **Vitamin K epoxide reductase (VKORC1)** [1, 2, 3], an enzyme essential for recycling oxidized vitamin K into its active reduced form [1, 3]. - This reduction prevents the activation of **vitamin K-dependent clotting factors** (II, VII, IX, X), leading to anticoagulation [1, 3]. *Inhibition of gamma glutamyl carboxylase* - **Gamma-glutamyl carboxylase** uses reduced vitamin K as a cofactor to carboxylate specific glutamic acid residues on clotting factors [1, 3]. - While essential for clotting factor activation, this enzyme itself is **not directly inhibited by warfarin** [1, 3]. *Activation of Vitamin K epoxide reductase* - Activating **VKORC1** would increase the production of reduced vitamin K, thereby **promoting coagulation** rather than inhibiting it [1, 2]. - This is the opposite of warfarin's intended therapeutic effect. *Activation of gamma glutamyl carboxylase* - Activating **gamma-glutamyl carboxylase** would enhance the carboxylation and activation of **clotting factors**, leading to procoagulant effects [1, 3]. - This mechanism contradicts warfarin's role as an **anticoagulant**.
Question 675: Mechanism of action of tranexamic acid is
- A. Decrease vascular permeability
- B. Smooth muscle contraction
- C. Activates Plasmin formation
- D. Prevents fibrinolysis (Correct Answer)
Explanation: ***Correct: Prevents fibrinolysis*** - Tranexamic acid is an **antifibrinolytic agent** that works by inhibiting the activation of plasminogen to plasmin. - By preventing the formation of plasmin, it stabilizes **fibrin clots** and reduces bleeding. *Incorrect: Decrease vascular permeability* - This is primarily the mechanism of action of drugs like antihistamines or corticosteroids, which work on **inflammation** and **allergic reactions**. - Tranexamic acid does not directly target vascular permeability; its primary role is in **hemostasis**. *Incorrect: Smooth muscle contraction* - This describes the action of drugs like **vasoconstrictors** (e.g., epinephrine) or agents that promote uterine contractions (e.g., oxytocin). - Tranexamic acid has no direct effect on **smooth muscle contraction**. *Incorrect: Activates Plasmin formation* - This is the opposite of tranexamic acid's action; drugs that activate plasmin, such as **tissue plasminogen activators (tPAs)**, are used to break down clots. - Tranexamic acid specifically **inhibits plasminogen activation**, thereby preventing plasmin formation.
Physiology
3 questionsWhich of the following stimuli is detected by the vestibular macula?
Ossicles of middle ear are responsible for which of the following ?
Which of the following is responsible for localization of sound ?
NEET-PG 2013 - Physiology NEET-PG Practice Questions and MCQs
Question 671: Which of the following stimuli is detected by the vestibular macula?
- A. Change in head position
- B. Linear acceleration (Correct Answer)
- C. None of the options
- D. Gravity
Explanation: ***Linear acceleration*** - The **maculae** (in the utricle and saccule) are specifically designed to detect **linear acceleration**, including both dynamic movements (speeding up in a car, elevator motion) and the constant linear acceleration of **gravity**. - Hair cells in the maculae are displaced by movements of the **otolithic membrane** containing **otoconia** (calcium carbonate crystals) in response to linear acceleration forces. - The utricle primarily detects **horizontal linear acceleration**, while the saccule detects **vertical linear acceleration**. *Gravity* - While gravity is indeed detected by the maculae, gravity is actually a form of **constant linear acceleration** (9.8 m/s²). - The maculae use gravity to determine **static head position** and orientation, but this is a subset of their broader function of detecting linear acceleration. - "Linear acceleration" is the more comprehensive and physiologically accurate term. *Change in head position* - This term is too broad and encompasses both **linear** and **angular (rotational)** movements. - **Angular acceleration** (rotation) is detected by the **semicircular canals**, not the maculae. - The maculae specifically detect linear position changes relative to gravity, not rotational changes. *None of the options* - This is incorrect because the vestibular macula clearly detects linear acceleration as its primary function.
Question 672: Ossicles of middle ear are responsible for which of the following ?
