Comparative Physiology

To solve the problem, we need to determine the formula for Inspiratory Capacity (IC).

1. Understanding Inspiratory Capacity (IC):
Inspiratory Capacity is the maximum amount of air a person can inhale after normal exhalation. It is calculated by adding the Tidal Volume (TV) and the Inspiratory Reserve Volume (IRV).

2. Analyzing the Options:
(1) TV + IRV + ERV: This is incorrect because Inspiratory Capacity is not the sum of Tidal Volume, Inspiratory Reserve Volume, and Expiratory Reserve Volume. This combination gives a different respiratory volume.
(2) TV + IRV: This is the correct formula for Inspiratory Capacity. It is the sum of Tidal Volume (TV) and Inspiratory Reserve Volume (IRV), representing the volume of air that can be inspired after normal exhalation.
(3) VC + RV: This combination refers to Vital Capacity and Residual Volume, which are not part of the Inspiratory Capacity.
(4) ERV + RV: This combination refers to the Expiratory Reserve Volume and Residual Volume, which are also not part of the Inspiratory Capacity.

3. Identifying the Correct Answer:
The correct formula for Inspiratory Capacity is TV + IRV.

Final Answer:
The correct answer is Option B: TV + IRV.

Calcium ions bind to troponin in the muscle fibers, which causes a conformational change that removes the masking of active sites on actin.
This allows myosin heads to bind to actin, initiating muscle contraction. Therefore, statement (2) is correct.
Final Answer:
Binds to troponin to remove the mask of active sites of actin for myosin.

To solve the problem, we need to identify the part of the skeletal muscle described in the statement.

1. Understanding the Question:
The statement mentions the central part of the dark band (A band) in skeletal muscle, which lacks the thin filaments. This is referring to the region where only the thick filaments (myosin) are present.

2. Analyzing the Options:
- Z line (Option A): The Z line is the boundary between sarcomeres, but it is not the central part of the dark band.
Sarcomere (Option B): A sarcomere is the functional unit of muscle contraction, but it refers to the entire structure that includes both the dark and light bands.
Henson's disc (Option C): This is the correct answer. The central part of the A band in skeletal muscle, where there is only thick myosin filaments, is called the Henson's disc.
Krause's membrane (Option D): This term is not relevant to muscle structure and is incorrect in this context.

3. Conclusion:
Based on the description and the analysis of the options, the correct term for the central part of the dark band without the thin filaments is:

Final Answer:
The correct option is (C) Henson's disc.