Exam Four Study Guide
Popular in Exercise Science
verified elite notetaker
Popular in OTHER
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
American Studies/ History 2410- 80
verified elite notetaker
This 35 page Study Guide was uploaded by Drake Kuhlmann on Thursday February 19, 2015. The Study Guide belongs to 269 at Kansas taught by in Spring2012. Since its upload, it has received 67 views. For similar materials see Exercise Science in OTHER at Kansas.
Reviews for Exam Four Study Guide
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 02/19/15
Chapter 13 04142012 Integrates the body as a unit 0 Provides active muscles with continuous stream of nutrients and oxygen 02 transport and delivery 0 Removes metabolic byproducts Maximal limits of aerobic energy transfer are set by 0 ATP synthesis capacity 0 02 transport and delivery A pump 0 The heart A highpressure distribution circuit 0 Arteries and arterioles Exchange vessels 0 Capillaries A lowpressure collection and return circuit 0 Veins and venules 100000 miles of blood vessels in an averagesized adult 0 if strung out could circle the earth 4 times Distribution of blood in the body 0 Small arteries veins and capillaries contain 75 of total blood volume 0 The heart contains 7 Provides impetus for blood ow Located in the mediastinum of the thoracic cavity 0 23 of its mass including the apex lie to the left of the body s midline o weighs less than 5 kg Approximately 40 million beats per year 0 Enough summed force to lift a human 100 miles above the earth At rest the heart pumps 1400 gallons of blood per day 0 303 million gallons over a 75 year lifespan Myocardium 0 Cardiac muscle Cardiac myocytes 0 Cardiac muscle cells Morphology 0 Many similarities to skeletal muscle but a few important differences Cardiac myocytes interconnect in a latticework fashion a lntercalated discs I Gap junctions n Tsystems occur at the Zlines Individual cardiac myocytes can t contract independently like skeletal muscle 0 Syncytium Network of cells n lntercalated discs I Gap juncitons Passage from one cell to another Cytosol to cytosol o Ephatic conduction Transfer of impulses from one cell to another 0 2 hollow chambers sides 0 Right heart Receives deoxygenated blood from systemic circulation Pumps blood to the lungs for aeration through pulmonary circulation 0 Left heart Receives oxygenated blood from pulmonary veins Pumps blood to the systemic circulation n Ascending thoracic aorta o lnterventricular septum o A thick solid muscular wall that separated the right and left hearts Both sides are composed of atrial and ventricular chambers o Atrioventricular valves separate the atria from the ventricles Allow blood ow in one direction a Atrium to ventricle Atrioventricular valves 0 Right atrioventricular valve Tricuspid valve 0 Left atriovetricular valve Mitral or bicuspid valve Semilunar valves 0 Valves that allow blood to exit the ventricles 0 Actually exist in the arterial walls just outside the myocardium o Prevent blood ow back into the ventricles Right semilunar valve 0 Pulmonary semilunar valve From right ventricle to pulmonary trunk to pulm veins Left semilunar valve 0 Aortic semilunar valve From left ventricle to ascending aorta to aorta arch Thinwalled sacklike Receives and stores blood during ventricular contraction 70 of blood returning to atrium ows directly into the ventricles before the atrium contracts The simultaneous atrial contractions force remaining blood into the ventricles Almost immediately after atrial contraction ventricles contract to propel blood into pulmonary or systemic circulation As ventricular pressure builds the AV valves snap shut All 4 heart valves remain closed for about 0206 seconds 0 During this brief interval of rising ventricular tension Heart volume stays the same Muscle ber length remains unchanged Called quotlsovolumetric contraction periodquot When ventricular pressure exceed arterial pressure the semilunar valves are forced open Spiral and circular arrangements of bands of cardiac muscle quotwrings outquot blood from ventricles Arteries to arterioles to capillaries Left ventricle to ascending thoracic aorta to aortic arch to descending thoracic aorta to abdominal aorta to left and right common iliac arteries Arteries known as resistance vessels 0 Dramatically alter their internal diameter to regulate blood ow Peripheral vessels do not permit blood to quotrun offquot as fast as it is ejected from the left ventricles 0 Thus the distensible aorta must store a portion of the blood as it s ejected this creates a pulse of pressure 0 quotpulse ratequot and quotheart ratequot are identical for healthy people