- A. Amplification of sound intensity
- B. Reduction of sound intensity
- C. Protecting the inner ear
- D. Reduction of impedance for sound transmission (Correct Answer)
Explanation: ***Reduction of impedance for sound transmission*** - The ossicles (malleus, incus, and stapes) act as a **lever system** to match the impedance between the air-filled outer ear and the fluid-filled inner ear. - This impedance matching ensures that maximum sound energy is transferred to the cochlea, preventing significant **sound reflection**. *Amplification of sound intensity* - While the ossicles do slightly amplify the sound pressure, their primary role is not extensive amplification but rather **impedance matching**. - The amplification achieved is a byproduct of efficient energy transfer, rather than a direct goal of increasing sound intensity for its own sake. *Reduction of sound intensity* - This function is primarily attributed to the **acoustic reflex**, where the middle ear muscles contract to stiffen the ossicular chain in response to loud sounds. - The primary function of the ossicles themselves is to transmit sound efficiently, not to reduce intensity under normal conditions. *Protecting the inner ear* - While the **acoustic reflex** (involving middle ear muscles attached to the ossicles) offers some protection against very loud sounds by stiffening the ossicular chain, this is a separate, reflexive mechanism. - The intrinsic structure and primary mechanical function of the ossicles are centered on efficient sound transmission, not direct physical protection of the inner ear.
Question 673: Which of the following is responsible for localization of sound ?
- A. Cochlear nerve
- B. Cochlea
- C. Superior olivary nucleus (Correct Answer)
- D. Cochlear nuclei
Explanation: ***Superior olivary nucleus*** - The **superior olivary nucleus** is the first site in the auditory pathway where binaural (two-ear) input is integrated, which is crucial for **sound localization**. - It processes **interaural time differences (ITDs)** and **interaural level differences (ILDs)** to determine the horizontal position of a sound source. *Cochlear nerve* - The **cochlear nerve** transmits auditory information from the cochlea to the brainstem but does not perform the initial processing for sound localization. - It carries impulses for both ears independently, which are then integrated at higher centers. *Cochlea* - The **cochlea** is responsible for converting sound vibrations into electrical signals (transduction), encoding properties like pitch and loudness, but not directly for sound localization. - It acts as a mechanical analyzer, separating sound into its frequency components. *Cochlear nuclei* - The **cochlear nuclei** receive input solely from the ipsilateral cochlear nerve and primarily process monaural (one-ear) auditory information. - While they are a crucial relay in the auditory pathway, they do not integrate binaural cues for sound localization.
Surgery
1 questionsWhich levels of cervical lymph nodes are included in a modified radical neck dissection?
NEET-PG 2013 - Surgery NEET-PG Practice Questions and MCQs
Question 671: Which levels of cervical lymph nodes are included in a modified radical neck dissection?
- A. I-IV
- B. I-V (Correct Answer)
- C. I-III
- D. II-VI
Explanation: ***I-V*** - A modified radical neck dissection typically removes lymph nodes from levels **I through V**, along with preservation of one or more non-lymphatic structures (sternocleidomastoid muscle, internal jugular vein, or spinal accessory nerve). - This extensive dissection addresses potential metastasis to these node groups from head and neck cancers, crucial for adequate oncologic clearance while aiming for functional preservation. *I-III* - This limited dissection would likely be insufficient for many head and neck cancers, as spread often extends beyond level III. - It would miss potential metastases in the lower jugular and posterior triangle nodes, increasing the risk of recurrence. *I-IV* - This dissection omits **level V**, which includes the posterior triangle nodes, a common site for metastatic spread, especially for cancers of the oropharynx, hypopharynx, and thyroid. - Excluding level V would be considered an incomplete radical or modified radical neck dissection in many clinical scenarios. *II-VI* - This option incorrectly excludes lymph nodes at **level I** (submental and submandibular nodes), which are critical draining sites for many oral cavity cancers. - Including level VI (anterior compartment nodes) is typically part of a central compartment neck dissection, often performed for thyroid cancer, but is usually not part of a standard modified radical neck dissection for other head and neck primaries unless specifically indicated.