Muscles Basics

Question 1

name the three types of muscles and state whether they are vol or invol

Answer 1

cardiac = invol
skeletal = vol
smooth = invol

Question 2

skeletal muscle functions

Answer 2

motion
posture
protection
thermogenesis
vascular pump

Question 3

skeletal muscle properties

Answer 3

elasticity
excitability
conductivity
contractability

Question 4

name the types of muscle contractions and what they involve

Answer 4

isometric- tension generated but muscle length and joint angle are constant
concentric isotonic- muscle shortens
eccentric isotonic- muscle lenghtens

Question 5

name features of striated muscle

Answer 5

appearance
comprised of tubular cells called myofibrils
multinucleated

Question 6

what are myofibrils

Answer 6

smaller units of muscle fibres

contain long protein filaments

Question 7

what is a sarcomere

Answer 7

basic functional unit of a muscle fibre

Question 8

what are the major proteins involved in force generation

Answer 8

actin and myosin

Question 9

is myosin thicker or thinner than actin?

Answer 9

thicker

Question 10

how do actin and myosin generate tension

Answer 10

they form a cross bridge with myosin heads oulling actin filaments towards the centre of the sarcomere, shortening the muscle

Question 11

what happens to the length of actin and myosin filaments during myscle contraction/relaxation

Answer 11

no change

Question 12

list the steps in muscle contraction

Answer 12

1. action potential travels to sarcoplasmic reticulum- calcium ions released into sarcoplasm
2. calcium ions bind with troponin, removing tropomyosin from binding sites on actin filament
3. myosin heads charged with energy from atp breakdown
4. energy binds myosin to binding sites on actin creating the cross bridge
5. power stroke occurs- myosin heads pull sarcomere together
6. myosin heads bind with more atp, providing energy to release myosin from actin

Question 13

what factors affect force production

Answer 13

cross-sectional area- larger myofibrals generate greater force
fiber arrangement- pennate fiber arrangements produce larger force than parallel
muscle length- long muscle do not produce more force

Question 14

why are muscles thick

Answer 14

larger diameter fibres = more cross bridges = greater force gen

Question 15

why are muscles long

Answer 15

longer muscles generate bigger movements

Question 16

why are pennate arrangements beneficial

Answer 16

maximise number of fibres in an area, increasing force production