Skeletal Muscle Histology

Front 1

Muscle cells, called __, are elongated, arranged in parallel, and organized in ___, which is composed of many ___, which extend entire length of myofiber

Back 1

myofibers

fascicles

myofibrils

Front 2

Myofibrils are mostly __, which are both __ and ___ filaments that contract the muscle, and are found in the ___

Back 2

myofilaments

actin and myosin

sarcoplasm

Front 3

Muscle cell development:

1. Mesenchymal cells of myotomes differentiate into mononuclear ___ and undergo ___

2. these fuse and form ___ which are multinuclear, called a ___

3. mature muscle cells are organized into contractile units from mytotubes, have limited proliferative capacity and are called ___

Back 3

1. myoblasts; mitosis

2. myotubes; syncitium

3. satellite cells

Front 4

Characteristics of skeletal muscle in histo?

Back 4

elongated, unbranched, cylindrical, flattened nuclei below sarcolemma, striated

Front 5

What are the three types of striated muscle?

Back 5

skeletal muscle

visceral striated muscle

cardiac muscle

Front 6

What makes skeletal muscles striated?

Back 6

myofilaments (actin and myosin) are arranged in parallel and in register, creates striations seen in light microscopy

Front 7

Striated muscle:

1. I-bands are ___ in polarized light

2. A-bands are __ in polarized light

3. Z-discs is where?

4. where is nucleus?

5. myofibrils are in parallel with___ axis

6. mitochondria are in __

7. area btwn 2 successive Z-discs is the ___, the fxnal unit of muscle contraction

Back 7

1. isotropic

2. anisotropic

3. btwn the I-bands (bisects it)

4. at periphery

5. longitudinal

6. parallel

7. sarcomere

Front 8

I-band:

1. thick or thin filament?

2. bisected by __

3. contains actin or myosin or both?

Back 8

1. thin

2. z-disc

3. actin only (thin only)

Front 9

A-band:

1. area btwn ___

2. contains actin or myosin or both?

Back 9

1. btwn 2 I-bands

2. both actin and mysoin (both thin and thick)

Front 10

Z-disc: scaffold for __ filaments to attach

Back 10

thin (actin)

Front 11

H-band:

1. thin or thick filament?

2. bisected by __

Back 11

1. thick

2. M-line (only thick)

Front 12

M-line:

1. band of __

2. keeps __ filament in place

Back 12

1. proteins

2. thick

Front 13

Organization of actin:

1. arranges in __ structure

2. positive end attaches to ___

3. positive end has what protein to help it attach?

4. positive end gets help attaching from what?

5. negative end is capped by what protein?

Back 13

1. helical

2. z-disc

3. alpha-actinin

4. nebulin

5. tropomodulin

Front 14

F-actin (fibrous):

1. double stranded helix formed from __

2. ___ is entwined w/in F-actin

3. it masks the ___ binding site on actin

Back 14

1. G-actin (globular)

2. tropomyosin

3. myosin

Front 15

Troponin:

1. regulates____

2. has what 3 globular subunits?

3. what do the 3 subunits bind?

Back 15

1. tropomyosin

2. TnC, TnI, TnT

3. TnC: binds calcium

TnI: binds to actin (blocks binding of actin-myosin)

TnT: binds to tropomyosin, anchoring it

Front 16

Myosin in the sarcomere:

1. what is the major myosin subtype in skeletal muscle?

2. has what three areas/parts?

3. myosin head is __ that functions in the presence of bound actin

4. the coiled coil tail allows___ to pack tails together, creating _ arrangements in skeletal muscle

Back 16

1. myosin II

2. head (x2), neck (x2), tail (x2)

3. ATPase

4. myosin II; bipolar

Front 17

Accessory proteins of sarcomere:

1.___: molecular springs from z-line/disc, helps center thick filament

2.___: binds actin to z-disc

3. ___: intermediate filament that connects sarcomeres to each other around z-discs

4. ___: hold thick filaments together

5.___: links ECM to actin filaments (through dystroglycans)

Back 17

1. titin

2. alpha-actinin

3. desmin

4. M-line proteins

5. Dystrophin

Front 18

Back 18

1. alpha-actin

2. Z line

3. A band

4. H band

5. M line

6. tropomodulin

7. nebulin

8. titin

9. M line proteins (mysomesin, M-protein, obscurin)

10. dystrophin

11. desmin

Front 19

1. around each A-I junction, there is a __

2. this consists of 2 __ and 1___

Back 19

1. triad

2. 2 terminal cisterna of sarcoplasmic reticulum and 1 T-tubule

Front 20

1. Terminal cisterna= intracellular ___ stores

2. T-tubule= invagination of ___ that localizes AP's to interior of myofiber

Back 20

1. Ca2+

2. plasma membrane (sarcolemma)

Front 21

Front 22

NMJ/Motor end plate organization:

1. nerve branches into axons of individual __ terminals

2. releases __ from synaptic vesicles into primary cleft and ___ of individual myofibers

