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physio lab exp#7
skeletal muscle contraction, electromyography, and reflexology
| Question | Answer |
|---|---|
| There are three types of muscles: | skeletal, cardiac, and smooth |
| skeletal muscles (4) | Voluntary, Striated, Long, and multinucleated |
| cardiac muscles (3) | Involuntary, Striated, and Multinucleated |
| smooth muscles (4) | Involuntary, No striations, Short, and uninucleated |
| What are five basic muscle functions? | producing movement, regulating organ volume, moving substances within body, stabilizing body positions, and generating heat |
| Produces movement: Total body movements like walking or running and ________ movements such as grasping a pencil or nodding your head. | localized |
| Regulating organ volume: Sustained contractions of ________ prevent outflow of the contents of a hollow organ | sphincters |
| Moving substances within the body: muscles ______ to move substances, (blood, urine), throughout the body. | contract |
| Stabilizes body positions: Stabilizes joints and helps maintain body positions such as sitting or standing; ________ muscles contract continuously | postural |
| Generates heat: Muscle tissue produces heat when it contracts; used to maintain ____ _____ temperature. | core body |
| Excitability | the ability of a muscle to receive and respond to a stimulus. |
| Contractibility | the ability of a muscle to contract forcibly when adequately stimulated by an action potential. |
| Extensibility | the ability of a muscle to be stretched or extended without being damaged. |
| Elasticity | the ability of a muscle fiber to resume its resting length, (recoil), after being stretched. |
| skeletal muscle tissue layers are referred to as _____ _______ | deep fascia |
| There are THREE Connective tissue deep fascia layers: | Epimysium, Perimysium, and Endomysium |
| skeletal muscle morphology has 4 levels. what are they? | 1st level:Muscle Organ, 2nd level: Fascicle, 3rd level: muscle fiber, 4th level: Myofibril |
| 1st level: Muscle Organ | The whole muscle is covered externally by the epimysium |
| 2nd level: Fascicle | A portion of muscle; discrete muscle cells segregated from the rest of the muscle by perimysium |
| 3rd level: Muscle fiber | Each individual fiber (cell) is surrounded by endomysium |
| 4th level: Myofibril | rod-like contractile element composed of bundles of myofilaments. |
| A segment of myofibril is called a SARCOMERE, which is the what? | the contractile unit composed of myofilaments and made up of contractile proteins. |
| A sarcomere is also the distance between two “Z” disks, which serve as _________ systems for the for the myofilaments in the sarcomere. | anchoring |
| skeletal muscle myofilaments. Two types: | actin and myosin |
| actin | thin filaments |
| myosin | thick filaments |
| (3) types of Actin myofilaments: | G-Actin (globular actin), Tropomyosin, and Troponin Complex (TnI, TnT, TnC) |
| (3) Poloypeptide complex: Tnl | an inhibitory subunit that binds to actin. |
| (3) Poloypeptide complex: TnT | binds to tropomyosin and helps position it on actin. |
| (3) Poloypeptide complex: TnC | binds calcium ions |
| Muscle at rest has the myosin binding sites blocked by ___________! | Tropomyosin |
| What happens to make tropomyosin move, exposing the myosin binding site? | when calcium binds to TnC |
| Myosin molecule has two parts to its structure: | heads and a tail |
| Myosin heads bind to _______, (myosin binding site), for muscle contraction! | G-actin |
| myofilament banding: A-Band: (Anisotropic) dark band | region of overlap between myosin and actin (contains both thick and thin myofilaments) |
| myofilament banding: A-Band: (Anisotropic) dark band | region of overlap between myosin and actin (contains both thick and thin myofilaments). |
| myofilament banding: I-Band: (Isotropic) light band | area that contains actin myofilaments only. |
| myofilament banding: H-Zone: (derived from the German word “Heller” meaning bright) | a paler area within the A-band that contains myosin myofilaments only (thick filaments only) |
| myofilament banding: Z-disk: (derived from the German word “Zwischenscheibe” meaning in between) | these are the bands in between the I bands |
| myofilament banding: M- Line: (derived from the German word “Mittel” meaning middle) | this is the middle of the sarcomere |
| The arrival of the action potential triggers voltage-gated Ca2+ channels in the presynaptic membrane, and the resulting influx of Ca2+ causes what? | exocytosis of vesicles containing Acetylcholine thus contributing to the electropositivity of the intracellular environment |
