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Striated msucle cont
Question | Answer |
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function of muscle and list 3 types of muscle | -to generate force or movemnet in response to a physiologicla stiumulus example, skeletal muscle, cardiac muscle and smooth muscle |
major function of skeletal muscle | -control voluntary movement of bone underlie locomotion and work produciton -control breathing cycle of lung (diaphragm) -pump assisting in delivery venous blood |
major function of cardiac msucle | -specific to heard -biomechanical pump which is driving force to delivery blood to lung and tissue |
major function of smooth muscle | -mechanical control of organ system (digestive, urinary & reproductive tract, blood vessels of circulatory system, airway passage of respiratory system |
what is the common initiation trigger to all 3 types of muscle movement | - chemical neurotransmitter, paracrine factor, or by direct electrical excitation -a rise in free cytosolic calcium concentration |
structure of skeletal muscle | myofilament -> sarcromer -> myofibril -> myofiber -> fascicle -> muscle |
Sarcolemma | the plasma membrane underneath endomysium of the muscle cell |
Endomysium | external sheath surround single muscle fibers |
Perimysium | an external sheath around fascicle |
Epimysium | an external sheath extedning from tendon which surround the whole muscle |
Neuromuscular Junction | the synapse formed when motor nerve axon contact muscle fiber near the middle of fiber |
Motor end plate | specialized region of sarcolemma in cloest contact iwht pregynatic nerve terminal |
In physiological excitation of skeletal muscle, what chemical binding trigger action potential | Ach (acetylcholine) |
what does Ach binding to nicotinic receptor trigger? | graded depolarizing end-plate potential or actional potential if the membrane potential is over firing threshold |
how many motor neuron does one single muscle cell respond to? | 1 |
Motor unti | group of muscle fiber innervate by all of the collateral branches of a single motor neuron |
Innervation Ratio | it is determined by the number of muscle fibers innervated by a single motor neuron. Therefore wide range of forces and a graded range of shortening can be gernerated |
Example o small innervation ratio movemnet | High-precision movement of extraocular muscle, control positioning movement of eyes 3 muscles fibers per neuron |
Example of large innervation ratio movement | postural control by soleus muscle 200 muscles fibers per neuron |
Why striated muscle has striated appearance? | -they have highly organized sacromere within thick and thin filament the alternating light and dark band contribute to the striated appearance |
A band | -dark region -region of myosin (thick) filament antisotropic to polarized light |
I band | -region where thin (actin) filament is not overlapped with think filament -istropic to polarized light |
Z disk | -dark line in the middle of I band -tether thin filament with single myfibril together and teher each myofibril to its neighbor and align sarcomere -the diameter of the myofibril |
Sarcomere | -repeat unit between one Z disc to another |
how many thin filament surround thick filament in a cross section view when thick and thin filament overlap | 6 actin thin filament srround each thick filament (myosin) -hexagonal array |
During contraction, which band change length and which one remain constant | I band shorten and A band remain unchanged |
structure of thin filament | -Actin 13 individual actin monomer ==> single strand of Factin filament x 2 ==> double-strand alpha helical polyer |
two regulatory actin-protein binding protein associate with F actin | tropomyosin & troponin |
How many actin monomer does 1 tropomyosin reacting with | Seven |
function of tropomyosin | regulating the binding of myosin head group to actin |
How alpha helix dose tropomyosin has | 2 identical alpha-helics that coil sround each other |
List each component of Troponin | 1) Troponin T : bind to Tropomyosin 2) Troponin C : bind calcium ion, closely related to calmodulin (another calcium binding protein) 3) Troponin I: bind actin which inhibit contraction |
Troponin Complex | troponin heterotrimer subunit: (T, I, C) which interact directly with actin filament |
Structure of Myosin | Hexamer with 2 heavy chain, 2 alkali light chain and 2 regulatory light chain |
component of heavy chain of myosin | 1) rod: alpha helics that wrap around each other, the tail of myosin 2) hinge: molecules flare open to form 2 globular head 3) Head: binding site for actin, binding site for ATP hydrolysis, 1 essential and regulatory light china |
Function of alkali light chain of myosin | essential for myosin stabilization |
function of regulatory light chain of myosin | regulate ATPase activity of myosin through phosphorylation and dephosphorylation in calcium dependent and independent kinase |
Importance of head region of heavy chain | region where cross-bridges between the thick and thin filament of the sarcomere |
Titin | -large protein run alongside with thick filament -tethered from M line to each neighboring Z disk -involve in elastic behavior of muscle -maintaining the resting length of muscle during relaxation |
Nebulin | -large protein that wrap around the actin filament -run from Z disk |
M line | the attachment of myosin molecules within the thick filament |
