The Human Nervous System. Neuron- A Nerve Cell Cell body Cell body Contains the nucleus and other...
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Transcript of The Human Nervous System. Neuron- A Nerve Cell Cell body Cell body Contains the nucleus and other...
The HumanNervousSystem
Neuron- A Nerve Cell
Cell bodyContains the nucleus and other
organellesDendrites
Receive stimuliConduct impulses toward the cell
bodyAxon
Carries impulses away from the cell body
Axon Structure
Myelin sheathInsulating coat of plasma
membranesSections of sheath are called
“Schwann Cells”Unmyelinated axons carry impulses
much slower than myelinated axons
Nodes of RanvierBare axonal membrane between
Schwann cells
The Synapse
Synapse The gap between nerve cells
NeurotransmitterChemicals that carry nerve signals across the synapse
Reflex Arc
The reflex arc responds to a stimulus without the immediate involvement of the brain
Central Nervous System(CNS)
• Brain• Spinal Cord
Cerebrum
Directs voluntary movementSensory processingLanguage and communicationLearning and memory
Cerebellum
Regulates sense of balanceCoordinates voluntary muscle movement
Medulla Oblongata
BreathingHeart rateBlood pressureSwallowing and digestion
Peripheral NervousSystem (in blue)
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
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