1. Introduction to the Module
Lecture Content:
Functions of the Respiratory System
Anatomy - structure and function relationships
Gas Movement in the cardiorespiratory system
Tidal breathing relationship to gas exchange.
Functions of the Respiratory System all relates to it's anatomy. All cardiac output flows through the
pulmonary circulation. There is a large surface area for diffusion. All the CO is going through the
blood vessels towards the lungs, this makes the lungs it a useful site.
Functions:
• Gas Exchange - Large SA and close proximity. This is very efficient.
• Blood pH control - Henderson Hassel-Bach equations.
• Remove blood clots from the circulation
• Defence against microbes - it is good for immune function. There will a lot of WBC that live in
the lungs.
• Heat and Water loss through ventilation - there is heat exchange with the air but this is
controlled. We do not want to lose much water through this.
• Blood reservoir (Pulmonary vessels)
• Metabolic functions - active and inactive stuff e.g Ang II, BL, PGs, 5HT, Hist, Adr/Nadr, Sub P.
Functions of the upper airways:
Filtering - articulate matter gets stick on the lining of the mucus.
Warming - There is a good blood supply to the nose, this acts as a heat exchanger
Humidifying - we also add eater water to the heat air. There is fluid lining the membrane to the
alveoli to stop them form drying out.
Distribution.
Trachea has a C-shaped hyaline cartilage ring. This gives structure. As we move down into the
bronchus and bronchiole, we have more smooth muscle.
We have nerves, sensory and motor nerves. They give use control of the smooth muscle.
Capillaries are embedded in the wall, and so there is a short diffusion distance.
Clara cells produce mucus and the cilia cells push the mucus out.
Type 2 cell, they are missing in babies. This produces respiratory stress making it hard from them to
breath.
,Generation 0-16 - we have to move the gas all the way through. The trachea is bigger and each time
we go down, they are getting smaller.
Generation 17 onwards is where the gas exchange occurs.
As you get further down, there is a big increase in the total cross sectional area, even thought he
bronchus and bronchioles and alveoli are smaller in diameter. This results in a massive surface area.
There are about 3x106 alveoli with a surface area of 75x104cm2
Area and Gas Velocity:
By generation 17 velocity is less than the speed of diffusion.
Flow= Velocity x Area
Increasing total cross sectional area results in degreasing gas velocity.
Linking Velocity to gas transport
Mechanisms in Gas Transport:
Convection Diffusion
Moves down fluid/gas Moves down concentration
pressure gradient gradient
Flux= Velocity x Fick's Law (distance is very
Concentration important).
Found in 'larger' tubes Found at sites of gas
exchange
Conducting airways - blood Alveoli - systemic capillaries
vessels
Used to move O2/CO2 long Used to move O2/CO2 short
distances around the body distances around the body
Dead Space:
The volume of gas within the respiratory system where no gas exchange takes place. There are no
alveoli (anatomic), no airflow (unventilated alveoli) and no blood pressure (un-perfused alveoli)
There must be V and Q. Airflow and perfusion.
,First 16 generations have no alveoli and so no gas exchange. This results in anatomic dead space.
Alveolar dead space is usually since there is gas exchange in the alveoli. Therer4bg r can be
temporary changes such as during diseased states.
It is affected by:
Body Size, Age (slightly increases with age), Head position and Drugs
Anatomic Dead Space + Alveolar Dead Space = Physiological Dead Space.
(150ml) (0ml) (150ml)
Tidal Breathing and Ventilation:
Pattern of breathing:
In the tidal breathing, the tidal volume will be taken. Also breathing at certain rate.
VT- Tidal Volume (Volume expired in each breath) = 500 ml
fR- Respiratory Frequency (number of breaths/min) = 12 breaths/min
VE- Minute Ventilation (volume of air expired/min) = VT x fR
= 500x12
= 6000 ml/min
We need to have standard measurements, hence why we measure expired air.
The amount that goes into the alveolus space is what goes into gas exchange.
, Ventilation is matched to metabolism. This can be done by various ways, deeper breaths or
increasing the frequency.
The 4.2 litres of air about 20% of Oxygen. At rest, oxygen consumption is only 250 ml/min. the thing
that is driving the rate of expiration is to get rid of carbon dioxide.
Summary
• Multiple non-respiratory roles
• Roles of upper airways
• Generation of 0-16 are the conducting zone (anatomical dead space) and gas moves by
convection
• Generations 17-23 are gas exchange zones (alveoli) and gas moves by diffusion
• Alveolar ventilation is matched to metabolism.
