1.3 Neuromuscular system Flashcards
Identify the role of the nervous system during exercise exercise?
Recruit different muscle fibre types depending on the demands of the activity.
Explain what the nervous system allows the muscles to do
Adjusts the strength of contraction and uses sensory organs to allow a muscle to stretch further in PNF
What does PNF stand for
Proprioceptive neuromuscular facilitation
Identify and describe what other systems the peripheral nervous system consists of
The peripheral nervous system consists of the nerves that branch out from the spinal cord. The Sympathetic and Parasympathetic systems are part of the peripheral nervous system as they transmit impulses from the brain to the parts of the body that need adjusting during exercise.
Describe the structure of the peripheral nervous system?
The peripheral nervous system consists of the nerves that branch out from the spinal cord.
Explain the difference between the Sympathetic and Parasympathetic nervous systems and give e.g.
Sympathetic: prepares the body for exercise (fight or flight response) e.g. increase HR, BP
Parasympathetic: opposite effect of the sympathetic nervous system, it relaxes the body and slowing down many high energy functions. Rest and relax e.g. slows heart and breathing rate, lowers BP
Identify the different types of muscle fibres
- Slow Oxidative (type 1)
- Fast Oxidative glycolytic (type 2a)
- Fast Glycolytic (type 2x)
What factor is genetically determined in terms of skeletal muscles?
Skeletal muscles contain a mixture of all three types of fibre BUT not in equal proportions. The quantity of variety is genetically determined
Identify the characteristic of the muscle fibre predominantly used by a marathon runner
Slow oxidative type 1 - Suitable for low intensity exercise over a length period of time - such as long distance running, swimming. Produce energy in the presence of oxygen.
- Slow contraction speed
- small motor neurone size
- low force produced
- low fatiguability
- low anaerobic capacity
- high mitochondrial density
- high capillary density
- high myoglobin content
Identify the characteristics of the muscle fibre predominately used by a games player, such as rugby
Fast Oxidative glycolytic type 2a - more resistant to fatigue as they are predominantly used in events such as 1500m/games where a longer burst of energy is required. Energy source for type 2a is glycogen.
- fast contraction speed
- large neurone size
- high force produced
- medium fatiguability
- medium aerobic capacity
- medium mitochondrial density
- medium capillary density
- medium myoglobin content
- high anaerobic capacity
Identify the characteristics of the muscle fibre predominantly used by a 100m sprinter
Fast Glycolytic fibres type 2x - these fibres fatigue very quickly therefore used for short, intense bursts of effort. Produce energy anaerobically.
- fast contraction speed
- large neurone size
- high force produced
- high anaerobic capacity
- high fatiguability
- low aerobic capacity
- low mitochondrial density
- low capillary density
- low myoglobin content
Identify which muscle fibre has the highest Aerobic capacity
Slow Oxidative type 1
Explain why there is a high mitochondrial density in Slow Oxidative fibres?
Mitochondria produces energy in the presence of oxygen therefor slow oxidative muscle fibres produce energy aerobically
Explain the difference between the structural and functional characteristics when describing a muscle fibre
Structural characteristic = concerns the make up of the fibre e.g. myoglobin, mitochondrial, capillary density, size, colour
Functional characteristic = what the fibre does - its function e.g. does it fatigue easily , force, contractile speed and force, aerobic/anaerobic
Briefly explain the difference in the structural characteristics of a Slow Oxidative and Fast Glycolytic muscle fibre
Slow Oxidative: HIGH capillary density, HIGH aerobic capacity, LOW anaerobic capacity, HIGH mitochondrial density
Fast Glycolytic: LOW capillary density, LOW aerobic capacity, HIGH anaerobic capacity, LOW mitochondrial density
Identify what a motor unit consists of
A motor unit consists of a motor NEURONE and its group of muscle fibres
True of False:
All the different types of muscle fibres can be found in ONE particular motor unit
FALSE
Only ONE type of muscle fibre can be found in one particular motor unit
Explain the contraction of a muscle fibre occurs
The motor neurone transmits a nerve impulse to the muscle fibre for a contraction to occur
Describe the structure and function of a motor neurone
Each motor neurone consists of branches which end in the neuromuscular junction on the muscle fibre. The motor neurone transmits a nerve impulse to the muscle fibre allowing it to contract.
