CNS & Muscular Control Flashcards
Name the 6 components of the Neuromuscular Junction
- Sarcolemma
- Presynaptic Terminal
- Synaptic Vesicles
- Synaptic Cleft
- Presynaptic Membrane
- Mitochondria
What is Action potential ?
Positive electrical charge inside the motor unit, which conducts the nerve impulse down the neurone into the muscle fibre
What happens when motor unit receives a stimulus and creates Action Potential?
A.p must reach or be above the threshold charge
All the muscle fibres within that motor unit will do react at the same time with max. Force
What will happen if the AP doesn’t reach the threshold charge?
None of the muscle fibres will contract
What is the synaptic cleft?
Small gap between the motor end plate and muscle fibre
What Neurotransmitter transmits the AP across the synaptic cleft?
Acetylcholine (Ach)
How is Muscle action potential created
I’d enough neurotransmitter us secreted and electrical charge is above the threshold
State the ‘All or None Law’
When stimulated ALL the fibres within a motor unit contract completely or not at all.
If more motor units are stimulates the result is increase in the strength/force of contraction.
Give an overview of the nervous pathway that causes a muscular contraction. (8)
- CNS sends electrical impulse to the motor neurone
- Motor neurone sends nervous impulse
- Action Potential conducts nerve impulse as a wave of electrical charge from axon to motor end plate
- Neurotransmitter (Acetylcholine) is needed to carry the impulse across the neuromuscular junction
- If enough Ach is secreted and electrical charge is above threshold, muscle AP is created
- Creates wave of contraction down the muscle fibre
- When motor unit receives AP that reaches threshold charge, muscle fibres contract with max force (All or None Law)
What are the 3 types of muscle fibres?
- Type 1 (slow oxidative)
- Type IIa (fast oxidative glycolytic )
- Type IIb (fast glycolytic)
Type 1
Colour. Myoglobin Conc.
Size. Glycogen Stores
No.Mitochondria
No.capillaries
Colour: red Size: small Mitochondria: many Capillaries: many Myoglobin conc: high Glycogen stores: low
Type IIa
Colour. Myoglobin Conc.
Size. Glycogen Stores
No.Mitochondria
No.capillaries
Colour: pink Size: intermediate Mitochondria: many Capillaries: many Myoglobin conc: high Glycogen stores: intermediate
Type IIb
Colour. Myoglobin Conc.
Size. Glycogen Stores
No.Mitochondria
No.capillaries
Colour: white Size: large Mitochondria: few Capillaries: few Myoglobin conc: low Glycogen stores: high
Type 1
Contractile Speed. Anaerobic Capacity
Contractile Strength
Fatigue Resistance
Aerobic Capacity
Contractile Speed: slow Contractile Strength: low Fatigue Resistance: high Aerobic Capacity: high Anaerobic Capacity: low
Type IIa
Contractile Speed. Anaerobic Capacity
Contractile Strength
Fatigue Resistance
Aerobic Capacity
Contractile Speed: fast Contractile Strength: intermediate Fatigue Resistance: moderate Aerobic Capacity: moderate Anaerobic Capacity: high
