11.2 Movement (HL) Flashcards
Which 3 systems control motion?
Skeletal
Muscular
Nervous
Define ligaments
Connect bones to bones
Define tendons
Connect bones to muscles
What is the function of the joint capsule?
Seals the joint space and provides stability
What are the 6 main types of joints?
Pivot
Saddle
Hinge
Ball and socket
Condyloid
Plane
What is a myofibril?
A single strand of muscle fibre
What is a sarcomere?
The repeating unit on a myofibril
What are features of muscle fibre structure?
Multinucleate
Lots of mitochondria
Specialised ER (sarcoplasmic reticulum (with Ca2+ ions))
Contain tubular myofibrils
Continuous membrane surrounding the muscle fibre (sarcolemma) with T tubules
What are the two myofilaments in a sarcomere?
Myosin (thick)
Actin (thin)
What is the function of Z lines?
Hold the myofilaments in place and the end of the actin - myosin - actin complex
What is the A band?
The dark zone with myosin (and actin)
What is the I band?
The lighter zone with actin
What is the H zone?
The section with only myosin
What are the 4 steps to muscle contractions?
- Depolarisation and calcium ion release
- Actin and myosin cross-bridge formation
- Sliding mechanism of actin and myosin
- Sarcomere shortening
Describe depolarisation and calcium ion release as a step of a muscle contraction
Action potential from a motor neuron causes acetylcholine to be released into the synaptic cleft and spread down the sarcolemma and muscle via T tubules
Sarcoplasmic reticulum releases Ca2+
Describe actin and myosin cross bridge formation and a step of a muscle contraction
On actin binding site for the myosin head are covered by troponin and tropomyosin which Ca2+ bind to exposing the active sites so the myosin heads can form cross-bridge
Describe sliding mechanism of actin and myosin as a step of a muscle contraction
ATP binds to the myosin bridge breaking it then ATP hydrolysis causes the myosin head to move to the next site
This drags the myosin along
Describe sarcomere shortening as a step of a muscle contraction
Z lines are pulled closer together
Which two zones are decreased during a muscular contraction?
H zone and I band