That s why we can take a quotpulse ratequot and say it is quotheart ratequot Arterial blood pressure re ects the combined effects of arterial blood ow per minute and the resistance of the ow offered by the peripheral vasculature 0 At rest in normotensives the highest pressure that is generated in the left ventricles averages 120 mm Hg 0 Systole o The brachial artery at the level of the right atrium is used as the measurement point 0 SBP provides an estimate of the work of the heart and the force of blood exerted against the arterial walls 0 Pressure exerted against arterial walls during diastole of the cardiac cycle 0 7080 mm Hg 0 DBP indicates peripheral resistance The ease that blood ows from the arterioles to the capillaries The muscle pump 0 The rhythmic action of muscular activity and the consequent compression of the vascular tree That is why many people faint when forces to stand upright without movement for extended periods 0 Table tilt experiments Person is strapped to table and held horizontally until HR and BP stabilize If table is tilted upright a Blood pressure in the lower extremities edema o Hydrostatic pressure shift due to gravity 0 Continuing to walk cycle job etc facilitates blood ow throughout the vascular circuit 0 Reduces venous pooling o Increases lactate removalbuffering o Decreases potential deleterious effects of catecholamines on cardiac function Resting SBP can exceed 300 mm Hg 0 Arteries have become hardened with fatty deposits within the lumen or because the vessel s connective tissue layer has thickened o Arteries offer excessive resistance to peripheral blood ow because of neural hyperactivity or kidney malfunction 0 An estimate of myocardial work 0 RPP or quotdouble productquot is an index of relative cardiac work and relates closely to directly measured myocardial oxygen consumption and coronary blood ow 0 RPP can range from 6000 to 40000 0 RPP provides an objective yardstick to evaluate the effects of cardiac performance of various clinical surgical or exercise interventions Balance between systemic blood pressure and blood ow to various Ussues Neurochemical factors regulate heart rate and blood vessel opening 0 Example 5 of resting Q 5 Lmin goes to skin normally 20 of resting Q goes to skin during exercise in a hot humid environment o quotShuntingquot of blood in a closed system 0 Intrinsic Regulation 0 Heart s Electrical Activity 0 Electrocardiogram ECG 0 Cardiac Cycle 0 Extrinsic Regulation 0 Autonomic Neural In uences 0 Central Command In uences 0 Peripheral Input 0 Distribution of blood Myocardium is selfexciting tissue 0 Inherent rhythmicity is 100 bpm Normal excitation sequence 0 Sinoatrial SA Node Pacemaker of the heart right auricle o Atrial intermodal pathways 3 pathways through which electrical impulses travel more rapidly than through normal cardiac mms cells 0 Atrioventricular AV Node Intraatrial septum small slow conducting bers that slow the electrical impulse just enough for a 1 second delay 0 Bundle of His 0 Bundle branches 0 Ventricular Purkinje system Specialized cardiac muscle cells that rapidly conduct impulses up to 6 times faster than normal myocardial cells n Allows for uniform simultaneous contraction of the ventricles Electrocardiogram ECG o Depolarization waves P wave a Atrial depolarization QRS complex a Ventriculardepolarization o Repolarization waves Atrial T wave a Atrial repolarization I Usually occurs during QRS unnoticeable Ventricular T wave a Ventricular repolarization 0 Time domain amplitude The amplitude is dependent upon several factors a The distance between the heart and the electrodes n The tissue makeup between the heart and electrodes n The orientation of the lead axis P wave amplitudes n 12 mV QRS amplitude a 14 mV T wave amplitude a 23 mV 0 The events occurring from the beginning of one heartbeat to the beginning of the next is one cardiac cycle Diastole 0 Period of relaxation Systole 0 Period of contraction Curves lines in the Cardiac Cycles Figure 0 00000 Pressure in the aorta Pressure in the left atrium Pressure in the left ventricle Blood volume in the left ventricle Surface ECG Phonocardiogram Atria as primer pumps 0 7075 of blood ows directly from the great veins into the ventricles before the atria contract 0 atria contraction causes an additional 2630 ventricular lling Therefore atria serve as primer pumps that increase ventricular pumping to 2530 0 Normally the heart provides 300400 more blood than is required by the body Therefore if the atria fail we can still get by a At rest the signs of atrial failure probably go unno ced n During exercise atrial failure probably manifests most readily through