The Nervous System

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

Anatomy

Of A Synapse:

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

MonosynapticReflex Arc:

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

B) Neuroglias:

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) Anatomy:

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) The CNS:

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

Meninges:

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)

D/D: Concussion: A) Coup

D/D: Concussion: B) Contre Coup

D/D: Contusion

D/D: Hematomas

D/D:Craniotomy

D/D: Bell’s Palsy

D/D: Parkinson’s