Lecture 12 - Muscle tissue-Skeletal, cardiac and smooth muscle Flashcards
Three main types of muscle
skeletal, cardiac and smooth muscle
Skeletal muscle structure
Long, cylindrical, multinucleate cells, obvious striations
One skeletal muscle fibre is one skeletal muscle cell
Skeletal muscle function
voluntary movement, locomotion, manipulation of the environment, facial expression, voluntary control (also for posture and standing)
Skeletal muscle location
in skeletal muscles attached to bones or occasionally to skin (allows movement of the skeleton)
Gross anatomy of the skeletal muscle
Epimysium - Connective tissue sheathing the muscle
Endomysium - Protecting individual muscle fibers
Perimysium - Sheaths bundles of muscle fibers
Fascicles - Bundles of muscle fibers
Hundreds of myofibrils typically in one muscle fibre which contain contractile units known as myofilaments that are required for muscle contraction
________ of myofibrils typically in ______ muscle fibre which contain ….
Hundreds of myofibrils typically in one muscle fibre which contain contractile units known as myofilaments that are required for muscle contraction
Sarcolemma
Cell membrane of the muscle fibre
Transverse tubule (T-tubule)
invagination of the sarcolemma into the cell
Sarcoplasmic reticulum
similar to endoplasmic reticulum. store and release calcium
NMJ
NMJ - motor neuron connected to skeletal muscle fibre at the NMJ
Each skeletal muscle fibre is connected to a motor neuron
Motor neuron - 1 per fibre
Muscle myofibril
Sarcomere = area between 2 Z lines
Sarcomeres are repeated thousands of times
From Z line into the sarcomere are the thin filaments and from the M line to the outside of the sarcomere are the thick filaments sticking out
Sarcomeres
repeating unit in skeletal muscle
area between 2 Z lines
Sarcomeres are repeated thousands of times
Myofilament structure
Actin = Contain binding sites for thick filament Tropomyosin = Protein strand that covers binding sites in relaxed state Troponin = Sits on tropomyosin and responds to signals for contraction, responds to calcium Myosin = Main protein of thick filament, elongated with distinctive head, head binds and “walks” along thin filament in order to create a contraction
Actin
Contain binding sites for thick filament
Tropomyosin
Protein strand that covers binding sites in relaxed state
Troponin
Sits on tropomyosin and responds to signals for contraction, responds to calcium
Myosin
Main protein of thick filament, elongated with distinctive head, head binds and “walks” along thin filament in order to create a contraction