8Microanatomy Lect - Muscle & Histo (Chapter 11 )

Front 1

Back 1

A: Skeletal Muscle – striated, long parallel arrangement, multiple peripheral nuclei
B: Cardiac Muscle – striated, branched cells, central nucleus, Intercalated disks
C: Smooth Muscle – fusiform, central “cork screw nucleus”

Front 2

Non-striated muscle type

Back 2

smooth

Front 3

Skeletal muscle cell (muscle fiber)
Is multinucleated, and formed from fusion of individual ___ during development

Back 3

myoblasts

Front 4

Skeletal muscle cells are long, cylindrical cells (a muscle cell is called a fiber) having ___ nuclei. Each muscle cell is surrounded by a ___

Back 4

-multiple, peripherally located
-basal lamina

Front 5

Nomenclature: (Sarco = flesh)
-Sarcolemma:
Sarcoplasm:
Sarcoplasmic reticulum:

Back 5

-the muscle fiber (cell) plasmalemma
-the muscle fiber cytoplasm
-specialized muscle endoplasmic reticulum

Front 6

Endomysium – CT surrounding individual muscle cells, composed of ___ and external lamina (___)

Back 6

-reticular fibers
-basal lamina

Front 7

Perimysium – thicker CT that surrounds and defines ___ (functional bundles of muscle fibers)

Back 7

fascicles

Front 8

Epimysium – dense CT that surrounds ___ (a collection of fascicles)

Back 8

the entire muscle

Investing fascia of gross anatomy

Front 9

Types of muscle contraction:

___ – not voluntarily controlled
___ – slight contraction that gives muscle firmness, assisting stability of joints and posture

Back 9

-Reflexive
-Tonic

Front 10

Types of muscle contraction:

Phasic
___ – muscle length does not change
___ – muscle length changes
>>___– contracting muscle shortens during movement
>>___ – contracting muscle lengthens during movement (lowering an object or squatting down)

Back 10

-Isometric
-Isotonic
-Concentric
-Eccentric

Front 11

Type I (___, ___, ___) – not easily fatigued (___ muscles/endurance)
___ myoglobin content (oxygen binding protein)
___ mitochondria and ___ in oxidative enzymes
___ myosin ATPase reaction velocity
Location:
Predominate in the ___ muscles and other ___ muscles of humans to maintain upright posture, soleus muscle of the calf

Back 11

Type I (red, slow twitch, slow oxidative) – not easily fatigued (postural muscles/endurance)
High myoglobin content (oxygen binding protein)
Many mitochondria and high in oxidative enzymes
Slow myosin ATPase reaction velocity
Location:
Predominate in the deep back muscles and other postural muscles of humans to maintain upright posture, soleus muscle of the calf

Front 12

Type IIb (___, ___, ___) – power and rapid contraction but easily fatigued
___ myoglobin content
___ mitochondria and ___ in oxidative enzymes
___ myosin ATPase reaction velocity
Location:
___

Back 12

Type IIb (White, fast twitch, fast glycolytic) – power and rapid contraction but easily fatigued
Low myoglobin content
Few mitochondria and low in oxidative enzymes
Very fast myosin ATPase reaction velocity
Location:
extraoccular eye muscles

Front 13

Type IIa ___, ___) they make up ___ motor units that have intermediate characteristics from those described above

Back 13

Type IIa (Intermediate, fast oxidative glycolytic) they make up fast twitch fatigue resistant motor units that have intermediate characteristics from those described above

Front 14

All muscles are combinations of

Back 14

the 3 fiber types

Front 15

Does H & E staining reveal fiber type on the basis of color?

Back 15

No; NADH-TR does

Front 16

In NADH-TR:
The ___ stain darker. They are ___ in mitochondrial enzymes. They correspond to the red fibers seen in vivo (___).
The larger lighter staining fibers correspond with ___ fibers (___ ).

