(1) Central Nervous System (CNS) - brain and spinal cord
(2) Peripheral Nervous System (PNS) - cranial and spinal nerves.
- Sensory (afferent) Neurons - transmits impulses TO the CNS
- Motor (efferent) Neuron System - transmits impulses FROM the CNS to effectors.
a) Somatic Nervous System - directs contraction of skeletal muscles
b) Autonomic Nervous System - controls activities of organs and various involuntary muscles, such as cardiac and smooth muscles. Has 2 systems that generally target the same organs but are antagonistic.
i. Parasympathetic Nervous System "Rest and Digest"or "Brake" - activates tranquil functions. E.g. secretion of saliva or digestive enzymes.
ii. Sympathetic Nervous System "Fight or Flight"or "Accelerator" - prepare body for action. E.g. increasing heart rate, increasing sugar release from liver to blood.