Describe the ‘all or none law’
The motor neurone sends a signal to the muscle fibres and either all of them contract or none. The impulses have to be of sufficient intensity to stimulate all of the muscle fibres in a motor unit to contract. It is NOT possible for a motor unit to partially contract.
Describe the process of wave summation and what it achieves
Wave summation occurs when there is a repeated nerve impulse with no time to relax, producing a smooth sustained contraction rather than twitches/bursts (tentanic contraction). Fast and frequent impulses
Important when increasing the strength of muscular contraction.
True or False:
Calcium in required in the process of a muscular contraction
True
Calcium is required because each time the nerve impulse reaches the muscle cell, calcium in released.
Describe what is meant by a tetanic contraction?
A muscles fullest contractile state e.g. scrum = applying full force on something thats not moving. A sustained muscle contraction caused by a series of frequent and fast repeated impulses during wave summation.
Identify what PNF is it used for?
Advanced stretching technique and the most effective form of flexibility training to improve range of movement
Describe what is meant by the CRAC technique
C ontract
R elax
A ntagonist (one contracts one relaxes)
C ontract
Which proprioceptor detects how far/fast a muscle is being stretched and produces the stretch reflex?
Muscle Spindles
Identify the function and location of Muscle Spindles
Muscle spindles detect how far a muscle is being stretched and produce the stretch reflex. They lay in between the skeletal muscle fibres.
Explain the importance of a reflex action and identify which proprioceptor produces it
Muscle spindles trigger the stretch reflex action causing the muscles to contract which prevents over stretching and injury
Identify which proprioceptor detects levels of tension in a muscle
Golgi tendon organs
Explain the function of Golgi tendon organs
Detect tension in the muscle and produce autogenic inhibition
During which stage of PNF are the Golgi tendon organs predominant?
When the muscle is contracted isometrically, Golgi muscle tendons detect the increase in muscle tension and signal to the brain allowing the antagonist muscle to relax and lengthen.
How do we control the strength of contraction?
Recruit larger motor units (the bigger the stronger). Recruit more motor units. Recruit more fast twitch muscle fibres.
Describe the structure of a motor unit
Motor neurone and group of muscle fibres
What is action potential and when is it used?
Its a signal that needs to be strong enough to cross the neuromuscular junction in order for a muscle to contract.
True of False:
By increasing the rate of stimulation to a muscle we can get a greater force of contraction
True
By increasing the rate of stimulation to a muscle we can get a greater force of contraction
Explain the term ‘twitch’
A single contraction
Which proprioceptor produces the reflex action/stretch reflex
Muscle spindles as they detect the overstretch and cause the muscles to contract to prevent injury.
What is autogenic inhabitation and what receptors are involved in this process?
The sudden relaxation of muscles in response to high tension.
Explain why a muscle is able to stretch further after completing PNF?
Once the muscle is stretched after being isometrical contracted, the golgi tendon organs are responsible for the antagonist muscle relaxing
What process is delayed/inactive when a muscle is isometrically contracted after being stretched in PNF?
Stretch reflex
What is a passive stretch?
When you stay stretched in a position with the assistance of a partner
Describe the structure of the nervous system
The nervous system consists of two main parts.
1. The central nervous system is made up of the brain and spinal cord.
2. The peripheral nervous system is made up of nerves that branch off from the spinal cord and extend to all parts of the body (includes the sympathetic & parasympathetic systems)
Identify the processes that can increase the strength of a muscular contraction
Wave summation
Spatial summation
Describe the process of spatial summation and what it achieves
Spatial summation occurs when the strength of contraction changes by altering the number and size of the muscles motor units.
Sharing workload over different motor units by recruiting different motor units at different times to reduce fatigue.
Difference activities require different strength of contraction, this depends on the number and size of motor units recruited.
Describe the function of proprioceptors
Proprioceptors are sensory organs in the muscles, tendons and joints that inform the body of the extent of movement that has taken place.
Explain the process of PNF and identify the role of the proprioceptors during this advanced stretching technique
- Start by the individual performing a passive stretch with a partner. The stretch in the muscle is detected by muscle spindles and if stretched too far, a stretch reflex occurs.
- The individual then isometrically contracts the muscle in a stationary position. The muscular tension is detected by golgi muscle tendons and deactivating the stretch reflex.
- The individual performs a passive stretch again and the golgi muscle tendons are responsible for relaxing the antagonist muscle (autogenic inhibition) allowing the muscle to be stretched further.