Back 16

-smaller fibers
-higher
-Type I
-white
-Type IIb

Front 17

___ are composed of collections of fibers, bound by a perimysium

___ contain collections of myofibrils, which extend the entire length of the cell

___ are composed of myofilaments

Myofilaments (2 types):

Back 17

-Fascicles
-Fibers
-Myofibrils
-Thick filaments & Thin filaments

Front 18

Thin filament:
___ is a double helix polymer of globular monomers of G-actin

Back 18

F-actin

Front 19

___ is a long thin molecule that wraps around and binds to the groove of actin filaments

Back 19

Tropomyosin

Front 20

Troponin
TnT –
TnC –
TnI –

Back 20

Troponin
TnT – binds to tropomyosin
TnC – binds Ca+
TnI – Inhibits actin-myosin binding

Front 21

Thick filaments contain about 250 ___ molecules

Back 21

myosin

Front 22

Myosin- Composed of 2 identical heavy chains, each
containing a globular head containing binding sites for:
___
also 2 pairs of light chains

Back 22

Myosin- Composed of:
-2 pairs of light chains
-2 identical heavy chains
Contain a globular head containing binding sites for:
Actin & ATP

Front 23

Back 23

Front 24

With H&E staining, the A band stains ___ and the I band stains ___ . The Z line is a dark line that ___

Back 24

-darkly
-lightly
-bisects the I band

Front 25

A sarcomere is the region between two successive ___. The sarcomere is the ___

Back 25

-Z lines
-functional unit of striated muscle

Front 26

Sliding filament model:
___ filaments slide past ___ filaments
___ bands shorten
Sarcomere shortens (Z disks are drawn closer)
___ does not change in length

Back 26

-Thin
-thick
-I bands and H
-A band

Front 27

EM shows that the I band contains ___ filaments only

Back 27

thin

Front 28

___ contains thick and thin filaments that overlap

Back 28

A band

Front 29

___ contains only thick filaments, is a light band that bisects the A band and has a darker M line in its center

Back 29

H band

Front 30

___ is where thin filaments are bound together by the protein ___

Back 30

-Z line
-alpha-actininin

Front 31

___ is narrow, dark region at the center of H bands.
where adjacent thick filaments are linked

Back 31

M line

Front 32

Back 32

Front 33

Skeletal Muscle Contraction:
When Ca+ concentration is ___ the binding site on actin, for myosin binding, is blocked

Back 33

low

Front 34

Skeletal Muscle Contraction:

When Ca+ is high, Ca+ binds to ___ , which results in a conformational change that breaks the ___ bond, tropomyosin moves slightly and reveals the binding site on actin for myosin binding

Back 34

-troponin C
-troponin I–actin

Front 35

Skeletal Muscle Contraction:

When Ca+ is pumped back into the SR, the cytosolic Ca+ concentration is low again,
Tropomyosin returns to its resting state and ___ binding is blocked

Back 35

actin-myosin

Front 36

Skeletal Muscle Contraction Cycle
1. Attachment (rigor) –

Back 36

myosin is bound to actin

Front 37

Skeletal Muscle Contraction Cycle
2. Release -

Back 37

myosin is uncoupled from actin and binds ATP

Front 38

Skeletal Muscle Contraction Cycle
3. Bending: ___ causes myosin head to bend and advance a short distance relative to the thin filament

Back 38

Hydrolysis of ATP

Front 39

Skeletal Muscle Contraction Cycle
4. Force Generation:

Back 39

myosin binds to actin and returns to its original conformation – forcing movement of the thin filament along the thick filament (ADP is lost)

Front 40

Skeletal Muscle Contraction Cycle
5. ___ - cycle can repeat

Back 40

Reattachment

Front 41

Children with Muscular Dystrophy appear to have large muscular ___, yet they continue to weaken
focal ___ replacement of muscle fibers is seen in the biopsy. This fatty replacement, together with hypertrophic myofibers and increased endomysial fibrosis, is responsible for the pseudohypertrophy seen in the calves of patients with ___.

