Respiratory system Flashcards
Function of the respiratory system?
- To bring in air/ Oxygen to the body from the external environment so oxygen can be delivered to the muscles and tissues.
- Expel carbon dioxide/ waste products from the body.
Nose (function)
Filters and warms the air with a mucus membrane and hairs (cilia)
Pharynx
Throat
Larynx
Voice box, meets the trachea
Epiglottis
- Tissue that covers the trachea so food goes down the oesophagus
- Ensures that food is diverted into the oesophagus and not the trachea.
Bronchi
Distribute air
Nasal passage
Humidify air
Diaphragm
Contracts and pulls air into the lungs
Inspiration (breathing in)- active process as it requires contraction
- External intercostal muscles contact causing the ribcage to move upwards and outwards
- Diaphragm which forms the floor of the thoraic cavity contracts downwards and flattens.
- These actions together cause an increase in the volume of the thoraic cavity and decrease in the pressure within the lungs.
- Pressure gradient ( high to low)
- Air moves into lungs
Expiration (breathing out)- passive process since no muscular contractions are involved
- External intercostal mucles relax causing the ribcage to move downwards and inwards
- Diaphragm relaxes causing it to rise
- These movements decrease the volume of the thoraic cavity
- Then pressure increases within the lungs
- Pressure gradient (high-low)
- Air is forced out of the lungs
Why do the internal intercostal muscles and abdominals contract during exercise whilst expiring?
- Breathing rates are increased during exercise
- So expiration is aided by the internal intercostal muscles and abdominal muscles
- These pull the ribcage down more quickly and with greater force
What is the difference between a lung volume and a lung capacity?
A lung capacity is made up of two or more volumes
Tidal volume (definition)
- Volume of air inspired or expired per breath
Tidal volume (typical value at rest)
500ml
What is the change of tidal volume during exercise?
It increases
Inspiratory reserve volume (definition)
Following inspiration the amount of air that you could continue to inspire if required.
Inspiratory reserve volume (typical value at rest)
3100ml
What is the change of inspiratory reserve volume during exercise?
It decreases
Expiratory reserve volume (definition)
Volume of air that remains in the lungs after expiration
Expiratory reserve volume (typical value at rest)
1200ml
What is the change of expiratory reserve volume during exercise?
It decreases
Residual volume (definition)
The amount of air that remains in the lungs after maximal expiration
How do you work out residual voloume?
TLC-VC
Residual volume (typical value at rest)
1200ml
What is the change of residual volume during exercise?
It remains the same
Inspiratory capacity (definition)
Maximum volume of air inspired from resting expiratory levels
How do you work out Inspiratory capacity?
TV+IRV
Inspiratory capacity (typical value at rest)
5000ml
What is the change of inspiratory capacity during exercise?
It increases
Vital capacity (definition)
The maximum volume expired follwing maximum inspiration
How do you work out vital capacity?
IRV+TV+ERV
Vital capacity (typical value at rest)
5000ml
What is the change to vital capacity during exercise?
Slight decrease
Total lung capacity (definition)
The complete volume of air present in the lungs after maximal inspiration
How do you work out total lung capacity?
VC+RV
Total lung capacity (typical value at rest)
6000ml
What is the changes to total lung capacity during exercise?
Slight decrease
Minute ventilation (definition)
The volume of air inspired or expired per minute
How do you work out minute ventilation?
TV+ breathing rate
Minute ventilation (typical value at rest)
7500ml
What are the changes to minute ventilation during exercise?
Dramatic increase
Ventilation during exercise
- During exercise both the rate (frequency) and depth (tidal volume of breathing increases in direct proportion to the intensity of the activity.
- This is in order to satisfy the demand by the working muscles for oxygen and to remove the carbon dioxide and lactic acid that has been produced.
How does tidal volume increase?
By utilising both the inspiratory and expiratory reserve volumes
What are the two sites for gaseous exchange in the body?
- Between the air in the alveoli of the lungs and the blood in the surrounding alveolar capillaries
- Between the tissues/ muscles of the body and the surrounding blood capillaries
What is partial pressure?
The pressure that is exerted by an individual gas when it exists in a mixture of gases.
What gases is atmospheric pressure composed of and what are there percentages?
Nitrogen- 79%
Oxygen- 21%
Carbon dioxide- 0.03%
Together they exert a pressure of 760mmHg
What is the total atmospheric pressure?
760 mmHg
How do you find out the partial pressure?
By doing
760 divided by the percentage then multiply it by 100
How do you represent partial pressure of oxygen?
pO2
What is the distance between 2 pressures called?
Pressure gradient
Diffusion of o2
- By the time air has reached the alveoli the partial pressure of oxygen has reduced to only 105mmHg
- Blood entering the alveolar capillaries has a partial pressure of oxygen at 40mmHg
- Pressure gradient of 65mmHg is formed
- This causes oxygen to diffuse from the alveoli into the capillary blood. (high-low)
- Process continues until the pressure on both sides of the repiratory membrane is equal.
Diffusion of co2
- In the meantime, the partial pressure of co2 within the blood entering the alveolar capillaries has a partial pressure of 45mmHg when compared to that of alveoli at 40mmHg.
- Pressure gradient of 5mmHg
- Carbon dioxide will diffuse from capillary blood into the alveoli until pressure on both sides of the respiratory membrane becomes equal
What are factors that enable efficient diffusion at the alveoli ?
- Thin capillary membrane (diffusion distance is short) between alveoli and the blood
- The numerous alveoli create a large surface area
- The alveoli are surrounded by a vast network of capillaries which further provides a huge surface area for gas exchange.
- Slow flow of blood as reduced cross sectional area
What factors determine the partial pressure of any gases?
- Overall pressure
- Concentration of individual gas (%)
What significance does the size of the gradient have on the process of diffusion?
The higher the gradient the faster the diffusion
What challenges does the body have at altitude? What is the impact of breathing and oxygen delivery?
- Altitude lowers total air pressure
- So partial pressure of oxygen will be lower in the alveoli
- Smaller gradient now exists between the alveoli and capillary
- Resulting in slower diffusion of oxygen into blood