shortness of breath o Ventricular lling diastole 0 Period of rapid lling of the ventricles Occurs during the rst 13 of ventricular diastole when ventricular pressure is at a low point a During the middle 13 of ventricular diastole only small amounts of blood enter the ventricles o The nal 13 of ventricular lling involves atrial contraction for an additional 2530 of lling o Ventricular emptying systole o lsovolumetric isometric contraction All valves are shut no change in volume large increase in pressure 23 sec enough to push open the semilunar valves 0 Period of Ejection When left ventricular pressure exceeds 80 mm Hg and the right ventricular pressure exceeds 8 mm Hg semilunar valves open 70 of ventricular ejection occurs during the rst 13 of systole rapid ejection and the remaining 30 is ejected over the next 23 of systole slow ejection o lsovolumetric isometric relaxation All valves are shut large decrease in ventricular pressure 36 sec enough to pull open the AV valves o EndDiastolic Volume EDV During diastole lling increases ventricular volume to 110120 mL 0 Stroke Volume Output SV During systole ejection decreases ventricular volume by 70 mL 0 Endsystolic Volume ESV End diastolic stroke volume end systolic volume 4050 mL 0 Ejection Fraction EF Stroke volume divided by enddiastolic volume ejection fraction 60 0 When the heart contracts strongly ESV can be as low as 10 20 mL 0 When large amounts of blood ow into the ventricles during diastole EDV can be as high as 150180 mL 0 Therefore increases in SV up to twice its resting value can occur as a result of Increasing EDV Decreasing ESV 0 Under normal ambulatory conditions extrinsic controls can 0 Decrease heart rate down to 2530 bpm 0 Increase heart rate in excess of 200 bpm The cardiovascular control center in the brain 0 Located in the ventrolateral medulla o Regulates the heart s stroke volume and the preferential distribution of blood to tissues Autonomic Nervous System control over heart rate and circulation 0 These functions superimpose on the inherent rhythm of the myocardium Sympathetic division n lnnervates the atria and ventricles Parasympathetic division n lnnervates the atria only Central command is located in the primary motor cortex and in the ventrolateral medulla 0 Rapid adjustments in heart rate and vessel diameters for tissue perfusion Occurs both before anticipatory and during exercise 0 Central command provides the greatest control over heart rate during exercise Heart rate rapidly increases by decreased parasympathetic and increased stimulating input from the brain s central command 0 Peripheral receptors in blood vessels joints and muscles 0 Chemoreceptors o Mechanoreceptors Afferent impulses from these receptors Group 3 and 4 afferents From pacinian corpuscles and unencapsulated nerve ending receptors n Modi es vagal parasympathetic or sympathetic in uence accordingly o Metabore ex Chemically sensitive receptors Regulates sympathetic muscle activation Occurs primarily during concentric muscle actions 0 Baroreptors Located in the aortic arch and carotid sinuses Negative feedback controls n lnhibit sympathetic in uence from the cardiovascular center Slows heart rate a Blunt an inordinate rise in arterial blood pressure Dilate the peripheral vasculature Decreases blood pressure Examples n Carotid artery palpation to monitor exercise intensity 0 Blood vessels have capacity to hold 20 L 0 Total blood volume is 45 L o The capacity of large portions of the vasculature to either constrict or dilate provides rapid blood redistribution shunting to meet metabolic needs and optimize blood pressure Governed by Poisuille s Law 0 Increasing energy expenditure during exercise requires rapid adjustments in blood ow 0 Onset of exercise Active muscle vasculature dilates local arterioles n Well developed system Other areas constrict vasculature n Splanchnic and renal visceral vasculature n Exercise intensitydependent above 90 bpm a Two factors in uence nonactive tissue blood shunUng Neurohormonal increases in sympathetic activity Humoral increases in circulating vasoconstrictors During exercise vasodilation can occur from local factors 0 Autoregulatory mechanisms Decreases in 02 supply and pH Increases in temperature C02 adenosine Mg K and NO 0 Cardiac Output 0 Q The amount of blood pumped by the heart per minute Maximal Q re ects the functional capacity of the cardiovascular system to meet energy demands Dependent upon a Heart rate a Strokevolume The quantity of blood ejected from the heart with each beat o 3 common methods to measure Q Direct Fick method a 2 factors 0 Mean change in 02 saturated between arterial and mixed