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
[{'content': 'Which of the following is expected to increase in response to haemorrhage? \nSelect and explain. \nA. Aeriolar dilation in skeletal muscle, B. Sympathetic activity, C. Sodium excretion, D. Water excretion', 'role': 'user'}, {'content': 'Answer: B \nExplanation: When hemorrhage occurs, there is no stimulation of aerial baroreceptors and so sympathetic output is increased leading to vasoconstriction and reflex tachycardia Increased secretion of Vasopressin and aldosterone also occurs in circulatory shock. Both these hormones cause retention of sodium and water thus increasing BP Vasoconstriction occurs mainly in skin and viscera diveing blood to vital organs. Blood vessels of the brain and hea are spared. Ref: Textbook of medical physiology by N Geetha, 2nd edition, page no. 184,185', 'role': 'assistant'}]