Nervous System

Maintaining homeostasis a billion messages at a time…

Functions

• Monitor changes: sensation– Stimuli: sensory input (receptors)– Internal and external

• Integrate– Processes– Interprets – Generates response

• Respond– Motor output– Activates effector organs

Two divisions

• Central nervous system (CNS)– brain and spinal cord– Center for integration and control

• Peripheral nervous system (PNS)– Nerves and assoc. cells outside of CNS– Spinal nerves: carry information to and from the

spinal cord– Cranial nerves: carry information to and from the

brain

Central Nervous System

• Integration and command center– Relays messages– Processes information– Analyzes information– Dictates motor responses

Peripheral Nervous System

• Communication lines• Link all parts of the body to the CNS

Divisions of the PNS

• Sensory (Afferent) Division: TO the CNS– Somatic afferent fibers: skin, skeletal muscles,

joints– Visceral afferent fibers: visceral organs

• Motor (Efferent) Division: FROM the CNS– Stimulates effector organs– Effect (bring about) motor response• Contraction• Secretion

Branches of the Motor Division

• Somatic Nervous System– Somatic motor nerve fibers– CNS to skeletal muscles– Voluntary – conscious control

• Autonomic Nervous System– Visceral motor nerve fibers– CNS to smooth and cardiac muscles and glands– “a law unto itself” - involuntary

And finally: divisions of the Autonomic Nervous System

• Control same visceral organs• Opposite effects: antagonistic

• Sympathetic: fight or flight– Emergency situations– mobilization

• Parasympathetic: rest and digest– Nonemergency functions– Conserves energy

Sympathetic

• Release adrenaline and noradrenaline

• Increases heart rate and blood pressure

• Increases blood flow to skeletal muscles

• Inhibits digestive functions

CENTRAL NERVOUS SYSTEMBrain

Spinalcord

SYMPATHETIC

Dilates pupil

Stimulates salivation

Relaxes bronchi

Accelerates heartbeat

Inhibits activity

Stimulates glucose

Secretion of adrenaline,nonadrenaline

Relaxes bladder

Stimulates ejaculationin male

Sympatheticganglia

Salivaryglands

Lungs

Heart

Stomach

Pancreas

Liver

Adrenalgland

Kidney

Parasympathetic

• Calms body to conserve and maintain energy

• Lowers heartbeat, breathing rate, blood pressure

CENTRAL NERVOUS SYSTEMBrain

PARASYMPATHETIC

Spinalcord

Stimulates salivation

Constricts bronchi

Slows heartbeat

Stimulates activity

Contracts bladder

Stimulates erectionof sex organs

Stimulates gallbladder

Gallbladder

Contracts pupil

Summary of autonomic differences

Autonomic nervous system controls physiological arousal

Sympatheticdivision (arousing)

Parasympatheticdivision (calming)

Pupils dilate EYES Pupils contract

Decreases SALIVATION Increases

Perspires SKIN Dries

Increases RESPIRATION Decreases

Accelerates HEART Slows

Inhibits DIGESTION Activates

Secrete stresshormones

ADRENALGLANDS

Decrease secretionof stress hormones

Root Words

• Peri: about, around, enclosing, surrounding• Aff: to• Eff: out, from• Visc: of or pertaining to the internal organs• Soma: body• Auto: self

Brain: basic anatomy

Lobes of the cerebrum…