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The Nervous System: Chief control system; voluntary or
involuntary Responds to changes in/out of body 100 Billion cells throughout the body CNS: brain and spinal cord act as a
switching center for impulses Peripheral nerves: a cable system
A) Neurons: Anatomy1) Cell body (CB): branches send or
receive nerve impulses (NI)
2) Dendrites: thin extensions of cell body; conduct NI back toward CB
3) Axon: conduct NI away from CB
Myelin sheath: fatty tissue, covers axon
A) Neurons: Physiology:Synapse: impulses jump over space bet. neurons
Neurotransmitters: substances located at end of nerve fibers
A) Neurons: Properties:1) excitability: ability to respond to stimulus
2) conductivity: ability to transmit signal
A) Neurons: 3 Types:1) Efferent: “exiting” (motor) neurons;
send info to muscles/glands of CNS
2) Afferent: “returning” (sensory) neurons; carry info from sensory receptors back to CNS
3) Interneurons: “between” (connecting) process sensory information
A) Neurons: Impulses Form bundles called “nerves” that bear
electrical messages Some nerves are combinations of at least two
types of nerves Electrical E stored; then released when cells
receive outside or internal chemical stimulus Released E travels through nerve cell
causing an impulse, then transmitted to other receptors in the body
B) Neuroglias: Function to support, connect,
protect, remove debris Do not transmit impulses “Brain Blood Barrier” found along
the capillary walls of the brain: allows some chemical substances to reach brain, but blocks others
C) The CNS: Anatomy: Brain and spinal cord; control center Receives/interprets all stimuli; sends
NI to muscles and glands Voluntary control, involuntary
movement; seeing, hearing, thinking, secretion of hormones, memory, responding to outside stimuli
C) The CNS: Four Parts1) Brainstem:
a) Midbrain: visual reflexes
b) Pons: respiration
c) Medulla oblongata: heart, lungs, swallowing, vomiting, coughing, sneezing
2) Cerebellum: musculoskeletal movements; posture, balance, muscle tone
C) The CNS: Four Parts3) Cerebrum: L/R hemispheres; outer covering
cerebral cortex: conscious decision-making
Four Lobes:
a) frontal: voluntary mvts, emotions, morality
b) parietal: senses, taste
c) temporal: memory, equilibrium, emotion, hearing
d) occipital: vision, expression
C) The CNS: Four Parts4) Diencephalon: deep portion,
thalamus and hypothalamus Relay center for sensations Integrates Autonomic Nervous
System (ANS): heart rate, BP, Temp. regulation, H20/electrolyte balance, digestion, behavior, glands
C) CNS: Cerebrospinal Fluid: Watery fluid flows throughout the
brain, surrounds spinal cord Cradles, cushions, protects brain Spinal Cord: Fills space in vertebral
canal (SC housed) Spinal Meninges: protect SC,
surrounded by CSF
C) CNS: Spinal Meninges1) Dura Mater: outermost; a tough, fibrous
membrane covering entire length of SC with channels for blood to enter brain
2) Arachnoid Mater: middle; weblike structure across the space containing CSF
3) Pia Mater: innermost; thin membrane containing BV that nourish the SC
*Epidural space: between dura mater and vertebrae; injections given here
D) Peripheral Nervous System (PNS) 12 pairs of cranial nerves; carry impulses
to and from the brain 31 pairs of spinal nerves; carry
messages to and from the spinal cord/torso to extremities
Divided into two subsystems according to function:
A) Somatic Nervous System
B) Autonomic Nervous System
D) Peripheral Nervous System (PNS)1) Somatic Nervous System:
a) receive/process sensory input; from skin, muscles, tendons, joints, eyes, tongue, nose, ears
b) voluntary contraction of skeletal muscle
D) Peripheral Nervous System (PNS)2) Autonomic Nervous System:
from CNS to glands; cardiac, various membranes; secretions
a) Sympathetic: reacts to stress with the “fight or flight” response
b) Parasympathetic: maintains homeostasis
E) Diseases and Disorders: Concussion Multiple Sclerosis
Contusion Myasthenia Gravis
Spina Bifida Parkinson’s
Hydrocephalus Epilepsy
Cerebral Palsy Tourette’s
Alzheimer’s Paralysis
Amyotrophic Lateral Sclerosis (ALS)