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physio lab exp#7

skeletal muscle contraction, electromyography, and reflexology

QuestionAnswer
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