PHIS 206 1st EditionExam # 2 Study Guide Lectures: 10 - 18Lecture 10 I. 3 Categories of Muscles1.) Skeletal: voluntary control-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 conversion of ATP to ADP and Energy is released III. Muscle Physiology-Sarcolemma: plasma membrane in a muscle cells-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 -Muscles connected to bones by tendons and have a level of plasticity-Contraction in which skeletal elements move: isotonic contraction (with same Force)-Dimensions stay the same: isometric contractionV. 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 quicklyLecture 11I. Muscle Mechanics―Skeletal Muscles-Tetanic stimulus: no relaxation between stimuli -Long contractions: deliver a tetanic stimuluso motor neurons spread out and innervate more that 1 muscle cell-Motor unit: 1 motor neuron and all of the muscle cells it innervates so all cells simultaneously contract fine movements = smaller motor units-SUMMARY: can vary duration of contraction and strength of stimulus in skeletal musclesII. Smooth Muscles-No striations because myosin and actin are organized in all directions/irregular-Rate of contraction is slower and less forceful because of the irregular elements-Can propagate action potentials from 1 cell to another (CANNOT for SKELETAL) conductive cells if stimulated, everything (wave of contraction) will contract/relax at the same time-Smooth muscles will relax if waste product increase and O2 production decreasesIII. Cardiac Muscles-hybrid between skeletal and smooth-is striated and cylindrical (like SKELETAL muscle)-action potential can propagate in 1 direction (like SMOOTH muscle) NOTE: Smooth muscles, however, can propagate action potentials in ALL directions.-3 Basic Types1.) Atrial2.) Ventricular3.) Conductive-In any tissue, a group of cells that are connected so that they can transmit action potentials to each other: syncytium IV. Atrial and Ventricular-Similarities look like striated muscle cells contractile  generate action potentials-DifferencesDuration of plateau (refractory period: atrial 150 millisec v. ventricular 300 millisec)atrial: maximum rate of contraction is ≈ 360/minuteventricular: maxium rate of contraction is ≈ 180/minuteatrial: contracts with more frequency, longer refractory periodV. Mechanism of Stimulation―Cardiac Muscle-same as routine of skeletal muscle (sarcolemma, sarcoplasm, etc…)-rhythmic contraction b/c of rather “leaky” cells different parts of heart have different levels of leakinesso Drift rapidly if more leaky: higher frequencies to reach thresholdso Drift slowly if less leaky: lower frequencies to reach thresholdsVI. Cardiac Cycle: from one end of the contraction to another-left ventricular pumps blood to everywhere except lungs-2 Gross Phases1.) Systole: heart contracting2.) Diastole: heart resting-Sino-Atrial (S-A) Node: most “leaky”; generates action potentials more frequently than any other parts of the heartLecture 12I. How The Blood Works―Mechanical-Blood is a fluid  Fluids always flow downhill (high to low pressure)-Heart valves: only 1 way valves Valves will open when pressure pushing in is greater than pressure pushing back From pulmonary, it goes down Left Atrial, and down Left Ventricular to systemic  From systemic, it goes down Right Atrial, and down Right Ventricular to pulmonary-Systole: heart contracting-Diastole: heart relaxing soon will be 0 mmHg heart fills passively; expands where heart is closed in membrane at the end: heart begins to contract (1st : atrial contracts)-Period of isometric contraction: volume stays same, only pressure is increased by ventricles-Period of ejection: blood is being ejected from ventricles-End-Systolic ≈ 50 mL-End-Diastolic ≈ 125 mL-Stroke 75 mL-Normal Cardiac Output = 5 L/minute 5 L in left will soon go to 5 L in rightII. How The Blood Works―Blood Flow -Starling Law of Heart: harder; you heart ejects in stroke = heart entering in diastole Summary: cardiac output = return  Length/Tension relationship gives heart the unique property of having input = output III. External Factors that Modify Cardiac Output-Parasympathetic: decreases heart activity/output-Sympathetic: increases heart activity/output*Sterling’s Law is an INTERNAL factor!-Autoregulation: if you exercise a muscle, O2 increases, arterials dilate smooth muscle relaxes when O2 increaseso blood flows through o Venus return increases, so heart pumps extra volumeIV. Electrical Properties of the Heart -Since the stroke volume = difference b/w end systole and end diastole, the heart gains efficiency if there is a time when every cell simultaneously relaxes or contracts-Excitation Fastest contraction: S-A Node Atrium: have simultaneous relaxation/contraction; will stay that way until 1st cell that generated