Neuromuscular Disease (NMD) Flashcards
define the neuromuscular system
combination of the nervous system and muscles working together to permit movement
what is a neuron, and what does it consist of?
A basic unit of nervous tissue; made up from:
- nerve cell bodies
- dendrites
- axons
define what a nerve is
a bundle of axons held together with connective tissue
function of myelin sheath
- insulation
- protection
list the 3 different types of muscles
- skeletal
- cardiac
- smooth
list the 3 characteristics of muscle tissue
- excitable
- conductive
- elastic
function of skeletal muscle
Contracts in response to stimulation by somatic motor nerves which conveys impulses from the CNS
functions:
- maintains posture
- supports soft tissue
- maintain body temperature via shivering
list the characters of skeletal muscle - myofibrils
- densely packed
- aligned
- rod like elements
- contain sarcomeres (contractile units)
list the characteristics of skeletal muscle - sarcomeres
- functional units of muscle fibres
- align along the myofibril
- composed of thick and then myofilaments
list the steps of sliding filament mechanism of contraction
- Myosin attaches to actin
(which then pulls actin towards centre of sarcomere) - Pulls z lines towards each other
- sarcomeres shorten, muscle fibres shorten, entire muscle contracts = movement
Describe the Neuromuscular Junction (NMJ)
- situated midway along length of muscle fibre
- contain nicotinic receptors
At rest what is the body’s muscle tone
partially contracted (taut)
how is a taut muscle tone maintained at rest
different motor units contracting at different times
is muscle tone present when sleeping or unconscious
no
what happens when skeletal muscle is damaged
due to skeletal muscle fibres not being able to divide; will be replaced by scar tissue which is non contractile
describe hypertrophy
- response to regular and forceful use of a muscle
- increase in number of contractile proteins and diameter of individual fibres
describe atrophy
Response to disuse
- fibres shrink as contractile proteins are broken down and recycled
Define Neuromuscular Disease
Includes all diseases/disorders that impairs the functioning of muscles either:
- directly; due to muscle pathology
- indirectly; due to nervous system
list the causes of NMD
- failure of electrical impulses to be conveyed to nerve
- failure of chemical message to bridge synaptic cleft
- failure of muscle to contract
Symptoms of NMD
- muscle weakness
- atrophy
- continuous spasm (myotonia)
- muscle twitching
- pain
- breathing or swallowing difficulty
Causes of NMD
- genetic mutation
- viral infection
- auto immune disorder
- hormonal disorder
- metabolic disorder
- dietary deficiency
- drugs
- unknown
at what level of the motor pathway does Parkinson’s disease originate
- basal ganglia (produces dopamine)
- substantianigra
what is Duchenne muscular dystrophy (DMD)
progressive muscle wasting involving mutation of DNA
at what level of the motor pathway does DMD originate
muscles
