muscles and neuromuscular junction

Question 1

what are the functions of a muscle

Answer 1

movement, stability, temperature regulation, protection

Question 2

muscle

Answer 2

organ, attaches to bone via tendons, covered by a fascia

Question 3

fascicle

Answer 3

collection of fibers

Question 4

fibers

Answer 4

a single muscle cell; collection of fibrils

Question 5

sarcolemma

Answer 5

membrane of muscle cell

Question 6

sarcoplasm

Answer 6

cytoplasm in muscle cell

Question 7

organelles in muscle fiber

Answer 7

multinucleated, multiple mitochondria, sarcoplasmic reticulum (specialized ER)

Question 8

myofibrils

Answer 8

connection of filaments

Question 9

myofilaments

Answer 9

smallest unit of muscle structure, contain actin, myosin, and sarcomere

Question 10

actin

Answer 10

thin double spiral protein with receptor sites (looks like double helix)

Question 11

myosin

Answer 11

thick protein with cross bridges

Question 12

sarcomere

Answer 12

structural and functional unit of skeletal muscles (arrangement of actin and myosin)

Question 13

a band

Answer 13

full length of myosin and the overlapping part of actin in the sarcomere

Question 14

i band

Answer 14

just the length of the rest of the actin

Question 15

neuron

Answer 15

nerve cell/nerve impluse

Question 16

impulse

Answer 16

action potential

Question 17

acetylcholine

Answer 17

neurotransmitter that is released into the cleft from the synaptic vesicles

Question 18

acetylcholinesterase

Answer 18

enzyme that breaks down acetylcholine, causes muscle to respond

Question 19

the neuromuscular junction is when ______________

Answer 19

the axon of neurons meet muscle fibers

Question 20

cross bridge cycle

Answer 20

a series of molecular events causing muscle contraction

Question 21

sarcomere

Answer 21

the functional unit of muscle contraction

Question 22

how is the cross bridge cycle initiated?

Answer 22

calcium ions released from the sarcoplasmic reticulum bind with troponin causing tropomyosin to move away from myosin binding sites on the actin filaments.

Question 23

step 1

Answer 23

activated myosin heads form cross bridges with actin. Inorganic Phosphate is released and a strong bond forms

Question 24

step 2

Answer 24

ADP is released and the myosin head privots. The actin filaments slide towards the center of the sarcomere

Question 25

step 3

Answer 25

ATP binds to the myosin head causing the head to detach

Question 26

step 4

Answer 26

ATP is hydrolyzed into ADP and inorganic phosphate releasing energy. This activates the myosin head and returns it to the cocked position.

Question 27

how does the cross bridge cycle end?

Answer 27

when calcium ions are actively transported back into the sarcoplasmic reticulum. Troponin shifts shape and tropomyosin moves to cover the myosin binding sites on the actin.