topic 7

Question 1

what is an extensor muscle?

Answer 1

a muscle that contracts to cause extension of a joint

Question 2

what is a flexor muscle?

Answer 2

a muscle that contracts to reverse the extension of a joint

Question 3

what joins muscles to bones?

Answer 3

tendons

Question 4

what joins bones to bones?

Answer 4

ligaments

Question 5

what is the function of cartilage in a joint?

Answer 5

acts as a shock absorber
absorbs synovial fluid

Question 6

what separates bones in a synovial joint?

Answer 6

a cavity filled with synovial fluid

Question 7

what are myofibrils made up of?

Answer 7

sarcomeres

Question 8

what is a muscle made up of?

Answer 8

sarcomeres form myofibrils
many myofibrils form one muscle fibre
many bundles of muscle fibre, surrounded by connective tissue, forms a muscle

Question 9

what are the two proteins in a sarcomeres called?

Answer 9

thin one is actin and thick one is myosin

Question 10

what is the process of the sliding filament theory?

Answer 10

• nerve impulse arrives at neuromuscular junction
• calcium ions released from sarcoplasmic reticulum
• calcium ions diffuse through sarcoplasm, and attach to troponin molecule, causing it to move
• tropomyosin on actin filament shifts, exposing myosin binding sites on actin filaments
• myosin heads bind with myosin binding sites, forming cross-bridges
• ADP and Pi on myosin head are released
• myosin changes shape, and myosin head nods forward, and actin moves over the myosin
• ATP molecule binds to myosin head
• myosin head detaches from actin
• ATPase on myosin head hydrolyses ATP, forming ADP and Pi
• myosin head changes shape and returns to upright position