NERVOUS SYSTEM

PERIPHERAL N.S.errything else

CENTRAL N.S.brain & spinal cord

SENSORY DIVISIONafferent nerves

MOTOR DIVISIONefferent nerves

SOMATIC N.S.voluntary*

AUTONOMIC N.S.Involuntary*

SYMPATHETIC“Fight-or-flight”

PARASYMPATHETIC“Rest-n-digest”

SOMATIC NERVOUS SYSTEM• control of skeletal muscles with conscious effort• the end neurons connected to the muscles release

the neurotransmitter Acetylcholine, causing myofibrils to contract

THREE TYPES OF MUSCLES- Skeletal- Smooth- Cardiac

MUSCLE

MYOFIBRIL/ MUSCLE FIBER/ MUSCLE CELL

AXON TERMINAL

SYNAPTICCLEFT

Acetylcholine(Ach)

REFLEX ARC• Involuntarily reaction to a

stimulus• sensory neuron sends signal

to spinal cord; spinal cord sends message to muscle

• bypasses the brain• Evolutionarily evolved for

time-sensitive reactions

AUTONOMIC SYSTEM• controls smooth muscles without conscious effort• Regulates functions of our internal organs• Heavily related to the Endocrine System

• blood pressure, heart rate, breathing rates, body temperature, digestion/metabolism, water balance, the production of body fluids (saliva, sweat, and tears), urination, defecation, sexual response, etc.

GANGLION (ganglia)

• a cluster of neurons with a common purpose

• somatic ganglia – bundles of nerves connected to skeletal muscles

• sympathetic ganglia vs parasympathetic ganglia

• the sympathetic and parasympathetic systems innervate the same organs but have opposite effects

SYMPATHETIC PARASYMPATHETICNorepinephrine • increased heart rate• dilated blood vessels• dilated airways• dilated pupils• activates sweat glands• slows “less important”

processes such as digestion

fight or flight