Muscles (1) - 15% Flashcards
What are the 5 function of Muscle ?
Support Movement of Body Transport of Blood Transport of Gas Transport of food
Skeletal Muscle Fibers (FACT CARD)
An individual muscle cell is called a muscle fiber
A muscle fiber is enclosed by a plasma membrane called the sarcolemma
The cytoplasm of a muscle fiber is called a sarcoplasm
Within the sarcoplasm, the extensive T-tubules allow transport of substances throughout the muscle fiber
The sarcoplasmic reticulum (SR) stores calcium
The Myofibril (FACT CARD)
Myofibrils are made up of sarcomeres
A sarcomere is composed of protein filaments: myosin and actin
Interactions between the filaments is responsible for muscle contraction
Myosin, the thick filament, is composed of two protein strands, each folded into a globular head at one end
The thin filament is composed of actin, tropomyosin, and troponin, with one end attached to a Z-disk
What is a Alpha Motor Neuron ?
One motor neuron innervates many muscle fibres, collectively called the motor unit
What is the Sliding Filament Theory?
https://www.youtube.com/watch?v=NEUpdQ7OjeA
Muscle contraction is initiated by an a-motor
The motor neuron releases acetylcholine - opens up ion gates in the muscle cell membrane
Sodium enters the muscle cell depolarizing the plasmalemma
The action potential travels throughout the plasmalemma and through the T-tubules, which releases stored Ca2+ ions
ATP binds to myosin head and myosin detaches from binding site
ATP hydrolysis to ADP+Pi provides E for myosin head to return to its ‘cocked’ position
Ca2+ ions bind with troponin, lifting the tropomyosin molecules off the active sites on the actin filament for the myosin head to bind to
The myosin head tilts, pulling the thin filament past the thick filament—power stroke (Pi is released)
ADP is released and rigour state is entered
Muscle contraction ends when Ca2+ is actively pumped out of the sarcoplasm back to the sarcoplasmic reticulum (more ATP needed)
