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MusclePhys_Part1
PhysiologyOfMuscle_Part1
| Question | Answer |
|---|---|
| What are the FUNCTIONS of muscles? | MJTPP 1. Movement - depends on type/location of muscle tissue 2. Joint stabilization 3. Thermogenesis 4. Protection 5. Posture maintenance |
| All muscle tissues share basic characteristics, what are they? | (CEEE) 1. Excitability - respond to action potential 2. Extensibility - able to stretch 3. Elasticity 4. Contractility |
| What is ISOMETRIC contraction? | In muscles, the ability of the muscle to contract w/o any movement |
| Compare skeletal, cardiac and smooth muscle with regards to CELL SHAPE | 1. Skeletal - cylindrical 2. Cardiac - Cylindrical & branched 3. Smooth - Fusiform (spindle-shaped) |
| Compare skeletal, cardiac and smooth muscle with regards to STRIATIONS | 1. Skeletal - Striated 2. Cardiac - Striated 3. Smooth - Non-striated (still has actin/myosin but not as organized) |
| Compare skeletal, cardiac and smooth muscle with regards to NUCLEUS | 1. Skeletal - Multi-nucleated & peripheral 2. Cardiac - Uninucleated & central 3. Smooth - Uninucleated & central |
| Compare skeletal, cardiac and smooth muscle with regards to CONTROL | 1. Skeletal - Voluntary 2. Cardiac - Involuntary 3. Smooth - Involuntary |
| Compare skeletal, cardiac and smooth muscle with regards to SPECIAL STRUCTURES | 1. Skeletal - None 2. Cardiac - Intercalated discs 3. Smooth - May be single or multi unit |
| T/F Although Skeletal muscle has voluntary control, sometimes they're overtaken by the brain | TRUE |
| Describe SKELETAL muscle's VOLUNTARY movement | Only have contractility in ONE direction * requires multiple muscles to create simple movements (flexion & extension) * complex movements (circumduction) |
| What stabilizes movement and joints in SKELETAL muscle? | Synergistic muscles |
| How does SKELETAL muscle function with regards to PROTECTION? | Shock absorption * protects abdominal viscera * stronger muscles = greater protection/increased joint stability |
| What is the SKELETAL muscle's INVOLUNTARY movement? | Thermogenesis: Shivering reflex * asynchronous & involuntary * controlled by ANS & HYPOTHALAMUS * initiated by hypothalamic nuclei in PRIMARY MOTOR CENTER |
| What function does the POSTERIOR NUCLEI provide in shivering? | Makes sure you don't freeze! |
| How does the SKELETAL muscle's involuntary movement help in maintaining posture? | Involves stretch reflexes: 1. Static reflexes 2. Phasic reflexes |
| How are static and phasic reflexes regulated? | Regulated by gamma neurons which adjust tension in the muscle spindles |
| What are STATIC reflexes? | long term sustained contractile events |
| What are PHASIC reflexes? | Dynamic and short term corrective responses (QUICK!) |
| List in order (small -> largest) the anatomy of a skeletal muscle | 1. Nucleus 2. Muscle fiber = muscle cell 3. Muscle fascicle (bunch of muscle fibers) 4. Skeletal muscle (bunch of muscle fascicles/blood vessels/nerves) 5. All muscle fibers & fascicles have CONNECTIVE TISSUE to hold them together |
| List the major components of a MUSCLE FIBER (cell) | 1. Sarcolemma (cell membrane) 2. T-tubules 3. Sarcoplasm (all stuff inside cell) 4. Multiple nuclei |
| List the components of SARCOPLASM | 1. Sarcoplasmic reticulum 2. Myofibrils 3. Mitochondria 4. Glycogen granules (energy storage) |
| Describe and list what makes up MYOFIBRILS | Myofibrils made up of TWO TYPES of microfilaments: 1. Thin filaments 2. Thick filaments |
| What are the THIN FILAMENTS of myofibrils? | 1. Troponin 2. Actin 3. Tropomyosin |
| What are the THICK FILAMENTS of microfibrils? | MYOSIN |
| Thick and thin filaments work together and organized into? | Sarcomere |
| What is a SARCOMERE? | The SMALLEST functional unit of skeletal muscle |
