Term
| Describe how muscle cells develop? |
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Definition
1. enlongation of mesenchyme to form myoblast
2. myoblast continue to divide and then stop
3. divides again as actin and myosin to form myofilaments |
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Term
| What is the term for adult muscle cells? |
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Definition
| myocytes or muscle fibers |
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Term
| What are the 3 types of muscles? |
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Definition
1. skeletal
2. cardiac
3. smooth |
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Term
| Which muscle type is the most common in the human body? |
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Definition
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Term
| Why is skeletal muscle considered a "synctium"? |
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Definition
| cells fuse embryonically, thus a single cell may contain several hundred nuclei |
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Term
| where are the nuclei located in skeletal muscle? |
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Definition
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Term
| What causes contractions in skeletal muscle? What is the term to describe this type of contraction? |
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Definition
| nerve impluses; the term is neurogenic |
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Term
| describe the steps for skeletal muscle contraction |
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Definition
| 1. single nerve cell or fiber (neuron) branches and terminates at a motor end plate, the action potential travels down the nerve stimulating the contraction |
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Term
| Where is cardiac muscle found? |
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Definition
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Term
| what are intercalated discs? |
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Definition
| special junctions where the cardiac muscle cells are tightly joined |
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Term
| What type of contraction occurs in cardiac muscle |
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Definition
| myogenic (initiates in the muscle itself) |
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Term
| Where does contraction initiate in cardiac muscle |
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Definition
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Term
| What are Purkinje Fibers? |
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Definition
| specialized cells that carry action potentials to distant parts of the heart |
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Term
| describe the shape of smooth muscle cells? |
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Definition
| enlongated, spindle shaped |
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Term
| describe positional information of nucleus of smooth muscle cells |
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Definition
| single nucleus centrally located |
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Term
| Where are unitary smooth muscle fibers found? |
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Definition
| walls of digestive tract, uterus, and urinary tract |
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Term
| describe the contraction of unitary smooth muscle |
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Definition
| spontaneous, rhythmic contactions initiated by the stretching of the muscle as the organs fill |
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Term
| What type of movement is unitary smooth muscle suited for? |
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Definition
| slow, sustained contractions |
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Term
| Where is multiunit smooth muscle located? |
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Definition
| walls of blood vessels, iris of eye, wasll of sperm ducts |
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Term
| What type of contraction is in multiunit smooth? |
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Definition
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Term
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Definition
| small bundles of skeletal muscle surrounded by endomysium, held together by perimysium |
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Term
| what is the function of epimysium |
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Definition
| surrounds and holds many fasciculi together to form individual muscles |
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Term
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Definition
| atttach skeletal muscle to skeletal elements |
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Term
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Definition
| tendons that form broad, thin sheets |
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Term
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Definition
attachment site that remains fixed in position when the muscle shortens
proximal locaton |
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Term
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Definition
end attached to the element that moves
distal location |
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Term
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Definition
| a motor neuron + the muscle fibers it supplies |
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Term
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Definition
| groups of myofilaments that are seen with light microscope |
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Term
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Definition
| functional units of myofibrils |
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Term
| define muscle contraction |
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Definition
| tension resulting from interaction of myosin and actin |
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Term
| define isotonic contraction |
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Definition
| muscle contraction that induces shortening of muscle against constant load or force |
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Term
| define negative work contraction |
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Definition
muscle may increase in length during a contraction
(ex hamstring) |
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Term
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Definition
| movement of a distal limb segment toward a more proximal one (decreasing the angle between the 2 segments) |
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Term
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Definition
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