Muscle contraction

Stimuls: nerve impulses that are caried by the motor neuron to the muscle fibre

Principle: based on slighting of myosin filaments toward the actin filaments

Basic components involved in muscle contraction:

motor neuron - neuron that conducts nerve impulses from the CNS to the muscle fibre

neuromuscular junction - the point of contact between motor neuron and muscle cell

Motor unit - conection between muscle fibre and motor neuron

acetylcholine - chemical substance, neurotransmitter that is responsible for muscle tonus formation

Sacroplasmic reticulum - special type of endoplasmic reticulum which contains Ca²⁺ when muscles relaxes

troponin - protein that indicates muscle contraction

Ca²⁺ - ions need for muscle contraction

ATP - source of energy for muscle contraction

Myosin and Actin - filaments involved in muscle contraction

Mechanism of muscle contraction: = The sliding filament theory

1. transmition of nerve impulse

- nerve impulse is carried by motor neuron to the neuromuscular junction, in next step vesicles of neuromuscular junction release acetylcholines and muscle start tonus

2. formation of muscle contraction

- after muscle tonus formation Sarcoplasmic reticulum releases Ca²⁺ (when it´s within Sarcoplasmic reticulum - actin and myosin start to repulse), troponin initiates myosin to form cross-bridges toward the actin filaments complex actin-myosin bond and muscles contraction occure, when Ca²⁺ returns to the Sarcoplasmic reticulum using ATP actin and myosin starts to repuls and muscles relaxes