EX PHYS Exam 3

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EX PHYS Exam 3
2014-11-16 21:43:54
cardiorespiratoy system
ex phys
exercise physiology
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  1. Three main purposes of the cardiorespiratory system
    • transports O2 and nutrients to tissues
    • remove CO2 wastes from tissues
    • regulation of body temperature
  2. Define and state the function of various vessels in the vascular system.
    (* smooth muscle for control of flow)
    • Arteries* - muscular tubes that transport blood to tissue under high pressure - branches from the aorta.
    • Arterioles* - Branches from the arteries which have smooth muscles which act as control valves to distribute blood to the capillaries.
    • Capillaries - Branches from the arterioles that permit the exchange of fluids and nutrients with interstitial spaces.
    • Venules - Tubular structures that collect blood from capillaries
    • Veins* - Tubular conduits to return blood to heart.
  3. opening of atrioventricular valves
    Mitral (bicuspid) and Tricuspid valves are attachted to chordae tendinae which are attached to papillary muscles that contract to open valves.
  4. list 12 structures of the heart
    • Superior & Inferior vena cava
    • Right atrium
    • Tricuspid valve (right atrioventricular valve)
    • Right ventricle
    • Pulmonary valve (semi-lunar)
    • Pulmonary artery
    • Pulmonary vein
    • Mitral valve (bicuspid or left atrioventricular valve)
    • Left ventricle
    • Aortic valve  (semi-lunar)
    • Aorta
    • Coronary arteries
  5. Order of blood flow through the heart
    • Superior + Inferior vena cava
    • In Right Atrium
    • Through Tricuspid valve
    • In Right Ventricle
    • Out Though Pulmonary valve
    • Through Pulmonary Artery
    • To lungs (exchange)
    • Through Pulmonary Veins
    • In Left Atrium
    • Through Mitral (bicuspid) Valve
    • In Left Ventricle
    • Out Aortic valve
    • Through Aorta to body and coronary arteries at base of aorta
    • coronary veins drain into coronary sinus which deposits directly into right atrium
  6. Right Side of the Heart
    • Pulmonary circuit
    • Deoxygenated blood to lungs via pulmonary arteries
    • Returns Oxygenated blood to left heart via pulmonary veins
  7. Left Side of heart
    • Systemic circuit
    • oxygenated blood to whole body via arteries
    • returns deoxygenated blood to right heart via veins
  8. Blood distribution at rest
    • Venous  64%
    • Arterial  15%
    • Heart 7%
    • cappillaries 5%
  9. ______  ____ are intercellular connections that permit the transmission of electrical impulses from one muscle fiber to another. So when one fiber is depolarized to contract, all connecting heart fibers contract as a unit. this arrangement is called ______ _____
    • intercalated discs
    • functional syncytium
  10. Compare / Contrast Myocardium and Skeletal Muscle
    • Cardiac muscle is also striated and similar to Type I - Slow muscle fiber.
    • Highly aerobic and contain more mitochondria that type I skeletal.
    • Cardiac fibers are shorter, have only one nuclei, and are connected in a tight series.
    • Cardiac fibers branch, whereas skeletal are elongated and do not.
    • Involuntary contraction
    • Heart fibers all connected by intercalated discs discs
  11. Heart contraction (cardiac cycle)
    • cardiac cycle - the repeating pattern of contraction and relaxation of the heart         
    • -lasts about 0.8 sec at RHR of 75 bpm
    • -systole - contraction phase
    • -diastole - relaxation phase
    • -generally used to refer to contraction and
    • relaxation of ventricles
    • -but, atria also have systole and diastole phases
    • -atrial contraction -- same time as ventricle relaxation
    • -atrial relaxation -- same time as ventricle contraction
    • -amount of time ventricles spend in each phase depends on if individual
    • is at rest or exercising
    • --RHR (75 bpm)   =
    • -0.3 sec for systole
    • -0.5 sec for diastole
    • --exercise HR        
    • -large reduction in time spent  in diastole (0.13 sec) (180 bpm)
    • -systole less affected (0.2sec)
    • Has autorhythmicity
  12. autorhythmicity
    show rhythmic activity without being driven by rhythmic external stimulation
  13. ECG
  14. Describe ECG waves
  15. Conductive tissue, specialized cardiac muscle tissue
    • Sino-atrial Node (SA node) - Node at the junction of the superior vena cava and right atrium - starting point for the heart beat depolarization wave
    • Atrio-ventricular node (AV node) - A node located at the juncture of the right atrium and interventricular septum, transfers depolarization wave from the atria to the ventricles
    • Atrioventricular bundle (AV bundle) - Specialized cardiac tissue that conducts the depolarization wave through the ventricles
    • Purkinje fibers - Fibers under the endocardium that conduct the depolarization wave to the cardiac muscle fibers
  16. path of electrical activity in heart
    • Signal originates at SA node cells, which polarize independently; Automaticity.
