Physiology 534 Exam Iv: Skeletal Muscle

Front 1

Epimysium is made of what kind of CT?

What vasculature lies in epimysium?

Back 1

Dense CT


Bld vessels, nerves

Front 2

What vasculature lies in perimysium?

Back 2

Bld vessels, nerves
Muscle spindles

Front 3

What vasculature lies in endomysium?

Back 3

Capillaries

Front 4

Purpose of satellite cells

Back 4

Stem cells

Remain in basal lamina

Can divide & fuse with myofibers to create large myofibers

Front 5

Characteristics of Myofibers

Back 5

1. Multinucleated, along perimenter
2. Striated
3. Basal lamina made by myoblast
4. Angular-looking cells
5. Cannot divide
(take on more nucleus by fusing with satellite cells)

Front 6

Difference between Pennate & Strap

Back 6

Pennate can undergo greater changes in tension

Strap capable of greater changes in length

Front 7

Is there more stress at the ends(musculotendinous jxn) of myofibers or midsection?

Back 7

-The ends have larger SA
-When F develops-->transmitted to tendon and because of large SA less stress at jxn. More stress at the midsection.

Front 8

Golgi Tendon organ

Back 8

-Force
-lie at the jxn btw myofibers & tendons/aponeurosis
-axon embedded in collagen
-Upon contraction-->distorts axon endings-->AP

Front 9

Muscle spindles

Back 9

-Lie within the perimysium
-Stretch reflex
-Upon stretching-->spindles activated-->depolarization

Front 10

Trophism

Back 10

Neurons secrete tropic factors which bind to receptors on myofibers causing altered cellular activity.

Front 11

Embryonic development of skeletal m?

Back 11

Mesoderm

Front 12

Embroyonic devopment of myofibers

Back 12

Mesenchymal cells-->myoblast-->myotube-->myofiber

Front 13

Why would a myofiber need additional nuclei?

Back 13

Large myofibers need to maintain protein synthesis for fiber growth

Front 14

Sarcoplasmic reticulum

Back 14

Another name for the ER

Storage area for calcium, released with an action potential in T-tubule

Front 15

Sarcolemma

Back 15

-PM of muscles
-has voltage-gated Na/K channels

Front 16

Invaginations of the sarcolemma is called?

Back 16

T-tubules that allows AP conduction interior

Front 17

Thin filaments are linked where?

Back 17

Z-line

Front 18

thick filaments are anchored to?

Back 18

M-line

Front 19

What does contraction do?

Back 19

Thin filaments slide towards M-line

Pulls Z-disc towards center

Front 20

Tropomyosin

Back 20

Regulatory proteins that blocks binding of thick filaments

Front 21

What happens with Ca++ present with tropomyosin

Back 21

Ca binds to Troponin-->binds to to tropomyosin-->exposes myosin binding sites

Front 22

What are the 3 subunits of Troponin?

Back 22

1. Tn-T: where tropomyosin binds
2. Tn-C: where Ca binds
3. Tn-I: inhibition

Front 23

Myosin head has what important feature?

Back 23

It has ATPase

Front 24

A band

Back 24

Where thick & thin filaments overlap

Front 25

I-band

Back 25

Thin filaments only

Front 26

Titin

Back 26

extends from z-line to m-line

limits stretch

Front 27

Desmin

Back 27

-Not in smooth
-links Z-line of one myofibril to adjacent myofibril
-genetic errors result in weak muscle bc no coordination

Front 28

Dystrophin

Back 28

achors actinof cell on inside to glycoproteins of the CM

genetic error, change in length no transmitted to glycoproteins externally

Front 29

Duchenne muscular dystrophy

Back 29

No dystrophin

No structural stability linking contractile proteins to CM

death of muscle fibers, look large bc filled with fat

Front 30

Hypertrophy

Back 30

Inc. in cell size, NOT #

Stretch signal-->Inc. protein synthesis-->inc. cell size-->recruitment of satellite cells

Front 31

Stimulant of satellite cells

Back 31

IGF-1-->hypertrophy

Front 32

Inhibitor of satellite cell proliferation

Back 32

Myostatin

No inhibition of satellite cell proliferation

Front 33

Hyperplasia

Back 33

Increase cell #, NOT size

Front 34

Atrophy

Back 34

Dec. in myofiber # or size

Caused by loss of innervation

Front 35

What happens to motor neurons that lose innervation and then motor neurons grow back

Back 35

New motor units larger than normal, will not be in normal mosaic pattern

Front 36

What happens in aging

Back 36

Atrophy-->loss of myofibers-->replaced by fat cells

Satellite pool dec-->limits repair ability-->loss of myofiber

Dec. in # of motor units

Front 37

Attachment (rigor)

Back 37

-Crossbridge formation
-High affinity for ATP

Front 38

Release

Back 38

ATP binds to myosin-->conformational change in head-->dec. myosin affinity for actin-->release crossbridge

Front 39

Hydrolysis/Bending

Back 39

-ATP hydrolyzed
changes shape of myosin head-->moves towards Z-line

Resting state (low Ca++)-->tropomyosin & troponin block myosin on actin

Front 40

Power stroke

Back 40

-release of ADP + pi-->inc. affnity for myosine & actin-->pull of myosin towards sarcomere-->shortening

Front 41

Postsynaptic terminal for skeletal muscule

Back 41

-Junctional folds
-Ach binds to nicotinic cholinergic receptors

Front 42

Role of Ca++

Back 42

Depolarization-->Voltage sensing DHSR change conformation-->signals RyR-->opens Ca++ channels in SR

Front 43

How does relaxation occur involving Ca++?

Back 43

Ca ++ ATPase on SR moves Ca++ back into SR

Ca++ ATPase has a higher affinity for Ca++ than troponin does.

Front 44

If we administer Lidocaine (blocks AP) what would happen?

Back 44

everything downstream will be blocked

Front 45

If we block or dec. Ach receptors what would happen?

Back 45

End plate potential dec.

Front 46

If we block or dec. SR Ca++ ATPase what would happen?

Back 46

dec. in sarcomere Ca++ reuptake

inc. duration of cross bridge cycling

inc. myofiber shortening or force

Front 47

Defect in dystrophia (muscle weakening & atrophy)

Back 47

dec. myofiber shortening or force

Front 48

Blocking AchE

Back 48

Inc. end plate potential, myofiber AP, sarcomere Ca++ release, sarcomere Ca++ reuptake, cross bridge cycling, dec. myofiber shortening for force

Front 49

What records electrical activity of the motor unit

Back 49

EMG (electromyologram)

Front 50

Spontaneous contraction of myofiber (independent of motor neuron)

Back 50

Fibrillation

Front 51

Spontaneous firing of a motor unit

Back 51

Fasciculation