| Question | Answer |
| 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 |
