B3.3 Muscle & Motility

Question 1

What is a sessile organism?

Answer 1

organism that remain in one location

Question 2

What is locomotion?

Answer 2

moving from one place to another

Question 3

What are myofibrils?

Answer 3

thread-like structures in muscles composed of repeating sacromeres

Question 4

What are sacromeres?

Answer 4

contractile unit of a muscle

Question 5

What are sacromeres composed of?

Answer 5

thick filaments (myosin) and thin filaments (actin)

Question 6

What is a Z-line, where is it and what is it’s function?

Answer 6

boundary of a sacromere, has actin filaments attached

Question 7

What is a M-line, where is it and what is it’s function?

Answer 7

in the centre of a sacromere, middle of myosin filaments

Question 8

What happens to Z-lines during contraction?

Answer 8

they are coming closer together

Question 9

What is an I band?

Answer 9

region where only actin is present

Question 10

What is an H band?

Answer 10

region where only myosin is present

Question 11

What is an A band?

Answer 11

region where myosin is present when muscle is relaxed and overlap between actin and myosin when muscle is contracted

Question 12

What is the sliding filament theory?

Answer 12

when muscle contracts, actin filaments slide over myosin filaments towards the centre of the sacromere

Question 13

Explain the pathway/steps of muscle contraction on sacromere level (4)?

Answer 13

• myosin head with ATP attached hydrolyses ATP into ADP
• myosin head attaches to actin (crossbridge formed)
• myosin head bends and moves actin towards centre
• another ATP attaches to myosin head causing it to detach from actin

Question 14

What is tropomyosin?

Answer 14

protein that covers the surface of actin to prevent the myosin heads from attaching unnecessarily when muscle is relaxed

Question 15

What is troponin?

Answer 15

protein that moves tropomyosin away when calcium attaches

Question 16

What is sacroplasm?

Answer 16

cytoplasm of muscle cell

Question 17

Where are calcium ions released from?

Answer 17

sacroplasmic reticulum

Question 18

What causes a muscle to go from relaxed to contracted state?

Answer 18

release of calcium that binds to troponin and move away the tropomyosin, so myosin heads can bind

Question 19

What’s the role of titin in muscle contraction (3)?

Answer 19

• connecting Z discs and M lines to provide support and stability
• helps sacromeres to come back to normal state
• prevents overstretching

Question 20

List structures and bands in sacromere

Answer 20

Question 21

What are the antagonistic muscle pairs?

Answer 21

muscles that accomplish opposite movement

Question 22

Why muscles need anatagonistic pairs?

Answer 22

because they can only pull and need this pair to move the other way

Question 23

What’s the example of anatgonistic muscle pair?

Answer 23

biceps and triceps

Question 24

What is neuromuscular junction?

Answer 24

where a motor neuron and muscle fiber meet

Question 25

Which neurotransmitter is involved in muscle contraction?

Answer 25

acetylcholine

Question 26

What is a motor unit?

Answer 26

complex of motor neuron that can connect to multiple muscle fibers

Question 27

What's the function of motor neuron that connects to multiple muscle fibers?

Answer 27

coordinated contraction (at the same time)

Question 28

What are motor neurons?

Answer 28

nerve cells that transmit messages from CNS to effector organs (muscles or glands)

Question 29

What is the difference between endo- and exoskeletons?

Answer 29

endoskeleton: internal skeleton exoskeleton: external skeleton

Question 30

Which group of organisms have exoskeleton and what it is made of?

Answer 30

arthropods, chitin, the exoskleton must be replaced as the animal grows

Question 31

What are synovial joints?

Answer 31

joints that are enclosed in a joint capsule and seperate bones by synovial fluid

Question 32

What's the function of synovial fluid?

Answer 32

acts as lubricant to reduce friction

Question 33

What covers the end of bones?

Answer 33

articular cartilage

Question 34

What's the function of articular cartilage?

Answer 34

act as a pillow and absorb shock

Question 35

How bones are connected in synovial joint?

Answer 35

by ligaments, which are bands of connective tissue made of collagen that provide stability and protection from dislocation

Question 36

How muscles are attached to bones?

Answer 36

via tendons

Question 37

What's the structure of collagen?

Answer 37

triple hexlices

Question 38

What is a ball and socket joint?

Answer 38

rounded head of femur fitting into cup-like socket of pelvis (in hip joint)

Question 39

List the anatomy of the hip joint

Answer 39

- joint capsule - synovial fluid - synovial membrane - ligament - cartilage - *head of femur - *socket

Question 40

How can you measure joint angles?

Answer 40

goniometer

Question 41

What happens to intercostal muscles when exhaling?

Answer 41

- internal contract - ribcage moves down

Question 42

What happens to intercostal muscles when inhaling?

Answer 42

- external contract - ribcage moves up

Question 43

What are the reasons for locomotion (moving whole organism)?

Answer 43

finding food, mate, espacing, migration

Question 44

What are the adaptations for swimming in marine animals?

Answer 44

- smooth body shape to avoid water resistance - hairless body, smooth - blowhole - mouth does not connect to lungs (prevents water entering lungs) - fins, tails - blubber (fat)

Question 45

What are the possible movements at synovial joint?

Answer 45

- Flexion - Extension - Rotation - Abduction - Adduction

Question 46

What happens in microimage when muscle is contracting?

Answer 46

- dark bands stay the same (myosin and actin overlap) - light bands get shorter (actin) - sacromere is shorter