B3.3 Muscles and Motility

Question 1

motile vs sessile

Answer 1

moves on its own vs can only change body form in response to stimuli

Question 2

examples of motile organisms and their adaptations

Answer 2

• brown-throated 3-toed sloth is arboreal so has 3 long toes and bones and muscles adapted to hanging and pulling
• amoeba use cytoskeleton to move plasma membrane
• paramecia use cilia to move

Question 3

example of sessile organism and its adaptations

Answer 3

• venus flytrap lives in soil low in N so it gets it from insects by closing their leaves on them upon the insect landing then secreting enzymes
• barnacles have corral fans to filter food

Question 4

tropism

Answer 4

movement of plant (usually) towards stimulus

Question 5

structure of muscles

Answer 5

made of bundles of muscle fibres, which are made of bundles of myofibrils; composed of sarcomeres attached end to end

Question 6

structure of muscle fibres

Answer 6

multinucleate, myofibrils with sarcomeres: sarcolemma (plasma membrane), sarcoplasm, sarcoplasmic reticulum

Question 7

draw and label a relaxed sarcomere

Answer 7

Z-line at ends, squiggly titin, actin on outside, myosin connected at M-line

Question 8

how do muscles contract

Answer 8

stimulation and sliding filament theory:
1. action potential stimulates sarcoplasmic reticulum to release Ca2+
2. Ca2+ binds to troponin on actin and exposes myosin binding sites
2. ATP attaches to bent myosin head and hydrolyzes into ADP and P, changing shape to be able to attach to actin
2. P released and myosin attaches
3. ADP released and myosin bends again, moving actin inwards
4. ATP attaches and myosin detaches

Question 9

origin vs insertion bones

Answer 9

anchor vs moves because of muscle contraction (lever)

Question 10

what are muscles that perform opposite movements called?

Answer 10

antagonistic muscles

Question 11

titin

Answer 11

acts as spring in sacromere to relax after contraction, avoid overstretching, holds myosin in place

Question 12

what kind of neurons transfers electrical impulses?

Answer 12

motor neurons

Question 13

where are electrical impulses in motor neurons released?

Answer 13

at neuromuscular junctions (synapse, terminal end), neurotransmitter (acetylcholine) released

Question 14

motor unit

Answer 14

motor neuron and set of muscle fibres it controls

Question 15

ratio of motor neurons to fibres

Answer 15

1:10 - 200

Question 16

arthropods

Answer 16

have exoskeletons made of chitin

Question 17

synovial joint

Answer 17

where 2 bones move against each other; cartilage covers bones, bones connected by ligaments, within cartilage and ligaments is synovial fluid

Question 18

ball-and-socket joint

Answer 18

type of synovial joint that allows flexion, extension, and rotation (eg femur ball in pelvis socket)

Question 19

goniometer

Answer 19

measures ROM (degrees, distance, direction) of joint

Question 20

example of antagonistic muscles

Answer 20

external intercostal muscles contract, stretching internal intercostal muscles and creating potential energy for them to contract next

Question 21

how does ribcage work as a lever?

Answer 21

ribs levers, vertebrae fulcrum

Question 22

reasons for locomotion in animals

Answer 22

1. foraging for food
2. escaping danger
3. searching for mate
4. migration
5. dispersal

Question 23

dolphin adaptations for swimming

Answer 23

streamlined body, almost no hair, flat tail, no rear legs, flippers for steering, sealable blowhole on head, holds breath for mins

Question 24

what makes dolphins mammals?

Answer 24

endotherms, produce milk, double circulatory system, long-term parental care

Question 25

hinge joint

Answer 25

type of synovial joint that allows flexion and extension (eg knee)