During vigorous exercise, high rates of aerobic respiration produce carbon dioxide, lowering blood pH. Which sequence correctly describes the nervous coordination pathway that restores blood pH to normal?
Chemoreceptors in the carotid arteries detect a decrease in pH →\rightarrow→ increased frequency of impulses via sensory neurones to the medulla oblongata →\rightarrow→ increased frequency of impulses via sympathetic neurones to the sinoatrial node (SAN).
Baroreceptors in the aorta detect a decrease in pH →\rightarrow→ increased frequency of impulses via sensory neurones to the hypothalamus →\rightarrow→ increased frequency of impulses via parasympathetic neurones to the sinoatrial node (SAN).
Chemoreceptors in the carotid arteries detect an increase in pH →\rightarrow→ increased frequency of impulses via motor neurones to the cerebellum →\rightarrow→ decreased frequency of impulses via sympathetic neurones to the atrioventricular node (AVN).
Baroreceptors in the aorta detect a decrease in pressure →\rightarrow→ increased frequency of impulses via sensory neurones to the medulla oblongata →\rightarrow→ increased frequency of impulses via parasympathetic neurones to the sinoatrial node (SAN).
135 exam-style questions on OCR GCSE Biology 3.1 Coordination and control – the nervous system, covering 3.1.1 Structure of the nervous system, 3.1.2 Coordinated response, 3.1.3 The reflex arc, 3.1.4 Structure of the eye, 3.1.5 Defects of the eye, 3.1.6 Structure and function of the brain, 3.1.7 Difficulties of investigating brain function, and 3.1.8 Limitations in treating nervous system damage. Each one has a worked solution and a mark scheme showing where the marks go.