Muscle And Integument: Overview Of Cns,pns, Muscle

Front 1

Desribe the role of the following brain regions.

- primary motor cortex
- supplementary motor cortex
- premotor and supplementary motor areas

Back 1

- primary motor cortex: contralateral control of muscles
- supplementary motor cortex: "abstract" planning
- premotor and supplementary motor areas: planning and executing motor activity

Front 2

Direct or indirect activation pathway?

Corticospinal tract

Back 2

Direct activation pathway: runs in contralateral lateral funiculus in spinal cord.

Front 3

Direct or indirect activation pathway?

Rubrospinal tract

Back 3

Indirect activation pathway: synapse in ipsilateral red nucleus, then send axons to contralateral alpha mortor neurons and interneurons.

Front 4

Direct or indirect activation pathway?

Corticobulba tract

Back 4

Indirect activation pathway: synapse in brainstem reticular and vestibular nuclei, then send axons to alpha mortor neurons and interneurons.

Front 5

Role of cerebellum.

Back 5

- helps coordination, posture
- contribute to smooth execution of movement
- involved in motor learning

Front 6

Role of basal ganglia.

Back 6

- helps control movements of extremities
- postural control

Front 7

Upper or lower motor neuron?

- large dentritic field: major information integration site.

Back 7

lower motor neuron

Front 8

Long vs. short nerves.

- highly vulnerable to tauma and inflammation

Back 8

long nerves

Front 9

T/F: High precisional movement is correlated with smaller motor units.

Back 9

True

Front 10

Upper or lower motor neuron?

- injury to it causes flaccid paralysis with reduced reflexes, muscle atrophy and wasting.

Back 10

lower motor neuron

Front 11

Upper or lower motor neuron?

- injury to it causes hyperreflexia, hypertonicity.

Back 11

upper motor neuron

Front 12

Are action potential generated at the neuromuscular junctions?

Back 12

No. Binding of Ach to nicotinic receptor causes Na to enter muscle cell, generating a depolarizing current which flows to adjacent membrane where APs are generated.

Front 13

In a skeletal muscle fiber, where do you find the triad that is made up by T tubule (sarcolemma) and SR(terminal cisternae)?

Back 13

At AI junction.

Front 14

What is the content of the followng structure in a skeletal muscle fiber?

- T tubule
- SR

Back 14

- T tubule: extracellular fluid (high Na, low K+)
- SR: Ca2+ store

Front 15

Thick filament is a polymer of which protein?

Back 15

myosin

Front 16

What are the two binding sites in a myosin head?

Back 16

1. actin binding site
2. ATP binding site (ATPase activity)

Front 17

Thin filament is a polymer of which protein?

Back 17

actin

Front 18

What is this protein in a skeletal muscle fiber?

- helical, lie in the groove formed by every 7 actins of thin filament.
- blocks actin binding site for myosin head groups

Back 18

tropomyosin

Front 19

What is this protein in a skeletal muscle fiber?

- three subunits
- one binds tropomyosin
- one binds calcium
- one binds actin

Back 19

troponin

Front 20

How many thin filaments surround each thick filament?

How many thin filaments are there for each thick filament?

Back 20

- 6
- 2

Front 21

Where are the following located in a muscle cell?

- voltage sensor DHP
- calcium release channel (ryanodine receptor)

Back 21

- voltage sensor DHP: on T-tubule
- calcium release channel (ryanodine receptor): on SR

Front 22

What is this process called?

- AP in a muscle cell spreads down to T-tubule
- induce DHP conformational change
- CRC open
- muscle contraction

Back 22

excitation-contraction coupling

Front 23

How is Ca2+ stored in SR in a muscle fiber?

Back 23

by binding to calsequestrin (low affinity for Ca2+)located on the inside of SR.

Front 24

How is Ca2+ resequestered into SR in a muscle fiber?

Back 24

by SR ca2+ pump on lateranl portions of SR, then binds to calsequestrin.

Front 25

When does myosin head have high affinity for actin thin filaments?

Back 25

after it has split bound ATP into ADP and Pi which are still attached.

Front 26

When does myosin head have low affinity for actin thin filaments?

Back 26

when it binds to ATP.

Front 27

T/F: Cross-bridge cycling occurs synchronously during muscle contraction.

Back 27

F.
Cross-bridge cycling occurs asynchronously so that at any given time there are cross-bridge formed and some re-cycling.

Front 28

Which of the following shortens during muscle contraction?

- A band
- I band
- H zone

Back 28

- I band
- H zone

* A band stays the same

Front 29

What is the length of a resting sarcomere?

Back 29

2.25 um:
- 1.65 um thick filament (A band)
- 1/2 I band
- 1/2 I band

Front 30

This structure holds the thick filament together.

Back 30

M line

Front 31

This structure holds the thin filament together.

Back 31

Z line

Front 32

Isometric or isotonic?

- generate high tension without shortening

Back 32

isometric

Front 33

Isometric or isotonic?

- no useful work generated

Back 33

isometric

Front 34

Isometric or isotonic?

- cross bridge cycling at low rate

Back 34

- isometric

Front 35

Isometric or isotonic?

- muscle shortens at constant force equal to the load

Back 35

isotonic

Front 36

Spatial or temporal summation?

- increase muscle tension by high frequency stimulation.
- converts contraction from a single twich to a fused tetnus.

Back 36

temporal

Front 37

Spatial or temporal summation?

- increase muscle tension by recruiting more motor units

Back 37

spatial

Front 38

At what load does a muslce operate at maximal efficiency?

Back 38

Intermediate load (1/3 of maximal load)

Front 39

Why at long initial sarcomere length, stimulation of muscle generates little tension?

Back 39

lack of overlap between thick and thin filaments.

Front 40

Why at short initial sarcomere length, stimulation of muscle generates little tension?

Back 40

interference of thin filaments from either side of the sacomere.

Front 41

At what sarcomere length is maximal tension generated in a muscle?

Back 41

When there is maximal overlap between thick and thin filaments. (1.95-2.25 um)

Front 42

What determines the maximal force a muscle can generate?

Back 42

the rate at which it shortens.

Front 43

Isometric or isotonic?

- many crossbridges formed
- crossbridges cycle at low rate

Back 43

isometric (maximal load, no length shortening)

Front 44

Isometric or isotonic?

- few crossbridges formed
- crossbridges cycle at very rapid rate

Back 44

isotonic with no load

Front 45

What type of muscle fiber is this?

- fast twich glycolytic (fatiguing)

Back 45

Type IIB

Front 46

What type of muscle fiber is this?

- fast twich oxidative/glycolytic

Back 46

Type IIA

Front 47

What type of muscle fiber is this?

- slow twich oxidative

Back 47

Type I

Front 48

What type of muscle fiber is this?

- red meat

Back 48

Type I and Type IIA

Front 49

What type of muscle fiber is this?

- recruited for intense and powerful activities that can not be sustained for long periods of time.

Back 49

Type IIB: fast twitch fast glycolytic (fatiguing)

Front 50

What type of muscle fiber is this?

- recruited for higher intensity activities that require sustained muscle function.

Back 50

Type IIA: fast twitch fast oxidative/glycolytic

Front 51

What type of muscle fiber is this?

- recruited for low intensity prolonged activity such as postural maintanence.

Back 51

Type I: low twitch slow oxidative