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53 Cards in this Set
- Front
- Back
Define Ventilation |
Exchange of air in the lungs |
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Define Respiration |
Gas exchange bw - air and blood in the lungs (external respiration) - blood and other tissues in the body (internal respiration) |
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Gas exchange |
1. Ventilation 2. Respiration - internal - external |
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Ventilation @ rest and @max exercise |
Rest = 4-6 L/min Max = 150 L/min |
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Define Ventilatory system |
System that regulates the gaseous state of the body’s external environment to effectively aerate body fluid |
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VS consists of: |
Conductive portions; - nose, mouth, trachea and primary bronchi Transitional and respiratory zones - bronchioles, alveolar ducts and alveoli |
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Conducting zones |
- small number of large tubes which offer little resistance to air flow - no gas exchange - “anatomical dead space” - warm, humidify and filter air, converting from ambient temp/pressure/saturation (ATPS) to body temp/pressure/saturation (BTPS) |
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Transitional and respiratory zones |
- large number of small tubes which resist gas flow - gas exchange site |
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What’s Boyle’s law |
Inverse relationship bw volume and pressure Volincreases pressure decreases |
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What drives ventilation ? |
Boyle’s law |
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How do lungs expand without possessing any muscles? |
They adhere to the chest wall -> follows movement of chest Change in thoracic cavity vol = change in lung vol |
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How much air can the VS hold? |
~3 L |
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Average sized adult lung (weight & volume) |
~ 1 kg ~ 4-6 L |
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Surface area of alveoli |
50-100m^2 |
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Describe alveoli |
- elastic thin walled membranous sacs -~ 0.3um diameter - surface of gas exchange be lung tissue and blood |
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How does gas exchange happen at the alveoli |
- highly vascularised - receive largest blood supply - @rest each RBC passes 2-3 alveoli in 0.5-1 sec - @max exercise 1 pint (~0.5L) of blood flows through lung tissue vessels in 1 sec |
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What’s the air-blood barrier |
2 cells thick Capillary and alveoli walls |
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Each minute @ rest how much ; o2 co2 pass through the alveoli |
~250 ml of o2 leave alveoli -> blood ~200 ml of co2 leave blood -> alveoli |
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Each minute at intense exercise how much o2 transfers across the air blood barrier |
~ 25 x o2 amount at rest |
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What purpose does ventilation serve during rest and exercise? |
Maintain constant (and favourable) concentration of o2 and co2 |
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Mechanisms of inspiration |
- diaphragm contracts, flattens and moves down ~10 cm = increase volume decrease intrapulmonic pressure (below atmospheric press - lungs inflate - increased inspiration movement = increase filling |
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Residual lung volume |
Volume in lungs after max expiration (0.8-1.4 L) Allows constant flow of |
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How does the thoracic volume increase during inspiration ? |
Diaphragm and external intercostals : increase thorax/ decrease intra-thoracic pressure External intercostals: lift the ribs and rotated them outwards (up and away: bucket handle) Accessory muscles = pec Minot, serratus anterior, scaleni muscles and sternocleidomastoid : lift the thorax (increase its dimensions ) |
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What is the diaphragm |
Striated musculofibrous tissue Dome shaped Creates an air tight seperation bw the abdominal and thoracic cavities Can move ~ 10 cm |
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Mechanisms of expiration |
Passive process : natural recoil of the lung tissue, relaxation of respiratory muscles Abdominal muscles: contract and increase intra-abdominal pressure, thereby forcing the diaphragm upwards Internal intercostals: lower the ribs and move them closer together-> reduces thoracic dimensions |
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What is lung volume dependent on (4) |
Age Gender Height Body size/composition |
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Spirometer |
Measures lung volumes |
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Lung capacities |
Derived by adding 2 or more volumes together |
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Tidal volume |
Amount of air we breathe in and out at rest volume (~400-1000mL) |
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Inspiratory reserve volume |
Max inspiration following tidal inspiration (2.5-3.5 L) |
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Exploratory reserve volume |
Max expiratiry at end of tidal expiration (1-1.5 L) |
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Residual lung volume |
- volume in lungs after max expiration (0.8-1.4L) - allows constant flow of gas bw blood and alveoli --> preventing flactuations in gas during regular breathing - increases with age --> reduced elasticity of lung tissues (regular exercuse blunts this) - cannot be directly measured by spirometery |
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Name the different lung capacities (4) |
Functional residual capacity Inspiritory capacity Forced vital capacity Total lung capacity |
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Functional residdual capacity |
volume in lungs after tidal inspiration FRC =ERV + RV |
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Inspiratory capacity |
max volume inspired following tidal expiration IC = TV + IRV |
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Forced vital capacity |
Max volume expired after max inspiration FVC = IRV + TV + ERV = 3-5 L |
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Total lung capacity |
volume in lungs after max inspiration TLC = IC + FRC = RV + ERV + TV + IRV = 4-6 L |
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Static lung function |
volumes/capacities assessed during a single breath |
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Dynamic lung function |
volumes/capacities of air moved over a time period |
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What do dynamic lung function consider |
1. Amount of air moved in each breath (FVC) 2. Speed at which the air is moved (breathing rate) |
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What do dynamic lung volumes depend on |
resistance of respiritory passage lung compliance (stiffness) |
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What is FEV1.0 to FVC ratio and what does it reflect |
forced expiratory volume in 1s / forced vital capacity x100 Reflects; - pulmonary expiratory power - overall resistance to air movement |
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FEV1.0/FVC for healthy individuals, and what is to indicate obstructive lung disease |
expel ~85% of their vital capacity in 1s --> less than 70% = obstructive lung disease --> <40% = severe obstructive lung disease ( emphysema or bronchial asthma |
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How to calculate Maximum voluntary ventilation(MVV) |
for 1 min is calculated by assessing volume of air during rapid and deep breathing over 15 s period |
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Typical range of MVV |
35-40 x amount of air you would expire in 1s (FEV1.0) Men = 140-180 Lmin-1 Female = 80-120 Lmin-1 Obstructive lung disease = ~40%of expected MVV |
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Dynamic lung function tests provide info re: |
- the severity of obstructive and restrictive lung diease - little info regarding aerobic fitness |
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Does ventilation limit maximal aerobic capacity ? |
No - even though feel "out of breath" or "winded" normal pulmonary ventilation does not limit maximal aerobic performance for most individuals |
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Define pulmonary ventilation |
= total volume of air breathed in and out each minute Ve= breathing rate x tidal volume |
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How do you increase ventilation |
Increase rate or depth of breathing |
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Define alveolar ventilation |
Portion of inspired air that reaches the alveoli and participates in gas exchange (mL/minute) |
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Define Anatomical dead space (VD) |
Air that fills the conducting zone of the lungs (nose - bronchioles) ~30% testing TV |
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Why do we have VD |
Fresh air mixes with alveolar air to prevent drastic change in alveolar air composition = consistent arterial blood gases throughout the breathing cycle |
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Ve = |
VD + VE |