2. Volumes and Pressures
Lecture Content
• Lung Volumes and Capacities
• Ideal Gas Law, Dalton's Law and Boyle's Law
• Water Vapour Pressure
Lecture Content:
Functions of the Respiratory System
Anatomy - structure and function relationships
Gas Movement in the cardiorespiratory system
Tidal breathing relationship to gas exchange.
Functions of the Respiratory System all relates to it's anatomy. All cardiac output flows through the
pulmonary circulation. There is a large surface area for diffusion. All the CO is going through the
blood vessels towards the lungs, this makes the lungs it a useful site.
Functions:
• Gas Exchange - Large SA and close proximity. This is very efficient.
• Blood pH control - Henderson Hassel-Bach equations.
• Remove blood clots from the circulation
• Defence against microbes - it is good for immune function. There will a lot of WBC that live in
the lungs.
• Heat and Water loss through ventilation - there is heat exchange with the air but this is
controlled. We do not want to lose much water through this.
• Blood reservoir (Pulmonary vessels)
• Metabolic functions - active and inactive stuff e.g Ang II, BL, PGs, 5HT, Hist, Adr/Nadr, Sub P.
Functions of the upper airways:
Filtering - articulate matter gets stick on the lining of the mucus.
Warming - There is a good blood supply to the nose, this acts as a heat exchanger
Humidifying - we also add eater water to the heat air. There is fluid lining the membrane to the
alveoli to stop them form drying out.
Distribution.
Trachea has a C-shaped hyaline cartilage ring. This gives structure. As we move down into the
bronchus and bronchiole, we have more smooth muscle.
We have nerves, sensory and motor nerves. They give use control of the smooth muscle.
Capillaries are embedded in the wall, and so there is a short diffusion distance.
Clara cells produce mucus and the cilia cells push the mucus out.
Type 2 cell, they are missing in babies. This produces respiratory stress making it hard from them to
breath.
,Generation 0-16 - we have to move the gas all the way through. The trachea is bigger and each time
we go down, they are getting smaller.
Generation 17 onwards is where the gas exchange occurs.
As you get further down, there is a big increase in the total cross sectional area, even thought he
bronchus and bronchioles and alveoli are smaller in diameter. This results in a massive surface area.
There are about 3x106 alveoli with a surface area of 75x104cm2
Area and Gas Velocity:
By generation 17 velocity is less than the speed of diffusion.
Flow= Velocity x Area
Increasing total cross sectional area results in degreasing gas velocity.
Linking Velocity to gas transport
Mechanisms in Gas Transport:
Convection Diffusion
Moves down fluid/gas Moves down concentration
pressure gradient gradient
Flux= Velocity x Fick's Law (distance is very
Concentration important).
Found in 'larger' tubes Found at sites of gas
exchange
Conducting airways - blood Alveoli - systemic capillaries
vessels
Used to move O2/CO2 long Used to move O2/CO2 short
distances around the body distances around the body
Dead Space:
The volume of gas within the respiratory system where no gas exchange takes place. There are no
alveoli (anatomic), no airflow (unventilated alveoli) and no blood pressure (un-perfused alveoli)
There must be V and Q. Airflow and perfusion.
,First 16 generations have no alveoli and so no gas exchange. This results in anatomic dead space.
Alveolar dead space is usually since there is gas exchange in the alveoli. Therer4bg r can be
temporary changes such as during diseased states.
It is affected by:
Body Size, Age (slightly increases with age), Head position and Drugs
Anatomic Dead Space + Alveolar Dead Space = Physiological Dead Space.
(150ml) (0ml) (150ml)
Tidal Breathing and Ventilation:
Pattern of breathing:
In the tidal breathing, the tidal volume will be taken. Also breathing at certain rate.
VT- Tidal Volume (Volume expired in each breath) = 500 ml
fR- Respiratory Frequency (number of breaths/min) = 12 breaths/min
VE- Minute Ventilation (volume of air expired/min) = VT x fR
= 500x12
= 6000 ml/min
We need to have standard measurements, hence why we measure expired air.
The amount that goes into the alveolus space is what goes into gas exchange.
, Ventilation is matched to metabolism. This can be done by various ways, deeper breaths or
increasing the frequency.
The 4.2 litres of air about 20% of Oxygen. At rest, oxygen consumption is only 250 ml/min. the thing
that is driving the rate of expiration is to get rid of carbon dioxide.
Summary
• Multiple non-respiratory roles
• Roles of upper airways
• Generation of 0-16 are the conducting zone (anatomical dead space) and gas moves by
convection
• Generations 17-23 are gas exchange zones (alveoli) and gas moves by diffusion
• Alveolar ventilation is matched to metabolism.
2. Volumes and Pressures
Lecture Content
• Lung Volumes and Capacities
• Ideal Gas Law, Dalton's Law and Boyle's Law
• Water Vapour Pressure