| Steps leading to muscle contraction: (1) action potential generated is propogated along the __________ and __ - ______ | Sarcolemma and T-Tubules |
| Steps leading to muscle contraction: (2) action potential triggers ____ release from presynaptic terminal | Ca2+ |
| Steps leading to muscle contraction: (3) Ca2+ ions bind to _________. It's conformational change removes the blocking action of tropomyosin. What does this lead to? | troponin, actin active site being exposed |
| Steps leading to muscle contraction: (4) contraction: Binding of the myosin head to myosin binding site; also known as _____- _________ formation. | cross-bridging (At this stage, myosin has ADP and Pi bound) |
| Steps leading to muscle contraction: (5) The power stroke, in which the myosin head pulls the actin chain past itself and ___ is released. | ADP |
| Steps leading to muscle contraction: (6) Binding of a new ATP molecule is necessary for what? | release of actin by the myosin head. |
| Steps leading to muscle contraction: ATP hydrolysis occurs immediately and the myosin head is cocked. Another cycle begins when what? | the myosin head binds to a new binding site. |
| Sliding Filament Theory: In PARTIALLY contracted muscle the distance between the two Z-disks is _______ | reduced, so the sarcomere shrinks. |
| Sliding Filament Theory: In PARTIALLY contracted muscle the I-Band distance _________ | decreases |
| Sliding Filament Theory: In PARTIALLY contracted muscle the H-Zone distance __________ | decreases |
| Sliding Filament Theory: In PARTIALLY contracted muscle the A-Band distance _________ | remains unchanged |
| Sliding Filament Theory: In MAXIMALLY contracted muscle the distance between the Z-disks is ________ | reduced further |
| Sliding Filament Theory: In MAXIMALLY contracted muscle the I-Band and H-Zone distances do what? | essentially disappear |
| Sliding Filament Theory: In MAXIMALLY contracted muscle the A-Band distance ________ | remains unchanged |
| Rigor Mortis: no _______ __________ produced during rigor mortis! Organism’s muscles become stiff. | action potential |
| What is the cause for the muscle stiffening seen in rigor mortis? one reason involving the cross-bridging between actin and myosin | cross-bridging between actin and myosin cannot be detached because of ATP exhaustion. |
| What is the cause for the muscle stiffening seen in rigor mortis? one reason involving Ca2+ | Ca2+ begins to leak from the sarcoplasmic reticulum which accumulates and mineralizes in the muscle |
| The first observable muscle twitch you see is called what? | “threshold voltage.” |
| Recall the “all-or-none” principle. The stimulus must be _____ enough for the muscle to contract. | strong |
| What are the three periods of muscle twitch? | latency period, contraction period, and relaxation period |
| latency period | Period-time between stimulation and actual response |
| contraction period | length of time to get maximal response |
| relaxation period | dissociation of actin from myosin, myofilaments sliding back to original positions |
| temporal summation | occurs when a single presynaptic neuron fires many times in succession, causing the postsynaptic neuron to reach its threshold and fire. |
| spatial summation | occurs when excitatory potentials from many different presynaptic neurons cause the postsynaptic neuron to reach its threshold and fire. |
| temporal summation: __________ frequency, _________ voltage | increasing, constant |
| spatial sumation: __________ frequency, _________ voltage | constant, increasing |
| Electromyography: Coactivation describes a phenomenon between two antagonistic muscles such as the biceps and triceps. Explain: | When the biceps muscle is activated forcefully, there is a minor increase of activity in the triceps. (and vice versa) |
| Its physiological meaning is not well understood, although it perhaps serves to what? | stabilize the elbow joint |
| Electromyography: Calculation of Velocity | velocity = distance/time |
| Referred pain (reflective pain) | pain perceived at a location other than the site of the painful stimulus |
| why does referred pain occur? | the nerves that feed some parts of the body also feed other parts of the body. Stimulation of a nerve in one part of the body (by a pain source) can cause the sensation of that pain in another branch of the nerve in a different part of the body. |
| to observe this, you will submerge your elbow in a bucket of ice and record the sensation of numbness across the _________ and ____ | forearm and hand. |
Created by:
cmccartney2
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