The Neuromuscular System - Applied Anatomy and Physiology (Paper 1) Flashcards
What does the autonomic nervous system regulate
The function of our internal organs as such as the heart and controls some of our skeletal muscles within the body
How does the autonomic nervous system work
Works involuntarily
How is the movement of muscles controlled by
The brain via nerves
What is the neuromuscular system
Where the muscles and nervous system work together to allow movement
When do changes in the neuromuscular system take place
Before,during and after the exercise
What system are the sympathetic and parasympathetic systems apart of
The autonomic nervous system
What is the role of the parasympathetic and sympathetic systems
Transmit information from the brain to the parts of the body that need to adjust what they are doing to prepare for exercise
What does the sympathetic system prepare
The body for exercise and is often referred to as the fight or flight response
What does the parasympathetic system do
Opposite effect of the sympathetic system and relaxes the body and slows down many high energy functions
What are the types of muscle fibres
Slow oxidative (type 1 or slow twitch fibres)
Fast oxidative glycolytic (type 2a)
Fast glycolytic (type 2b)
What is the proportion of muscle fibres dependant on
Dependant on different people and what sport they play
E.g. elite endurance athletes will have a greater proportion of slow twitch fibres in the leg muscles, whereas elite sprinter will have high proportion of fast twitch fibres in the leg muscles
What are slow twitch fibres
-slower contraction speed than fast twitch fibres
-better adapted to lower intensity exercise
-Produce most of their energy anaerobically
What are fast twitch fibres
-faster contraction speed than slow twitch fibres
-generate much greater force of contraction
-fatigue very quickly
-produce most energy anaerobically
-two types 2a 2b
What are type 2a fibres
-fast oxidative glycolytic
-fibres more resistant to fatigue than 2b
-used for 1500m in athletics where a longer burst of energy is needed
What are type 2b fibres
-Fast glycolytic
-fibres fatigue much quicker than type 2a
-used for highly explosive event e.g. 100m
What is the contraction speed of each of the muscle fibres
Type 1: Slow (110m/s)
Type 2a: Fast (50m/s)
Type 2b: Fast (50m/s)
What is the motor neurone size in each of the muscle fibres
Type 1: Small
Type 2a: Large
Type 2b: Large
What is the motor neurone conduction capacity in each fibre
Type 1: Slow
Type 2a: Fast
Type 2b: Fast
What is the force produced in each of the muscle fibres
Type 1: low
Type 2a: High
Type 2b: High
What is the fatigability on each if the muscle fibres
Type 1:low
Type 2a:medium
Type 2b:High
What is the mitochondrial density in each if the muscle fibres
Type 1: high
Type 2a: medium
Type 2b: low
What is the myoglobin content on each if the muscle fibres
Type 1: High
Type 2a: medium
Type 2b: low
What is the capillary density in each muscle fibre
Type 1:high
Type 2a:medium
Type 2b:low
What is the aerobic capacity on each muscle fibre
Type 1:very high
Type 2a:medium
Type 2b:low
What is the anaerobic capacity of each muscle fibre
Type 1: low
Type 2a: high
Type 2b: very high
What is the glycolytic enzyme activity of each muscle fibre
Type 1: low
Type 2a: high
Type 2b: very high
What is the fibre type determined by
Genetics, however it is possible to increase the size of muscle fibres through training (hypertrophy)
What are muscle fibres grouped into
Motor units
What does a motor unit consist of
-Motor neurone
- and it’s muscle fibre
How many types of muscle fibres can be found in a motor unit
Only one muscle fibre can be found in one particular motor unit
Muscle fibres work with…
The nervous system so that a contraction can occur. The motor neurone transmits the nerve impulse to the muscle fibre
Each motor neurone has….
