7.1 - Getting moving

Question 1

What are the 3 types of muscle?

Answer 1

1. skeletal
   2 . smooth
2. cardiac

Question 2

What are muscles made up of?

Answer 2

muscle fibres

Question 3

What is the function of tendons?

Answer 3

connects muscle to the bone

Question 4

What binds muscle fibres together?

Answer 4

connective tissue (which makes up tendons)

Question 5

What is the cell surface membrane of a muscle fibre called?

Answer 5

sarcolemma

Question 6

What is the cytoplasm of a muscle fibre called?

Answer 6

sarcoplasm

Question 7

What is the endoplasmic reticulum of a muscle fibre?

Answer 7

sarcoplasmic reticulum

Question 8

Why are muscle cells multinucleated?

Answer 8

each muscle cell has several nuclei

Question 9

Why are muscle cells multinucleated?

Answer 9

a single nucleus cannot effectively control the metabolism of such a long cell

Question 10

What are T tubules?

Answer 10

deep infoldings within the sarcolemma, which runs close to the sarcoplasmic reticulum

Question 11

Where are the mitochondria found in a muscle fibre?

Answer 11

sarcoplasm

Question 12

What is the function of a mitochondria?

Answer 12

site of aerobic respiration - generating ATP

Question 13

What is each muscle fibre made up?

Answer 13

numerous myofibrils

Question 14

What makes up each myofibril?

Answer 14

repeating contractile units called sarcomeres

Question 15

What are the 2 proteins that make up a sarcomere called?

Answer 15

1. myosin
2. actin

Question 16

Which protein makes up thin filaments?

Answer 16

actin

Question 17

Which protein makes up thick filaments?

Answer 17

myosin

Question 18

How are muscle controls brought about?

Answer 18

co-ordinated sliding of these protein filaments with the muscle cells sarcomeres.

Question 19

What are the 2 other protein molecules found on actin molecules?

Answer 19

1. troponin
2. tropomyosin

Question 20

How do you determine 1 sarcomere unit?

Answer 20

distance between the two Z lines

Question 21

What are the darkest areas of the sarcomere caused by?

Answer 21

overlap of myosin & actin

Question 22

What is the H zone?

Answer 22

sections on the sarcomere which contains only myosin

Question 23

What is the M line on a sarcomere?

Answer 23

provides attachment site for myosin

Question 24

What is the I band?

Answer 24

contains only actin

Question 25

What is the Z line of a sarcomere?

Answer 25

provides attachment for actin

Question 26

What is the A band?

Answer 26

contains areas where only myosin is present & areas where myosin & actin overlap

Question 27

During contraction, what happens?

Answer 27

actin moves between myosin. this shortens the length of the sarcomere & hence the length for the muscle

Question 28

What is the structure of myosin?

Answer 28

- fibrous protein - each molecule has a tail & a head

Question 29

What is the structure of actin?

Answer 29

- globular protein - many molecules link together in a chain - two chains twist together to form an actin filament

Question 30

what is tropomyosin?

Answer 30

fibrous protein around actin chains

Question 31

What is troponin?

Answer 31

protein attached to the actin chain at regular intervals

Question 32

what is the sequence of muscle contraction?

Answer 32

1. nerve impulse arrives at neuromsuclaur junction & Ca2+ ions are released from the sarcoplasmic reticulum 2. Ca2+ diffuse trhough the sarcoplasm 3. Ca2+ bind to troponin molecules, causing them to change shape & mover tropomyosin away 4. this exposes myosin binding sites on the actin filament 5. an actin-myosin cross-bridge forms as the myosin head can now attach to the actin filament. ADP & Pi on the myosin head are released 6. the mysosin cnages shape & head nod forward moving the actin filament along (power stroke) 7. ATP bind to mysosin head causing myosin to detach. ATPase hydrolyse ATP forming ADP & Pi 8. hydrolysis changes the shpae of the myosin head which returns to its original postiions & cycle starts again