HTHSCI 1H06 Lecture Notes - Lecture 7: Iris Sphincter Muscle, Autonomic Nervous System, Sympathetic Nervous System

• School: McMaster University
• Department: Health Sciences
• Course: HTHSCI 1H06
• Professor: Peter Helli

Document Summary

Ans: a branch of your nervous system that controls your glands and involuntary muscles (heart and smooth muscle). Also sometimes called the visceral nervous system; visceral meaning internal organs. The most important part of ans is for homeostatic regulation. Central nervous system: figures out what to do with all this information. Somatic: like a long cord running to muscle from spinal cord. Most organs have sympathetic and parasympathetic motor output, but usually one is dominated. Sympathetic input speeds up heart rate (tachycardia) and increase the force of contractions (i. e. , a positive inotropic effect) This is an appropriate response for preparing for fight and flight. Parasympathetic (dominant) input slows heart rate (bradycardia) and decreases the strength of contractions (negative inotropic effect) This is, of course, an appropriate response for rest and relaxation. Visceral arterioles have almost only sympathetic input. The iris sphincter muscle has only parasympathetic inputs. Causes muscles to contract (it constricts the pupil).