Final answer:
None of the statements provided are true: a) Humoral input refers to afferent or efferent input to the respiratory centre from neurons that are excited by means other than blood-born stimuli. b) Central chemoreceptors are located in the medulla and are affected by changes in the cerebrospinal fluid. c) Peripheral chemoreceptors are located in the carotid artery and respond to increases in blood potassium levels.
Step-by-step explanation:
The correct answer is D) None of the above. None of the statements provided are true.
a) Humoral input refers to afferent or efferent input to the respiratory centre from neurons that are excited by means other than blood-born stimuli. This statement is incorrect because humoral input actually refers to the influence of chemical substances in the blood on physiological processes. It does not specifically refer to afferent or efferent input to the respiratory center.
b) Central chemoreceptors are located in the medulla and are affected by changes in the cerebrospinal fluid (CSF). This statement is incorrect because central chemoreceptors are located in the brain and brainstem, not just the medulla. They are primarily affected by changes in the levels of carbon dioxide and hydrogen ions in the CSF.
c) Peripheral chemoreceptors are located in the carotid artery and respond to increases in blood potassium levels. This statement is incorrect because peripheral chemoreceptors are located in the carotid arteries and aortic arch, and they mainly respond to changes in blood oxygen levels, carbon dioxide levels, and hydrogen ion levels (pH), not blood potassium levels.
In summary, none of the statements provided are true.