Skeletal Muscle

Question 1

structure of muscle

Answer 1

muscle belly wrapped in connective tissue
perimysium wraps fascicles
myofibril containing many sarcomere

Question 2

sarcomere structure

Answer 2

made of myofilaments - thick myosin with globular head) & thin actin

Question 3

actin and tropomyosin structure

Answer 3

double helix
tropomyosin covers myosin binding sites

Question 4

other proteins involved

Answer 4

titin - molecular spring
nebulin - stability
desmin

Question 5

sliding filament basic

Answer 5

filaments slide past each other overlapping and causing gross structure to shorten

Question 6

sarcoplasmic reticulum

Answer 6

interconnecting tubules surrounding myofibrils
regulates calcium
store and releases ca on stimulation

Question 7

cross bridge stages

Answer 7

AP arrives
Ca released from sr
Ca attaches to troponin
tropomyosin uncovers binding sites
ATP breaks down changing angle of myosin head
Pi released from head changing angle = powerstroke
head picks another ATP and actin released
repeats

Question 8

length tension relationship

Answer 8

1st filaments overlap = no tension as short
2nd some overlap but stretches and causes tension
3rd less overlap = less myosin head to interact with actin = less tension (less cross bridge)

Question 9

force velocity relationship

Answer 9

faster movement less time for myosin head to attach (shortening)
myosin stretch further during lengthening