Neuromuscular System Flashcards
Muscle spindles
These detect how far and how fast a muscle is being stretched and produce the stretch reflex
Golgi tendon organs
These are activated when there is tension in a muscle
The role of muscle spindles in PNF
Are very sensitive proprioceptors that lie between skeletal muscle fibres
They are often called stretch receptors as they provide information to the central nervous system about how fast and how far a muscle is being stretched
The central nervous system then sends an impulse back to the muscle telling it to contract, which triggers the stretch reflex
This reflex action that causes the muscles to contract to prevent overstretching reduces the risk of injury
Role of Golgi tendon organs in PNF
These are found between the muscle and tendon
They detect levels of tension in the muscle
When the muscles contract isometrically in PNF, they sense the increase in muscles tension and send inhibitory signals to the brain which allows the antagonistic muscle to relax and lengthen
This is known as auto genetic inhabitation
Isometric contraction
Where there is tension in a muscle but no visible movement
Autogenic inhibition
Where there is a sudden relaxation of the muscle in response to high tension. The receptors involved in this process are Golgi tendon organs
What’s examples does the parasympathetic nervous system do to the body
Constrict pupils
Stimulates salvation
Slows heartbeat
Constricts bronchi
Stimulates digestion
Contracts bladder
What’s examples does the sympathetic nervous system do to the body
Dilate pupils
Inhibit salvation
Accelerates heartbeat
Dilate bronchi
Inhibits digestion
Stimulates glucose release
What are the types of muscle fibres that can be identified
Type 1 - slow oxidative
Type11a - fast oxidative glycolytic
Type 11x - fast gycolytic
What are characteristics of type 11x muscle fibres
Fast glycolytic
Very fast speed of contraction
Very quick to fatigue
Very high force production
White in colour
Very high in PC stores
What are the characteristics of a type 2a muscle fibre
Fast oxidative glycolytic
Fast speed of contraction
High force levels
High PC stores
Quick to fatigue
Pink in colour
Speed endurance events
What are the characteristics of type 1 muscle fibres
Slow twitch
High numbers of mitochondrial
High levels of myoglobin
High capillary density / red in colour
High levels of fat stores
High levels of oxidative enzymes
Slow to fatigue
Low levels of force production
In muscle recruitment what is the all or none rule
Once the motor neurone stimulates the muscle fibres, either all of them contract or none of them. A minimum amount of stimulation is required to start the contraction – this called the threshold
Wave summation
Change in stimulus frequency to increase force/tension
If another stimulus is applied before the muscle relaxes completely, then more tension results
What is spatial summation
Changes in the strength of contraction are bought about by altering the number and size of the motor units involved
E.g kicking in rugby uses a lot of motor units whereas darts only need a few motor units involved