Branches that end in the neuromuscular junction on the muscle fibre
What is a neuromuscular junction
Where the motor neurone and the muscle fibre meet
Each muscle is made up of what
Many motor units and they vary in size
E.g. a small muscle used for fine movements (like eye movements) will have few motor units. Whereas a large muscle group used for gross motor control (like the quads) will have motor units with a motor neurone feeding hundreds of fibres
What is the all or none law
Once the motor unit stimulates the muscle fibres either all of them contract or none of them contract
A threshold is required to start a contraction. If the impulses is equal or above the threshold all muscle fibres in a motor unit will contract
Is it possible for a motor unit to partially contract
No, because the threshold has not been met
What is the minimum amount of stimulation to start a contraction called
A threshold
What happens if the sequence of impulses is equal to or more than the threshold
All the muscle fibres in a motor unit will contract
What happens if the sequence of impulses is less than the threshold
Then no muscle action will occur
Define the all or none law
Where a sequence of impulses has to be of sufficient intensity to stimulate all of the muscle fibres in a motor unit in order for them to contract. If not none of them will contract
What is wave summation
Where repeated activation of a neurone stimulating a given muscle results in a greater force of contraction.
The greater the frequency of the stimuli, the greater the tension developed by the muscle.
What is need to be present for a muscle to contract
Calcium
Calcium is also released when a nerve impulse reaches the muscle cell
What happens if calcium builds up in a muscle cell
If calcium builds up in a muscle cell, it’s because there are recreated nerve impulses with no time to relax. This produces a forceful, sustained, smooth contraction also known as a tetanic contraction
Define tetanic contraction
A sustained muscle contraction caused by a series of fast repeating stimuli.
Produces a forceful, sustained, smooth contraction as a result of calcium build up in cell due to no relaxation time
What is spatial summation
- the recruitment of additional and bigger motor units within a muscle to develop more force.
- occurs when impulses are received at the same time at different places on the neurone. This fires the neurone
- e.g. a basketball player will use lots of large, fast twitch motor units in their quadriceps muscles to try an achieve as much height as possible to get the rebound
Define spatial summation
When the strength of a contraction changes by altering the number and size in the motor units
What does PNF stand for
Proprioceptors neuromuscular facilitation
What is PNF
An advanced stretching technique considered to be one of the most effective forms of flexibility training for increasing range of motion
What are the several mechanisms that make PNF possible
Muscle spindles
Golgi tendon organs
What are muscle spindles
-very sensitive proprioceptors that lie between skeletal muscle fibres
-they provide information to the central nervous system about how fast and how far a muscle is being stretched
- the CNS sends an impulse which triggers the stretch reflex
-this reflex action that causes the muscle to contract to prevent over stretching reduces risk of injury
Define muscle spindles
Proprioceptors that detect how far and how fast a muscle is being stretched and produce the stretch reflex
What are the Golgi tendon organs
-proprioceptors found in between the muscle fibre and tendon.
-detect levels of tension in muscles
-when muscle is contracted isometrically in PNF they sense the increase in muscle tension
-send inhibitory signals to the brain which allows the antagonist muscle to relax and lengthen-autogenic inhibiton
Define Golgi tendon organs
Proprioceptors that are activated when there is tension in a muscle
Define isometric contraction
Where there is tension in a muscle but no visible movement
Define autonomic 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 is the first step to PNF
- Individual performs passive stretch. They extends the leg until tension is felt. This is done by the help of a partner
- If the muscle is being stretched too far then a reflex should happen
What is the second step of PNF
- the individual then isometrically contracts the muscle fro at least ten seconds by pushing their leg against their partner who supplies enough resistance to hold the leg in a stationary position
What is the third step of PNF
- leg is lifted again and the golgi tendon organs are responsible for the antagonist muscle relaxing which means the leg stretches further
- process is repeated until no more gains are possible
What is the role of the Golgi tendon organs in PNF
- they detect levels of tension in a muscle
- when a muscle is contracted isometrically in PNF they sense the increase in muscle tension and send inhibitory signals to the brain which allows the antagonist muscle to relax and lengthen and delay the stretch reflex. This is known as autogenic inhibition.
