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81 Cards in this Set
- Front
- Back
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Describe skeletal muscle.
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Striated muscle, multinucleated, elongated, organized, lots of mitochondria.
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Describe smooth muscle.
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Elongated, uninucleated, not distinctly organized, no striations, used for internal muscle.
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Describe cardiac muscle.
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Have striations and intercalated disks. This helps to transfer chemical signals. Not as organized as skeletal muscle, but more organized than smooth muscle. Branched. Uninucleated.
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How do function groups in muscles work together?
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They have antagonistic skeletal groups working in opposite directions. As one flexes, another relaxes. For example, the biceps and the triceps, the hamstrings and the quadreceps.
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Describe the organization of muscle fibers.
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Muscle --> bundles --> fibers --> cell --> myofibrils.
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What are the functions of the sarcoplasmic reticulum and the T-tubules in a muscle cell?
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the sarcoplasmic reticulum delivers Calcium to the cell and the T-tubules carry the action potential to the cell.
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What is troponin's role in the sarcomere?
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To help actin bind to tropomysoin.
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What does the sliding filament theory basically entail?
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Actin and mysoin slide past each other in order to create a shortened sarcomere.
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If there is no ATP in the muscles, then what happens?
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The muscles will remain contracted and the muscles will remain stiff.
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If ATP levels are high and CA2+ is high in the muscles, what happens?
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The muscles contract.
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If ATP concentrations are high and Ca2+ concentrations are low, what happens?
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the muscles relax.
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What is the process of crossbridge formation?
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Calcium binds to troponin, so that myosin can bind to tropomysoin. Then a "power stroke" occurs, moving myosin along the actin helix. Myosin is released from the binding site when ATP is released in the form of ADP and P and can reattach to the next available site along the actin helix.
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Describe the anatomy of a neuromuscular junction.
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They contain a "motor end plate" which contains ample ACh, also consist of axon terminals, and Schwann cell sheaths. Somatic motor neuron branches at the distal end of the nerve, and schwann cells.
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Describe the motor endplate.
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modified into a motor endplate. Contains receptors for neurotransmitters like ACh. Binds to muscle fiber.
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What does the synapse control?
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The opening of Na+ channelsAch binds to ligand-gated ion channels and Na+ goes in and K+ goes out.
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What mechanical changes does the AP cause in a muscle cell?
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AP activates a mechanical disruption in DHPR, which opens the sarcoplasmic reticulum, which releases Ca2+.
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How is Ca2+ removed from the cell?
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By an ATPase from the sarcoplasmic reticulum that transports Ca2+ back into the cell.
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How does the DHPR channel work?
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Upon depolarization, DHPR opens and detaches from RYR calcium channel and opens Ca2+ from the Sarcoplasmic Reticulum.
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How does Botox work?
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Works by blocking the voltage-gated channel and release of ACh. This inhibits vesicle docking, so no neurotransmitters can be released. This prevents Ca2+ from binding.
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What would blocking AChE do to the muscles, and why?
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Would make the muscles in a permanently contracted state because there would be no way to get ride of the ACh.
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What causes muscle relaxation?
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Sarcolemma repolarizes (closes the RYR channels), the Ca++ channels close, pumps out of cytoplasm and into the sarcoplamic reticulum, the Ca2+ is released from troponin --> tropomysic shifts back into original position --> myosin binding site is covered up.
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Where is the action potential generated from in cardiac muscle?
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Nearby cells.
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What are the differences between cardiac muscle and skeletal muscle?
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The Ca2+ that drives the AP in skeletal muscle only comes from the sarcoplasmic reticulum, and in cardiac muscle it comes from the ECF and the sarcoplasmic reticulum. Also, in Skeletal muscle, there exists both a DHRP and a RYR, and in cardiac muscle there is only an RYR channel.
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What is the stretch reflex?
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The muscles contract or relax due to a muscle stretch that correlates with antagonistic muscle groups. Only exists in vertebrates.
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Describe the pattern of a stretch reflex.
