PHIS 206 1st EditionLecture 10Outline of Last Lecture I. 2 Neurons―Autonomic Nervous SystemII. Autonomic StimulationIII. Somatic Nervous SystemIV. NeurotoxinsOutline of Current Lecture I. 3 Categories of MusclesII. Skeletal MuscleIII. Muscle PhysiologyIV. Muscle Cell ContractionsV. Muscles Are Elastic VI. Muscle TypesCurrent LectureI. 3 Categories of Muscles1.) Skeletal: voluntary control-Under microscope, cell appears as a cylinder with striations (stripes)-Other names for skeletal: striated/voluntary2.) Smooth (Visceral/Involuntary): no striations3.) Cardiac: makes up walls of the heartII. Skeletal Muscle-Striations caused by bundles of long, slender proteins in a regular rhythm actin: fairly THIN bundles myosin: THICK bundles THIN and THICK bundles are connected by cross-bridges-sarcomere: repeating unit; middle of one filament to another (length-2 microns)-Loaded with mitochondria to change dimensions, work is required, so then Energy is required conversion of ATP to ADP and Energy is released -Muscles generate heat (moisture evaporates, heat absorbed for homeostasis)III. Muscle Physiology-Sarcolemma: plasma membrane in a muscle cellsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-Sarcoplasm: cytoplasm of muscle cell-Sarcoplasmic reticulum: endoplasmic reticulum of muscle cell-When muscle cell contracts, thick and thin bundle size stays the same, BUT the ends of the filaments get closer near the ends: sliding filament-So what happens in all of these parts? When a motor neuron’s action potential reaches the sarcolemma, it then goes down into the T-Tubules and the sarcoplasmic reticulum (which gets leaky). Then, it reaches the sarcoplasm. From there, the action potential causes a release of Ca2+ (to help make muscles contract) and increased Ca2+ induces crossbridges and makes filaments slide. IV. Muscle Cell Contractions-Can either contract or not-Muscles connected to bones by tendons and have a level of plasticity-Contraction in which skeletal elements move: istonic contraction (with same Force)-Dimensions stay the same: isometric contraction-Everyday life: use BOTH contractions combinedV. Muscles Are Elastic -Length v. Tension (slowly upward increase until string cannot be stretched anymore)-Active tension: height of peak; maximum reach and then will be decreasing-Passive tension: does not require energy; resistant to being stretched; property of anything elasticVI. Muscle Types-Red muscles: do not twitch with as much power; resistant to fatigue Red muscle color comes from the red protein myoglobin, which has a large concentration of O2 Myoglobin takes up space that can be used for actin and myosin, so not as much Energy can be generated-White muscles: can generate enormous power; fatigue
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