unit 3 definitions for flashcards.txt

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  1. anatomic dead space?
    The air that fills the nose, mouth, trachea and other non diffusible conducting portions of the respiratory tract. 150 to 200 mL, or about 30% of resting Tidal Volume in healthy people
  2. bicarbonate?
    • Consists of the weak acid carbonic acid, and its salt, sodium bicarbonate.
    • CO2 + H2O= bicarbonate, this reaction reverses in the lung to allow CO2 to leave the blood and be expired.
  3. carbonic acid?
    Useful within the body's chemical buffering system. It is the weak acid in the reation. Carbonic acid forms when bicarbonate binds with H+ ions.
  4. chemoreceptor?
    Small structures located on the aortic arch and corotid ateries. They activate the brain's respiratory neurons and provide early warning against reduced oxygen pressure. They stimulate ventilation in response to: increased carbon dioxide, increased temperature, and increased acidity; decrease in blood pressure and possibly a decline in circulating potassium
  5. FEV1/FVC?
    The forced expiratory volume-to-foreced viatl capacity. Percentage of FVC expelled in 1 second. This reflects expiratory power and overall resistance to aire movement in the lungs. Normal FEV1/FVC values averages about 85%
  6. Forced Vital Capacity?
    Total air volume moved in one breath from full inspiration to maximum expiration or vice versa. FVC varies with body size and body position during measurement; values usually average 4 to 5 L in healthy young men and 3 to 4 L in healthy young women. Large lung volumes probably reflect genetic endowment because exercise training does not change appreciably static lung volumes
  7. hemoglobin?
    The iron containing protein pigment constituting the main component of the body's 25 trillion red blood cells. It increases the blood's oxygen carrying capacity 65-70 times above that normally dissolved in plasma
  8. hyperpnea?
    Increased ventilation during physical activity. This cannot be truly explained by chemical stimulation
  9. hyperventilation?
    "overbreathing" causes an increase in expired CO2 which causes a decrease in H+ ions which will increase plasma pH.

    An increase in pulmonary ventilation that exceeds the oxygen needs of metabolism. It quickly lowers normal alveolar carbon dioxide concentration, which causes excess carbon dioxide to leave body fluids in the expired air. Several seconds can produce lightheadedness and can lead to loss of consciousness
  10. minute ventilation?
    • volume of air breathed each minute.
    • min vent= RR x TV

    During quiet breathing at rest, an adult's breathing rate averages 12 breaths per minute, and the Tital Volume averages about 0.5 L of air per breath. Under these conditions the volume of air breathed each minute, equals 6 L, thus termed minute ventilation
  11. mechanoreceptor?
    Sensory input from joints, tendon, and muscles provide peripheral influence to adjust ventilation during exercise known as reflex hyperpnea
  12. myoglobin?
    Iron-protein compound found in skeletal and cardiac muscle. Each molecule contains one iron atom in contrast to Hb. Myoglobin adds additional oxygen to muscle by facilitating oxygen transfer to the mitochondria at the start of exercise and during intense exercise when cellular PO2 decreases considerably
  13. OBLA?
    Onset of blood lactate accumulation. When lactate accumulation exceeds lactate removal. Occurs between 55-65% VO2 max

    Exercise intensity or oxygen uptake where blood lactate begins to increase above a baseline level of about 4mM*L-1 indicates the point of Onset of Blood Lactate Accumulation normally between 55% and 65% of VO2max in healthy, untrained subjects and often more than 80% VO2max in highly trained endurance athletes.
  14. partial pressure of gas?
    The net diffusion of a gas occurs only when a difference exists in gas pressure. Specific gas' partial pressure gradient represents the driving force for its diffusion. Movement at the alveolar-capillary and tissue-capillary membranes always progresses from an area of higher partial pressure to lower partial pressure
  15. physiological dead space?
    Portion of alveolar volume with poor perfusion or inadequate ventilation. Possibly from under perfusionof blood or decrease alveolar surface. PE of COPD

    The portion of alveolar volume with poor tissue regional perfusion or inadequate ventilation. Only a negligible physiologic dead space exists in healthy lungs but it can increase to 50% of resting Tital Volume. This occurs when perfusion during hemorrhage or blockage of the pulmonary circulation becomes inadequate from an embolism or blood clot of alveolar ventilation becomes inadequate in chronic pulmonary disease. Adequate gas exchange and aeration of blood are impossible when the lung's total dead space exceeds 60% of lung volume
  16. ventilatory threshold?
    • The point at which pulmonary ventilation increases disproportionately with oxygen uptake during graded exercise. At this exercise intensity, pulmonary ventilation no longer links tightly to oxygen demand at the cellular level. The excess ventilation correlates directly to carbon dioxide's increased output from the buffering of lactate that begins to accumulate from anaerobic metabolism
    • Point when lactate begins to accumulate
  17. afterload?
    Enhanced diastolic filling and more complete ventricular emptying during exercise despite an increased resitence to flow due to the upright body position.
  18. angina pectoris?
    Characterized by acute chest pain, it occurs from an imbalance between the oxygen demands of the heart and its oxygen supply. Pain results from metabolite accumulation within an ischemic segment of heart muscle
  19. bradycardia?
    HR <60bpm, stimulated through parasympathetic response

    Retardation of the sinus discharge rate slowing the heart. Influenced by acetylcholine, the parasympathetic nervous system hormone, via the cell bodies originating in the cardioinhibitory portion of the medulla by way of the vegas nerve
  20. catecholamines?
    Neural hormones, epinephrine and norepinephrine, which increase myocardial contractility and accelerate SA node depolarization to increase heart rate
  21. preload?
    Increased venous return that causes greater ventricular filling in the diastole during the cardiac cycle
  22. rate pressure product?
    • RPP=SBP x HR.
    • Closely reflects measurment of myocardial oxygen uptake and coronary blood flow inhealthy individuals over a range of exercise intensities. Provides an estimate of myocardial workload and O2 uptake.

    Index of relative cardiac work closely reflecting directly measured myocardial oxygen uptake and coronary blood flow in healthy subjects over a range of exercise intensities. Studies of cardiac patients have linked the RPP to the onset of angina and ECG abnormalities and RPP has also assessed various clinical, surgical, and exercise interventions for their effects on cardiac performance including aerobic training to increase the RPP of patients before they experience the onset of heart disease symptoms
  23. tachycardia?
    >100bpm, stimulated through the sympathetic response
  24. concentric hypertrophy?
    Modest thickening of the left ventricular cavity improving heart stroke volume due to long-term aerobic training
  25. eccentric hypertrophy?
    Increased size of the left ventricular cavity improving heart stroke volume due to long-term aerobic training. Usually returns to control levels when training intensity is reduced
  26. heart rate reserve?
    Lower and upper threshold heart rate level calculated at a percentage of the difference between resting and maximum heart rate
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unit 3 definitions for flashcards.txt
2012-03-28 17:06:04
Exercise physiology definitions

Ex Phys unit 3 definitions
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