2 -Skeletal Muscle

Question 1

Synonym for muscle fiber.

Answer 1

Muscle cell

Question 2

Plasma membrane of a skeletal muscle fiber, surrounds the cytoplasm (i.e. sarcoplasm).

Answer 2

Sarcolemma (i.e. sarc = flesh)

Question 3

Sarcolemma is associated with a coat of polysaccharides containing embedded collagen fibrils. These fibrils fuse with the […] of the muscle.

Answer 3

Tendon

Question 4

Subunit of muscle.

Answer 4

Fasiculi

Question 5

A fasciculus consists of a bundle of […].

Answer 5

Muscle fibers

Question 6

Each muscle fiber consists of a bundle of […].

Answer 6

Myofibrils

Question 7

Portion of a myofibril between two adjacent Z discs.

Answer 7

Sarcomere

Question 8

Filaments that make up the sarcomere.

Answer 8

Actin/Thin and Myosin/Thick

Question 9

Three proteins that make up an actin filament.

Answer 9

Actin, troponin, and tropomyosin

Question 10

Component of actin filament, helical backbone, contains “active sites” where myosin can bind.

Answer 10

F-actin

Question 11

Protein of actin filament, lies on top of F-actin, covers active/binding sites when contraction is undesired.

Answer 11

Tropomyosin

Question 12

Protein of actin filament, attached intermittently along tropomyosin, contains three different proteins.

Answer 12

Troponin complex

Question 13

Actin filaments attach to both Z discs of a sarcomere and […] with myosin filaments.

Answer 13

Interdigitate

Question 14

Bands that make up a sarcomere.

Answer 14

1 Complete A band, two halves of I bands

Question 15

A protien that maintains alignment between actin and myosin filaments, acts as a spring between a Z disce and the end of a myosin filament.

Answer 15

Titin

Question 16

Synapse between a motor neuron and a skeletal muscle fiber.

Answer 16

Neuromuscular junction

Question 17

Tiny, fluid-filled space between cells at a synapse.

Answer 17

Synaptic cleft

Question 18

Stores molecules of transmitter in the presynaptic axon terminals, walls are made out of membrane.

Answer 18

Synaptic vesicle

Question 19

Neurotransmitter associated with the synapes of the NMJ.

Answer 19

Acetylcholine (i.e. this will ALWAYS be the case)

Question 20

Location of acetylcholine receptors in NMJ.

Answer 20

Embedded in the plasma membrane of the postsynaptic cell

Question 21

The process by which a signal is passed between neurons or other excitable cells.

Answer 21

Synaptic transmission

Question 22

Function of an action potential sent to a NMJ.

Answer 22

Release ACh into the synaptic cleft via synaptic vesicles.

Question 23

As the AP arrives at the axon terminal it opens […] causing a depolarization.

Answer 23

voltage-gate calcium channels

Question 24

Force permitting synaptic vesicles of the NMJ to undergo exocytosis, releasing ACh into the synaptic cleft.

Answer 24

Flow of calcium ions into the axon terminal

Question 25

Amount of ACh molecules per each synaptic vesicle.

Answer 25

~5000

Question 26

Amount of synaptic vesicles released per AP.

Answer 26

300

Question 27

Upon ACh entering the synaptic cleft in can bind to ACh receptors embedded in the [...]

Answer 27

Muscle fiber sarcolemma

Question 28

Enzyme found in the synaptic cleft, breaks down ACh.

Answer 28

Acetylcholinesterase (i.e. some ACh is removed via reuptake or is dissolved)

Question 29

Triggers the movement of cations (i.e. typically sodium) into muscle fibers via the opening of an ion channel.

Answer 29

Binding of two ACh molecules to a single ACh receptor

Question 30

Graded potential produced due to the influx of sodium into a muscle fiber.

Answer 30

Excitatory postsynaptic potential (i.e. an end plate potential)

Question 31

Can be recorded in muscle fibers due to the result of random discharge of a single synaptic vesicle.

Answer 31

Miniature end plate potential (mEPP)

Question 32

Invaginations of the sarcolemma into the interior of the muscle fiber, lie at right angles to the myofibrils, are made of membrane and filled with ECF.

Answer 32

Transverse (T) tubules

Question 33

Structure that carries the electrical signal into the interior of a muscle fiber.

Answer 33

T-tubule

Question 34

Membranous structure that is adjacent and mostly parallel to the myofibrils, in contact with the T tubules, and a storage depot for calcium ions

Answer 34

Sarcoplasmic reticulum

Question 35

A t-tubule protein, "senses" changes in voltage due to action potential.

Answer 35

Dihydropyridine receptor

Question 36

Interacts with dihydropyridine receptor, acts as a calcium release channel.

Answer 36

Ryanodine receptor

Question 37

Ion the is released from the sarcoplasmic reticulum to the sarcoplasm surrouding the myofibrils upon ryanodine receptor activation.

Answer 37

Calcium

Question 38

Causes actin and myosin to dissociate.

Answer 38

ATP binding to myosin

Question 39

Causes a conformational change in myosin that "cocks" the head.

Answer 39

Hydrolyziation of ATP to ADP plus phosphate (i.e. both of which remain attached)

Question 40

Result of calcium binding to troponin C.

Answer 40

Troponin pulls on tropomyosin revealing the active site of actin (i.e. thus mysoin head can now bind to form a cross bridge)

Question 41

Term for the head of myosin being attached to actin.

Answer 41

Cross bridge

Question 42

Cause of myosin head "sprining"/"uncocking".

Answer 42

Release of phosphate group (i.e. ADP remains attached)

Question 43

Myosin and actin remain attached to each other until [...] is released from myosin.

Answer 43

ADP