1. The Human Nervous System

2. Neuron- A Nerve Cell Contains the nucleus and other organelles
Cell body
Contains the nucleus and other organelles
Dendrites
Receive stimuli
Conduct impulses toward the cell body
Axon
Carries impulses away from the cell body

3. Axon Structure Insulating coat of plasma membranes
Myelin sheath
Insulating coat of plasma membranes
Sections of sheath are called “Schwann Cells”
Unmyelinated axons carry impulses much slower than myelinated axons
Nodes of Ranvier
Bare axonal membrane between Schwann cells

4. The Synapse Synapse The gap between nerve cells Neurotransmitter
Chemicals that carry nerve signals across the synapse

5. Reflex Arc
The reflex arc responds to a stimulus without the immediate involvement of the brain

6. Central Nervous System (CNS)
Brain
Spinal Cord

7. Cerebrum Directs voluntary movement Sensory processing
Language and communication
Learning and memory

8. Cerebellum Regulates sense of balance
Coordinates voluntary muscle movement

9. Medulla Oblongata Breathing Heart rate Blood pressure
Swallowing and digestion

10. Peripheral Nervous System (in blue)

11. Peripheral Nervous System
Sensory Division
Bring information to the CNS
Motor Division
Carries signals away from the CNS
Somatic (voluntary) nervous system controls skeletal muscle action
Autonomic nervous system (involuntary) controls organ systems and smooth muscle

12. Divisions of the Autonomic Nervous System
Sympathetic
Stress responses (Fight or Flight)
Pupils dilate
Mouth dries up (saliva decreases)
Heart rate increases
Blood flow to skeletal muscle increases
Parasympathetic
Relaxation response
Heart rate slows
Pupils constrict
Stimulates salivation
Digestive processes stimulated