INI-CET 2017 Practice Questions

Q: Which of the following is the constituent of the marked area in the given electron microscope picture of the muscle?

$\alpha$-actinin. ***$\alpha$-actinin*** - The image highlights the **Z-disc**, which is primarily composed of **$\alpha$-actinin**. - **$\alpha$-actinin** anchors the **thin filaments (actin)** at the Z-disc and helps maintain the structural integrity of the sarcomere. *Nebulin* - **Nebulin** is a large protein associated with thin filaments, regulating their **length** and contributing to their **stability**, but it is not the main constituent of the Z-disc. - It extends along the entire length of the thin filament, rather than forming the Z-disc itself. *Titin* - **Titin** is the largest known protein, responsible for the **elasticity** of muscle and connecting the Z-disc to the M-line. - While it associates with the Z-disc, it does not constitute the primary structural component of the Z-disc itself. *Tropomodulin* - **Tropomodulin** caps the **pointed (minus) end** of the **actin filaments**, regulating their length and ensuring stability in the sarcomere. - It is located at the ends of the thin filaments, away from the Z-disc.

Q: Which is not true regarding the procedure done with the needle shown below?

Breath holding is not necessary. ***Breath holding is not necessary*** - This statement is **FALSE** - breath holding **IS necessary** during lumbar puncture to maximize **opening pressure** measurement and reduce **CSF pressure variations**. - Patients are typically instructed to hold their breath in **expiration** to minimize movement artifacts and obtain accurate pressure readings. *Coagulopathy is not an absolute contraindication* - This statement is **TRUE** - coagulopathy is considered a **relative contraindication**, not an absolute one for lumbar puncture. - The procedure can often be performed safely after **correcting clotting abnormalities** or with careful risk-benefit assessment and meticulous technique. *Bevel should be facing upwards while inserting the needle* - This statement is **TRUE** - the needle should be inserted with the **bevel facing upwards** (or laterally in lateral position) to minimize **dural trauma**. - This orientation allows dural fibers to **spread rather than cut**, reducing the risk of **post-dural puncture headache (PDPH)**. *To be done in lateral recumbent position* - This statement is **TRUE** - **lateral recumbent position** is one of the standard positions for lumbar puncture, especially for measuring **opening pressure** accurately. - Alternative **sitting position** may be used for obese patients or those with difficult anatomical landmarks, but lateral recumbent remains a correct approach.

Q: Calculate the tetanizing frequency based on the contraction dynamics of gastrocnemius muscle of frog shown in the image?

20-25 Hz. **20-25 Hz** - Tetanizing frequency (or fusion frequency) is the stimulation rate at which individual muscle twitches fuse to produce a **smooth, sustained contraction** (tetanus). - For the **frog gastrocnemius muscle**, a common model in physiology, this frequency typically falls within the **20-25 Hz range**. *10-15 Hz* - At this lower frequency, the muscle would likely exhibit **incomplete tetanus** or summation, where individual twitches are still discernible, but tension is increasing. - This range is generally insufficient to achieve a **smooth, fused tetanic contraction** in the frog gastrocnemius. *15-20 Hz* - This range might produce **treppe** or early stages of incomplete tetanus, where successive contractions are slightly stronger, but the relaxation phase is still partially visible between stimuli. - While closer to the tetanizing frequency, it's generally not high enough to achieve **complete fusion** for the frog gastrocnemius. *30-35 Hz* - While this frequency would certainly result in a **fused tetanic contraction**, it's higher than the minimum required for the frog gastrocnemius, which means the muscle is already in complete tetanus at a lower frequency. - Using excessively high frequencies beyond the fusion frequency does not significantly increase tension and can lead to **faster fatigue**.

Q: There are two blood vessels shown below. Assuming that pressure along both the vessels is same and both of them follow linear flow pattern, what will be the amount of blood flow in A compared to B?

32 times. ***32 times*** - According to **Poiseuille's law**: Q = (ΔP × π × r⁴) / (8 × η × L), where flow is proportional to the **fourth power of radius** and inversely proportional to vessel length. - Vessel A has **double the diameter** (radius = 2r) and **half the length** (L/2) compared to vessel B: Q_A ∝ (2r)⁴/(L/2) = 32r⁴/L vs Q_B ∝ r⁴/L, giving ratio of **32**. *4 times* - This would occur with a much smaller radius difference between the vessels than what is shown. - Does not account for the **fourth power relationship** of radius with flow in Poiseuille's equation. *8 times* - This would result if vessel A had **double the diameter** but also **double the length** of vessel B. - Calculation: (2r)⁴/(2L) ÷ (r⁴/L) = 16r⁴/2L ÷ r⁴/L = **8 times**. *16 times* - This would occur if vessel A had **double the radius** but **equal length** to vessel B. - Calculation: (2r)⁴/L ÷ (r⁴/L) = 16r⁴/L ÷ r⁴/L = **16 times**.

