muscle 1

Question 1

voluntary muscles

Answer 1

connected to bones and present in sphincters with some exceptions
skeletal muscles.
striated
elongated cell
multiple peripheral nuclei
parallell musvle fibre (cell)
sarcoplastic reticulum (modified ER) and terminal cristernae contaiing Ca
t tubule
myofibrils

Question 2

involuntary muscle- cardiac

Answer 2

branching cell
single central nucleus
straited
present within the heart

Question 3

invountary muscle- smooth muscle

Answer 3

present in visceral organs, blood vessels, eye (vision accomodation pilorecetor)
non striated
spindle shaped cell
single central nucelus

Question 4

what are coluntary muscles covered by

Answer 4

dense connective tissue

Question 5

t tubeule

Answer 5

axon like fibre that transmits action potential into muscle

Question 6

bands of myofibril

Answer 6

alternating dark (A bands) and light bands (i bands) giving appearance of straiations. regular arrangement of thick and think fillaments which slide against each other changing muscle length

Question 7

functional unit of striated muscle

Answer 7

sarcomere that is found between two Z lines

Question 8

z lines

Answer 8

connects thin fillaments of two adjoining sarcomeres

Question 9

a band

Answer 9

made up of thick fillaments along with portions of thin fillaments that overlap on both ends of thick fillaments

Question 10

i band

Answer 10

constis of remiaing portion of think fillaments that do not project into a band

Question 11

h zone

Answer 11

lighter area within middle of a band where thin fillaments do not reach

Question 12

m line

Answer 12

extends vertically down middle of a band within centre of h zone

Question 13

where do motor neurons project from and thier endings

Answer 13

the spinal chord and the axons divide into multiple endings. each ending synapses with one muscle fibre cell to form one end place per cell

Question 14

action potentials and what they contract

Answer 14

each action potential transmitted through each motor neuron can contract multiple muscle fibre cells within the muscle bundle

Question 15

how many types of muscle fibres innervate the same muscle

Answer 15

two
slow twitch- innervated by a2 small diameter low threshold motor neurons
fast twitch- innervated by a1 large diameter high threshold motor neurons

Question 16

what is released after motor neuron action potential reaches end

Answer 16

achetylcholine into the space between the nerve and the muscle- motor endplate

Question 17

what receptors does acetylcholine bind to

what happens when acetylcholine binds to its receptor

Answer 17

nicotinic receptors on muscle plasma membrane which opens a channel that it is linked to leading to a lot of na into muscle with small amount of k leaving depolarizing the cell to threshold that activates fast na channels to produce AP.

AP is transmitted along plasma membrane through t tubule system casuing release of ca from the sarcoplasmic reticulum

Question 18

what can cause increased contratcion

Answer 18

increasing firing frequency of each motor neuron
recruiting more motor neurons to fire APs
recruiting a greater proportion of fast twitch muscle contraction which can develop greater contractile forces than slow twitch fibers