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Stimulus stretches a muscle, sends an inhibitory signal to the spinal chord inhibitory interneuron, the spinal chord send an inhibitory and a positive signal to two nerves, one toing to a contracting muscle and one going to a muscle that won't contract. This is an example of antagonistic muscle groups.
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Give two examples of neural circuits.
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Stretch reflex and central pattern generator.
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What is a central pattern generator?
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Nerual circuit that can activate sequential pattern activation neurons via neural signals that can continue without external stimulations.
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Give an example of a central pattern generator.
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grasshopper flight.
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What regulates the central pattern generator and why?
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The CNS because it is internal and censory.
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What two ways does the central pattern generator work by?
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Cellular ocelator and Network ocelators.
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Describe a cellular ocelator and give an example.
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Neuron that generates temporary patterned activity, but changes over time. Endogenous AP/variable membrane potential in a regular pattern.
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Describe a network ocelator and give an example.
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3+ neurons that inhibit each other in a cyclic inhibitory loop. Leech heartbeats/swimming.
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What is a twitch?
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One single AP in a neuron which causes a single action potential in a muscle fiber.
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What is a single fiber response?
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Skeletal muscles can sum "unfused tetanus" slight relaxation between stimulation.
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Unfused tetanus
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Maximum potential but allowed slight relaxation at intervals between each stimulus.
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Summation
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When another action potential has occurred before relaxation of the muscle, and therefore increases in strength.
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Complete summation and tetanus
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When maximum potential of the muscle is reached, and the muscle does not rest until fatigue. Will rest even with continued stimuli due to fatigue.
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Describe a motor unit.
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The motor neuron and the bivers it innervates. One fiber may hav eonly one motor neruone, but one motor neuron may innervate multiple muslce fibers.
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How is more force generated?
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The more motor units a muscle has, the more force it can gnerate.
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What is an isometric contraction?
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muscles don't shorten, similar to holding a 10 lb weight or pushing something.
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What is an isotonic contraction?
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When muscles shorten and tension is developed to move the load.
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What does the length-tension relationship between muscles determine?
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The diefficulty of generating force based on length of muscle.
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How much tension is in a muscle during relaxation?
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No tension.
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What is the optimal length for creating maximum tension?
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Muscle should be slightly stretched, but not overstretched, due to the optimal amount of actin myosin sliding.
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What are the three supplies of ATP in the muscles?
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Glucose--> lactate (under high intensity), Fatty acids (helps with mild efforts), and Creatine kinase Phosphate --> ATP and creatine (under very high intensity).
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What are the three muscle fiber types?
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Fast glcolytic Fibers, Slow Oxidative Fibers, and Fast oxidative glycolytic fibers.
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Describe Fast Glycolytic Fibers (FG)
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Contract Rapidly and produce ATP through creatin Phosphate and glycolysis. These are longer fibers and produce much force, but quickly fatigue. used for power lifting.
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Slow Oxidative Fibers (SO)
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Contract slowly, produce ATP from mitochondria, oxidative Respiration. Small in diameter, but have high endurance, like cross country running.
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Fast oxidative glycolytic Fibers (FOG)
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Difference in color due to the presence of myoglobin. Lighter fibers rely on glycolysis and don't need myoglobin and dark fibers use oxidative respiration. Intermediate.
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What fibers are required for slow walking?
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SO, and FOG -- need high endurance, low power.
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What fibers are required for intermediate speeds?
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FOG and some FG -- intermediate endurace and power.
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What fibers are needed for top speed?
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FG, low endurance, high power. Lots of lactate, creatine, and phosphate.
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What causes muscle fatigue during a burst exercise?
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Accumulation of Pi inhibits myosin ATPas which is a regulatory mechnism. Accumulation of K+ on T=tubules is thought to block ATP.
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What causes muscle fatigue during a low endurange or long-term endurance exercise?
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Fuel limitation -- uses all the glycogen in store, or psycological.
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Describe what happens to the muscle fibers during endurance training.
