Neuromuscular System-sem 2 Yr 1

increase intracellular Ca=increase # of crossbridge =increase force

calcium binds to troponin C which changes conformation uncovering the actin to allow myosin attachment. This site remains blocked when calcium is low

hypercalcemia can cause a sodium channel blocking effect thus causing flaccid paralysis
hypocalcemia cause the oposite with spontaneous opening of the Na channels due to voltage flux the result is spasticity
so intracellular ca is used from the SR but to retrieve it requires a pump for active transport- this requires ATP

calcium pulse from the SR-There is no calcium current across the cell membrane in SKELETAL muscle during action potential (opposite from cardiac and smooth muscle =incease calcium in blood gives flaccid paralysis of skeletal muscle and increase activity of smooth and cardiac muscle

type 1 are small diam fast conduction velocity, and High excitability (easy start) they have few fibers and low contraction force / unit (they are small) they are oxidative and are low fatigue
type 2 are largr, very fast, hard (low) excitability, they have many fibers and have high contraction force, they are glycolytic and high for fatigue
there are no "small, medium, or large"

isotonic includes concentric (bicep curl) and eccentric (a overly heavy weight) it has a change in lenght of muscle but the tension remains constant
auxotonic is a contraction with some flux at the end like with ventricles pumping the blood out
isometric is right because there is no change in length but force is generated such as hand grips

The given characteristics indicate that the muscle has a slow myosin isoenzyme, moderate Sr pump capacity, moderate diffusion diameter, small motor neuron size, high oxidative capacity (mt content, capillary density, myoglobin content), high fatigue resistance, moderate glycolytic capacity, low force, aerobic activity, and triglycerides as storage fuel. These characteristics are consistent with type 1 muscle fibers, also known as slow oxidative (SO) or white fibers. These fibers are characterized by their slow contraction speed, high endurance, and reliance on aerobic metabolism.

binding of crossbridges triggers the release of energy that is stored in the myosin-it is the rotation of the myosin head

hyperemia is blood flow
hypoxia and oxygen depletion may cause oxygen defict
O2 debt is the culmination of O2 deficits

The given answer, type 11B/ fg/ ft-b/fast glycolytic/white, is the correct answer because the characteristics mentioned in the question align with the traits of type 11B muscle fibers. These fibers have a very fast myosin isoenzyme (ATPase rate), high glycolytic capacity, low oxidative capacity, low fatigue resistance, and high force production. They also have a high diffusion diameter, high Sr pump capacity, and very large motor neuron size. These characteristics indicate that the muscle is designed for short-term, high-intensity activities and relies on anaerobic metabolism for energy production. Additionally, the reference to "white" in the answer refers to the color of these muscle fibers due to their low myoglobin content.

hypertrophy is the increase in the volume of an organ
hypoxia is O2 deficiency
maximal voluntary contraction a muscle that exerts more than 70% of its maximal force (compresses blood flow
reactive hyperemia is the right answer and
hyporemia is made up

The given characteristics suggest that the muscle is type 11A, also known as fog/ft-a, which refers to fast oxidative/red muscle fibers. These fibers have a high oxidative capacity, indicated by factors such as mt content, capillary density, and myoglobin content. They also have medium fatigue resistance and high glycolytic capacity. The presence of a fast myosin isoenzyme (ATPase rate) and a large motor neuron size further supports the classification of the muscle as type 11A.

ATP is used in binding Myosin head to actin and the E is stored in the head

Calcium is the correct answer because it acts as a second messenger in the binding of myosin to actin in skeletal and cardiac muscle. When calcium ions are released into the muscle cell, they bind to troponin C, which causes a conformational change in the troponin-tropomyosin complex. This change allows myosin to bind to actin, initiating muscle contraction. Without the presence of calcium, the binding of myosin to actin cannot occur, and muscle contraction cannot be initiated.

oxidation of fatty acids is the slowest but most efficient
phosphorylation is fast but a temporary fix while waiting for permanent
glycolysis is fast but inefficient

the type 2 are the first to stop at which point the type 1 will continue-albiet slower and with less force-but primary is the key word

extrafusal are the series of linked sarcomeres (z line-zline)(thick myosin and thin actins) the shortening of sarcomeres generates force and movement via alpha motor neuron AP>release of ACh>binds to nicotinic receptoe>EPP>AP in musc membrane
intrafusal=not controlled by alpha motor neuron-even though actin and myosin
parallel to extrafusal
nuclear chain fibers wrap around end of intrafusal as sensory nerve fibers along with nuclear bag fibers- they report musc contraction status via gamma Efferents
they are regulators-adjusting sensitivity of sensory system
they influence flow of info through 1A and 11 Afferents