B3.3 Muscle and Motility Flashcards
Give some examples of internal movement in organisms
- Peristalsis in the gut
- ventilation in the lungs
- ## movement in cytoplasm
Most plants are…
Sessile
Give an example of a motile organism adapted to locomotion
Bar-tailed godwits migrating from siberia to new zealand using wings for flight and doubling their body’s fat reserves before the journey.
Explain muscle contraction in terms of actin and myosin:
Actin is pulled towards the center of sarc by myosin, myosin has heads that can attach to the binding sites on actin, these heads undergo a cycle of binding to form a cross-bridge, pulling the actin myosin by abt 10nm then detaching and swiveling to the next binding site.
Example of sessile animal:
- Coral reefs that can extend their tentacles into the water when they filter-feeding, but can’t move to a new location.
Give the order of organization for muscle fibers:
Muscle fiber, myofibril, sarcomere, actin, myosin
Dark band
The center of a sarcomere that contains many myosin filaments that overlap with six equidistant actin filaments.
Roles of Titin in muscle contraction and relaxation:
- Releases potential energy when it recoils during muscle contraction, increases amount of force that a muscle can exert.
- Connects the end of myosin filaments in the correct position of the six parallel actin filaments.
- Prevents overstretching of the sarcomere.
What type of muscles are skeletal muscles composed of?
Striated Muscle fibers
Neuromuscular junction
The synapse between a motor neuron and a muscle fiber.
What neurotransmitter is used in a synapse between a synapse and a muscle fiber?
Acetylcholine
What features of a motor neuron allow it to stimulate simultaneous contractions in a group of muscle fibers?
- It has branches that form neuromuscular junctions with hundreds of different muscle fibers.
Motor Unit
One motor neuron together with all the muscle fibers that it stimulates.
What does the motor unit pattern achieve?
Coordinated contraction of a muscle with as few motor neurons as possible.
Skeleton
Hard framework that supports and protects an animal’s body.
Exoskeletons
Tough plates of chitin that cover most of the body surface in anthropoids such as spiders, crustaceans, and insects.
Endoskeleton
Bones in vertebrates 3ady
What is the role of skeletons?
They facilitate movement by providing an anchorage for muscles and acting as levers.
Which attachment of muscle causes movement?
The insertion at the fulcrum of 2 bones, not the orgin.
Describe the adaptations that come with the need for maximum force:
Short limb —> energy load is close to the fulcrum of th limb.
Describe the adaptations that come with the need for maximum movement and low force:
Longer limb —> Energy load is far from fulcrum
Where do bones meet? 👂🫷
JOINTS 🔥🔥
Where do bones meet? 👂🫷
JOINTS 🔥🔥
Bones in synovial joints
An anchorage for muscles and ligaments shaped to allow a range of movements.
Muscles in synovial joints
Cause movement at a joint by contracting and shortening the orgin and insertion of a a muscle on opposite sides of a joint.
Tendons in synovial joints
Tough collagen-rich cords of tissue that attach muscle to bone and transmit force from contractions.
Cartilage in synovial joints
Tough, smooth tissue covering bone at joints to prevent friction, absorb shocks, and prevent fractures.
Ligaments in synovial joints
Tough cords of tissue with much collagen that prevent movements that would dislocate the joints.
Joint capsule in synovial joints:
Tough ligamentous covering that seals the joint, holds in synovial fluid and prevents dislocation.
Hinge joints
- Allow movement in one plane: flexion (bending) and extension (straightening), the elbow and knee.
Ball-and-socket joint
Moves in three planes: protraction/retraction/abduction/adduction, and rotation, the hip.
How can the range of movement at a joint be measured?
- A goniometer by computer analysis of images.
Give 4 reasons for the importance of locomotion:
Foraging for food, escaping danger, searching for a mate mate, migration.
Examples of importance if locomotion in honeybees:
- Fly through flowers for nectar and pollen
- Fly back to their colony during storms to seek safety.
- Male bees fly at 10-40m to mate with a virgin queen not they find her.
- A swarm of bees migrating as a colony
Importance of locomotion in salmon:
- Swim to catch prey of small fish and large invertebrates.
- Swim to escape bluefin tuna and swordfish predators.
- Search for a female laying eggs in spawning grounds to shed sperm there.
- Migrate young from river to sea then back to river as adults to breed.
How are marine mammals adapted to streamlining (minimize resistance to motion):
- Widest near the front and tapering towards the rear, causing less drag.
- Flipper, dorsal fins, and flukes with teardrop profile in transverse section which reduces drag.
- Hairless skin to reduce friction.
How are marine mammals adapted for locomotion?
- Flippers used for steering instead of front legs.
- Tail Lukes (lobes to right and left) to increase thrust when moved.
- Dorsal fin to prevent rolling (stability)
- blubber for buoyancy
How are marine mammals adapted for periodic breathing between dives?
- Airways closed during dives using the nostrils or blowhole.
- Airways reinforced with rings of cartilage and smooth muscle to ensure ventilation can restart quickly after a dive.
