Histology - Muscle Tissues

Question 1

degrades ACh in synaptic cleft.

Answer 1

ACh esterase (AChE)

Question 2

a protein complex that connects the cytoskeleton of a muscle fiber to the surrounding extracellular matrix through the cell membrane.

Answer 2

dystrophin

Question 3

dervied from mesoderm, striated, capilaries in intercellular spaces. Slow and fast fiber types.

Answer 3

skeletal muscle

Question 3

aggregate at top of junctional folds

Answer 3

ACh receptors (AChRs)

Question 3

associated with sweat glands, contain both actin and myosin. contraction mechanism similar to smooth muscle cells, but ectoderm derived.

Answer 3

myoepithelial cells

Question 4

Contains the entire length of a single thick filament.

Answer 4

A-band

Question 5

Dense bodies (where actin attatches) instead of Z disks as in skeletal muscle; have noncontractile intermediate filaments (along w/dense bodies, form intracellular cytoskeleton); has slower contraction speed than skeletal.

Answer 5

Difference in Smooth and Skeletal Muscles

Question 6

calcium interacts with calmodulin, causing interaction between actin and myosin

Answer 6

Ca2+ in smooth muscle

Question 7

presynaptic element

Answer 7

lower motor neuron (LMN)

Question 8

cylinder-shaped, paralell, multinucleated, periferal nuclei. Mitochondria and myoglobin in high quantity.

Answer 8

skeletal muscle fibers structure

Question 9

great capacity for hyperplasia and hypertrophy, (ex: uterus in pregnancy)

Answer 9

smooth muscle regenration

Question 10

fast glycolitic muscle fibers, anaerobic respiration.

Answer 10

type II skeletal muscle

Question 10

type III collagen are located external to the basal lamina. Hugh compnent of endomesium fround smooth muscle.

Answer 10

reticular fibers

Question 11

calcium storage and release

Answer 11

Sarcoplasmic reticulum

Question 11

Purkinje fibers

Answer 11

Purkinje fibers

Question 12

receptors on t-tubule and SR interact to release calcium

Answer 12

depolarization down t-tubule

Question 13

On perfery of muscle fibers, can undergo hyperplasia (mitosis) and hypertrophy by fusing with other skeletal muscles.

Answer 13

satellite cells

Question 14

is the zone of thin filaments that is not superimposed by thick filaments.

Answer 14

I-band

Question 14

Autoimmune disorder. Autoantibodies bind acetylcholine receptors in skeletal muscle, causing muscle weakness and potential death. Treatment includes AChE inhibitors

Answer 14

myasthenia gravis

Question 14

branched, layered, mononucleated, central nucleus. Intercalcated discs with gap junctions, high mitochondria and myoglobin. diad at the Z disc.

Answer 14

structure of cms

Question 16

enzyme that aids in active calcium reuptake by SR after contraction.

Answer 16

calsequestrin

Question 17

A paler region within the A-band, zone of the thick filaments that is not superimposed by the thin filaments.

Answer 17

H-zone

Question 17

Stain dark and lie just inside sarcolema. Interaction between them and reticular fibers that harnesses the force of contraction of the myofilaments, like wringining a sponge, Causes “corkscrew nucleus”.

Answer 17

dense bodies

Question 18

Autonomic nervous system, Purkinje fibers (modified cardiac muscle cells), gap junctions.

Answer 18

cardiac muscle innervation

Question 19

indentations in surface of sarcolemma, may act like T tubules and sarcoplasmic reticulum of skeletal muscle

Answer 19

Caveolae of Smooth Muscle

Question 21

a layer of connective tissue, which ensheaths the entire muscle. dense irregular connective tissue, continuous with fascia.

Answer 21

epimysium

Question 22

derived from mesoderm, striated, rich capillary beds in intracellular connective tissue, located in proximal portion of heart and pulmonary vessels.

Answer 22

cardiac muscle

Question 24

a wispy layer of areolar connective tissue that ensheaths each individual muscle fiber. It also contains capillaries andnerves. It overlies the muscle fiber's cell membrane: thesarcolemma.

Answer 24

endomysium

Question 25

(from the German "Mittelscheibe", the disc in the middle of the sarcomere) formed of cross-connecting elements of the cytoskeleton.

Answer 25

M-line

Question 26

anchors thin myofilaments to Z disc.

Answer 26

a-actinin

Question 27

two chains of F-actin, tropomyosin and troponin associate. Ca2+ causes conformational change.

Answer 27

thin myofilaments

Question 29

two Z discs are brought closer together as myofilaments slide past each other.

Answer 29

Huxley’s sliding filament theory

Question 29

Dystrophin or sarcolemma molecules absent or reduced causing muscle weakness and potential death. Treatment controls symptoms to maximize quality of life.

