A&P AS Flashcards
What is a motor unit
A motor neurone plus all the muscle fibres it innervates.
What is a neurone
A type of nerve cell
What is an axon
Carries action potential (AP)/electrical impulse from the cell body to the neuromuscular junction.
Why is neuromuscular junction
Where the motor neurone communicates with the muscle fibres across the synapse .
What is a synapse
The space between the neuromuscular junction and skeletal muscle.
What’s the motor end plate
Area of muscle fibres which establishes synaptic contact with motor neurone.
What is resting potential
Where there is a lower charge inside the neurone than outside the neurone.
What is action potential
The electrical impulse carried down the axon.
What are neurotransmitters
chemical transmitters which diffuse across a synapse binding to receptor to initiate muscular contraction.
What is Acetyl choline
The neurotransmitter released at the neuromuscular junction and diffuses across the synapse .
What is the all or non law
If the AP threshold is reached, all the muscle fibres in the motor unit are initiated. If the AP threshold is NOT reached then none of the muscle fibres are initiated.
What is the step by step guide to answering motor unit questions
- define what a motor unit is.
- resting potential.
- AP threshold reached.
- AP carried down axon to neuromuscular junction.
- Neuromuscular junction releases ACh which diffusers across the synapse .
- ACh bind to receptors on the motor end plate and all the muscle fibres in that motor unit contract(as the AP threshold was reached).
- If the AP threshold wasn’t reached then none of the muscle fibres in the motor unit would contract.
What is the effect of number of motor units recruited
- The greater the strength of the stimulus from the CNS.
- The greater the number of motor units recruited.
3.The greater force of muscular contraction.
Effect of the type of motor unit recruited
1.Type 1 are small and produce low force of contraction over a long period.
2.Type 2a size and time of contraction are between type 1 and 2b
3. Type 2b are large and produce a large force of contraction over a short period of time.
What is isotonic contraction
The muscle is changing length while exerting a force
There are 2 types:
1. Concentric isotonic - muscle shortens
2. Eccentric isotonic - muscle lengthens
Eg lifting and lowering phases of a weight training exercise
What is isometric contraction
The muscle remains the same length while exerting a force.
Isometric contraction stops movement.
Eg crouch phase of a rugby scrum
What is concentric contraction and give a sporting example
The muscle shortens while exerting a force.
Concentric contraction causes movement.
Eg triceps brachii and pectoralis major when preforming the upwards phase of a press up.
What Is eccentric contraction and give a sporting example
The muscle lengthens while exerting a force
Eccentric contraction controls the movement
The muscle acts like a break to control the lowering movement
The muscle s usually working against gravity
Eg triceps brachii and pectoralis major when preforming the downward phase of a press up.
What is the function of a motor unit
To carry electrical impulses form the CNS to the muscle fibres to initiate muscle contraction.
Effect of synchronisation of motor units.
Not all motor units are fruited at the same time
1st motor units recruited are type 1-force of contraction low
2nd motor units recruited are type 2a-force of contraction increases
3rd motor units recruited are type 2b- force of contraction increases further
What are the 3 types of muscle fibre
Type 1 : slow oxidative (SO)-endurance fibres
Type 2a:fast oxidative glycolic (FOG)- speed endurance fibres
Type 2b:fast glycolic (FG)-speed/power fibres
Games players have a mix of all fibres
What is myoglobin
Myoglobin: a protein in muscle cells that stores oxygen for cellular respiration
What is a phosphocreatine
A chemical compound that stores energy in muscles Brain and heart its a rapid energy source for muscle contractions.
It regenerates ATP form ADP.
What is the primary type of muscle fiber characterized by high endurance?
Type 1 muscle fibers
Which muscle fiber type is known for rapid contraction and high force production?
Type 2b muscle fibers
True or False: Type 2a muscle fibers are a hybrid of type 1 and type 2b fibers.
True