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Histology
Muscle tissue
| Concept | Explanation |
|---|---|
| Muscle cells specialization | structurally and functionally specialized for contraction |
| Two types of protein filaments(myofilaments) | thin filaments (actin) and thick filaments(myosin) |
| Muscles form by.. | mesenchymal cells differentiating into muscle cells |
| Three muscle types | skeletal muscle, cardiac muscle, & smooth muscle |
| All muscles composed of... | elongated cells, called fibers |
| Muscle fibers contain.. | myofibrils, made of contractile proteins actin (thin filament) and myosin (thick filament) |
| Sarcoplasm | The cytoplasm of muscle |
| Sarcolemma | Muscle cell membrane |
| Epimysium | Dense layer of Connective(CT) that surrounds entire muscle & Contains Muscle fascicles |
| Perimysium | CT that surrounds each fascicle and Contains Muscle fibers |
| Endomysium | Delicate CT (reticular fibers and basal lamina) that surrounds each muscle cell (fiber) and Contains Myofibrils |
| A bands | made of thick (myosin) filaments overlapping thin (actin) filaments |
| H bands | in the center of A bands. They lie between the free ends of the thin filaments and contain only myosin filaments |
| M lines | bisect H bands. They are where adjacent thick filaments connect. |
| I bands | contain only thin filaments |
| Z lines (disks) | bisect I bands. Alpha actinin attaches actin filaments to the Z line |
| Skeletal muscle movement | voluntary, Stimulation for their contraction and relaxation is under conscious control |
| skeletal muscle is innervated by.. | Large motor nerve axons |
| A single muscle fiber is individually innervated by.. | Nerve branches, and a smaller axon |
| Neuromuscular junction OR motor end plate | site where impulse from axon transmits to skeletal muscle fiber |
| Terminal end of each efferent (motor) contains.. | number of vesicles with neurotransmitter acetylcholine |
| Cause of synaptic vesicles fusing with the plasma membrane | Impulse at axon terminal |
| Elements that allows muscle to accomplish contraction | motor end plates |
| Uncontracted sarcomere | Z-lines are at maximum distance apart and overlap of myofilaments is at the resting state |
| Partially contracted sarcomere | Z-lines moved closer together and the overlap between thin and thick filaments has increased |
| Fully contracted sarcomere | Z-lines are as close together as they can get and Overlap between myofilaments is maximized |
| Transverse section | section of skeletal muscle reveals individual muscle fibers grouped into bundles called fascicles |
| Longitudinal section | a tissue sample cut parallel to the length of the muscle fibers |
| Cardiac muscle Fxn | Involuntary contraction of the heart |
| Cardiac myocytes | Shorter, branched, interconnected from end to end by intercalated disks |
| (T/F) Intercalated disks are visible as dark lines in the light microscope | True |
| (T/F) intercalated disks do not contain desmosomes | False |
| (T/F) Desmosomes link adjacent cells mechanically | True |
| (T/F) gap junctions do not link cells electrically | False |
| Desmosomes fxn | provide strength so that the cell do not get ripped apart during contraction |
| Composition of Gap junctions | connexin proteins |
| connexin proteins | form a pore through which cells communicate |
| (T/F) skeletal muscle and cardiac muscle is striated | True |
| Purkinje Fibers | Modified cardiac muscle cells that Contain large amounts of glycogen and Fewer myofibrils Thicker cells |
| Smooth muscle cells (fibers) | spindle-shaped, Packed together tightly, and each surrounded by basal lamina and reticular fibers |
| (T/F) In smooth muscle cells Actin and Myosin filaments are not tightly arranged but just crisscross through cell | True |
| (T/F) Smooth muscle cells have abundant mitochondria, some rough ER and large Golgi complex | True |
| Smooth Muscle Tissue appearance | spindle‐‐shaped |
| Smooth Muscle Tissue location | Walls of hollow organs such as the gastrointestinal tract or blood vessels |
| (T/F) In smooth muscle tissue there are dense bodies on cell membrane and intermediate filaments | True |
| Contraction of Muscle tissue | like a “squinch” than a uniform shortening |
| (T/F) Calcium ions enter the cell to initiate contraction of smooth muscle | True |
| Binding of calcium ions for smooth muscle contraction | bind to calmodulin – this activate myosin kinase |
| (T/F) Skeletal muscle can undergo limited regeneration | True |
| Satellite cells | inactive myoblasts that become activated and proliferate and fuse after injury |
| (T/F) Cardiac muscle has regenerative ability after early childhood | False |
| Death of cardiac muscle leads to.. | replacement by dense connective tissue scar |
| (T/F) Smooth muscle is not capable of active regeneration | False |
| (T/F) Muscle fibers undergo mitosis and replace damaged tissue | True |
Created by:
satya.benoit