    • Signal passes via intercalated discs to cells neighboring SA node which depolarize slower than signal through Internodal Tracts
    • Internodal Tract Bachmanns Bundle takes signal to left atrium
    • And Internodal Tract takes signal to AV node which delays signal 0.1 seconds
    • signal passes through Bundle of HIS
    • through Right bundle, Left < Posterior fasicle, Anterior fasicle
    • finally to the Purkinje Fibers which pass the signal to the muscle cells
  17. P Wave - ____
    QRS wave - ______
    T wave - _____
    • P wave - Atrial depolarization
    • QRS wave - Ventricular depolarization and atrial repolarization
    • T wave - Ventricular repolarization
  18. pressure changes in ventricle during cardiac cycle
    • Pressure is low as ventricles fill
    • Increases slightly when atria contact
    • Rises sharply when ventricles contract
    • Exceeds pressure in pulmonary artery and aorta. and semi-lunar valves open
  19. Compare the systolic and diastolic phases with regards to the length of each phase during rest and exercise
    • --RHR (75 bpm)  
    • 0.3 sec for systole
    • 0.5 sec for diastole
    • --exercise HR        
    • -large reduction in time spent  in diastole (0.13 sec) (180 bpm)
    • -systole less affected (0.2sec)
  20. Define Blood Pressures, Pulse Pressure, and Mean Arterial Pressure.
    • Systolic Blood Pressure (SBP) is the pressure generated during ventricular systole
    • Diastolic Blood Pressure (DBP) is the pressure during ventricular relaxation.
    • Pulse Pressure (PP) is the difference
    • PP = SBP - DBP
    • MAP is the average aortic pressure during the cardiac cycle.
    • MAP = DBP + PP/3
  21. 2 Factors that influence MAP
    • Cardiac Output
    • Total Vascular Resistance
    • MAP = CO x TPR
  22. Graph how blood pressure, heart rate, and stroke volume change as a function of VO2
  23. Define Cardiac Output and list two equations to find it
    • total amount of blood that is pumped per minute
    • CO = HR x SV
    • CO = MAP/TPR
  24. How is blood pressure taken by auscultation.
    • cuff is inflated until blood flow is occluded while listening to brachial artery with a sphygmomanometer
    • Sounds produced by turbulence of blood
    • flow
    • the first sound heard is when systolic blood pressure has overcome the occlusion
    • sound ceases when diastolic blood pressure has overcome the occlusion
  25. Effects of sympathetic and parasympathetic systems on cardiac function
    • Parasympathetic nervous system
    • – Via vagus nerve
    • – Slows HR by inhibiting SA and AV node
    • Sympathetic nervous system
    • – Via cardiac accelerator nerves
    • – Increases HR by stimulating SA and AV node
    • Low resting HR due to parasympathetic tone
    • Increase in HR at onset of exercise
    • – Initial increase due to parasympathetic withdrawal
    • --Up to ~100 beats/min
    • – Later increase due to increased SNS stimulation
  26. Cardiovascular control center affects cardiac function (Baroreceptors)
    • Two baroreceptors
    • - Aortic Baroreceptors (vagus nerve)
    • -Carotid Baroreceptors (on carotid sinus)
    • Send signals to medulla oblongata
    • Pressure too high - efferent signal sent via parasympathetic fibers (vagus) to SA node, acetylcholine release for inhibitory effect.
    • Pressure too low - signal sent via sympathetic fibers (cardiac nerves) to release norepinephrine at SA node.
