Tachypnoea means

Correct Answer: A

Rationale: The correct answer is A: Rapid shallow breathing. Tachypnoea refers to an increased respiratory rate, which can lead to shallow breathing. Rapid breathing helps to compensate for inadequate oxygen levels. Choice B is incorrect because tachypnoea is not typically associated with deep breathing. Choices C and D are incorrect as they describe slow breathing patterns, which are opposite to tachypnoea.

Correct Answer: C

Rationale: The correct answer is C because in the classic pathway of complement activation, C1 binds to two antibodies attached to an antigen, forming an immune complex. This binding triggers a cascade of reactions leading to the activation of complement proteins. Choice A is incorrect as C1 does not bind directly to the cell wall of bacteria. Choice B is incorrect as C1 does not bind to the plasma membrane of bacteria. Choice D is incorrect as C1 does not bind directly to a cell surface antigen. The key step in the classic pathway is the recognition of immune complexes by C1, initiating the complement activation cascade.

Correct Answer: C

Rationale: The correct answer is C because pressure decreases as air moves from a region of higher pressure to lower pressure. At label '4', the air pressure is higher due to inhalation, and at label '5', the pressure is lower as air exits during exhalation. Therefore, P4 is always lower than P5. Choices A and B are incorrect because pressure dynamics change during inhalation and exhalation. Choice D is incorrect as pressure imbalances exist during breathing.

Correct Answer: C

Rationale: The correct answer is C because the chloride shift actually causes RBCs to shrink, not swell. During the chloride shift, chloride ions move out of RBCs in exchange for bicarbonate ions to maintain electrochemical equilibrium. This process helps maintain pH balance in blood. Choices A and B are correct as they accurately describe aspects of the chloride shift. Choice D is incorrect because the chloride shift is primarily driven by a decrease in PCO2, not a rise.

Correct Answer: C

Rationale: The correct answer is C: pneumotaxic centers. The pneumotaxic centers are located in the pons and regulate the rate and depth of breathing by inhibiting the apneustic centers in the medulla. This inhibition helps to promote passive or active exhalation. A: DRG (dorsal respiratory group) is responsible for the initiation of inspiration. B: VRG (ventral respiratory group) is involved in both inspiration and expiration. D: LRG is not a recognized respiratory center in the brainstem. In summary, the pneumotaxic centers play a crucial role in regulating breathing by inhibiting the apneustic centers, leading to exhalation.