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SO and FOG fibers become more abundant, thereofre increasing oxidative apacity, increasing mitochondrial density, increasing in kreb's cycle density, increasing blood supply to the muscle for O2 and decreasing CO2 and increasing and nutrients via VEGF signals.
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What happens to the muscle fibers during Power lifting or burst activities?
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Increase in muscle mass, fiber diameter, but not muscle cells. Increase in the amout of myosin and actin fibers, increase in glycolytic activity to generate a lot of lactate, increase in FG fibers, increase in creatine phosphate storage.
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What is required for muscle mass maintenance?
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Neural stimulation.
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What are some causes of muscle atrophy?
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Neural damage
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How do electric fish produce their AP?
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Myosites are adated to produce AP without contraction, only by increasing their voltage inside the cell. Contain nicotonic ACh receptor and have greater than 600 volt output.
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What are the two types of flight?
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Synchronous and Asynchronous.
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What is involved with synchronous flight?
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Controls 1 wing that is elevated and depresses-- two separate contractions.
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What is involved with asynchronous flight?
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Each contraction can control more than one wing beat due to the elastic properties that help pull the wings back into place. Instead of contractions, the elasticity snaps them back into place. 1 ATP can have multiple contractions triggered by stretch. You see a significatn decrease in Ca2+ ATPase.
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Describe smooth muscle.
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Small, spindle shaped, with one nucleus, containing dense bodies, actin filaments. have a rudimentory SR -- not as developed as skeletal muscles, but still important. Contain actin, myosin, tropomysoin. No sarcomeres. Have myosin isoforms.
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What respiration does smooth muscle use?
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Completely aerobic and doesn't fatigue.
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What are slow wave potentials?
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AP of smooth muscle when they reach threshold.
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What is pharmacomechanical coupling?
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When chemical signals change muscle tension without changing membrane potential.
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What regulates smooth muscle contraction?
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Stimulatory and inhibitory NT (NE relaxes the gut), Hormones and paracrine agents, can be stretch activated, and sometimes autorhythmic. generate your own deplarizing membrane potential.
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How are smooth muscle cells connected in a single-unit?
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Tightly coupled by gap junctions, and therefore depolarize together and function as a single unit. IE small blood vessels and GI tract.
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How are smooth muscle cells connected in a multi-unit?
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not electrically united, stimulated independenlty. Few gap junctions, hormonal and neurostimulated. not stretch-sensitive, large arteries, respiratory arteries.
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Name an instance when smooth muscle changes from multi-unit to single-unit.
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The uterus in pregnancy.
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How does the smooth muscle contract?
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Still have filaments that slide and contract; however, they just contract in several different directions.
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Describe the mechanism of smooth muscle contraction.
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Respond to stimuli -- Intercellular Ca2+ levels increase when released from SR and from outside cell -- Ca2+ binds to CaM -- Ca2+CaM activates MLCK. MLCK phosphorylates light chains and stimulates myosin ATPase. Crossbridges slide and create muscle tension.
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What is the difference between smooth muscle and skeletal muscle?
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Ca2+ comes from outside of the cell in smooth muscle and its reole is different. Also, smooth muscle has MLCK and CaM instead of RYR.
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How does smooth muscle relax?
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Ca2+ levels lower and is pumped out of the cell and back into SR. -- Ca2+ unbinds from CaM -- Myosin phosphatase removes phosphate from mysoin, decreases Myosin ATPas activity. -- less myosin ATPas is less muscle tension.
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What is the partial pressure equation?
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Partial pressure = factional content x total pressure
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What happens to the barometric pressure if you increase altitude?
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Total pressure decreases.
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What is the normal pressure at sea level?
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1 atmosphere or 160 mmHg
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What is the composition of air?
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21% oxygen and 78% nitrogen
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What happens to the solubility of gases if you increase the temperature?
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solubility decreases.
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What happens to the solubility of gases if you increase salinity?
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solubility decreases.
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What are the two types of alveoli?
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One type is for gas exchange and one type secretes a surfactant (last thing to develop in a neonate)
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