Back 41

-calves
-fat
-Duchenne muscular dystrophy

Front 42

Dystrophin – is a cytoskeletal protein located beneath the sarcolema and plays a role in ___ via dystroglycan proteins

Back 42

linking to laminin (ECM protein)

Front 43

Absense of dystrophin causes ___ (___ disorder) causing progressive muscle weakness in boys

Back 43

-Duchenne’s muscular dystrophy
-X-linked

Front 44

Biopsy from patient, showing the myopathic features:
-___ myofibers
-___endomysial fibrosis.

Back 44

-atrophic & hypertrophic
-increased

Front 45

Satellite cells between plasma membrane of the muscle fiber and its external lamina serve as ___ for muscle regeneration – this process has limitations
fibrosis occurs to repair injury if the external lamina is disrupted

Back 45

stem cells

Front 46

Triad = SR-TT-SR at the ___ junction
[Note: TT = transverse tubules (T-tubules)]

Back 46

A-I

Front 47

___ act to rapidly spread depolarization throughout the muscle fiber so that there is widespread release of Ca2+ from the SR allowing for uniform contraction of the muscle fiber.
Voltage gated Ca2+ channels open in the sacs of the sarcoplasmic reticulum –releasing Ca2+ into the ___.

Back 47

-T-tubules
-sarcoplasm

Front 48

Myelinated axons of motor neurons approach muscle, lose their myelin sheath, and form dilated endings on muscle cells called ___ (3 names)

Back 48

Myelinated axons of motor neurons approach muscle, lose their myelin sheath, and form dilated endings on muscle cells called motor endplates, myoneural junctions or neuromuscular junctions

Front 49

Axon terminals contain synaptic vesicles filled with the neurotransmitter ___

Back 49

acetylcholine (ACh)

Front 50

___ in the muscle contain ACh receptors that bind the ACh that crosses the synaptic cleft

Back 50

Junctional folds

Front 51

___ - a single motor axon and all the muscle fibers it innervates.
Motor units can be very ___ for muscles that require course movements, such as the quadiceps femoris muscle. Or they can be ___, but many in number, in muscles that require fine control such as the extraocular muscle

Back 51

-Motor unit
-large
-small

Front 52

Myesthenia Gravis
Is an autoimmune disease in which ___. Myasthenia gravis is characterized by

Back 52

-antibodies are made to the ACh receptor
-progressive weakness that remits with rest and is worsened by exercise

Front 53

Myesthenia Gravis
___ eyelids and ___ of all muscles of eye movement – no focal deficit

Back 53

-Drooping
-weakness

Front 54

Atrophy - shrinkage of muscle fibers
___ can occur in comatose or immobilized patients

___ - muscle cells are dependent on trophic substances supplied by motor neurons and will atrophy following nerve injury

Back 54

-Disuse atrophy
-Denervation

Front 55

most common motor neuron disease

Back 55

ALS

Front 56

ALS:
clinical onset in ___
within several years often leads to death due to ___
___ atrophy

Back 56

-early middle age
-respiratory failure
-Denervation

Front 57

Rapid tap of the tendon causes a rapid stretch of the muscle spindle, which initiates the ___ reflex

Back 57

monosynaptic deep tendon

Front 58

-Muscle spindle is a ___ receptor
-spindle cells (2 types): ___
-(Has afferent and efferent innervation)

Back 58

-stretch
-Nuclear chain fiber & Nuclear bag fibers

Front 59

The muscle fibers that produce force for movement of bones termed

Back 59

extrafusal fibers

Front 60

The spindle cells are termed ___ fibers. They contract to shorten the spindle and retain the ___ of the stretch sensitive region.

