1. The Nervous System
The body’s nervous system is divided into two parts:
Central Nervous System
Peripheral Nervous System

2. Peripheral Nervous System
Sensory and motor neurons connected to the CNS
Nerves run to and from the brain and spinal cord (cranial and spinal nerves)
Made of 1) Somatic Nervous System
and the 2) Autonomic Nervous System

3. 2) Somatic Nervous System
Made up of sensory nerves (bodyCNS)
Motor nerves (transmit CNSbody)
Under conscious control

4. Somatic System
Carries impulses from external environment via sensory neurons that keep the CNS informed of changes, and the motor neurons adjust the position of skeletal muscles to maintain the body’s well being
It does this through 12 pairs of cranial nerves and 31 pairs of spinal nerves

5. Cranial Nerves
Transmit information about sense of smell, sight, hearing and taste, as well as general sensory receptors in the head region

6. Spinal Nerves Emerge from the spinal cord
Named for the region they come from (i.e.Thoracic)
Each one has a dorsal root (sensory fibers) that transmit info from sensory receptor to spinal cord, a spinal ganglion swelling (dorsal root ganglion) where cell bodies of sensory neurons are found, and a ventral root (motor fibers) that leaves the spinal cord to the muscles or glands.

7. 1) Autonomic Nervous System
Not consciously controlled (heart beat, peristalsis)
Maintains homeostasis of internal environment
Made up of the Sympathetic and Parasympathetic Nervous Systems (these control body organs)

9. Instead of using a single efferent (motor) neuron, as the Somatic system does, the ANS uses 2 neurons between the CNS and effector.
First neuron = Preganglionic Neuron (has mylein).
The cell body and dendrites are within the CNS
It synapses with a Second neuron in a Ganglia outside the CNS  Postganglionic Neuron (unmyleinated)

10. Sympathetic Nervous System
Has a shorter Preganglionic Neuron, longer Postganglionic Neurons
Sets off “Flight-or-fight” reaction
Releases Noradrenalin at synapses with effector
Heart and breathing rates increase when SNS is stimulated
Sympathetic nerves cause pupils in eyes to become large in response to low light

11. Parasympathetic Nervous System
Has longer Preganglionic Neurons, shorter Postganglionic Neurons
Opposite to the SNS
When threat has passed, PNS slows heart and breathing rates
Releases Acetylcholine (Ach) at synapse with effector
Reverse effects of the SNS
Parasympathetic nerves reduce the size of pupils when light levels are high