  27. Three factors that regulate stroke volume, describe
    • End-diastolic volume (EDV) - (Pre-load)
    • -how much blood is in the ventricles at the end of diastole
    • Average aortic pressure - (Afterload)
    • -MAP pressure the heart must overcome to eject blood
    • Strength of ventricular contraction (Contractility)
    • -enhanced by: circulating epinephrine and norepinephrine, direct sympathetic stimulation of heart
  28. Factors that contribute to venous return
    • Venoconstriction - reduced volume stored in veins, increase return to heart.
    • Muscle Pump- contractions compress veins, increase return to heart
    • Respiratory Pump (predominant factor that promotes venous return during exercise)- pressure within chest decreases and within diaphragm increases with inspiration
  29. 3 factors that influence EDV
    • Venous return rate - predominant variable
    • i.e. Venoconstriction
    • Muscle Pump
    • Respiratory pump
  30. Frank-Starling effect
    • the strength of ventricular contraction increases with enlargement of EDV that causes a stretching of the myocardium
    • In relation to training:
    • EDV is decreased, ventricular contraction decreases lowering blood pressure and decreasing how hard the heart works.
  31. List adaptations resulting from endurance training
    • CO increases
    • SV increases - primary factor
    • increase in diastolic filling as well as decrease in EDV
    • HR slowing (vagal effect)
  32. determinants of blood flow and peripheral resistance
    • Cardiac output (Qc or CO) - rate blood flows from the heart
    • Peripheral resistance (R) - resistance to blood flow through the circulatory system
    • Produced by arterioles
    • Arterioles open - R low; closed - R increases
    • Blood volume - Total amount of blood in the body
    • Affects Qc due to "venous return"
    • Not a problem during steady state exercise
    • May be a problem if blood pools (collects) in body segments
    • Blood viscosity
  33. Fick Equation
    VO2 = CO x (a-v)O2 difference
  34. Redistribution of Blood Flow During Exercise
    • • Increased blood flow to working skeletal muscle
    • – At rest, 15–20% of cardiac output to muscle
    • – Increases to 80–85% during maximal exercise
    • • Decreased blood flow to less active organs
    • – Liver, kidneys, GI tract
  35. Two main mechanisms that increase blood flow to exercising muscles
    • Increase CO
    • Redistribution of blood flow
  36. CO increases during exercise due to 2 main reasons
    • Increased Heart Rate
    • -linear increase to max hr
    • Increased SV
    • -Increase, then plateau at ~40% VO2 max
    • -No plateau in highly trained subjects
  37. Factors that determine circulatory response to exercise
    • a. type of exercise
    • b. intensity of exercise
    • c. duration of exercise
    • d. environmental conditions
  38. Circulatory Response To Incremental exercise
    • a. HR, CO, & blood flow to muscle increase directly with VO2 uptake
    • b. CO & HR plateau at VO2max
    • c. double product = HR x SBP
    • (1) estimates workload placed on heart
    • (2) guidelines for prescribing exercise
  39. Circulatory Response To Arm vs Leg Exercise
    • a. at any given intensity - HR & BP higher for arm work vs leg work
    • b. HR = higher because SNS output to heart greater with arm work
    • c. BP = higher because of vasoconstriction in inactive leg muscles with arm work
  40. Circulatory Response To Intermittent Exercise
    • a. HR & BP recovery depends on
    • (1) fitness level
    • (2) environmental conditions
    • (3) duration & intensity of exercise
    • b. IF low intensity, cool environments = then complete HR, BP recovery within 5-7 minutes
    • c. IF higher intensity or hot/humid environments = then HR & BP do not recover ... cumulative increase
    • (1) Possible to do many more repeated light bouts of exercise, can tolerate only limited # of high intensity bouts or bouts in hot/humid environments
  41. Circulatory Response To Prolonged Exercise
    • a. constant work rate, prolonged exercise
    • (1) CO maintained (CO = HR x SV)
    • (2) SV decreases but HR increases to compensate
    • (3) cardiovascular drift - due to rising body temperature
    • (a) due to skin vasodilation & dehydration
    • (b) both decrease venous return which reduces SV
    • b. if hot/humid environments - response is exaggerated
  42. Pulmonary Respiration v. Cellular Respiration
    • • Pulmonary respiration
    • – Ventilation– Exchange of O2 and CO2 in the lungs
    • • Cellular respiration.
