chapter 11 - the musculoskeletal system (muscles)

Question 1

what is skeletal muscle

Answer 1

• voluntary control / contraction (brings two bones together)
• structure: stripes, striated, multi nucleated
• location: legs, arms, facial muscles

Question 2

what is smooth / non-striated muscle

Answer 2

• involuntary control
• structure: long tapered cells
• location: lining of / walls of internal organs and blood vessels

Question 3

what is cardiac muscle

Answer 3

• involuntary contraction of the heart muscle
• structure: striated, branched, tapering at ends
• location: walls of the heart

Question 4

what are the properties of muscles

Answer 4

• allows muscles to work together to create movement
• all muscles contract / shorten
• extensibility: ability to stretch
• elasticity: ability to return to original length after being stretched

Question 5

explain the macro structure of the skeletal muscle

Answer 5

• cross section of the belly is made up of bundles of muscle fibres / cells held together by connective tissue, surrounded by blood vessels
• muscle fibre: sarcolemma, sarcoplasm, contains myofibrils (thread like structure)
• myofibrils: contain two types myofilaments actin and myosin
• myofilaments: actin and myosin make up units of sarcomeres (z line to z line)

Question 6

what is the sliding filament model

Answer 6

• when muscles contract sarcomeres shorten
• actin and myosin slide over one another (myosin heads)
• z lines closer together, shortening sarcomere, muscle fibre, whole muscle
• ADP is required for shortening (myosin heads)
• to relax actin and myosin are pulled past each other, original position

Question 7

three types of muscles

Answer 7

• skeletal
• smooth / non-striated
• cardiac

Question 8

what are ligaments

Answer 8

• connect bones to bones, support bones at joints

- elastic protein fibrous connective tissue, very strong

Question 9

what are tendons

Answer 9

• connect bone to muscle, connect bone to cartilage
• inelastic protein fibrous connective tissue
• exert pull on bone when muscle contracts

Question 10

skeletal muscles working together

Answer 10

• muscles can pull bones together but cannot push them away
• one set of muscles contract to pull muscle in one direction, another set of muscle contracts to pull muscle in opposite direction
• all muscles that cause movement are paired

Question 11

what is the origin

Answer 11

• the end of a muscle that is fixed in a stationary position

Question 12

what is insertion

Answer 12

• the end of the muscle that is attached to the moveable muscle

Question 13

what is the belly

Answer 13

• the fleshy portion of the muscle in between the tendons of the origin and insertion

Question 14

what is the agonist

Answer 14

• prime mover: muscle hat causes the desired action

Question 15

what is the antagonist

Answer 15

• muscle that has a contraction opposite to that of the agonist

Question 16

what is the synergist

Answer 16

• muscles that helps prime mover

- produces same movement or steadies a joint during a particular movement

Question 17

what is the fixator

Answer 17

• when a synergist immobilises a point

- acts as a stabiliser of one part of the body during movement of another part

Question 18

what is muscle tone

Answer 18

• maintaining partial contraction of skeletal muscles
• at any one time some muscle fibres are contracted whilst others are relaxed
• muscle tone is due to many muscles taking turns to contract
• muscle tone holds many of our body parts in position

Question 19

what is posture

Answer 19

• the characteristic way a person sits or stands