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Pulmonary Systems Chapter 9 in text.

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Presentation on theme: "Pulmonary Systems Chapter 9 in text."— 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


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 3 main functions GAS EXCHANGE ANIMATION

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 Main idea of the lungs is that they are a very compact and convenient area for gas exchange Probably read in the text that, although lungs weigh only about 1 kg, if spread out, would cover the same area as ½ a tennis court, or 1 whole badminton court Alveoli Where all the action happens!! Latin for “little cavity” Alveoli is completely intertwined with capillaries; and the walls of the alveoli and the cappilaries are both thin enough to allow oxygen and carbon dioxide to travel through the walls

8 Diaphragm contracts (flattens) Moves downward (10cm) Thoracic volume
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 Lungs do not contain muscle that contracts them (Like the heart) Instead, diaphragm controls thoracic volume and subsequent pressure. Ribs rise due to contraction of intercostal muscles

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 Ribs move down due to relaxation intercostal muscles (breathing at rest) Feel that pressure increase when you are swimming underwater, holding breath Expiration during exercise is far more forceful due to the actions of the intercostal and abdominal muscles  more forceful expiration to eliminate Co2  also increased differences in pressure that results in increased oxygen being drawn in. What do you notice about the arrows on both of these pages?? Up down up down or down up down up Can simplify and say that when diaphragm goes down, air goes in and when diapraghm goes up, air goes out


11 Lung Volumes

12 Lung Volumes Static lung volume tests Dynamic 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 Static= space available Dynamic = power / force behind expiration

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

14 Static Lung Volumes TV- breath normally- this is your tidal volume
IRV- breath normally, breath out normally, then breath in as much as you can. This is inspiratory reserve- it is the max capacity for air in the lungs. Can be 2-3 litres Breath normally ERV- Breath in normally, then breath out as much as you can – average one litre of air FVC (Forced vital capacity) = maximum you can force in and out of lungs IRV + ERV RLV- residual- the lungs are never empty- RLV is the amount left in them after forced expiration. Usually one litre\ TLC- Total lung capacity = amount you can force in/ out + residual volume left- TLC = IRV + ERV + RLV

15 Dynamic lung volumes Depend on Volume of air moved and the
Speed of air movement FEV/FVC ratio MVV Remember dynamic is looking at the power behind what you can breath

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. FVC= max amount expired after maximal inspiration Ususally used in the diagnosis of obstructive lung diseases such as emphysema, asthma etc

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 Anatomical dead space = air that isn’t in alveoli and is therefore no good at all as is not involved with gas exchange in the blood

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


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 CO2 Transport in Blood In physical solution As carbamino compounds
(~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

27 Temp- increse in body temp directly stimulates neurons to fire to tell the diaphragm and intercostal muscles to act

28 Regulation at rest: Plasma Pco2 and H+ Concentration
The partial pressure of CO2 provides the most potent respiratory stimulus at rest [H+] in the cerebrospinal fluid bathing the central chemoreceptors provides a secondary stimulus driving inspiration If you hold your breath, the thing that forces you to breath again is the high Co2

29 Ventilatory Regulation During Exercise
Chemical control Po2 Pco2 [H+] Nonchemical control Neurogenic factors Cortical influence Peripheral influence During exercise Remember oxygen debt and deficit? Start exercise- rapid increase in breaathing rate- 1st 20 seconds = plateau Stop exercise- fairly rapid slowing down, but remains at 40% of what was happening during exercise Think about what happened in lactate threshold test Chemical- levels of these three prompt action Co2 is by product of atp production; Hydrogen is produced in glycolysis  Kreb’s cycle Nonchemical- Neural control- brain tells the neurons to tell the diaphragm and intercostals to relax/ contract  inflate Cortical- anticipatory effect Peripheral- respiration increases because the joints/muscles are moving  receptors

30 Ventilation in steady rate exercise
Of oxygen ( V E/ V O2) 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 CO2) 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 CO2 production associated with buffering of lactic acid Another threshold!

32 Have to increase ventilation to increase amount of oxygen to enable aerobic respiration

33 Pulmonary adaptations to Exercise
Chapter 13

34 Goals of aerobic training

35 Adaptations to Maximal exercise Minute ventilation increases
Increased oxygen uptake Pulmonary adaptations often some of the first to be noticed basically reduced feeling of breathlessness in untrained 20 weeks of training increased pulmonary muscle strength by 16%  intercostals and diaphragm better able to create pressure differences which result in inspiration/ expiration

36 Submaximal Exercise Ventilatory equivalent for oxygen
Ventilatory muscles stronger Ventilatory equivalent for oxygen ( V E/ V O2) 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. Ventlatory equivalent for oxygen is the ratio of the amount of air breathed to the amount of oxygen obtained

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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