Peripheral Nervous System = PNS parts of the nervous system OUTSIDE of the CNS 1) cranial nerves (12 pairs) 2) spinal nerves (31 pairs) 3) sensory receptors PNS sensory division (afferent division) sends info from sensory receptors to the CNS motor division (efferent division) sends info from CNS to the effector structures such as skeletal muscle and organs Hence the motor division is divided into the autonomic or somatic nervous system AUTONOMIC involuntary division that conducts impulses to the organs in the body SOMATIC voluntary division that conducts impulses to the skeletal muscle Autonomic nervous system is further divided into 2 divisions parasympathetic nervous system and sympathetic nervous system Parasympathetic involved in non emergency functions (relaxation) Sympathetic involved in emergency functions. Hence it is termed the fight-or-flight response MAJOR DIFFERENCE sympathetic uses a lot of energy whereas parasympathetic conserves energy