venous blood 0 Av 02 difference mL100mL Oxygen consumed in 1 minute 0 V02 mLmin n Bene ts Criterion gold standard method Precise Clinical use a Draw backs 0 Very invasive arterial puncture Mixed venous blood must come from pulmonary trunk Clinical use only lndicator Dilution method a lnvolves arterial and venous puncture but not catheterization n Inject inert dye in a vein and measure its concentration in a known quantity of arterial blood C02 rebreathing method a Determining cardiac output by substituting CO2 for O2 in the Fick equation a Uses a rapid CO2 gas analyzer n Noninvasive common lab technique a May accurately re ect exercising conditions versus invasive procedure o The process of ambient air moving into the lungs and exchanging gases Lungs and external respiration 0 Function Exchange of 02 and C02 between cells and the environment Cells require 02 and must get rid of C02 Cells have no contact with atmosphere Cells must rely on external respiration of pulmonary funcUon Nosemouth trachea bronchi bronchioles alveoli Pulmonary respiratory 4 components of respiratory function 0 Pulmonary ventilation Minute ventilation Air moves into the lungs from the atmosphere 0 External respiration Exchange of 02 and C02 between lungs and blood 0 Gas Transport From lungs to tissue through the circulation Actually a function of the circulorespiratory system 0 Internal respiration Exchange of 02 and C02 between blood and cells where tissue respiration is going on Alveoli 0 Site of gas exchange from external respiration 0 Extensive capillarization in alveoli walls 0 Very thin bloodgas barrier Alveoli membrane and capillary membrane Pores of Kohn 0 Small pores located throughout each alveolus 0 Release pulmonary surfactant Decreases surface tension decreases alveolar resistance to expansion 0 Allows gas exchange between adjacent alveoli Not all of the air that enters our bodies reaches the alveoli 0 Part of each breath remains in the conducting zone 0 Unused breathventilation is called Dead space ventilation Vd 0 Space this ventilation occupies is referred to as anatomical dead space 0 What reaches the alveoli is alveolar ventilation Va 2 general types of ventilation 0 Dead space ventilation Vd 30 of TV at rest o Alveolar ventilation Va 70 of TV at rest Mechanics of ventilation o Air ow Movement of air into and out of the lungs Occurs because of the intrapulmonary pressure changes Intrapulmonary pressure changes are the result of changes in the size of the thoracic cavity 0 Negative pressure ventilation intrapulmonic pressure 0 Expiration at rest is a 2 part process Inspiratory muscle relaxation a For expiration the diaphragm and intercostals relax a Thoracic cavity returns to its original size n This increases intrapulmonary pressure greater than ambient a Air ows outward to the atmosphere Elastic recoil of the lung tissue 0 Expiration during exercise Expiratory muscles n Abdominal group n Internal intercostals Lower ribs and move them closer together Facilitates expiration 0 Inspiration 0 Inspiratory muscles cause the size variations in the thoracic cavity Diaphragm n Contraction occurs from stimulus of right and left phrenic nerves n Flattens and makes the thoracic cavity longer External intercostals n Contraction lifts ribs n Increases transverse diameter a Increased thoracic size accompanied by decrease in intrathoracic pressure a Air moves from high pressure area ambient to love pressure in the body Scalene muscles n Raises rst 2 ribs 0 Oxygen cost of respiration 0 Respiratory muscles require portion of oxygen consumption 0 Rest 12 of V02 minimal 3 to 6 mL used for respiratory muscles 0 Heavy exercise 810 V02 240 to 500 mL used for respiratory muscles 0 Pulmonary surfactant 0 resistance to plural cavity expansion increases during inspiration 0 Alveolar surface tension Fluid surrounding each aveous H20 has a naturally high surface tension when volume is low a Constricts the alveoli from expanding o Surfactant Lipoprotein with phospholipids proteins and Ca Reduces surface tension of surrounding alveolar uid allows aveoi to expand easier Phases of ventilation o Expiration or exhalation Ve 0 Inspiration or inhalation Vi Ve Vt x F o Tidal volume x frequency Ve TV x breathing rate 0 Minute ventilation tidal volume x respiratory rate VentilationPerfusion Ratio 0 Ratio between volume of air that ventilates that alveoli and volume of blood that ows through the pulmonary capiaries 0 At rest 42 L min1 of alveolar ventilation n 70 of minute ventilation 5 L min1 of blood ow to pulmonary capiaries n Cardiac output a 42 divided by 5 84 ventilationperfusion ratio 0 Light exercise 8 ventilation perfusion 