Q: A patient has a blood glucose level of $200 \mathrm{mg} \%$ and GFR of 90. The transport maximum of the patient is as shown in the picture given below. What is the amount of glucose excreted?

30 mg/min. ***30 mg/min*** - The amount of **glucose filtered** by the kidneys is calculated as GFR × plasma glucose concentration, which is 90 mL/min × 2 mg/mL = **180 mg/min**. - The **transport maximum (Tm)** for glucose is 150 mg/min, meaning the kidneys can reabsorb a maximum of 150 mg/min of glucose per minute. - Since more glucose is filtered (180 mg/min) than can be reabsorbed (150 mg/min), the excess is excreted in urine. - **Glucose excreted** = Filtered - Reabsorbed = 180 mg/min - 150 mg/min = **30 mg/min**. *Incorrect: 50 mg/min* - This would be incorrect as it doesn't match the calculation based on the given values. *Incorrect: 90 mg/min* - This represents the GFR value, not the amount of glucose excreted. *Incorrect: 180 mg/min* - This represents the total amount of glucose filtered, not the amount excreted after reabsorption.

Q: Calculate the FEV1/FVC ratio from the spirometry reading shown below.

80-89 %. ***80-89 %*** - **Normal FEV1/FVC ratio is >70% in adults, with healthy individuals typically showing 80-90%.** - From the spirometry graph, the total vital capacity (FVC) after full exhalation is approximately **4500 mL**. The volume exhaled in the first second (FEV1) is approximately **4000 mL**. - Therefore, FEV1/FVC = (4000 mL / 4500 mL) × 100% = **88.8%**. This falls within the 80-89% range, indicating **normal lung function**. *60-69 %* - This percentage indicates **severe airflow obstruction**, where the FEV1 is significantly reduced relative to the FVC, which is not supported by the graph's values of **FEV1 ~4000 mL** and **FVC ~4500 mL**. - A ratio of 60-69% is seen in **moderate to severe obstructive lung disease** (COPD, severe asthma). *70-79 %* - This range suggests **mild airflow obstruction**, corresponding to an **FEV1/FVC ratio** that is borderline or slightly reduced (below the normal 80% threshold but above the diagnostic cutoff for obstruction at 70%). - While less severe than 60-69%, it still implies some degree of airway limitation, which is not the case with the calculated ratio of 88.8%. *90-99 %* - This percentage implies an **FEV1/FVC ratio** of 0.9 or higher, meaning that nearly all of the vital capacity is exhaled in the first second. While **88.8%** is close to this range, it does not fall within it. - A ratio this high might be seen in individuals with **excellent lung function** or paradoxically in some cases of **restrictive lung disease** where both FEV1 and FVC are proportionally reduced, but the exact calculated value from the graph is 88.8%, which falls just below 90%.

Question 1

Which of the following is the constituent of the marked area in the given electron microscope picture of the muscle?

Accepted Answer

$\alpha$-actinin

Answer

Nebulin

Answer

Titin

Answer

Tropomodulin

Question 2

Which is not true regarding the procedure done with the needle shown below?

Accepted Answer

Breath holding is not necessary

Answer

Bevel should be facing upwards while inserting the needle

Answer

To be done in lateral recumbent position

Answer

Coagulopathy is not an absolute contraindication

Question 3

Calculate the tetanizing frequency based on the contraction dynamics of gastrocnemius muscle of frog shown in the image?

Accepted Answer

20-25 Hz

Answer

10-15 Hz

Answer

15-20 Hz

Answer

30-35 Hz

Question 4

There are two blood vessels shown below. Assuming that pressure along both the vessels is same and both of them follow linear flow pattern, what will be the amount of blood flow in A compared to B?

Accepted Answer

32 times

Answer

4 times

Answer

8 times

Answer

16 times

Question 5

A patient has a blood glucose level of $200 \mathrm{mg} \%$ and GFR of 90. The transport maximum of the patient is as shown in the picture given below. What is the amount of glucose excreted?

Accepted Answer

30 mg/min

Answer

50 mg/min

Answer

90 mg/min

Answer

180 mg/min

Question 6

Calculate the FEV1/FVC ratio from the spirometry reading shown below.

Accepted Answer

80-89 %

Answer

60-69 %

Answer

70-79 %

Answer

90-99 %

INI-CET 2017

Anatomy

Internal Medicine

Physiology