The Nervous System Functions Divisions Neurons Functions n

The Nervous System Functions, Divisions, & Neurons

Functions n Sensory Input n Integration n Motor functions

Divisions of Nervous System n Central nervous system (CNS) n Peripheral nervous system (PNS)

Central Nervous System n Brain n Spinal cord

Peripheral Nervous System n n Consists of nerves and ganglia Further divided: ¡ ¡ Afferent division (sensory) Efferent division (motor)

Efferent Division of PNS n Further divided: ¡ Somatic nervous system (voluntary) ¡ Autonomic nervous system (involuntary)

Autonomic nervous system n Further divided: ¡ Sympathetic ¡ Parasympathetic

Nerve Tissue n Neuron n Neuroglia (glial cell)

Neuron

Types of Neurons n Afferent (sensory) n Efferent (motor) n Inter-neurons (association neurons)

Neuroglia n n Do not conduct nerve impulses Serve as protection and nourishment for neurons

Nerve Impulses n Resting membrane n Stimulation of neuron

Resting membrane n n Non-conducting neuron Lots of Na+ outside neuron Lots of K+ inside neuron, but even more negative ions found inside Membrane is polarized

Stimulation of Neuron n n A stimulus changes the membrane to allow passive movement of ions. Stimulus must be strong enough to make membrane highly permeable (threshold).

Action Potential – Nerve Impulse n Depolarization n Reverse polarization n Repolarization

Action Potential Animation n Nerve Impulse

Conduction of Impulse n Action potential must continue the length of a neuron n Neurotransmitters carry impulse across the synaptic cleft to new neuron

Continuous vs Saltatory Action Potentials

Reflex Arcs n n n Functional unit of nervous system Allows for rapid response to stimulus Components: ¡ ¡ ¡ Receptor Sensory neuron Integration center Motor neuron Effector