effect of concentration of intracellular calcium ion on cross-bridge cycling | increase Ca2+, Allow cross-bridge cycling to continue Decrease Ca2+,stop the cross-bridge cycling and muscle relax |
2 calcium binding site on Troponin C | 1) N loob (low affinity calcium binding site) bind and release calcium when it rise or fall in sacroplasm, regulate binding of actin to myosin 2) C lobe (high affinity site), occupied by calcium or magnesium in a physiological condition |
Effect of binding Ca2+ to the low affinity site of troponin | confirmation change in troponin complex 1) Troponin I, move away from actin/tromyosin filament and permitting tromyosin molecule to move 2)Toponin T, push tropomyosin away from actin filament into the groove and allow myosin to bind to actin |
List the steps in Cross-bridge cycle | 1) ATP Binding (release from rigid state) 2) ATP Hydrolysis (myosin move to new position) 3) Cross-bridge formation (cross-bridge state) 4) P dissociate from myosin (power stroke) 5) ADP dissociate from myosin (rigid state of myocin-actin complex) |
Rigor mortis | -extreme muscle rigidity, develop after death from lack of ATP -myosin head remind 45 degree respect o actin and myosin filament |
What must be present for myosin to be release from actin | ATP |
At which step does skeletal and cardiac muscle control contraction cycle? | cross-bridge formation step skeletal and cardiac muscle will prevent cross-bridge formation until tropomyosin move out actin in response to increase calcium concentration |
how to classify different muscle types | 1)its histological appearance 2) how muscle is controlled 3) its anatomical position |
how different muscle type innverated? | skeletal muscle: electrical nerve activation cardiac muscle: electrical signal generate inside the heart itself |
straited muscle vs smooth muscle in muscle movement | 1) straited muscle move by sliding actin and myosin filament through process of cross-bridge formation, power storke and regulated by calcium and ATP 2) smooth muscle has similar process except Myosin light chain kinase is needed to phosphylate myosin |
list 3 properties of muscle tissue | contractile, excitable, extensible |
what is the function of satellite cell | it has limited ability for skeletal muscle repair and growth. however it has limited turnover rate |
Where do we find satellite cell? | found around adult muscle fibers |
what does satellite cell differentiate into? | myocytes |
2 clinical correlation with satellite cell | 1) Duchenne muscular dystophy (depletion of satellite cell and lack of dystrophy) 2) satellite cell activity decrease with age |
sacro | flesh |
Sarcoplasm | cytoplasm of skeletal muscle cell |
Sarcolemma | plasma membrane of skeletal muscle cell |
Sarcoplasmic reticulum | the endoplasmic reticulum of muscle cell |
What is specific function of sarcoplasmic reticulum? | it is highly specialized for calcium storage |
Sarcomere | structural and functional unit of skeletal muscle |
what is the myofiber made up of? | it is individual muscle cell made up of bundles of protein called myofibril |
What is the main component of myofibril? | actin + myosin |
what filament attach to Z disc? | actin filament |
What filament attach to M line | Myosin filament |
which band of sacromere shorten during contraction? | I band and H zone A band remain the same length |
where do we find dystrophin on the sarcomere? | It is on Z disc and attach actin to the cell |
Golgi tendon organ | - Specialized proprioceptive receptor (sense position within 3D space) - increase afferent output when muscle is contract |
Muscle spindle | -specialized stretch receptor within Muscle -provide information on the degree of muscle stretching -increase afferent output in response to stretch |
what happen to golgi tendon organ and muscle spindle when muscle is contracted? | the Golgi tendon will increase its afferent out frequency Muscle spindle will remain the same or decrease as it mainly response to stretching |
what happen to golgi tendon organ and muscle spindle when muscle is stretched? | the muscle spindle will increase its afferent output while golgi tendon organ will not |
what type of junction we found in intercalated disc of cardiac muscle | 1) demosome, prevent cell from fall apart 2) gap junction: transmission of AP |
what is the shape of smooth muscle during relaxation? | cigar shaped nucleus |
what is the shape of smooth muscle during contraction? | spiral shaped nucleus |
What type contraction does smooth muscle produce? | Involuntary , weak and slow contraction |
which two muscle tissue are uninucleate? | Cardiac and smooth muscle |
how does smooth muscle arrange to contribute to its peristalsis movement? | ALternate contraction between inner circular layer and outer longitudinal layer |
what happen if we contract the inner circular layer? | the diameter of cell decrease and length of cell increase |
What happen if we contract the outer circular layer? | the diameter of cell increase and length of cell decrease |
What is difference between smooth and striated muscle contraction? | Striated muscle contact by shortening the length. Smooth muscle around tubular organ, contract and move in wave (peristalsis) through alternation contraction of inner circular and outer longitudinal layer. |
Give an example of area where smooth muscle is undergo constant regeneration? | Uterine wall (highly active cell regenerate during menstrual cycle) -can form benign tumor (fibroid) due to high replication rate |
What is presence to control the peristalsis movement of smooth muscle | Nerve tissue between 2 layers |