Answer 29

muscular dystrophies

Question 31

fusiform-shaped, often in perpendicular layers, surrounded by basal lamina.

Answer 31

structure of smooth muscle fibers

Question 32

new myofibrils form to increase fiber diameter

Answer 32

hypertrophy of skeletal muscle fibers

Question 34

200-300 myosin molecules, 2 heavy and 2 light chains per myosin.

Answer 34

thick myofilaments

Question 36

Ca2+ required to initiate contractions, binds to calmodulin (no troponin is smooth muscle) which regulates myosin kinase (transfers P+ group from ATP to light myosin on heads), cross-bridging occurs(enzymes are slower than skeletal, so slower formation)

Answer 36

Chemical Reaction of Smooth Muscle

Question 37

Occurs following death because the lack of ATP preventing the dissassociation of actin and myosin. ATP important for relaxing muscle, dissociation of thin and thick myofilaments.

Answer 37

rigor mortis

Question 39

prominent in wound contraction and tooth eruption deriving from connective tisues.

Answer 39

myofibroblasts

Question 40

lower motor neuron (LMN) + muscle fibers

Answer 40

motor unit

Question 41

They connect heart muscle cells, allowing them to work as a single functional organ. Have lateral and transverse portions. Lateral has gap junctions, and faces less stress in contraction. Transverse region contains adherens junctions.

Answer 41

Intercalated discs

Question 42

Functional units of muscle fiber. Defined by Z lines.

Answer 42

sarcomere

Question 43

anchors thick myofilaments to Z discs

Answer 43

titin

Question 44

triad of structures at A-I junction, t-tubule, terminal cisternal of SR.

Answer 44

triad of structures at A-I junction

Question 45

monitors length and changes in length of muscle, and participates in stretch reflexes. In OMM, an important target for effective treatment, i.e. counter-strain technique.

Answer 45

muscle spindle

Question 46

slow oxidative muscle fibers, aerobic respiration

Answer 46

type I skeletal muscle

Question 47

indicating the contracted state of the cell

Answer 47

"cork-screw" nucleus

Question 48

a sheath ofconnective tissue that groupsmuscle fibers into bundles (anywhere between 10 to 100 or more) or fascicles.

Answer 48

Perimysium

Question 49

mononucleate, central nucleus no striations or sarcomeres no t-tubules, but have caveolae involuntary control by ANS

Answer 49

differences from skeletal muscle

Question 50

Interferes with the release of acetylcholine from LMN causing muscle paralysis and potential death. Treatment can include an anti-toxin.

Answer 50

botulism

Question 51

derived from mesoderm (and ectoderm), no striations, loacted in walls of hollow viscera, blood vessels, glands, dermis.

Answer 51

smooth muscle

Question 52

Skeletal Muscle regulation of contraction

Answer 52

By binding of Ca2+ to TnC, causes tropomyosin movement and exposes myosin-binding sites on actin filaments

Question 53

Cardiac muscle regulation of contraction

Answer 53

By binding of Ca2+ to TnC, causes tropomyosin movement and exposes myosin-binding sites on actin filaments

Question 54

Smooth muscle regulation of contraction

Answer 54

By phosphorylation of myosin light chain by myosin light chain kinase in the presence of Ca2+-calmodulin complex

Question 55

Muscle spindle function

Answer 55

monitors length and changes in length of muscle, and participates in stretch reflexes

Question 56

T-Tubule Structure and Function

Answer 56

deep invagination of the sarcolemma that allow depolarization of the membrane to quickly penetrate to the interior of the cell, signaling Ca2+ release from sarcolema.

Question 57

Transverse Portion of Intercalcated Disc

Answer 57

Adhering Junctions: Zonula Adherens and Macula Adherens (Desmosomes)

Question 58

Lateral Portion of Intercalcated Disc

Answer 58

Gap Junctions

Question 59

triad

Answer 59

A transverse tubule surrounded by two SR cisterna. Contact between these structures is located at the junction of the A and I bands.

Question 60

Terminal Cisternae

Answer 60

Enlarged areas of the SR surrounding the t-tubules that store calcium (increasing the capacity of the SR to release calcium) and release it when an action potential courses down the t-tubules, eliciting muscle contraction.

Question 61

Contraction mechanism of smooth muscle - detailed

Answer 61

Ca2+ binds to and activates calmodulin, which then binds to caldesmon. This binding causes the caldesmon protein to disengage from the actin filament, exposing the myosin-binding sites on the actin filament. Myosin motor heads are phosphorylated by myosin light-chain kinase, allowing the myosin head to interact with the actin filament and cause contraction.