EXAM2_HE12_13_Muscle Flashcards
Sarcolemma, Sarcoplasm, Sarcoplasmic reticulum
- Sarcolemma- Plasma membrane
- Sarcoplasm- Cytoplasm
- Sarcoplasmic reticulum- Smooth ER
Where is Smooth, Skeletal, Cardiac muscle derived from ?
- Smooth-myoblasts from Visceral Lateral plate mesoderm
- Skeletal-myoblasts from Paraxial Mesoderm
- Cardiac- myoblasts from Visceral Lateral Plate mesoderm
Thin filament- Thick filament
thin- Skeletal/cardiac actin- tropomyosin-troponin
smooth muscle (actin and tropomyosin only)
thick- myosin II
Rhabdomyolysis- What indicates muscle damage? 3 Causes of damage?
Skeletal/Cardiac muscle damage releases TROPONIN and MYOGLOBIN into blood
- excess Mb in blood after skeletal muscle injury leads to fatal kidney damage
- trauma (car crash, electrocution)
- Exertional (crossfit)
- Nonexteritional (drugs, infections)
Organization of Muscle fibers? 5 orders of muscle and collagen coverings respectively.
What connects muscle to bone?
- Myofilaments (actin/myosin)
- Myofibrils (long rows of myofilaments)
- Muscle Fibers (myocyte)- endomysium;type III
- Fascicles (bundle of muscle fibers)-Perimysium typeI
- Muscle- Epimysium Type I
TENDONS- Muscle to bone
Describe 4 characteristics of Skeletal muscle
- long, cylindrical cells
- parallel arrangement
- multiple nuclei- peripherally located
- Striated- myofilament arrangement
Type I muscle fibers- speed, strength, composition?
Slow Fatigue resistant- Aerobic -more Mb, mitochondria, LESS glycogen infusions -Weaker-smaller diameter -better O2 diffusion, but less force
Type II Muscle fibers
Fast Fatigue quickly- anaerobic -more glycogen inclusions -LESS Mb, Mitochondria STRONGER- larger diameter-greater force
Describe Aband, I band, Zline regions
A band- Actin + Myosin I band- Actin only H band- Myosin only M line- cytoskeleton? Z line-
You have myofilaments that are arranged and structured in an organized fashion what type of muscle is it?
You have criss cross myofilaments what is it?
Skeletal and cardiac- organized
Smooth-criss crossed
In muscles, what layer is the blood supply in?
surrounding CT of each individual cell
if you suspect heart attack what protein do you check for in blood? if you suspect skeletal muscle breakdown?
troponin
rhabdomyolysis- Mb
Endomysium surrounds what? what made of?
surrounds cells- Type 3
Perimysium
surrounds fascicles; type 1
Epimysium
surrounds muscle- type 1
why are nuclei of skeletal muscle on the periphery of the cell?
the contractile fibrils are located through the middle and the nuclei are pushed out to the outside of the cells
dark band
Light band
What is inside the I band?
Dark- A band
Light - I band
Mline inside the A band
the Zline inside I band
Where are thick and thin filaments anchored?
Thin filaments anchored to Z line
Thick anchored to Mline
What proteins associated with the thin filament?
Thin- Tropomyosin, G-actin, troponin, F-actin
Thick- myosin II
DYSTROPHIN
accessory protein- Anchors sarcomeres to the sarcolemma and ECM around the myocyte with CT (fibroblasts)
Muscular dystrophies
genetic disorders lacking dystrophin (only in males) tears sarcolemma and cell will die. Skeletal and cardiac muscle degeneration- bad cells replaced with CT (FIBROSIS)
motor unit
Lower motor neuron (LMN) + muscle fibers it innervates
NM synapse- 4 steps of muscle contraction
- synaptic vesicle w/ ACh released into synaptic cleft
- ACh binds receptors in Junctional folds of sarcolemma
- muscle contracts
- AChE on sarcolemma degrades ACh in synaptic cleft so muscle can relax
External Lamina- Structure- Function
like basal lamina
holds everything together has ecm and allows fluid flow. type 3 collagen
Botulism
Black Widow
Myasthenia gravis
BOT- inhibits ACh release- paralysis
BW- causes release of ACh- spasms
MG- autoimmune- antibodies bind to AChRs- muscle weakness or death
Can’t keep eye open
T Tubule
- invagination of sarcolemma
- carries AP to SR
SR- function- 2 parts
What is Triad?
Ca bound to calsequestrin -AP signals Ca release 2 parts: Terminal cisterna Tubules Triad: 2 terminal cisternae + 1 T tubule
Muscle spindle
Golgi tendon organ
monitors length change
monitors tension change
What two ways does CNS sense what skeletal muscle is doing? Why relevant to OMT?
- muscle spindle (within muscle)- length change
- golgi tendon organ- tension change
also tendon sensory nerves
- Targets of counterstrain
Hyperplasia
satellite cells differentiate into myoblasts; requires intact external lamina
Muscle fiber death results in fibrosis
cardiomyocytes- structure, location
cardiac muscle fibers-
located in myocardium of heart & proximal portion of pulmonary veins
Cardiac muscle structure/ function
- Sarcomeres/striated
-autorhythmic/gap junctions/ANS regulates rate- - SINGLE NUCLEUS (Centrally located)
-branched (pull in multiple directions)
-INTERCALATED DISCS- Sites of attachments of end connections
-DESMOSOMES -
FASCIA ADHERENS- Actin
Intercallated disc
very irregular- not straight as seen at LM
Inside Cardiac Cells-
How they contract?
Where calcium?
SR compared to skeletal muscle?
CM gets calcium from outside the cell
- large T tubules used for calcium to pass into the cell.
- SR -sparse (source is extracelluar not intracellular like SM)
- DIAD- 1 terminal cisternae(incomplete) + 1 ttubule.
Purkinje fibers
Specialized cardiac cells in subendocardium - rapidly depolarize
-transmit impulse through myocardium
Cardiac Stress/injury
- Hypertrophy- increases in size and decreases inside volume
- dilated cardiomyopathy- large heart- large volume inside cavity
Smooth muscle- location- structure- shape-
Hollow organs, BV's, dermis, respiratory passages - arranged in perpendicular layers -Non striated fusiform shape -derived from one myoblast like cardiac -single central nucleus
Caveolae
SM- endocytotic vesicles (not regulated- no cathrene coat)
slowest way to bring calcium into cell
-Ca is in ECM like cardiac
but sm has no t tubules
Smooth Muscle fiber organization- what anchored to- what stabilized by? what shape?
-crisscross pattern of myofilaments
-actin anchored at dense bodies (similar to Z disk)
-stabilized by intermediate filaments
fusiform shape
3 ways of SM contraction
- Electrical (ANS)
- Mechanical (stretch-food bolus)
- Chemical (signaling-angiotensin II/ vasoconstriction)
Multiunit contraction vs single unit contraction
MU-multiple cells by single ANS neuron
SU-gap junctions allow contraction as single unit
SM response to stress/injury
Hyperplasia- regenerates via mitosis
Hypertrophy- addition of proteins
2 Non-Muscle contractile cells and examples
what most similar to?
- myoepithelial cells- glands
- Myofibroblasts- wound contraction/tooth eruption
- both have actin/myosin & similar to smooth muscle cells
