B3.3 Muscle and Motility

Question 1

Give some examples of internal movement in organisms

Answer 1

• Peristalsis in the gut
• ventilation in the lungs
• ## movement in cytoplasm

Question 2

Most plants are…

Answer 2

Sessile

Question 2

Give an example of a motile organism adapted to locomotion

Answer 2

Bar-tailed godwits migrating from siberia to new zealand using wings for flight and doubling their body’s fat reserves before the journey.

Question 2

Explain muscle contraction in terms of actin and myosin:

Answer 2

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.

Question 3

Example of sessile animal:

Answer 3

• Coral reefs that can extend their tentacles into the water when they filter-feeding, but can’t move to a new location.

Question 4

Give the order of organization for muscle fibers:

Answer 4

Muscle fiber, myofibril, sarcomere, actin, myosin

Question 5

Dark band

Answer 5

The center of a sarcomere that contains many myosin filaments that overlap with six equidistant actin filaments.

Question 6

Roles of Titin in muscle contraction and relaxation:

Answer 6

• 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.

Question 7

What type of muscles are skeletal muscles composed of?

Answer 7

Striated Muscle fibers

Question 8

Neuromuscular junction

Answer 8

The synapse between a motor neuron and a muscle fiber.

Question 9

What neurotransmitter is used in a synapse between a synapse and a muscle fiber?

Answer 9

Acetylcholine

Question 10

What features of a motor neuron allow it to stimulate simultaneous contractions in a group of muscle fibers?

Answer 10

• It has branches that form neuromuscular junctions with hundreds of different muscle fibers.

Question 11

Motor Unit

Answer 11

One motor neuron together with all the muscle fibers that it stimulates.

Question 12

What does the motor unit pattern achieve?

Answer 12

Coordinated contraction of a muscle with as few motor neurons as possible.

Question 13

Skeleton

Answer 13

Hard framework that supports and protects an animal’s body.

Question 14

Exoskeletons

Answer 14

Tough plates of chitin that cover most of the body surface in anthropoids such as spiders, crustaceans, and insects.

Question 15

Endoskeleton

Answer 15

Bones in vertebrates 3ady

Question 16

What is the role of skeletons?

Answer 16

They facilitate movement by providing an anchorage for muscles and acting as levers.

Question 17

Which attachment of muscle causes movement?

Answer 17

The insertion at the fulcrum of 2 bones, not the orgin.

Question 18

Describe the adaptations that come with the need for maximum force:

Answer 18

Short limb —> energy load is close to the fulcrum of th limb.

Question 19

Describe the adaptations that come with the need for maximum movement and low force:

Answer 19

Longer limb —> Energy load is far from fulcrum

Question 20

Where do bones meet? 👂🫷

Answer 20

JOINTS 🔥🔥

Question 21

Where do bones meet? 👂🫷

Answer 21

JOINTS 🔥🔥

Question 22

Bones in synovial joints

Answer 22

An anchorage for muscles and ligaments shaped to allow a range of movements.

Question 23

Muscles in synovial joints

Answer 23

Cause movement at a joint by contracting and shortening the orgin and insertion of a a muscle on opposite sides of a joint.

Question 24

Tendons in synovial joints

Answer 24

Tough collagen-rich cords of tissue that attach muscle to bone and transmit force from contractions.

Question 25

Cartilage in synovial joints

Answer 25

Tough, smooth tissue covering bone at joints to prevent friction, absorb shocks, and prevent fractures.

Question 26

Ligaments in synovial joints

Answer 26

Tough cords of tissue with much collagen that prevent movements that would dislocate the joints.

Question 27

Joint capsule in synovial joints:

Answer 27

Tough ligamentous covering that seals the joint, holds in synovial fluid and prevents dislocation.

Question 28

Hinge joints

Answer 28

- Allow movement in one plane: flexion (bending) and extension (straightening), the elbow and knee.

Question 29

Ball-and-socket joint

Answer 29

Moves in three planes: protraction/retraction/abduction/adduction, and rotation, the hip.

Question 30

How can the range of movement at a joint be measured?

Answer 30

- A goniometer by computer analysis of images.

Question 31

Give 4 reasons for the importance of locomotion:

Answer 31

Foraging for food, escaping danger, searching for a mate mate, migration.

Question 32

Examples of importance if locomotion in honeybees:

Answer 32

- 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

Question 33

Importance of locomotion in salmon:

Answer 33

- 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.

Question 34

How are marine mammals adapted to streamlining (minimize resistance to motion):

Answer 34

- 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.

Question 35

How are marine mammals adapted for locomotion?

Answer 35

- 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

Question 36

How are marine mammals adapted for periodic breathing between dives?

Answer 36

- 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.