Lecture 5 - Skeletal Muscle Contraction

Question 1

Myofilaments are compose of?

Answer 1

Actin and myosin filaments

Question 2

Chains of sarcomeres are called?

Answer 2

Myofibirills

Question 3

Bundles of myofibrils are called?

Answer 3

Myofibers

Question 4

Bundles of myofibers are called?

Answer 4

Fascicles

Question 5

Muscles are made up of?

Answer 5

Multiple fascicles

Question 6

What surrounds myofibers?

Answer 6

Endomysium

Question 7

What surrounds fascicles?

Answer 7

Perimysium

Question 8

What surrounds muscles?

Answer 8

Epimysium

Question 9

Another word for sarcolemma?

Answer 9

Plasmolemma

Question 10

Invaginations of the sarcolemma are called?

Answer 10

T-tubules

Question 11

How many T-tubules per sarcomere?

Answer 11

Two

Question 12

Where are T-tubules located?

Answer 12

Close to cisternae of the sarcoplasmic reticulum

Question 13

The sarcoplasmic reticulum sequesters what ion to be used as needed?

Answer 13

Ca2+

Question 14

What do Z-lines do?

Answer 14

Anchor actin filaments

define individual sarcomeres

Question 15

Composed entirely of actin

Shortens as muscle contracts

Answer 15

I band

Question 16

Composed entirely of myosin

Shortens as muscle contracts

Answer 16

H band

Question 17

Composed entirely of myosin

Does not shorten as muscle contracts

Answer 17

A band

Question 18

Step 1: Action potential arrives at terminal end of nerve fiber
THEN…

Answer 18

Step 2: Voltage gated calcium channels open; Ca2 influx into axon terminal

Question 19

Step 2: Voltage gated calcium channels open; Ca2 influx into axon terminal
THEN…

Answer 19

Step 4: Exocytosis of synaptic vesicles carrying Ach from axon terminal into synaptic cleft

Question 20

Step 4: Exocytosis of synaptic vesicles carrying Ach from axon terminal into synaptic cleft
THEN…

Answer 20

Step 5: Ach binds to Ach receptors on sarcolemma

Question 21

Step 5: Ach binds to Ach receptors on sarcolemma

THEN…

Answer 21

Step 6: Ligand-gated sodium channels open

Question 22

Step 6: Ligand-gated sodium channels open

THEN…

Answer 22

Step 7: Na+ ion influx

Question 23

Step 7: Na+ ion influx

WHICH CAUSES..

Answer 23

Step 8: End plate depolarization

Question 24

Step 8: End plate depolarization

THEN…

Answer 24

Step 9: Voltage gated sodium channels open

Question 25

Step 9: Voltage gated sodium channels open | WHICH LEADS TO...

Answer 25

Step 10: Sarcolemma action potential.

Question 26

Step 10: Sarcolemma action potential. | LEADS TO...

Answer 26

Step 11: Depolarization of T-tubules

Question 27

Step 11: Depolarization of T-tubules | WHICH CAUSES...

Answer 27

Step 12: A conformational change in DHP receptors

Question 28

Step 12: A conformational change in DHP receptors | WHICH CAUSES...

Answer 28

Step 13: Ryanodine receptor Ca2+ channels open

Question 29

Step 13: Ryanodine receptor Ca2+ channels open | THEN...

Answer 29

Step 14: Calcium release from Sarcoplasmic reticulum; increasing cytosolic concentration of Ca2+ to 10 micromoles/liter

Question 30

Step 14: Calcium release from Sarcoplasmic reticulum; increasing cytosolic concentration of Ca2+ to 10 micromoles/liter THEN...

Answer 30

Step 15: Calcium binds to Troponin C, causing a conformational change

Question 31

Step 15: Calcium binds to Troponin C, causing a conformational change WHICH MEANS...

Answer 31

Step 16: Active sites on actin filaments become exposed

Question 32

Step 16: Active sites on actin filaments become exposed | ALLOWING...

Answer 32

Step 17: Myosin heads bind to actin active sites

Question 33

DHP receptor location

Answer 33

T-Tubules

Question 34

Ryanodine receptor location

Answer 34

Sarcoplasmic reticulum

Question 35

Cytosolic calcium increases by a factor of

Answer 35

100

Question 36

SRCA?

Answer 36

Pumps calcium back into the cisternae after release from action potential

Question 37

After action potential, what happens to Ach?

Answer 37

acetylcholinesterase degrades Ach into choline and acetate

Question 38

what is meant by excitation-contraction (elctro-mechanical coupling)?

Answer 38

converting energies from action potential into mechanical energy in the sliding filament mechanism

Question 39

Metacholine Carbachol Nicotine

Answer 39

have same effect as Ach but not broken down by AchAse causing spasms

Question 40

Neostigme Physostigmine diisopropyl fluorophosphates

Answer 40

inactivate AchAse

Question 41

Curare

Answer 41

prevents passage of impulses from nerve ending into muscle (muscle relaxation)

Question 42

Myasthenia Gravis

Answer 42

autoimmune disease antibodies attack AchAse neostigmine can be used to inactiate AchAse