Term
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Definition
| Cords of elastic connective tissue that transmit force from muscle to bone |
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Term
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Definition
| Bundles of individual nerve cells |
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Term
| What do muscle fibers have many of that most cells only have one of? |
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Definition
| Many nuclei and mitochondria |
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Term
| What is a sarcolemma analogus to? |
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Definition
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Term
| What is the sarcoplasm analogus to? |
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Definition
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Term
| What are the components of myofibrils? |
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Definition
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Term
| What are the terms for thick and thin filaments, respectively? |
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Definition
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Term
| What is the function of the sarcoplasmic reticulum? |
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Definition
| A sac that stores calcium ions |
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Term
| What is the function of T tubules? |
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Definition
| To transmit signals from the sarcolemma to the myofibrils |
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Term
| What are sarcomeres bordered by? |
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Definition
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Term
| In a sarcomere, what are thick filaments connected by? |
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Definition
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Term
| What band spans the length of thick filaments and the six thin filaments around them? |
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Definition
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Term
| What is the space in the middle of an A band, and why does it appear lighter? |
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Definition
| The H zone; it is missing thin filaments |
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Term
| What occupies the space between A bands? |
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Definition
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Term
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Definition
| Thin filaments and the Z line that connects them |
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Term
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Definition
| A long fibrous molecule that extends over actin to block the myosin-binding sites at rest |
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Term
| What is the functions of the three proteins on troponin? |
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Definition
| Attatches to actin strand, Binds to troponin, contains the calcium binding site |
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Term
| What are the two sites on a myosin head? |
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Definition
| An actin-binding site and an ATP-ase site that hydrolyzes ATP |
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Term
| What is the function of titin? |
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Definition
| To anchor actin to myosin and to exert an opposite force as sarcomeres lengthen so muscle fibers shorten |
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Term
| What areas of a sarcomere shorten during muscle contraction? |
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Definition
| The I band and H zone (thin filaments slide past thick) |
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Term
| When is the high energy form of myosin? |
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Definition
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Term
| When is the low energy form of myosin? |
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Definition
| After releasing the ADP after power stroke |
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Term
| When does myosin hydrolyze an ATP? |
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Definition
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Term
| When does myosin release an inorganic phosphate? |
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Definition
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Term
| What immidiately precedes a powerstroke? |
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Definition
| Myosin releasing an inorganic phosphate |
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Term
| When does myosin release an ADP? |
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Definition
| After the crossbridge cycle |
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Term
| When does a new ATP attatch to myosin? |
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Definition
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Term
| What ion is required for the binding of actin and myosin? |
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Definition
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Term
| Define excitation-contraction coupling |
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Definition
| The events that link an action potential to the contraction |
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Term
| As an action potential travels down T tubules, what are activated? |
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Definition
| voltage-sensitive Dihydropropyridine (DHP) |
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Term
| What does DHP stimulate, and what is its function? |
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Definition
| Ryanodine, to allow calcium to flow out of the SR |
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Term
| What is the effect of calcium binding onto a troponin? |
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Definition
| Tropomyosin shifts, exposing the myosin-binding sites |
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Term
| What causes calcium reuptake in skeletal muscle? |
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Definition
| Calcium, at high levels, binds to sites on the SR that close SR channels so Ca-ATPase can catch up |
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Term
| What can donate a phosphate to ADP to form ATP for muscles in exercise? |
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Definition
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|
Term
| What catalyzes creatine phosphate donating its phosphate to ADP? |
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Definition
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|
Term
| What causes the "burn" during exercise? |
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Definition
| Accumuation of lactic acid |
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Term
| How are twitches like action potentials? |
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Definition
| They are reproducible, all-or-nothing events |
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Term
| Why is there a latent period as the first phase of a twitch? |
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Definition
| Because excitation-contraction coupling must occur before crossbridge cycling |
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Term
| In what phase of a twitch does cytosolic calcium levels increase? |
