OPTA 222( nervous system)
What are Neurons?
Functional cells in the nervous system
What is a Glial Cell?
Provides metabolic support
Neuron Stucture: Axon
-Carry neuronal signal in unidirectional manner
-Carry materials in bidirectinal manner: cellular content and pathogens
Action Potential
this is how the nerve transmits signals down the axon
What is Resting Membrane Potential?
The voltage a membrane sits at before any part of the action potential begins, you must depolarize the membrane enough to hit threshold potential.
Depolarization?
Is the rise in the electrical membrane potential
Repolarization
Is a decrease in the membrane potential
Relative Reractory Period
This is the period of time after and action potential, elecric membrane potential drops below threshold potential. At this time cell membrane is Hyperpolarized and it hard to elicit and action potential.
Synapse
Is how neuron communicat with each other
Neurotrasmitters
signal trasmitting substances that pass between two different neurons through the synapse
Synapse Type: Axodendritic
between axon and dentrite of two different cells
Synapse Type; Axosomatic
between axon and body of two different cell
Synapse Type: Axoaxonic
between two axons of two different cells
Why do we discuss disorder of motor function in conjection with nervous system?
Neuron innevate muscles, motor disorders can be caused by neurons not functioning properly
Motor Function Disorders: Muscle Atrophy
-Reduced use of muscle strenght results in atrophy
defined by reduced nuscle diameter and fibers
-loss of protein filaments such as contractile proteins
Motor Function Disorders: Muscle Distrophy
- group of genetic disorders that produce progressive deteriation of the skeletal muscles
- due to muscle hypertrophy, atropy and necrosis
- effect muscle tissue not the nervous system
- if necosis is involve its part of fat and connective tissue
Motor Function Disorders: Nueromuscular junction
drugs and toxin that alter function at the junction example. Myasthenia Gravis; anibodies block and destroy ACh receptos at the junction
Motor Function Disorders: Drugs and Toxins Induced
Example butulism caused by c botulium, honey is a good enviroment for botulium to grow so a result babies under one can't have honey because botulism can affect babies GI systems and allow spores to germinate.
Motor Function Disorders: Peripheral nerve injury and repair
Two Types
-Segental demylination in Schwann Cell; part of Axon gets demyelinated make it difficult to transmit signal
-regen occurs;axon provides stimulus for remyelination,it thinner so still pron to injury
-Axon degeneration in the cell body or axon; axons shrink/die
regen occurs; is variable depending on the damgage, cell boy destoyed nueron dies, crush injurie partial of full recovery common, cut injury scar tissue can impede new axons
Motor Function Disorders: Mononueropathies
cause by localized condition; trauma, compression, infection, fractures
ex carpal tunnal is a compression type, cuased by compression in the. median nerve as it travel throuh the carpal bones and transverse carpal ligament
Motor Function Disorders: Polyneuropathies
-caused by demyelination on axon degeneration of peripheral nerves , imune reactions(GBS), Toxic agents(alcohol,lead), or disease(diabetes)
-symtoms:symetrical sensory,motor mixed sensormotor deficits
Motor Function Disorders: Cerebeller Disorders
Cerebeller is vital for coordination of movements
Disorder include: Ataxia, Nystagmus, Dymetria(improper measurement of distance in muscular acts), Intention Tremmers( tremmers when you reach for a target), Dysphasia( difficulty swallowing) , Dysarthria(poor speech motor control)
Motor Function Disorders: Basal Ganglia Associated Movement
basal Ganglia are subcortical Nuclei involve in control of movements.
Parkinson's is one of these disorders with it decrese in dopamine
Motor Function Disorders: Upper and lower motor neuron
UMN; rusults in disruption in the signal between the brain and spinal cord(ex stroke)
LMN; Result in disruption in the signal between the spinal cord and the muscle(ex GBS)