PHIS 206 1st Edition Lecture 10 Outline of Last Lecture I 2 Neurons Autonomic Nervous System II Autonomic Stimulation III Somatic Nervous System IV Neurotoxins Outline of Current Lecture I 3 Categories of Muscles II Skeletal Muscle III Muscle Physiology IV Muscle Cell Contractions V Muscles Are Elastic VI Muscle Types Current Lecture I 3 Categories of Muscles 1 Skeletal voluntary control Under microscope cell appears as a cylinder with striations stripes Other names for skeletal striated voluntary 2 Smooth Visceral Involuntary no striations 3 Cardiac makes up walls of the heart II 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 cells These 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 cross bridges and makes filaments slide IV V VI 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 combined 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 elastic 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 quickly
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