muscle excitation contraction

Question 1

what are the three main types of muscle in the body

Answer 1

skeletal
smooth non-strated
cardiac

Question 2

describe skeletal muscles functions/importances

Answer 2

under volentary control
develop force via contraction
help with posture and movement
produce heat
control over major openings
protection of internal organs

Question 3

describe the size scale of muscles from tissue level to muscles

Answer 3

myofillerments -> sarcomas -> myofibrils -> muscle fibers -> fasicals -> muscles

Question 4

what are the three protines involved duirng excitation of muscles, and their functions/interactions

Answer 4

voltage sensor: senses changes in voltage sent down t tubuls, interacts with ryanodine recetor when this occours
ryanodine receptor: a chanel between the SR and the interior of the cell wall. enables Ca to diffuse into the cell enabling contraction
SR calcium ATPase: senese rises in interacellular Ca, burns atp to pump this back into the SR

Question 4

what are the electric parts of muscle fibers

Answer 4

sarcolemma
sarcoplasmic reticulum
t tubuls

Question 4

decribe the make up of a muscle fiber

Answer 4

myofillerments actin and myosin interlink to make sarcoma units which make up myofibrils. bundelsof these are wrapped in the sarcolemma membrane with the sarcoplasmic reticulum between, and T tubules penetrating deep into the muscles to send signal.

Question 5

discribe the structures of myosin and actin

Answer 5

actin fibers make up the structure of sarcoma.
myosin is compirsed of a tail and head, this is the part which pulls on actin during contraction

Question 6

what is reqired to be present for myosin to bind to actin

Answer 6

Ca, enables the cross-bridge state to be formed.
no Ca present will stay in the cocked state
ATP so that myosin can release from actin and burn to store energy and move back

Question 7

what are the stages of the cross bridge cycle

Answer 7

relaxed state: myosin binds to atp releasing actin
cocked state: myosin burns atp storing energy as movement
cross-bridged state: when Ca is present myosin binds to actin in a new location
power stroke: myosin burns the energy stored from atp, shortening the sarcoma
attached state: ADP is released from myosin, cross bridge is still formed

Question 8

what are the factors which control tention of a contraction

Answer 8

the number of mucle fiber recuited (number of cross-bridges)
and the speed at which the muscle is stimulated

Question 9

how is the number of muscle fibers activated determined

Answer 9

neurons send signals to the muscles, more neurons firing, more tention developed

Question 10

what are action potentials
and what are the three classes of action potentials

Answer 10

signel action potentials:
forms a twitch, short burst of Ca into the cytoplasm
many action potentials:
sustained releases of Ca into the cytoplasm
maximal action potentials:
faster signals are sent, all Ca avalibal has been released into the cell due to fast signaling. tetanus has been reached, will fatigue or give up

Question 11

what is the length tention relationship of muscles

Answer 11

a muscle will be able to contract up to 50% of its length. if the muscle is streached then not many myosin fibers attach to actin, weak contraction.
if muscle slack not enough room for myosin to contract

Question 12

fast vs slow

Answer 12

fast : slow
large diameter : thin diameter
low mitochindra : high mitochindrai
white : red
low blood suppy : high blood suppy
fast fitauge : slow fatigure
fast time to tetaness: slow ttt