Topic 11 -Muscular System Flashcards
Skeletal muscle cells called
fibres
group of fibres
fascicle
whole muscle
group of fascicles
CT components of Skeletal muscle
Fascia
Tendons and aponeuroses
Fascia = CT 3 classifications
Epimysium -surrounds entire muscle
Perimysium -surrounds fascicles
endomysium -surrounds each muscle fibre
Tendons and aponeuroses
extensions of epi, peri and endomysium
anchors muscles to bone (periosteum), cartilage of skin or fascia of other muscles
tendon -rope like ex achilles
aponeuroses -sheet like ex galea aponeurotica= epicranial aponeurosis
skeletal muscle fibre structure 5 parts
multinucleated
1) Sarcolemma
2) Sarcoplasm
3) myofibrils
4) T tubules
5) sarcoplasmic reticulum (SR)
sarcolemma
cell membrane
sarcoplasm
cytoplasm
myofibrils
within each fibre there are several hundreds to thousands
composed of sarcomeres
sarcomere structure, made of two types of myofilaments
thin filaments
thick filaments
thin filaments
actin -functions in contraction
tropomyosin and troponin which regulate contraction (regulatory proteins)
thick filaments
composed of myosin -function in contraction
attached to Z discs by titin
has rod like tail with 2 globular heads
head extends towards actin and attaches to it forming a cross bridge
myofilaments create
dark and light bands (striations) of the sarcomere
banding pattern of sarcomere (5)
A band H zone I band Z discs M line
A band
dark=length of thick filament -myosin and actin (with troponin and tropomyosin)
H zone
lighter band at center of A band -myosin only
I band
light =actin (with troponin and tropomyosin) + titin
Z discs
in center of I band
actin and titin attach
connect sarcomeres: between 2 Z discs =1 sarcomere
sarcomeres join end to end at Z disc to form myofibrils
M line
where myosin tails (thick filaments) attach to each other at center of sarcomere
T tubules
continuation of sarcolemma that extend deep into fibre (cell)
directly encircle myofilaments at junction of A and I bands (2/sarcomere)
Sarcoplasmic reticulum
triad
smooth ER
2 enlarged areas of SR (terminal cisternae) and T tubule
How do muscles produce movement?
pulling on bones when they contract
using group action
lever systems
pulling on bones when they contract
origin=attachment of tendon to stationary bone
insertion=attachment to movable bone
using group action
agonist -major muscle producing the movement
synergist -help the agonist action and prevent undesirable motions caused by the agonist
antagonist -produces the opposite action of the agonist
lever systems
bone/muscle interaction at a joint parts: lever=bone and fulcrum=joint effort= contraction of agonist resistance=opposes movement (weight) effort must be greater than resistance to move