| The SARCOMERE is composed of various microfilaments and support structures, what are they? | 1. Titin 2. Myosin 3. M-Line: Myomesin & skelemin 4. Thin filaments 5. Z-Disc |
| What is TITIN? | 1. Largest known elastomeric protein 2. connects myosin to z-disc 3. thought to be critical in development of sarcomeres |
| Describe a MYOSIN MOLECULE | Consists of TAIL, HINGE, & HEADS * Heads contain active sites for 1) Actin 2) ATP |
| What is the M-LINE of the sarcomere? | Consists of MYOMESIN & SKELEMIN proteins, these proteins 1. stabilize myosin filaments 2. aid in transmission of force from sarcomere to cytoskeletal intermediate filaments |
| What activity occurs at the MYOSIN HEADS? | 1. Binding of ACTIN 2. Hydrolizing of ATP 3. Binding of Mg (magnesium) |
| What are THIN FILAMENTS composed of? | 1. G-actin 2. Nebulin 3. Tropomyosin 4. Troponin |
| What is G-ACTIN? | Molecules that are in helical arrangement, contains myosin binding sites |
| What is NEBULIN? | Filament that forms internal support & attachment for actin |
| What are TROPOMYOSIN & TROPONIN? | 1. Troponin molecules attach to tropomyosin filaments 2. Troponin has binding sites for Ca2+ 3. They're both used for 'control' |
| What is the Z-disc? | anchors the filaments and interacts with cytoskeletal framework |
| Describe the transmission of force from the sarcomere to the tissue | 1. sarcomeres linked by DISTROPHIN to sarcolemma 2. then via membrane proteins interacting with cytoskeletal framework |
| What is MUSCULAR DYSTROPHY? | Disease caused by distrophin not working |
| Describe the SLIDING FILAMENT MODEL in general | 1. synaptic transmission at neuromuscular junction 2. excitation-contraction coupling 3. contraction-relaxation cycle |
| Describe STEPS 1-4 events at the NEUROMUSCULAR JUNCTION (NMJ) in the Sliding Filament Model | 1. action potential arrives at pre-synaptic membrane 2. membrane depolz open voltage Ca+ chans 3. Ca influx into synaptic bulb 4. CALMODULIN activated by Ca2+ which a. activates protein kinase II which b. phosphorylates SYNAPSIN (motor protein) |
| Describe Steps 5-9 events at the NEUROMUSCULAR JUNCTION (NMJ) in the Sliding Filament Model | 5. Vesicle binds to membrane proteins (SNAREs) 6. Excocytosis of ACh 7. ACh binds to NICOTINIC receptors 8. Na+ influx creates End Plate Potential (EPP) 9. EPP spreads to edge of Motor End Plate & initiates A.P. in sarcolemma |
| Describe Steps 1-3 of Excitation-Contraction Coupling in the Sliding Filament Model | 1. A.P. spreads along sarcolemma & down t-tubules 2. Depol. of membrane alters memb. protein DIHYDROPYRIDINE L (DHP) configuration 3. Altered DHP config. signals RYANODINE Ca2+ receptors (RyR Ca2+) in terminal cisternae of sarcoplasmic reticulum |
| Describe Steps 4-5 of Excitation-Contraction Coupling in the Sliding Filament Model | 4. Ca2+ released into sarcoplasm and * binds to troponin * initiates a conformational/shape change in the troponin-tropomyosin complex exposing the binding sites for myosin on actin 5. Myosin binds to ACTIN (electrostatic attraction) |
| DescribeSteps 1-3 Contraction-Relaxation Cycle in the Sliding Filament Model | 1. Myosin attaching to Actin gets HYDROLIZED (phosphate coming from the splitting of ATP by Myosin ATPase) 2. Myosin conformational change, bends at neck towards M-line 3. ADP released by conformational change during "power stroke" |
| Describe Steps 4-6 Contraction-Relaxation Cycle in the Sliding Filament Model | 4. ATP binding site now avail for another ATP (along with Magnesium: Mg2+) 5. Splitting of ATP to ADP + P by myosin detaches & returns myosin to its active state 6. This single event creates a TWITCH |
| T/F It takes ATP to relax & get Ca2+ back to sarcoplasmic reticulum | TRUE |
| What kind of energy is 'relaxed state'? | Potential Energy |
Created by:
lophung
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