13.13 Muscles Flashcards
Smooth muscle definition
Contracts without conscious control
Where is smooth muscle found?
Walls of internal organs, stomach, intestine and blood vessels
Cardiac muscle definition
Contracts with conscious control (myogenic)
Where is cardiac muscle found?
In the heart
Skeletal muscle definition
Striated muscle used in locomotion, it is attached to bone via tendons
Where is skeletal muscle found?
In antagonistic pairs, ie biceps and triceps
Explain the structure of skeletal muscle going from biggest to smallest
cell membrane - sarcolemma
sarcoplasm
myofibrils
myofilaments containing actin and myosin
Name all the parts of a muscle diagram
Sarcomere
Z disc
M line
H zone
I band
A band
What is in the A band?
Dark in colour so has both actin and myosin
What is in the I band?
Light in colour so only has actin
Describe the sliding filament theory
Ca2+ released from the sarcoplasmic reticulum into sarcoplasm
Ca2+ diffuse snd bind to troponin and cause tropomyosin to move, exposing the myosin head binding site on the actin
Myosin heads bind to actin forming cross bridges
The myosin head pulls the actin filament a short distance over the myosin
ADP and Pi released from myosin head
ATP binds to myosin head, breaking the cross bridge and separating from actin
ATP hydrolyses by ATP hydrolase, energy released resets myosin head
Process repeats
What are the two things ATP is required for to do with muscles?
Sliding filaments during contraction
The active transport of calcium ions into the sarcoplasmic reticulum
ADP + phosphocreatine
ATP + creatine
ATP + creatine
ADP + phosphocreatine
