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Pulmonary Systems Chapter 9 in text. Mid session Available 21/8/07 – 28/8/07 Practice test now available Log on to WebCT “Assessments” “Mid session quiz”

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Presentation on theme: "Pulmonary Systems Chapter 9 in text. Mid session Available 21/8/07 – 28/8/07 Practice test now available Log on to WebCT “Assessments” “Mid session quiz”"— Presentation transcript:

1 Pulmonary Systems Chapter 9 in text

2 Mid session Available 21/8/07 – 28/8/07 Practice test now available Log on to WebCT “Assessments” “Mid session quiz” Start only when ready 30 minute time limit

3 Pulmonary Systems Review Structure Function

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5 Pulmonary Structure and Function The ventilatory system –Supplies oxygen required in metabolism –Eliminates carbon dioxide produced in metabolism –Regulates hydrogen ion concentration [H + ] to maintain acid-base balance

6 Mechanics of Breathing

7 Breathing At rest –Air in  Trachea- humidified and brought to body temperature –  divides into 2 branches  lungs –Lungs hold 4-6 litres of ambient air- huge surface area –300 million alveoli –250 ml oxygen in and 200 ml Carbon dioxide out each minute

8 Inspiration Ribs rise Diaphragm contracts (flattens) Moves downward (10cm) Thoracic volume Air in lungs expands Pressure to 5 mm Hg below atmospheric pressure Difference between outside air and lungs = air is sucked in until pressure inside and out is the same

9 Expiration Ribs move back down Diaphragm relaxes (rises) Thoracic volume Pressure Difference between outside air and lungs = air is pushed out until pressure inside and out is the same

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11 Lung Volumes

12 Static lung volume tests –Evaluate the dimensional component for air movement within the pulmonary tract, and impose no time limitation on the subject Dynamic lung volume tests –Evaluate the power component of pulmonary performance during different phases of the ventilatory excursion

13 Spirometry Static and Dynamic lung volumes are measured using a spirometer

14 Static Lung Volumes

15 Dynamic lung volumes Depend on Volume of air moved and the Speed of air movement FEV/FVC ratio MVV

16 FEV/FVC Ratio Forced Expiratory Volume Forced Vital Capacity Ratio tells us the speed at which air can be forced out of lungs Normal = 85% FVC can be expired in 1 second.

17 Maximal Voluntary Ventilation Breath as hard and fast as you can for 15 seconds Multiply by 4 And you have Maximal Voluntary Ventilation MVV- –Males: Litres –Females: Litres –Elite athletes up to 240 Litres

18 Minute Ventilation At Rest 12 breaths per minute Tidal volume = 0.5L per breath = 6 Litres of air breathed p/min During Exercise 50 breaths p/ minute Tidal Volume = 2 L per breath = 100L p/min

19 Alveolar Ventilation Minute ventilation is just total amount of air Alveolar ventilation refers to the portion of minute ventilation that mixes with the air in the alveolar chambers Minute ventilation minus anatomical dead space ( ml)- the air that is in the trachea, bronchi etc

20 Alveolar Ventilation = Minute ventilation (TV x breathing rate) – dead space

21 Gas exchange

22 Gas Exchange in the Body The exchange of gases between the lungs and blood, and their movement at the tissue level, takes place passively by diffusion

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24 Oxygen Transport in the Blood Blood transports oxygen in 2 ways: In physical solution — Dissolved in the fluid portion of the blood Combined with hemoglobin — In loose combination with the iron-protein hemoglobin molecule in the red blood cell

25 CO 2 Transport in Blood In physical solution –(~7%) dissolved in the fluid portion of the blood As carbamino compounds –(~20%) in loose combination with amino acid molecules of blood proteins As bicarbonate –(~73%) combines with water to form carbonic acid

26 Regulation of Pulmonary Ventilation

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28 Regulation at rest: Plasma Pco 2 and H + Concentration The partial pressure of CO 2 provides the most potent respiratory stimulus at rest [H + ] in the cerebrospinal fluid bathing the central chemoreceptors provides a secondary stimulus driving inspiration

29 Ventilatory Regulation During Exercise Chemical control –Po 2 –Pco 2 –[H + ] Nonchemical control Neurogenic factors –Cortical influence –Peripheral influence

30 Ventilation in steady rate exercise Of oxygen ( V E / V O 2 ) –Quantity of air breathed per amount of oxygen consumed –Remains relatively constant during steady- rate exercise- 25 L air breathed per 1L o2 consumed at 55% Vo2 max Of carbon dioxide ( V E / V CO 2 ) –Remains relatively constant during steady- rate exercise

31 Ventilatory Threshold The point at which pulmonary ventilation increases disproportionately with oxygen uptake during graded exercise The excess ventilation relates to the increased CO 2 production associated with buffering of lactic acid

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33 Pulmonary adaptations to Exercise Chapter 13

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35 Adaptations to Maximal exercise Minute ventilation increases Increased oxygen uptake

36 Submaximal Exercise Ventilatory muscles stronger Ventilatory equivalent for oxygen ( V E / V O 2 ) reduces  indicates breathing efficiency –This leads to Reduced fatigue in ventilatory muscles O2 that would have been used by those muscles can be used by skeletal muscle.

37 Pulmonary Adaptations Increased tidal volume Decreased breathing frequency Increased time between breaths (Increased time for oxygen to get into bloodstream) Therefore less oxygen in exhaled air


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