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53 Cards in this Set

  • Front
  • Back

Define Ventilation

Exchange of air in the lungs

Define Respiration

Gas exchange bw


- air and blood in the lungs (external respiration)


- blood and other tissues in the body (internal respiration)

Gas exchange

1. Ventilation


2. Respiration


- internal


- external

Ventilation @ rest and @max exercise

Rest = 4-6 L/min


Max = 150 L/min

Define Ventilatory system

System that regulates the gaseous state of the body’s external environment to effectively aerate body fluid

VS consists of:

Conductive portions;


- nose, mouth, trachea and primary bronchi


Transitional and respiratory zones


- bronchioles, alveolar ducts and alveoli

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)

Transitional and respiratory zones

- large number of small tubes which resist gas flow


- gas exchange site

What’s Boyle’s law

Inverse relationship bw volume and pressure


Volincreases pressure decreases

What drives ventilation ?

Boyle’s law

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

How much air can the VS hold?

~3 L

Average sized adult lung (weight & volume)

~ 1 kg


~ 4-6 L

Surface area of alveoli

50-100m^2

Describe alveoli

- elastic thin walled membranous sacs


-~ 0.3um diameter


- surface of gas exchange be lung tissue and blood

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

What’s the air-blood barrier

2 cells thick


Capillary and alveoli walls

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

Each minute at intense exercise how much o2 transfers across the air blood barrier

~ 25 x o2 amount at rest

What purpose does ventilation serve during rest and exercise?

Maintain constant (and favourable) concentration of o2 and co2

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

Residual lung volume

Volume in lungs after max expiration (0.8-1.4 L)


Allows constant flow of

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 )

What is the diaphragm

Striated musculofibrous tissue


Dome shaped


Creates an air tight seperation bw the abdominal and thoracic cavities


Can move ~ 10 cm

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

What is lung volume dependent on (4)

Age


Gender


Height


Body size/composition

Spirometer

Measures lung volumes

Lung capacities

Derived by adding 2 or more volumes together

Tidal volume

Amount of air we breathe in and out at rest volume (~400-1000mL)

Inspiratory reserve volume

Max inspiration following tidal inspiration (2.5-3.5 L)

Exploratory reserve volume

Max expiratiry at end of tidal expiration (1-1.5 L)

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

Name the different lung capacities (4)

Functional residual capacity


Inspiritory capacity


Forced vital capacity


Total lung capacity

Functional residdual capacity

volume in lungs after tidal inspiration


FRC =ERV + RV

Inspiratory capacity

max volume inspired following tidal expiration


IC = TV + IRV

Forced vital capacity

Max volume expired after max inspiration


FVC = IRV + TV + ERV


= 3-5 L

Total lung capacity

volume in lungs after max inspiration


TLC = IC + FRC


= RV + ERV + TV + IRV


= 4-6 L

Static lung function

volumes/capacities assessed during a single breath

Dynamic lung function

volumes/capacities of air moved over a time period

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)

What do dynamic lung volumes depend on

resistance of respiritory passage


lung compliance (stiffness)

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

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

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



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

Dynamic lung function tests provide info re:

- the severity of obstructive and restrictive lung diease


- little info regarding aerobic fitness

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

Define pulmonary ventilation

= total volume of air breathed in and out each minute


Ve= breathing rate x tidal volume

How do you increase ventilation

Increase rate or depth of breathing

Define alveolar ventilation

Portion of inspired air that reaches the alveoli and participates in gas exchange


(mL/minute)

Define Anatomical dead space (VD)

Air that fills the conducting zone of the lungs (nose - bronchioles)


~30% testing TV

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

Ve =

VD + VE