1.2 respiratory system Flashcards
Define diffusion
the movement of gases from an area of high concentration or partial pressure to an area of low concentration or partial pressure
Define gaseous exchange
the movement of oxygen from the air into the blood, and CO2 from the blood into the air
How are the alveoli adapted for gas exchange?
- walls are only one cell thick so there is a short diffusion pathway
- great blood supply due to extensive capillary network surrounding the alveoli
- large surface area
What muscles are used for inspiration at rest?
- diaphragm
- external intercostals
What muscles are used for inspiration during exercise?
- diaphragm
- external intercostals
- sternocleidomastoid
- scalenes
- pectoralis minor
What muscles are used for expiration at rest?
passive: diaphragm and external intercostals relax
What muscles are used for expiration during active?
- abdominals
- internal intercostals
What happens to the ribcage and diaphragm during inhalation?
- ribcage moves up and outwards
- diaphragm contracts and is pulled flat
What happens to the ribcage and diaphragm during exhalation?
- ribcage falls
- diaphragm relaxes and rises to dome shape position
Define tidal volume
volume of air breathed in or out per breath
Define minute ventilation
the volume of air breathed in or out per minute
How do you work out minute ventilation?
number of breaths (per min) x tidal volume
Define inspiratory reserve volume
the volume of air that can be forcibly inspired after a normal breath
Define expiratory reserve
the volume of air that can be forcibly expired after a normal breath
Define residual volume
the amount of air that remains in the lungs after maximal expiration
What happens to tidal volume during exercise?
increases
What happens to inspiratory reserve volume during exercise?
decreases
What happens to expiratory reserve volume during exercise?
slight decrease
What happens to residual volume during exercise?
stays the same
What happens to minute ventilation during exercise?
large increase
What is a spirometer?
a device used to measure the volume of air inspired and expired by the lungs
State the 2 purposes of gaseous exchange
- getting oxygen in air into the lungs so that it can diffuse into the blood and be transported to the cells of the body
- removal of CO2 from the blood
Define partial pressure
the pressure exerted by an individual gas when it exists within a mixture of gases
What is the partial pressure of oxygen in the alveoli?
100mmHg
What is the partial pressure of oxygen in the capillaries?
40mmHg
Define the concentration/diffusion gradient
explains how gases flow from an area of high concentration to an area of low concentration. the steeper the gradient, the faster the diffusion occurs
What is the partial pressure of carbon dioxide at the capillaries?
45mmHg
What is the partial pressure of carbon dioxide at the alveoli?
40mmHg
What is the partial pressure of oxygen in the capillary membranes surrounding the muscles?
40mmHg
What is the partial pressure of oxygen in the blood near the muscles?
100mmHg
What is the partial pressure of CO2 in the blood near the muscles?
40mmHg
What is the partial pressure of CO2 in the tissues?
46mmHg
What 3 factors are involved in pulmonary ventilation?
- neural control
- chemical control
- hormonal control
What is the effect of the sympathetic nervous system on breathing rate?
increases breathing rate
What is the effect of the parasympathetic nervous system on breathing rate?
decreases breathing rate
Where is the respiratory centre located?
medulla oblongata
What does the respiratory centre control?
the rate and depth of breathing and uses neural and chemical control
What are the 2 main areas of the respiratory centre?
- inspiratory centre: responsible for inspiration and expiration
- expiratory centre: stimulates the expiration muscles during exercise
Which nerve does the respiratory centre send an impulse down to increase inspiration?
phrenic nerve
Which nerve does the respiratory centre send an impulse down to increase expiration?
intercostal nerve
What happens to breathing rate when there is an increase in carbon dioxide and lactic acid?
- chemoreceptors (found in carotid arteries and aortic arch) detect changes in blood acidity
- they send impulses to the inspiratory centre
- the respiratory centre sends impulses down the phrenic nerve to stimulate more inspiratory muscles (sternocleidomastoid, scalenes and pectoralis minor)
- as a result the rate, depth and rhythm of breathing increase
How do stretch receptors work during exercise?
- during exercise the lungs are stretched more
- stretch receptors prevent over-inflation of the lungs by sending impulses to the expiratory centre and down the intercostal nerve to the expiratory muscles (abdominals and internal intercostals)
- so expiration occurs
What effect does a decrease in blood pressure have on breathing rate?
increases breathing rate
baroreceptors detect change in blood pressure
What are cilia?
Cilia are microscopic hair-like projections that help to sweep away fluids and particles
What are the effects of smoking on the alveoli?
Smoking can damage the walls of the alveoli meaning they break down and join together forming larger air spaces than usual which reduces gaseous exchange efficiency. The risk of chronic obstructive pulmonary disease (COPD) is also increased.
What is the affect of smoking on the respiratory system?
- Smoking can cause irritation to trachea and bronchi. It damages the cells lining the trachea, bronchi and bronchioles which are lined with cilia.
- smoking reduces lung function and increases breathlessness caused by the swelling and narrowing of the arteries
What happens when cilia are damaged?
When cilia are damaged, excess muscle builds up in the lung passages which leads to a smokers cough trying to clear the excess mucus
How does smoking affect oxygen transport?
- reduces oxygen-carrying capacity of the blood as carbon monoxide combines with haemoglobin much more readily than oxygen
- causes breathlessness during exercise