0 Heavy exercise 5 ventilation perfusion o Hyperventilation 0 Increased ventilation o disproportionate increase in Ve that occurs at the ventilator breakpoint Dyspnea o Difficult or labored breathing 0 One is unable to respond to the demand for ventilation Heart failure emphysema chronic bronchitis Conducting Zone 0 Trachea bronchi bronchioles o Passageway of air 0 Humidi es and lters 0 Protects lung tissue from drying out o No gas exchange occurs 0 Respiratory Zone 0 Gas exchange 0 300 million alveoli 0 surface area for diffusion tennis court o alveolus and capillary only 1 cell thick 0 blood gas barrier only 2 cell layers wide Lung volumes air ow volumes during single breaths Total lung capacity TLC o Entire air that can be contained in all the air passages 0 Gas in lungs after maximum inhalation Vital capacity VC 0 Largest volume of air that can be exhaled after a maximal inspiration Residual volume RV 0 Volume of air remaining in lungs after a complete exhalation air left in alveoli lnspiratory capacity IC 0 Volume of air inspired from rest to maximal inspiration 0 TV IRV Functional residual capacity FRC 0 Volume of air in lungs at rest Tidal volume 0 Volume of air inspired or expired per breath lnspiratory reserve volume IRV 0 Volume of air that can be inspired after a normal inspiration Expiratory reserve volume ERV 0 Volume of air that can be expired after a normal expiration Sustained air ow levels rather than air movement during a single breath 2 factors 0 Maximal quotstroke volumequot of the lungs 0 Speed of moving a volume of air 0 Will be affected by lung compliance 0 Measured by 3 things 0 Forced expiratory volume FEV at timed intervals 0 Forced vital capacity FVC VC 0 FEV to FVC ratio 0 Two basic types of lung disorders 0 Obstructive Emphysema or bronchial asthma o Restrictive Pulmonary brosis 0 Gas Exchange 0 Inspiration brings oxygen intro the lungs 0 Concentration of oxygen is higher in alveoli than capillaries 0 Concentration of carbon dioxide is higher in the capillaries than the alveoli O 0 Gas exchange occurs because of diffusion Random movement of molecule from an area for higher concentration to one of lower concentration mmHg is a measure of pressure P02 and PC02 represent partial pressures of oxygen and carbon dioxide respectively Dalton s Law of Partial Pressures In a mixture of gases each gas exerts a partial pressure that is proportional to its concentration Partial Pressure concentration x total pressure of gas mixture Pulmonary vein Oxygen is 40 mmHg Carbon dioxide is 46 mmHg Alveoli Oxygen is 100105 mmHg Carbon dioxide is 40 mmHg Differences is pressure of the gases in the alveoli and blood create a pressure gradient Alveolar oxygen 100 mmHg Venous oxygen 40 mmHg Gradient into capillaries is 60 mmHg Alveolar C02 40 mmHg Venous C02 46 mmHg Gradient into alveoli is 6 mmHg Blood transport of oxygen 0 Oxygen reaches tissues Dissolved in plasma 23 Combination with hemoglobin 9798 0 Carrying capacity of Hgb Oxyhemoglobin dissociation curve rest 0 Flat portionarterial Changes in P02 minimal effect on sat Saturation is maintained 0 Steep portion Changes in P02 large effect on sat Greater unloading of oxygen Decreased pH Increased muscle temperature Shifts curve to right Signi cance Greater unloading of oxygen in tissues 0 Blood transport of C02 0 C02 is carried in the blood in three ways Physical solution in plasma small amount 5 Combined with hemoglobin within the red blood cell 90 As plasma bicarbonate OOOO 0 C02 in the blood is like acid in the blood 0 H ion is buffered by Hb 0 Plasma proteins Over 600 skeletal muscles Muscle bers muscle Cells myocytes Muscles pull on bones to allow movement 0 They can t push Maintain posture Stabilize joints Generate heat 0 Using energy creates heat lsometric 0 Muscle remains the same length despite building tension lsotonic o Tension on muscle remains the same throughout the range of motion 0 Concentric Muscle shortens as it contracts o Eccentric Muscle lengthens as it contracts Isokinetic 0 Speed of the muscle motion remains the same despite changes in force amounts Flexion o Decreasing the angle of components of a limb Think of exing your bicep Extension 0 Increasing the angle of components of a limb Straightening your leg Adduction o Brings a limb closer to the midline of the body Think of adding to your body AbducUon o Takes a limb away from the midline of the body Supination o Rotation of the forearm so palms face upout Think of the typical barbell bicep curl exercise Pronation o Rotation of the forearm so palms face downback Rotation 0 Movement of limb in circular motion Depends on origin and insertion Origin o