3. binds postsynaptically to NAchRs, graded potential and AP follow in muscle, through__

Back 22

1. alpha-motoneuron

2. Ach; junctional folds

3. T-tubules

Front 23

1. a single alpha-motoneuron and all the fibers it innervates is called ___

2. increase or decrease in the number of these changes the amount of __ produced by a muscle

Back 23

1. motor unit

2. force

Front 24

1. ___ takes place at the triad through two proteins

2. when depolarized, ___ and ___ link up and allow intracellular Ca2+ to flow into the sarcoplasm

Back 24

1. excitation-contraction coupling

2. dihydropiridine receptor (DHPR) and ryanodine receptor (RYR)

Front 25

Binding of Ca2+ to troponin, moves ___, exposes __ binding site on actin

Back 25

tropomyosin

myosin

Front 26

1. Once the actin binding site is free, __ can regulate the molecular event in muscle contraction

2. ___ and __ will both leave as a result of the power stroke

Back 26

1. ATP

2. ADP and Pi

Front 27

Sliding filament mechanism:

1. process by which myosin head form __ w/ actin

2. contraction does what to the two filaments?

3. the filaments do not___ however

Back 27

1. cross-bridges

2. slides the two filaments past each other

3. physically shorten

Front 28

1. Connective tissue holds muscle fibers ___ and __ together

2. this organization continues as a ___ to attach the muscle

3. lots of __ and __ supply in the connective tissue

Back 28

1. individually and collectively

2. tendon

3. blood and nerve

Front 29

What is endomysium?

Back 29

fine reticular layer surrounding a single myofiber, small blood vessels and axons in here

Front 30

What is perimysisum?

Back 30

thicker, organizes groups of myofibers, together w/ fascicles, larger blood vessels and nerves in here

Front 31

What is epimysium?

Back 31

dense connective tissue surrounding fascicles, major blood and nerve supplies found here

Front 32

Circulatory system utilizes __ pathways to supply blood to myofibers

Back 32

connective tissue

Front 33

What are the 3 varieties of skeletal muscle myofibers?

Back 33

Type I or slow twitch "A"

Type II A or fast twitch oxidative/glyocyltic "I"

Type II B or fast twitch glyocyltic "An"

Front 34

Type I or slow twitch "A" myofibers:

1. aerobic or anaerobic or intermediate?

2. small or large?

3. red, white, or pink muscle fibers?

4. how much tension?

5. resistant to __

6. important for ___

7. small or large force?

Back 34

1. aerobic

2. small

3. red

4. not much

5. fatigue

6. sustained muscle contraction (ex. regulating posture)

7. small

Front 35

Which myofiber type has the lowest threshold for activation and is therefore the first recruited?

Back 35

Type I or slow twitch "A"

Front 36

Type II A or fast twitch oxidative/glyocyltic "I":

1. aerobic or anaerobic or intermediate?

2. small or large?

3. red, white, or pink muscle fibers?

4. resistant to ___

5. lots of ___ stored

6. how much force?

Back 36

1. intermediate

2. large

3. pink

4. fatigue

5. glycogen

6. intermediate

Front 37

Type II B or fast twitch glyocyltic "An":

1. aerobic or anaerobic or intermediate?

2. small or large?

3. red, white, or pink muscle fibers?

4. how much force?

5. not resistant to ___

6. lots of _ stored

Back 37

1. anaerobic

2. large

3. white

4. large

5. fatigue

6. glycogen

Front 38

Which type of myofiber produces the larges lactic acid?

Back 38

Type II B or fast twitch glyocyltic "An"

Front 39

Which type of myofiber has more NMJs than others?

Back 39

Type II B or fast twitch glyocyltic "An"

Front 40

What is the order that the three myofiber types are recruited?

Back 40

Type I (first), Type II A (second), Type II B (last)

Front 41

Muscle spindles:

1. __ fibers have single row of nuclei in center of fiber

2. __ fibers have nuclei collected in bundle in center of fiber

3. of these two types, one signals ___ muscle length and one signals ___ muscle length

Back 41

1. nuclear chain

2. nuclear bag

3. static; changes in

Front 42

Type I A:

1. wraps around how many spindle types at the center of spindle?

2. has ___ endings

3. provides info on what?

Back 42

1. all

2. annulospiral

3. length and velocity

Front 43

Type II:

1. innervates nuclear chain and only ____ fibers

2. has ___ endings

3. provide info on what?

Back 43

1. static nuclear bag fibers

2. flower spray

3. length only

Front 44

Golgi tendon organs:

1. sit at ___

2. more responsive to ___ than muscle spindles

3. use ___ axons

4. often used in __ circuits

Back 44

1. muscle-tendon junction

2. active muscle stretch

3. Ib

4. negative feedback

Front 45

1. What do extrafusal fibers do?

2. What do intrafusal fibers do?

Back 45

1. contract

2. tell brain and spinal cord the state of stretch of all the surrounding cells around it (mission control)