B3.3  Muscle and Motility

Guiding Questions:  
Guiding questions help students view the content of the syllabus through the conceptual lenses of both the themes and the levels of biological organization.

• How do muscles contract and cause movement?
• What are the benefits to animals of having muscle tissue?

​​Linking Questions:  
Linking questions strengthen students’ understanding by making connections between topics.  The ideal outcome of the linking questions is networked knowledge.

• What are the advantages and disadvantages of dispersal of offspring from their parents?
• In what ways does locomotion contribute to evolution within living organisms? 

AHL ​​B3.3.1-- Adaptations for movement as a universal feature of living organisms.

• State that movement can occur within a body or as locomotion from one place to another.
• Compare movement in motile and sessile species.
• List an example of a motile and a sessile species.​

AHL ​​B3.3.2— Sliding filament model of muscle contraction.

• Outline the relationship between muscle fibers, myofibrils and sarcomeres.
• Annotate a diagram of the sarcomere, including the role of the Z-line, titin, thin actin filaments, thick myosin filaments, light band and dark band.
• Explain the sliding-filament mechanism of muscle contraction, including the role of actin, myosin heads, cross bridges, ATP, and the power stroke.​

AHL ​​B3.3.3— Role of the protein titin and antagonistic muscles in muscle relaxation.

• State that a muscle can only exert force when it contracts. 
• State that lengthening of a muscle happens when it relaxes. 
• Define antagonistic pairs in relation to muscle movement.
• State an example of an antagonistic pair of muscles.
• Outline the role of the titin protein in muscle stretching.  
• Outline the mechanism by which the protein titin stores potential energy.​

AHL ​​B3.3.4— Structure and function of motor units in skeletal muscle.

• Outline the structure and function of a motor unit. 
  
• Annotate a diagram of a neuromuscular junction, including the function of the motor neuron, acetylcholine, and muscle fibre. ​​

AHL ​​B3.3.5— Roles of skeletons as anchorage for muscles and as levers.

• Compare and contrast the structure and function of endoskeletons with exoskeletons.
• Compare the function of muscles, joints and bones to that of a lever.​

AHL ​​B3.3.6- Movement at a synovial joint.

• Define synovial joint.
• State the function of structures found in a synovial joint, including the bones, cartilage, synovial fluid, ligaments, muscles and tendons. 
• Label a diagram of the human hip joint inclusive of:  femur, pelvis, joint capsule, synovial fluid, muscles, ligament and cartilage.

AHL ​​B3.3.7— Range of motion of a joint.

• Compare the articulation of hinge joints with that of a ball and socket joint.
• Measure the range of motion of the human hip in terms of flexion, extension, rotation, abduction and adduction.

AHL ​​B3.3.8- Internal and external intercostal muscles as an example of antagonistic muscle action to facilitate internal body movements.

• State the location of the internal and external intercostal muscles. 
• Describe the state of contraction of the internal and external intercostal muscles during inspiration and expiration.
• Outline the mechanism by  potential energy is stored during contraction of antagonistic muscles. 

AHL ​​B3.3.9- Reasons for locomotion.

• List reasons animal locomotion, with one example of each.

AHL ​​B3.3.10- Adaptations for swimming in marine mammals.

• Outline the adaptations for streamlining, locomotion and ventilation of lungs in marine mammals.