Back 60

-intrafusal muscle
-sensitivity

Front 61

CARDIAC MUSCLE:
___ positioned nuclei
The fibers (cells) are ___
Intercalated disks form end to end attachments between cardiac ___

Back 61

-Centrally
-branched
-myocytes

Front 62

CARDIAC MUSCLE:
T tubules are ___ than in skeletal muscle and are located at a ___
(Not at A-I junction as in skeletal muscle)

___ (SR and T tubule)

Large ___ span distance between T tubules

Back 62

-larger
-Z disk
-Diad
-Mitochondria

Front 63

Intercalated disc
Macula adherens (MA – inset #1)
Reinforces fascia adherens in the ___ & ___ domain of the disc

Back 63

lateral & transverse

Front 64

Intercalated disc
Gap junctions (GJ – inset # 2)
Occupy ___ region of disk

Back 64

lateral

Front 65

Intercalated disc
Fascia adherens (FA – inset #3)
Found in the ___ domain and is the major component (staining in H & E)
holds cells at their ends
Actin filaments attach here

Back 65

transverse

Front 66

Cardiac cells have ___ contractile activity
___ fibers coordinate contraction

Back 66

-spontaneous
-Purkinje

Front 67

Purkinje fibers:
Specialized for ___
Have few myofibrils
Form ___ junctions with cardiac muscle cells
Do not have ___ disks
Large pale cells

Back 67

-conduction
-gap
-intercalated
-

Front 68

Myocardial Infarction (MI):
-Death (necrosis) of cardiac muscle cells due to prolonged ___
-Repaired by ___ so function is lost in this region of the heart
-___ “cardiac enzymes” is measured to assess damage

Back 68

-ischemia (lack of blood)
-fibrous connective tissue
-Serum cardiac specific troponin

Front 69

Cardiac mus, distinct characteristics:
each muscle fiber has one or occasionally two, ___ positioned nuclei

the fibers (cells) are ___

fibers joined by ___ - specialized junctional complexes between cells that allow cells to act in synchrony (syncytium) via gap junctions

ultrastructurally, cardiac muscle has ___ at the Z line rather than triads at the A-I junction

Back 69

-centrally
-branched
-intercalated disks
-diads

Front 70

40% of cardiac muscle cell volume is occupied by ___ versus about 2% for skeletal muscle

Back 70

mitochondria

Front 71

Smooth Muscle

Non striated and ___ cells

Elongated, ___ cells with a ___ centrally located nucleus

Back 71

-fusiform
-spindle shaped
-single

Front 72

Smooth Muscle
Typically found in

Back 72

walls of hollow organs and blood vessels

Front 73

Smooth Muscle
-organized into sarcomeres? Filaments are loosely organized in association with ___ , which
serve same function as Z-line in striated muscle.

Back 73

-no
-dense bodies

Front 74

Smooth Muscle

___ is a cytoskeletal intermediate filament protein in all smooth muscle cells.
___ occurs in vascular smooth muscle cells in addition to desmin

Back 74

-Desmin
-Vimentin

Front 75

Smooth Muscle
Have no troponin, what is the Ca2+ binding protein?

Back 75

CALMODULIN IS Ca2+ binding protein.

Front 76

Smooth Muscle
Cytoplasmic densities/___
Are proteins (___), which anchor thin filaments and intermediate filaments
(Single arrows)
Analogous to ___ in striated muscle

Back 76

-dense bodies
-alpha-actinin
-Z lines

Front 77

Contraction of Smooth Muscle

An increase in cytosolic Ca+ concentration (via gated channels) stimulates smooth muscle ___

Calmodulin binds Ca+ and undergoes a ___

Calmodulin-Ca+ complex activates ___ (phosphorylates one of the myosin light chains)

When the globular head of myosin is phosphorylated it interacts with actin and stimulates myosin ATPase
Results in ___

Dephosphorylated myosin disassociates from actin
Relaxation of muscle

Back 77

-contraction
-conformational change
-myosin light chain kinase
-muscle contraction

Front 78

vascular smooth muscle NN by

Back 78

sympathetic nerves

Front 79

___ stimulates smooth muscle contraction in the uterus during labor

Back 79

Oxytocin

Front 80

Vascular smooth muscle is stimulated by

Back 80

passive stretch