Nokea
Which of the following anatomical structures is not part of the conducting zone?
- A. pharynx
- B. nasal cavity
- C. alveoli
- D. bronchi
Correct Answer: C
Rationale: The correct answer is C: alveoli. The conducting zone of the respiratory system includes structures that transport air to and from the gas exchange sites. Alveoli are the primary sites of gas exchange, not part of the conducting zone. Pharynx (A), nasal cavity (B), and bronchi (D) are all part of the conducting zone as they help in air transportation but do not directly participate in gas exchange like alveoli do. Therefore, alveoli is the correct answer as it does not belong to the conducting zone.
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Which statement is false about anatomical dead space?
- A. Anatomical dead space varies with age
- B. Can be estimated by the Fowlers method
- C. Significantly large in shallow breathing
- D. Measured by plotting N2 concentration against expired volume as in Bohr’s method
Correct Answer: D
Rationale: The correct answer is D because Bohr's method measures physiological dead space, not anatomical dead space. Anatomical dead space is constant and not affected by N2 concentration. A: Anatomical dead space does vary with age due to changes in lung dimensions. B: Fowlers method estimates anatomical dead space by measuring tidal volume and respiratory rate. C: Anatomical dead space is not significantly large in shallow breathing as it mainly involves the conducting airways, not the alveoli.
Prolonged inspirations can result from stimulating the ________ center.
- A. apneustic
- B. pneumotaxic
- C. expiratory
- D. baroreceptor
Correct Answer: A
Rationale: The correct answer is A: apneustic. Stimulation of the apneustic center in the brainstem prolongs inspiration by sending signals to the respiratory muscles to maintain inspiration. The apneustic center plays a role in regulating the depth and duration of breathing.
Explanation for why other choices are incorrect:
B: Pneumotaxic center helps regulate the respiratory rate by inhibiting inspiration, not prolonging it.
C: Expiratory center is responsible for controlling expiration, not inspiration.
D: Baroreceptor center is involved in regulating blood pressure, not respiratory functions.
The function of tracheal cilia is to
- A. Pass mucus out
- B. Pass mucus in
- C. Pass air out
- D. Pass air out
Correct Answer: A
Rationale: The correct answer is A: Pass mucus out. Tracheal cilia help move mucus, which contains dust, debris, and pathogens, out of the respiratory tract to prevent infections and maintain clear airways. This process is known as mucociliary clearance. Choices B, C, and D are incorrect because tracheal cilia do not pass mucus in, pass air out, or pass air in. Tracheal cilia specifically function to clear mucus out of the respiratory tract.
At high altitudes all of the following things occur in an effort to acclimatise EXCEPT
- A. Hypoventilation
- B. Polycythaemia
- C. Increased numbers of capillaries per unit volume in peripheral tissues
- D. O2 dissociation curve shifts to right
Correct Answer: A
Rationale: The correct answer is A: Hypoventilation. At high altitudes, the body adapts to the decreased oxygen availability by increasing red blood cell production (polycythaemia) to enhance oxygen-carrying capacity. This is supported by the shift of the oxygen dissociation curve to the right, facilitating oxygen unloading in tissues. Additionally, increased capillaries in peripheral tissues improve oxygen delivery. However, hypoventilation, or decreased breathing rate, is not a typical response to high altitudes. In fact, the body usually compensates by increasing ventilation to maintain adequate oxygen levels.
The chloride shift occurs in order to
- A. force oxygen out of the blood and into tissues
- B. transport bicarbonate ions into the blood plasma
- C. produce salt for the cytosol of blood cells
- D. produce carbonic acid
Correct Answer: B
Rationale: The correct answer is B because the chloride shift occurs to transport bicarbonate ions into the blood plasma. This process helps maintain acid-base balance in the body by exchanging chloride ions for bicarbonate ions to regulate pH levels. Choice A is incorrect as the chloride shift is not related to forcing oxygen into tissues. Choice C is incorrect as the chloride shift does not produce salt for the cytosol of blood cells. Choice D is incorrect as the chloride shift does not directly produce carbonic acid but rather helps in maintaining the balance of carbon dioxide and bicarbonate ions.