Answer
The autonomic nervous system (ANS)supplies motor innervation to glands, cardiac muscles, and smooth muscles. Overall ANS function is to regulate heart rate, blood pressure, body temperature, pulmonary airflow, pupillary diameter, digestion, energy metabolism, defecation, and urination.
The ANS has two divisions, namely, the sympathetic division ,and the parasympathetic division. The sympathetic division helps the body adapt to physical activities by increasing alertness, heart rate, blood pressure, inspiration,
blood glucose levels, and blood flow to skin and cardiac muscles. While simulating the previous enhancements, the sympatheic system(SPS) may, simultaneously, decrease blood flow to skin and digestive tract. These are responses in a situation where a subject feels threatened and must fight or flee--the fight or flight response of (Walter Canon).
The parasympathetic division( PSNS) may cooperate with or oppose the actions of the (SPNS). It is designated the rest or digest system because, typically, it functions to calm certain body processes. It depresses energy expenditure, facilitates normal body maintenance, and promotes digestion and waste elimination. Both subdivisions of the ANS operate simultaneously to maintain balance in bodily functions -- the autonomic tone tone-- which is a balance between sympathetic activity and parasympathetic activity. This balance, however, shifts --in favor of sympathetic tone or of parasympatheic tone according to the physiological needs of the body.
Work Step by Step
Some targets of the ANS are structures of the body wall, cutaneous blood vessels, sweat glands, and piloerector glands of hair follicles. The receptors of the ANS include nerve endings for stretch, tissue damage, blood chemicals, and body temperature.
An example of ANS effector activity is the modulation of heart rate during exercise or when one stands suddenly from a recumbent position. Inhibitory effects of ANS action are the slowing of the heart rate, and the decreasing of the tone of smooth muscles.
