The impulse for voluntary muscles for forceful breathing starts in

Correct Answer: C

Rationale: The correct answer is C: Cerebral hemispheres. The impulse for voluntary muscles for forceful breathing originates in the cerebral hemispheres where conscious control over breathing is regulated. The cerebral cortex sends signals to the respiratory muscles to increase or decrease breathing effort based on the body's needs. The other choices are incorrect because: A: Medulla (Pons) - This region of the brainstem is responsible for automatic breathing control, not voluntary forceful breathing. B: Vagus nerve - The vagus nerve is not directly involved in initiating voluntary breathing movements. D: Spinal cord - While the spinal cord plays a role in coordinating some aspects of breathing, it is not the primary center for voluntary forceful breathing control.

Correct Answer: A

Rationale: The correct answer is A: Non-ciliated Squamous epithelium. The alveolar epithelium in the lungs is composed of thin, flat cells called squamous epithelium. This type of epithelium allows for efficient gas exchange by providing a short diffusion distance. Ciliated epithelium (choice C) and ciliated columnar epithelium (choice D) are not found in the alveoli as they are more suited for moving mucus and debris in the respiratory tract. Ciliated squamous epithelium (choice B) is not a common epithelial type in the alveoli and is not as thin as non-ciliated squamous epithelium, making it less efficient for gas exchange.

Correct Answer: A

Rationale: The correct answer is A because vesicular, bronchovesicular, and bronchial breath sounds are distinguished based on their location over specific areas of the lung. Vesicular sounds are soft and low-pitched and are heard over most of the lung fields, bronchovesicular sounds are intermediate in pitch and are heard over the major bronchi, and bronchial sounds are loud and high-pitched and are heard over the trachea and larynx. Choices B, C, and D are incorrect as the distinction between these breath sounds is not based on volume, inspiration or expiration, or continuity of the sounds.

Correct Answer: A

Rationale: Step 1: IgA is the correct answer. It is found in breast milk and provides passive immunity to newborns through breastfeeding. Step 2: IgD is mainly found on the surface of B cells and is involved in the activation of B cells. Step 3: IgE is involved in allergic responses and parasitic infections, not typically found in high concentrations in breast milk. Step 4: IgG is the most abundant immunoglobulin in the bloodstream but is not typically concentrated in breast milk like IgA. Summary: IgA is the correct answer because it is specifically designed to provide passive immunity to newborns through breast milk, while the other choices do not serve this function.

Correct Answer: B

Rationale: The correct answer is B: 100 mm Hg. In arterial blood, the partial pressure of oxygen is typically around 100 mm Hg due to the oxygen-rich environment in the lungs. This value represents the pressure exerted by oxygen molecules in the blood. Choices A, C, and D are incorrect because they do not align with the normal range of oxygen partial pressure in arterial blood, which is around 100 mm Hg. Option A is too low, option C is slightly below the normal range, and option D is slightly above the normal range. Therefore, B is the most accurate representation of the typical partial pressure of oxygen in arterial blood.