    • – O2 utilization and CO2 production by the tissues
  43. Conducting zone
    • Conducts air to the respiratory zone
    • Humidifies, warms, and filters air
    • components:
    • -trachea
    • -bronchial tree
    • -bronchioles
  44. Respiratory Zone
    • Exchange of gases between air and blood
    • components:
    • -respiratory bronchioles
    • -alveolar sacs
  45. Muscles involved in respiration during rest and during exercise
  46. Tidal Volume (VT)
    volume inspired or expired with each normal breath; ~ 0.5L
  47. Inspiratory Reserve Volume (IRV)
    amount of lung volume available after a tidal inspiration; 2.5-3.5L
  48. Expiratory Reserve Volume (ERV)
    amount of air that may be exhaled after tidal expiration; 1-1.5L
  49. Residual Volume (RV)
    volume of air in the lung after maximum expiration; ~1L; larger in emphysema
  50. Vital Capacity (VC)
    the maximum amount of air that can be expired after a maximum inhalation
  51. Total Lung Capacity (TLC)
    volume of air that lungs can contain at maximal inspiration
  52. Functional Residual Capacity (FRC)
    Volume of air remaining after tidal end expiration, ERV+RV
  53. Inspiratory Capacity (IC)
    The maximum amount of air that can be inhaled after a tidal expiration
  54. Anatomic Dead Space
    • space where no gaseous exchange occurs
    • - first 16 generations of tubules
    • (1) composition of air same as atmospheric but is fully saturated;
    • (2) 1 ml per pound body mass
  55. Physiologic Dead Space
    • alveoli where no gas exchange occurs due to physiological factors; (the ratio of alveolar ventilation to pulmonary blood flow)
    • (1) due to alveoli that are not functioning or being ventilated (primarily related to Ventilation-Perfusion Ratio – see below)
    • (2) can be affected by underperfusion - e.g., hemorhage, pulmonary embolism
    • (3) can be affected by underventilation - e.g., emphysema, asthma
  56. Alveolar Space
    the area of the lung where gaseous exchange occurs
  57. Three conceptual volumes of the lungs
    • Anatomic Dead space
    • Physiologic dead space
    • Alveolar Space
  58. dynamic volumes
    • can help to identify the presence of respiratory diseases and disorders and to evaluate the effects of training on respiratory function during exercise
    • Forced Expiratory Volume (FEV1.O)
    • Maximum Voluntary Ventilation (MVV)
  59. Forced Expiratory Volume (FEV1.O)
    • amount of Vital Capacity forced out in 1 second 
    • i) healthy lung ~ 85%
    • ii) obstructive disease < 70%
    • iii) increases in restrictive fibrotic disease ( decreased VC)
  60. Maximum Voluntary Ventilation (MVV)
    • deep rapid breaths for 15 sec
    • i) healthy male = 140-180L; healthy female 80-120L
    • ii) obstructive lung disease - 40% less
  61. Dalton’s Law of Partial Pressures
    • (1) Each gas behaves independently of the other gases in the mixture
    • (2) Every gas diffuses from an area of high pressure to an area of low pressure
  62. Fick’s Law of Diffusion of Gases
    • (1)   V gas = A/T x D x (P1-P2)
    • V gas = rate of diffusion
    • A = tissue area
    • T = tissue thickness
    • D = diffusion coefficient of gas
    • P1 – P2 = difference in partial pressure
    • (2) velocity is greater if Pp differential is large, surface area is large, tissue is thin
    • (3) velocity is less if tissue is thicker
  63. Henry’s Law of the Solubility of Gases
    • (1) temperature & solubility basically constant
    • (2) CO2 is much more soluble than oxygen
    • (3) determines the amount carried in solution
  64. Calculate partial pressure of a gas
    • O2 = 20.93%
    • .2093 x 760 torr = PO2 159 mmHg
  65. Oxygen transport modes
    • 99% bound hemoglobin (Hb)
    • -Oxyhemoglobin: Hb bound to O2
    • -Deoxyhemoglobin: Hb not bound to O2
    • Plasma: 9-15 ml O2- Hgb has 70x carrying capacity of plasma
    • Amount of O2 transported per unit volume of blood is dependent on the Hb concentration. -Each gram of Hb can transport 1.34 ml O2 O2 content of blood (100% Hb saturation)
    • Males: 150 g Hb/L blood x 1.34 ml O2/g Hb = 200 ml
    • Females: O2/L blood130 g Hb/L blood x 1.34 ml O2/g Hb = 174 ml O2/L blood