Studied by 3 peoplemotile
can move from place to place
sessile
cannot move from place to place
skeletal muscles
muscles attached to skeletons that aid movement
striated muscle cells
bundled into muscle fibre cells
each muscle fibre contains:
contractile proteins
many nuclei
sarcoplasmic reticulum
sarcoplasm (specialised cytoplasm)
mitochondria
myofibrils
myofibrils
thick filaments: myosin
thin filaments: actin
bundles of actin and myosin slide past each other during muscle contraction
myofibrils structure
thick filaments: myosin, which are fibrous proteins with globular head
fibrous part of myosin anchors into thick filament
heads pointing away from M line
thin filaments: actin
globular proteins
two twisted chains: one thin filament
tropomyosin twisted around chain
troponin attached at regular intervals
bands meaning
h band: only myosin filaments
i band: only actin filaments
A band: only myosin filaments + both
M line: attachment for myosin
Z line: attachment for actin
sarcomere: section between two z lines
muscle contraction
myosin heads form cross-bridges by binding with sites on the actin filaments
myosin heads cock/change orientation which pulls actin filaments so they slide next to myosin “power stroke”
sarcomeres shorten as z lines are pulled closer together
antagonistic pairs
muscles can only pull not push, so they often work in antagonistic pairs
muscles maintain posture by antagonistic muscles both contracting at joints to keep it at the same angle
muscle contraction without movement
titin protein
muscle contraction and relaxation both rely on protein titin
large proteins that joins ends of myosin filaments to z line
the many folds in titin gives spring like properties
in relaxed muscle, sarcomere lengthens and titin is stretched out
titin stores chemical energy when stretched and prevents over stretching
during muscle contraction, sarcomeres tighten and titin proteins recoil releasing chemical energy
adds to force of contraction
skeletal muscle
skeletal muscle contracts when it receives an impulse from motor neurone via the neuromuscular junction
neuromuscular junctions are located between motor neurone and muscle cell
all this = motor unit
bones
provides anchorage for muscles to act as levers
vertebrates have internal bones/endoskeleton
invertebrates have external bones/exoskeleton
provide support for body of organism and facilitate movement
exoskeletons also provide protection
muscles and skeletons
muscles are anchored to the skeleton either on inside (exo) or outside (endo)
skeletons act as levers, transferring size and direction of force
levers have point of effort, point of load, and fulcrum
synovial joint
joint cavity filled with lubricating synovial fluid which reduced friction
fluid is produced by synovial membrane, which surrounds the joint
can exert: flexion, extension, rotation, abduction, adduction
human hip joint
ball and socket synovial joint
articulation is between bones of the femur (ball) and pelvis (socket)
cartilage covers bones and provides surface to prevent bones rubbing against each other
whole joint is encircled with ligaments to hold bone in place
muscles connected to bone via tendons
antagonistic muscles in ribcage
as external intercostal muscles contract, internal intercostal muscles stretch, resulting in store potential energy in titin protein of sarcomere
reasons for locomotion
foraging for food: guinea pigs, spend 70 percent of their time awake searching and eating plants
escaping from danger: salticidae spiders, jump out of way from predators
searching for a mate: salmon, ocean to fresh water rivers to mate
migration: caribou dear, travel over 3000 miles a year between their southern and northern ranges
adaptations for swimming
streamline shape of body to allow them to move with ease through viscous waters
flippers for stearing
tails form a fluke for propulsion
change to airways by evolution of blowholes to allow periodic breathing between dive
Note
Flashcard