1.1- muscular system Flashcards
What is the insertion?
The point of muscular attachment to a moveable bone, which gets closer to the origin during muscular contraction
What is the origin?
The point of muscular attachment to a stationary bone which stays relatively fixed during muscular contraction.
What is a fixator muscle?
A muscle that stabilises one part of the body while another causes movement
What is a concentric contraction?
A muscle shortens, producing tension, producing a force pulling the 2 bones closer together causing joint movement.
What is an eccentric movement?
Muscle lengthens producing tension, resisting force like gravity, controlling joint movement.
What is an isometric contraction?
Muscle contracts but does not change length, muscle creates tension as it pulls on the tendon attachments.
What is a motor unit?
Motor neurone and its muscle fibers
What does a motor unit do (simplified)?
Carries nerve impulses from the brain + spinal chord to muscle fibers, initiating muscular contraction
What does action potential do?
Conducts the nerve impulse as a wave of electrical charge down the axon to motor end plates
What is the point where the axon’s motor end plates and the muscle fiber meet called?
Neuromuscular junction
What is the small gap between the motor end plates and muscle fibre called?
Synaptic cleft
What does the action potential need to cross the synaptic cleft?
A neurotransmitter called acetlcholine (Ach).
What happens if enough neurotransmitteris secreted + is above a threshold?
A muscle action potential is created, creating a wave of contraction down a muscle fibre. All muscle fibers in a motor unit will contract with maximum force.
What happens if action potential doesnt reach the threshold?
None of the muscle fibers will contract (all or none law)
