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Flashcards in Muscle Tissue Deck (35):

General Feature of Muscle

- Basic Tissue Type (most abundant)
- Contractible
Highly vascularized
- Derived from embryonic mesoderm


Skeletal Muscle

- connected to bones - movement of extremities, etc.
- under voluntary control
- Striated
- Multi - nucleated- located in the periphery (almost outside of the cell)


Development of Skeletal Muscle

- Derived from mesoderm
- Embryonic mesoderm cells-> myoblasts->multinucleatd myotuble


Satellite Cells

- has a role in the regeneration of cells


Regeneration of Skeletal Muscle

- Damage occurs
- initially cleaned by macrophages
- Satellite Cells- fill in the gap and form a line which will regenerate the skeletal muscle


Plasticity of Skeletal Muscle

- able to change in size (volume) but not number
- Atrophy - decrease in the diameter of indiv muscle fibers
- Hypertrophy- increase in diameter


Connective Tissue of Skeletal Muscle

- Tightly packed similar to axons
- CT - collagen fibers
- Epimysium- packs the entire thing
- Perimysium- packs of multiple fibers
- Endomysium- Wraps individual Fibers


Actin and Myosin

- directy involved with contraction



- membrane portein
- Establishes a contact inside the cell with the actin component of cytoskeleton
- Connected with elements on the outside
- cross links actin with transmembrane glycoproteins
- creates a complex



- Proteins - form part of sacromere structure
- Resemble springs- when sarcomere contracts, you need some sort of force to bring it back to original structure
- on both sides of Z line


T tubules

0 transverse invaginations of sacrolemma


Terminal Cisternae

- Sacroplasmic reticulum
- surrounds microfibrils



- At junction of I and A band
- T tubule in the middle from saroleema
- 2 cisternae on each side from sarcoplasmic reticulum
- Plays a role in transmission of Ca that is released at the synapse
- Ca triggers the movement of muscle



- I band has the Z line in it (strictly Actin- very organized in circles of 6 filaments)
- A band containing Actin and myosin
- H band has the M line which anchors myosin ( strictly Myosin
- Regions with both myosin and actin- every myosin filament is surrounded by actin



- Actin binding protein
- More of a filamentous protein
- able to bind to actin at different spots



- Actin Binding protein
- Globular protein
- 3 subunits
1) TnT- specialized in binding tropomyosin
2) TnC- specialized in binding Ca
3) TnI- Inhibits the actin myosin interactions


Myofilaments Control of Muscle Contraction

- Ca comes in due to action potential - from sarcoplasmic reticulum
- Conformational change in troponin- binding site for myosin which was covered by tropomyosin
- myosin is now able to interact with actin
- ATPase activity- cleaves ATP to ADP (hydrolysis)
- When this happens myosin is able to interact with actin filaments
- Need Ca to cleave ATP and have a muscle contraction


Innervation by Motor Unit

- Single muscle fiber is innervated by only one motor neuron but one neuron may innervate more than one fiber


The motor end plate

- Presynaptic section has vesicles
- formation of junctional fold- number of T tubules
- Release occurs
- Neurotransmitter - acetylcholine - cholinergic neurons
- Folds need to have proper receptor
- Cholinesterase - if this wasn't there, there would be constant contractions- cleaves any excess acetylcholine



- Muscle spindle- specialized nerve ending
- Golgi Tendon Organ- formed capsule of nerve tissue
- Contains Afferent neurons held in place by network of collagen fibers
- Sends signals by movement of tendons
- Intrafusal Fibers- internal fibers
- Extrafusal Fibers- fibers not in the spindle


Nuclear Chain Fiber

- Chain of nuclei in the middle of the fiber


Nuclear Bag Fiber

- all the nuclei are in a central bag


Red Fibers

- Type I slow twitch
- Contain a large amount of myoglobin
- Contain many mitochondria
- Oxidative respiration
- Contract slow but continue for a long time


White Fibers

- Type II, fast twitch
- little myoglobin
- Glycolytic respoiration
- Abundant glycogen
- Contract quick but fatigue easy


Cardiac Muscle

- located in the heart
- involuntary control
- Striated
- Mono nucleated


Structure of Cardiac Muscle Fibers

- Fibers are different - shorter and connected via intercalated discs
- One fiber can branch


Intercalated Discs

- At the interdigitations - where the two cells come together- there is irregularity
- Cohesion maintained primarily by gap juncitons
- Fascia (Zonula Adherins) and Macula adherens (desomosmes) found in the vertical portions
- Gap junctions found in the horizontal portions


Conducting Pathway of the heart

- SA node--> AV node--> AV bundle (connects the atria to the ventricles)--> bundle branches--> purkinje fibers


Medulla Oblongata

- Has a cardio acceleratory and cardio inhibitor center
- Depending on where it is stimulated, it can accelerate or inhibit the beating of the heart


Natriuretic Peptides

- Atrial Natriuetic peptide (ANP)
- Ventricular Natriuretic Peptide (BNP)
- Maintain Blood pressure
- Promote elimination of water and Na through urination


Smooth Muscle

- In hollow organs
- Involuntary control
- non striated
- Mono nucleated
- Has a spindle shape characteristic
- Nucleus is usually in the center
- Most organelles are either on one end or the other
- Contains Dense bodies
- No T tubules
- Contains caveolae


Dense Bodies

- Has to do with the way these cells contract- different from other mucles
- Actinin- anchoring sites for actin filaments and intermediate filaments


Multi Unit Smooth Muscle

- Loosely packed
- more richly innervated for rapid contractions
- need more axons


Visceral Smooth Muscle

- Found in most hollow organs
- poorly innervated with slow movement



- Regions filled with vesicles of neurotransmitter
- interact with the smooth muscle at these