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 SYSTEM Brain Spinal cord SYMPATHETIC Dilates pupil Stimulates salivation Relaxes bronchi Accelerates heartbeat Inhibits activity Stimulates glucose Secretion of adrenaline, nonadrenaline Relaxes bladder Stimulates ejaculation in male Sympathetic ganglia Salivary glands Lungs Heart Stomach Pancreas Liver Adrenal gland Kidney

Parasympathetic Calms body to conserve and maintain energy Lowers heartbeat, breathing rate, blood pressure CENTRAL NERVOUS SYSTEM Brain PARASYMPATHETIC Spinal cord Stimulates salivation Constricts bronchi Slows heartbeat Stimulates activity Contracts bladder Stimulates erection of sex organs Stimulates gallbladder Gallbladder Contracts pupil

Summary of autonomic differences Autonomic nervous system controls physiological arousal Sympathetic division (arousing) Parasympathetic division (calming) Pupils dilate EYES Pupils contract Decreases SALIVATION Increases Perspires SKIN Dries Increases RESPIRATION Decreases Accelerates HEART Slows Inhibits DIGESTION Activates Secrete stress hormones ADRENAL GLANDS Decrease secretion of 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…