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Chapter 6 A&P
Muscular System
| Question | Answer |
|---|---|
| essential function of muscle tissue | contraction (shortening) |
| what myofilaments do skeletal muscle have? | actin and myosin |
| the ability of a muscle to contract depends on 2 types of _____________ | myofilament |
| what type of muscle cells are elongated? | skeletal and smooth |
| describe skeletal muscle | huge, cigar-shaped, multinucleated, voluntary, striated, motion is strong and quick, muscles tire easily |
| what kind of muscle is directly attached to the skeleton? | skeletal muscle |
| individual muscle fibers are wrapped in _______________ | connective tissue |
| coarser fibrous membrane | perimysium |
| many sheathed muscle fibers are wrapped with perimysium form a _____________ | fascicle |
| many fascicles are bundled together by a stronger connective tissue called | epimysium |
| connect muscle indirectly to bone, cartilage, etc. | tendons |
| epimysia bland together into strong, cord-like _________ on sheet-like ____________ | tendons; aponeuroses |
| what are the 3 functions of tendons? | anchor muscle. provide durability, and conserve space |
| describe smooth muscle fibers | spindle shaped, uninucleated, surrounded by small amount of endomysium, 2 layers (circle and longitudinal), and contractions are long and sustainable |
| describe smooth (visceral) muscle | NOT striated, involuntary, found on wall of hollow organs (stomach; urinary bladder), and propels substances along a tract |
| describe cardiac muscle | striated, involuntary, fibers are cushioned by small amounts of endomysium (spiral), fibers are branching and joined by special junctions (intercalated discs), steady contractions, can be stimulated for short amount of time |
| characteristics of producing movements with skeletal muscle | muscle contractions, locomotion and manipulation movements (responds to stimuli), and are distinct from the motions of the smooth and cardiac muscle |
| types of skeletal muscle functions | produce movement, maintaining posture and body position/stabilizing joints, and generating heat/additional functions |
| additional skeletal muscle functions are: | protecting internal organs, valves regulating passage, dilate and constrict pupils in the eyes, and activate arrector pili (make hair stand) |
| plasma membrane of fiber | sarcolemma |
| the nuclei in a fiber are pushed aside by special organelles called ______________ | myofibrils |
| I bands are called _______ and A bands are called _______ | light; dark |
| dark, midline interruption of the I band | Z disc |
| a tiny contractile unit - makes up myofibrils | sarcomeres |
| smaller structures within sarcomeres that actually provide the banding pattern | myofilaments |
| thin filaments are made of __________ and thick filaments are made of ____________ | actin filament; myosin filament |
| interconnecting tubules and sacs surrounding every myofibril; stores calcium and releases it when stimulated | sarcoplasmic reticulum (SR) |
| receive and respond to stimulus | excitability (responsiveness) |
| ability to be stretched | extensibility |
| one neuron and all muscle fibers it stimulates | motor unit |
| long thread-like extension of neuron | axon (nerve fiber) |
| when axon reaches muscle it branches into ___________ | axon terminals |
| the ends of axon terminals are called ___________ and are vesicles containing _________________ | Acetylcholine (ACh) - stimulates muscle; containing neurotransmitters |
| 1-4 steps of the action potential | 1. nerve impulse reach axon terminal 2. Ca in axon term. open & Ca2+ enter 3. lead some synaptic vesicles release ACh 4. ACh diffuses across synaptic cleft and attach to receptors (membrane proteins) in sarcolemma |
| 5-6 steps of the action potential | 5. If enough ACh is released, the sarcolemma becomes TEMPORARILY more permeable to Na+ and K+ 6. Depolarization causes an electrical current (action potential) then, muscle contracts |
| As action potential occurs, ACh is broken down by acetylcholinsterase (AChE) into __________ and __________ | acetic acid and choline |
| The action potential (A.P) stimulates the sarcoplasmic reticulum (SR) to release ________, triggering the binding of myosin to actin | Ca2+ |
| when the entire muscle reacts with different degrees of shortening or contraction is called a _____________ | graded response |
| 2 ways graded muscle responses can be produced | 1. Change the frequency of muscle stimulation 2. Change number of fibers being stimulated at a time |
| The muscle is stimulated so rapidly that there is no sign of relaxation; Contractions are smooth and sustained | Complete (fused) tetanus |
| Exhibited when the muscle is stimulated, but not yet in fused tetanus | Incomplete (unfused) tetanus |
| what happens when ATP releases energy? | muscle contraction |
| unique, high-energy molecule, found ONLY in muscle fibers | creatine phosphate |
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uhitsash
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