W9 - The Muscular System

Question 1

What are the primary functions of smooth muscle?

Answer 1

Digestion

Breathing

Circulation

Question 2

What shape are smooth muscles?

Answer 2

Fusiform shaped

Question 3

What do intercalated discs do for cardiac muscle?

Answer 3

Support synchronised contraction

Question 4

What are cardiac muscle cells also known as?

Answer 4

Cardiomyocytes

Question 5

What is the function of fascia adherens in a muscle fibre?

Answer 5

Mechanical support

Question 6

What are desmosomes?

Answer 6

Specialised adhesive protein complexes.

Question 7

What are desmosomes responsible for?

Answer 7

Maintaining mechanical integrity of tissues

Question 8

What 4 characteristics define the skeletal muscle?

Answer 8

Excitability

Contractility

Extensibility

Elasticity

Question 9

What does Titin do?

Answer 9

Keeps thick + thin filaments aligned.

Prevents muscle from overstretching.

Recoils muscle to resting length after stretching.

Question 10

What does Nebulin do?

Answer 10

Anchors actin to Z disc

Question 11

What is dystrophin?

Answer 11

Anchoring protein

Links actin filaments to other support proteins on the inner surface of each sarcolemma.

Question 12

What is muscular dystrophy?

Answer 12

Weakening + breakdown of skeletal muscle

Question 13

What are the 2 components of the motor unit?

Answer 13

A-motorneurone

Muscle fibres innervated by the AMN

Question 14

HENNEMANS SIZE PRINCIPLE

What is recruitment based on?

Answer 14

Force req, not the velocity of the movement.

Slow units are ALWAYS recruited, regardless of velocity.

Question 15

What are myogenic stem cells known as?

Answer 15

Satellite cells

Question 16

Satellite cells

Answer 16

Incorporation of satellite cell nuclei into existing muscle fibres seems a likely explanation for exercise-induced muscle fibre hypertrophy.

Question 17

Muscles Chemical composition

Answer 17

H20 ~75%

Protein ~20%

Salts + other substances ~5%

Question 18

What are the most abundant muscle proteins?

Answer 18

Titin

Myosin

Actin

Tropomyosin

Question 19

What does each 100g of muscle tissue contain in relation to myoglobin?

Answer 19

~700mg of myoglobin.

Question 20

A band, lighter or darker area?

Answer 20

Darker

Question 21

I band, lighter or darker area?

Answer 21

Lighter

Question 22

What is the z line made from?

Answer 22

a-actin

Question 23

What are the connection called between 2 sarcomeres from adjacent myofibrils?

Answer 23

Desmin

Question 24

What is the M band made of?

Answer 24

M protein

Myomesin

M creatine kinase (M-CK)

Question 25

What protein are the elastic filaments made from?

Answer 25

Titin

Question 26

What proteins come under the thin filament?

Answer 26

Actin Tropomyosin Troponin Nebulin

Question 27

What 2 structures come under the thick filaments?

Answer 27

C stripes M line

Question 28

What proteins comes under the C stripes in the thick filaments?

Answer 28

Myosin C protein

Question 29

What proteins are found in the z line?

Answer 29

a-actinin Desmin

Question 30

What does M-CK do?

Answer 30

Provides ATP from PC

Question 31

What does myomesin do?

Answer 31

Provides strong anchoring point for Titin

Question 32

What does an unusually large pennation angle of 30 degrees result in?

Answer 32

13% loss in an ind fibres force capacity.

Question 33

Do pennate muscles generate considerable power?

Answer 33

YES

Question 34

At what angle do muscle fibres lie to the tendon when in a unipennate fibre arrangement?

Answer 34

At an oblique angle to the tendon.

Question 35

What are the 3 ways in which pennate muscles differ from fusiform fibres?

Answer 35

Generally contain shorter fibres More ind fibres Less range of motion

Question 36

What are the purposes of the intracellular cytoskeleton?

Answer 36

Structural integrity in the inactive muscle cell Lateral force transmission to adjacent sarcomeres Connections to the cells surface membrane

Question 37

In what direction do T-tubules system run to the myofibril?

Answer 37

Perpendicular

Question 38

What does the term triad describe?

Answer 38

Repeating pattern of 2 terminal cisterns + 1 T tubule in each Z line region

Question 39

How many triads does each sarcomere contain?

Answer 39

2

Question 40

What is the purpose of the triad + the T-tubule system?

Answer 40

Function as a MICROTRANSPORTATION NETWORK. By spreading the AP/wave of depolarisation from fibres outer membrane inward to the deeper cell region.

Question 41

What does propagation of the AP stimulate the triad sacs to do?

Answer 41

Release Ca2+ to "activate" actin filaments.

Question 42

What is the optimal sarcomere length in which there's the greatest interaction between actin + myosin filaments?

Answer 42

2.0 - 2.25 micrometers

Question 43

Formula showing the dissociation of actomyosin

Answer 43

Actomyosin + ATP --> Actin + Myosin-ATP

Question 44

What happens to the energy from ATP hydrolysis in the dissociation of actomyosin?

Answer 44

Transduces into mechanical force when ADP + inorganic phosphate end products form.

Question 45

Major storage fuel for Type 1 fibres

Answer 45

Triacylglycerol

Question 46

Major storage fuel for Type 2a fibres

Answer 46

Creatine phosphate Glycogen

Question 47

Major storage fuel for Type 2x fibres

Answer 47

Creatine phosphate Glycogen

Question 48

Major storage fuel for Type 2b fibres

Answer 48

Creatine phosphate Glycogen

Question 49

What receptor can be found on T-tubules?

Answer 49

Dihydropyridine receptor (DHP)

Question 50

Ryanodine receptors

Answer 50

Intracellular Ca2+ channels

Question 51

What is calsequestrin? What does it do?

Answer 51

Most abundant Ca2+ binding protein. Allows Ca2+ req. for contraction to be stored at total conc of up to 20mM while the free Ca2+ conc remain at ~1mM.

Question 52

Where can calsequestrin be found?

Answer 52

Sarcoplasmic reticulum of skeletal + cardiac muscle

Question 53

What is calmodulin?

Answer 53

Calcium modulated protein

Question 54

What binds to calmodulin?

Answer 54

Calcium

Question 55

What does Ca2+-calmodulin activate?

Answer 55

Myosin Light-Chain Kinase (MLCK)

Question 56

What does MLCK do?

Answer 56

Phosphorylates light chains in myosin heads + ⬆️ myosin ATPase activity

Question 57

What do Na+ + K+ do to the activation of RyR?

Answer 57

Decrease it