This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
Stimulation of peripheral chemoreceptors causes: 
Select and explain. 
A. Bradycardia, B. Tachycardia, C. Either bradycardia or tachycardia, D. Neither bradycardia nor tachycardia
C: Either bradycardia or tachycardia
Answer: C: Either bradycardia or tachycardia 
Explanation: Peripheral chemoreceptor in the carotid and aoic bodies can produce variable effects on hea rate- Direct Effect: Vagal stimulation- Bradycardia Indirect effect : Hypoxia- Peripheral chemoreceptor stimulation - Hyperventilation and increased catecholamine secretion - Tachycardia and increased cardiac output Chemoreceptor reflex Receptors Peripheral chemoreceptors in carotid and aoic bodies Central chemoreceptors in the medulla. Stimulus Decrease in PaO2 Increase in Pa CO2, H+ ion conc Afferent IX (sinus nerve of Hering) and X (Vagus N) Center for Reflex Medulla Efferent Sympathetic and parasympathetic neurons to hea vasculature and adrenal medulla. Response Direct effect: Bradycardia Indirect effect: Hyperventilation , tachycardia, vasoconstriction, increased cardiac output and increased BP. Ref: Ganong&; s Review of Medical Physiology 26th edition Pgno: 581, 582