Nervous System

Sensory Input

receptors detect changes, afferent signals travel toward the CNS

Integration

The CNS processes information and selects a response

Motor output

efferent signals activate muscles or glands

Neuron

a specialized, excitable cell that receives process and transmits information

Dendrites

receive incoming information (detects sensation)

Cell body (soma)

contains the nucleus and integrates signals

Axon

conducts impulses away from the soma

Nucleus

contains the cells genetic materia

Myelin sheath

insulates the axon and speeds conduction

Axon terminals

communicate with another cell

Excitablilty

responds to changes in the internal or external environment

Conductivity

produces and transmits electrical signals along the cell membrane

Secretion

releases neurotransmitters from axon terminals

Extreme longevity

many neurons can function throughout a person’s lifetime

Amitotic

most mature neurons do not undergo cell division

High metabolic rate

neurons require a continuous supply of oxygen and glucose

Central Nervous System (CNS)

brain adn spinal cord, integrates information and coordinates responses

Peripheral Nervous System

Cranial nerves, spinal nerves and ganglia. Carries information between the CNS and the rest of the body

Sensory (afferent) division

carries sensory information toward the CNS

Somatic sensory

signals from the skin, skeletal muscles and joints (touch, temperature, pain, and body position)

Visceral Sensory

signals from internal organs and blood vessels (organ stretch, internal pressure, and chemical changes)

Motor (efferent) Division

carries motor commands away from the central nervous system

Somatic motor

controls skeletal muscle, usually under voluntary control

Visceral motor (autonomic)

controls cardiac muscle, smooth muscle, and glands. usually involuntary

Sympathetic

prepares the body for activity

Parasympathetic

supports rest and digestion

Organs of CNS

brain and spinal cord

Organs of PNS

cranial nerves, spinal nerves, ganglia, peripheral nerves

Afferent pathway

sensory division, carries information toward the CNS

Efferent pathway

motor division

Axon hillock

initiates the action potential

Node of Ranvier

gap between adjacent myelin segments

Saltatory conduction

the action potential travels rapidly from node to node

Neurilemma

outermost layer containing most of the cytoplasm

Schwann cell

forms one myelin segment in the PNS