Is one end of the muscle that is attached to a bone that doesn t move when the muscle contracts Insertion o Attaches to the structure that will be moved by the contraction of the muscle Muscles connect to bone via tendons Tendons 0 Transfer force from the muscle to the bone Epimysium o Surrounds the entire muscle Perimysium o Surrounds the fasciculi Endomysium o Surround each individual muscle ber Coalesce to form tendons Tendons connect both ends of the muscle Skeletal muscle 0 Fasciculi Tendon that surrounds a collection of muscle bers 0 Muscle ber Myo bril n Sarcomere Smallest functional unit of a skeletal muscle ber 0 Between two Z lines a Myo laments Parallel or longitudinal Quadrate or quadrilateral Triangular fan shaped Fusiform spindle shaped 0 Complex fusiform Pennate fan shaped o Unipennate o Bipennate o Mulipennate Circular The degree of pennation directly affects the number of sarcomeres per crosssectional muscle area 0 Pennation results in a loss of force 0 Pennation allows more sarcomeres to be packed into a given area The practical application of the sarcomere lengthtension curve 0 There are joint angles at which strength expression is greatest during isometric muscle contractions Hypertrophy Increases in the size of cells Lifting weights puts a stress on the muscle Enough stress will cause muscle damage The muscle repairs that muscle to be able to handle that amount of stress the next time 0 O O 0 Two basic dissociations among ber types 0 Contractile properties 0 Metabolic characteristics Two basic subdivisions 0 Slow twitch bers ST Characteristics El El Motor units selectively recruited during aerobic activity Prolonged exercise relies almost exclusively on ST bers 0 Limited remained glycogen after 12 hours of exercise exists in the quotunusedquot fast twitch bers n Creates low amounts of force a Receives large quantities of blood ow a Slow twitch bers type 1 bers 0 Fast twitch FT Characteristics n Generate force quickly high power a Speed of shortening is 35 times faster than ST bers n Anaerobic activities 0 Quick forceful muscles actions a Stop and go activities change change of pace sports a Fast twitch bers type 2 bers a quotwhitequot in color 0 Recruitment strategies 0 Low intensity exercise recruits predominantly slow twitch bers Increase in exercise intensity forces the body to recruit more fast twitch bers 0 Motor unit recruitment is intensity related 0 Speed of contraction o The ability of ber types to contribute to force production Maximal voluntary contraction MVC at slow controlled velocities a Slow and fast twitch bers are contributing to force production a All bers are being recruited MVC at fast velocities a Only fast twitch bers are able to contribute to force production a All bers are still being recruited Physical structure of the bers 0 Functional implications 0 Size differences 0 ST bers are generally smaller than FT bers 0 ST to FT continuum from smallest to largest Capillary densities o Aerobic energy production requires oxygen Must have a good blood supply ST bers have high capillary densities compared to FT bers 0 Structure of motor neurons 0 ST to FT size continuum from smallest to largest motor neurons 0 This is true for Size of the soma Diameter of the axon Thickness of the myelination Conduction in ber structure 0 ST to FT continuum from slowest to fastest motor neuron conduction velocities 0 Force production 0 Usually ST bers can t produce as much force as FT bers 0 Fatigue resistance 0 ST are fatigueresistant Aerobic vs anaerobic energy production capabilities Basic components of neurons 0 Cell body Nucleus Decides if the impulses is worthy to send down the axons o Dendrites Receiveimpulses o Axon Myelination Nodes of Ranvier Send impulses Axon terminals 0 Synaptic end bubs O o Neurotransmitter o The motor neuron and all the muscle bers it innervates 0 Motor neuron determines ber type Only ONE ber type per motor unit a ST n FT 0 The number of muscle bers in a motor unit innervated by 1 motor neuron varies o Gastrocnemius 2000 muscle bers per motor neuron 0 Eye muscles lt 10 muscle bers per motor neuron Ratio of muscle bers to motor neurons 0 Affects the precision of movement 0 The all or none law for motor units 0 Applies to individual motor units but not the entire muscle A motor unit is either activated completely or is not activated at all o Varying the number of motor units activated Smaller motor units 0 Low stimulus threshold 0 Larger motor units 0 Higher stimulus threshold 0 Largest motor units 0 Highest stimulus threshold 0 Exercise home page Cb cd click link Mens health noo
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'