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Definition
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Term
| In what phase of a twitch does cytosolic calcium levels decrease? |
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Definition
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Term
| Describe a concentric isotonic contraction |
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Definition
| Muscle shortens, tension remains constant |
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Term
| Describe an eccentric contraction |
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Definition
| Muscle lengthens while maintaining contraction |
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Term
| Define an isomeric contraction |
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Definition
| Tension is generated, but the muscle does not shorten because the load is greater than the generated force |
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Term
| What factor(s) affect the force generated by individual muscle fibers? |
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Definition
| The number of crossbridges that bind to actin |
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Term
| What factor(s) affect the force generated by whole muscles? |
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Definition
| Force generated in individual fibers, the number of muscle fibers contracting |
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Term
| What factors affect the number of muscle fibers contracting? |
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Definition
| Frequency of stimulation, fiber diameter, and changes in fiber length stimulation |
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Term
|
Definition
| When frequency of stimulation causes tension to rise in a stepwise fashion |
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Term
| Why does summation occur? |
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Definition
| Calcium does not have a chance to be reuptaked |
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Term
| What is the peak of summation called? |
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Definition
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Term
| What causes fused tetanus? |
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Definition
| Calcium is completely saturating troponin |
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Term
| What is the term for when a muscle is generating all the force it can? |
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Definition
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Term
|
Definition
| An increase in the number of active motor units |
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Term
| Define the size principle |
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Definition
| Both smaller motor units and smaller motor neurons are activated first |
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Term
| What kind of muscle has no stritations? |
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Definition
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Term
| Name three functions of smooth muscle |
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Definition
| Peristalsis, vasoconstriction, and vasodialation |
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Term
| Why does smooth muscle lack stritations? |
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Definition
| Thick and thin filaments are not arranged in sarcomeres |
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Term
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Definition
| Points of attatchment in smooth muscle between filaments and connective tissue inside the cells (transmits contractile force to the cell's exterior) |
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Term
| Where does calcium come from for a smooth muscle? |
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Definition
| The SR and ECF, but mostly the ECF |
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Term
| How does calcium get released from the SR in smooth muscle? |
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Definition
| By activating the IP3 second messenger system |
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|
Term
| What does released calcium bind to in a smooth muscle? |
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Definition
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Term
| What does the calcium-calmodulin complex do in a smooth muscle? |
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Definition
| Bind to and activate myosin light chain kinase (MLCK) |
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Term
| What does MLCK do in a smooth muscle cell? |
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Definition
| Catalyze phosphorlation of myosin crossbridges |
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|
Term
| What activates phosphatase in a smooth muscle? |
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Definition
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|
Term
| What structure releases neurotransmitters to smooth muscle? |
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Definition
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Term
| What determines if a smooth muscle is innervated excitatory or inhibitory? |
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Definition
| Whether the parasympathetic/sympathetic nervous system is dominating |
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Term
| Define pacemaker potentials |
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Definition
| Slow depolarizations caused by increased sodium, increased calcium, or decreased potassium permeability |
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Term
| Define slow-wave potentials |
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Definition
| Cyclical depolarizations and repolarizations caused by fluctations in sodium permeability |
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Term
| Which muscle types have gap junctions? |
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Definition
| Single-unit smooth and cardiac |
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Term
| What muscle type does not have summation? |
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Definition
| Cardiac (the heart wouldn't get a chance to refill) |
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Term
| How is calcium removed from skeletal muscle? |
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Definition
|
|
Term
| How is calcium removed from smooth muscle? |
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Definition
| 1. Ca-ATPase on SR; 2. Ca-Na countertransport on sarcolemma |
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|
Term
| How is calcium removed from cardiac muscle? |
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Definition
| 1. Ca-ATPase on SR; 2. Ca-Na countertransport on sarcolemma; 3. Ca-ATPase on sarcolemma |
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|
Term
| Name three places where multi-unit smooth muscle is found |
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Definition
| Walls of large blood vessels, small airways next to lungs, cilary muscles |
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|
Term
| Name three places where single-unit smooth muscle is found |
|
Definition
| Walls of hollow organs or viscera, digestive tract, reproductive tract |
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Term
| How is cardiac muscle similar in structure to skeletal muscle? |
|
Definition
| It is striated, has sarcomere structure, and has the troponin-tropomyosin structure |
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