Please enable JavaScript.
Coggle requires JavaScript to display documents.
LU11: Muscles (Modes of Locomotion (Swim & jet propulsion in water…
LU11: Muscles
Modes of Locomotion
-
Active flight & gliding
- Flying
- Advantage: Air have less friction, travel faster.
- Disadvantage: have airfoils-shaped wings, strong flight muscles & efficient respiratory system.
Crawl, walk, run, hop & climb on land
- Advantage: Air have less friction,hence, less resistance to animal movement.
- Disadvantage: have to overcome the gravity force & balancing.
- Adaptation: powerful muscle & strong skeletal support; tail for balancing.
Muscle Contraction
Sliding-filament model
- Actin & Myosin slide pass each other without length change.
Muscle Contracts:
- shorter distance between Z-line,
- A-band length remains,
- shorter I-band,
- H-zone disappear.
- Troponin binds to calcium ions, rearrange tropomyosin, expose myosin binding sites, myosin head forms a cross-bridge with actin, pulls actin in.
Muscle Relaxes:
- myosin binding sites on the actin are blocked by tropomyosin which influenced by troponin.
Mechanism of Movement
Animals with hard skeleton move the limbs with a pair of antagonistic muscle
(flexor & extensor muscles).
- Flexor muscle contraction, bend limbs.
- Extensor muscle contraction, straighten limbs.
Exoskeleton
Examples of Animals with Exoskeleton:
- Insects, arachnids, myriapods, crustaceans
Endoskeleton
Examples of Animals with Endoskeleton:
Hydrostatic Skeleton
Examples of Animals with Hydrostatic Skeletons:
- Cnidarian, planarian (flatworm), nematodes (roundworm), annelids (earthworm)
- Use muscles to move the fluid under pressure in closed body compartment / water-filled compartment.
- Peristaltic movement created by rhythmic contraction of longitudinal, circular & obligate muscles.
- Movement on mucus layer assisted by beating of epidermal cilia.
Versus
Muscular hydrostat
Invertebrate: Cephalopods (cuttlefish) have cuttlebone for buoyancy.
- Movement: Jet propulsion created by squeezing water out.
- Move tentacle by muscular hydrostat, forces transmitted through muscle flesh.
Muscle tissue
- composed of muscle fibers
- muscle contraction is stimulated by nerve impulse.
- Striated muscle
- overlapping of muscle filaments.
Skeletal Muscle
(body movement)
- voluntary
- tubular, multi-nucleated fibers
- attach to skeleton
-
Cardiac Muscle
(heart contraction)
- involuntary
- branched, uni-nucleated fibers
- in heart wall
-
- Non-striated muscle
- lacking cross-striations.
Smooth Muscle
(internal organ walls)
- involuntary
- spindle-shaped cells
- uni-nucleated fibers
-
-
Muscle Stimulation
- Nerve impulse stimulates the muscle tissue to generate action potential.
- T tubules spread action potential to sacroplasmic reticulum & depolarize it to release Ca.
- Ca binds to troponin - expose myosin binding sites - muscle contract (all-or-none manner).
Movement enables animals to
- Foraging for food,
- Escaping from danger,
- Finding mates.
