musculoskeletal system Flashcards
what are the three types of muscle?
- skeletal muscles
- smooth muscles
- cardiac muscle
what is skeletal muscle?
- move bones and enable us to walk, run and carry out a wide range of voluntary physical activities
- muscles are under conscious control and are attached to the bones of the skeleton
what are smooth muscles?
involuntary muscles (not under conscious control), control movement within internal organs such as the stomach and intestines
what is cardiac muscle?
heart muscle
- When cardiac muscle contracts, it reduces the space in the chambers of the heart and pushes the blood from the heart into the blood vessels.
what are myofibrils?
- thread-like structures within the sarcoplasm
- that run parallel to each other along the length of the fibre
- composed of many smaller myofilaments
what gives muscle its banded effect?
- the arrangement of the thick and thin myofilaments give the muscle cells its striations
- striations allow myofibrils to be divided into sarcomeres
what is extensibility?
ability for a muscle to be stretched or extended
what is perimysium?
- connective tissue
- holds bundles of muscle cells
- allows adjacent bundles to slide easily over one another as they contract
what is sarcolemma?
muscle cell membrane
what are bundles in muscles?
composed of muscle cells that lie parallel to each other
what are the characteristics of skeletal muscle fibres?
- many nuclei
- thin membrane
- 10- 100 micrometres in diameter
- dark bands of myosin
- light bands of actin
what are myofilaments and the 2 types
- makeup myofibrils
- made of protein
- thick myofilaments = myosin
- thin myofilaments = actin
what is the A band?
- runs the length of the myosin
- dark due to myosin and actin overlapping
what is the I band?
- from each end of the myosin.
- contains only actin so is light and thin
- can overlap z line
what is the M line?
- middle of sarcomere
what is the sliding filament theory?
suggests that sarcomeres shorten during muscle contraction because the actin and myosin slide over one another
what is the 1st step of the sliding filament theory?
calcium ions are released from the sarcoplasmic reticulum into the cells due to a nerve impulse
what is the 2nd step of the sliding filament theory?
calcium ions help the myosin to attach to the actin and cross bridges form
what is the 3rd step in the sliding filament theory?
causes the actin to get pulled and slides over the myosin called a power stroke. I bands and sarcomere shorten
what are actin-myosin cross bridges?
the join between the myosin and actin
what is the agonist?
the muscle that causes the desired action
- prime mover
what is the synergist?
the muscle that acts indirectly to steady a join
what is the origin of a muscle?
the end of a muscle that is fixed to the stationary bone
what is abduction?
to move further away from the body’s midline
