Lesson 4: Muscle motility Flashcards
(13 cards)
Structure of muscle cells
Has thread-like structures called myofibrils which are composed of repeating units called sarcomeres.
Structure of sarcomeres
two types of protein filaments: thick filaments (myosin) and thin filaments (actin),
Steps of the sliding filament theory
An action potential triggers the release of Ca 2+ ions from the sarcoplasmic reticulum.
Ca 2+ binds to troponin causing tropomyosin to move away from the myosin binding site on actin.
Myosin heads (energised by ADP and Pi) bind to the sites forming a cross-bridge.
The myosin head pivots, pulling the actin filament towards the centre and shortening the sarcomere.
ADP and Pi are released in this step.
A new ATP binds to the myosin head, breaking the cross-bridge.
The ATP is hydrolysed to re-energise the myosin head and bend it back to its original position ready to attach to a new spot on actin.
The role of titin
acts as a molecular spring which helps muscles return to their original length after contraction.
What are antagonistic muscle pairs? and example
Muscle pairs that work opposite to each other, such as the biceps and triceps.
What type of joint is the hip joint?
A synovial ball-and-socket joint.
What are the components of a synovial joint?
Cartilage, synovial fluid, ligaments, and tendons.
What is the function of synovial fluid?
To lubricate the joints.
Role of Cartilage
Cushions the ends of bones, reducing friction.
Role of Ligaments
Connect bones
Role of Tendons
Attach muscles to bones.
Rank these by range of motion from highest to lowest:
Hinge joints, Ball-and-socket joints, Pivot joints
Ball-and-socket joints
Hinge joints
Pivot joints
Adaptations for Swimming in Marine Mammals
Streamlined bodies
Flukes and flippers for propulsion.
