1.2 The Respiratory System Flashcards
What is the passage of air?
- Nose
- Pharynx
- Larynx
- Trachea
- Bronchi
- Bronchioles
- Alveoli
What muscles are used for inspiration at rest?
Diaphragm
External intercostals
What muscles are used for inspiration during exercise?
Diaphragm
External intercostals
Sternocleidomastoid
Scalene
Pectoralis minor
What muscles are used for expiration at rest?
Diaphragm
External intercostal
(relax)
What muscles are used for expiration during exercise?
Internal intercostals
Abdominals
Definition of gaseous exchange
The movement of oxygen from the air into the blood, and carbon dioxide from the blood into the air.
Features of alveoli to assist gaseous exchange
- Large SA –> more rapid diffusion
- Thin/moist walls –> short distance for diffusion
- Lots of capillaries –> large blood supply
Definition of diffusion
The movement of gas molecules from high to low concentration/partial pressure.
Definition of tidal volume
Volume of air breathed in or out per breath. Increases during exercise.
Definition of inspiratory/expiratory reserve volume
Inspiratory is the volume of air that can be forcibly inspired after a normal breath.
Expiratory is the volume of air that can be forcibly expired after a normal breath.
Definition of residual volume
The volume of air remaining in the lungs after maximum expiration.
Definition and calculation of minute ventilation
Volume of air breathed in or out per minute.
Minute ventilation = tidal vol x number of breaths/min
What does a spirometer measure?
Volume of air inspired and expired by the lungs.
What happens to CO₂ and O2 during gaseous exchange?
CO₂ diffuses from the blood capillary into the alveolus along the concentration gradient.
O2 diffuses from the high concentration in the alveolus to the low concentration in the blood capillary.
What happens to pressure during inspiration?
When the diaphragm and external intercostals contract, it causes the ribcage to move upwards/outwards which DECREASES pressure in the chest cavity as there is more space.
What happens to pressure during expiration?
When the diaphragm relaxes, it rises into a dome-shaped position which INCREASES pressure in the chest cavity.
What is the function of the respiratory system?
To get oxygen to the working muscles and get rid of CO2.
Gas exchange at the alveoli
O2 diffuses from alveoli into blood, CO2 diffuses from blood into alveoli.
Partial pressure of oxygen is higher in the alveoli than in the blood capillary.
This is because oxygen has been removed by the working muscles so the concentration/partial pressure in the blood is lower.
Oxygen will diffuse from the alveoli into the blood until the pressure is equal in both.
Gas exchange at the muscles
O2 enters the muscles from the blood, and CO2 enters the blood from the muscles.
How does smoking affect the respiratory system?
- Causes irritation in the trachea and bronchi.
- Reduces lung function.
- Increases breathlessness (swelling/narrowing of airways).
- Cigarette smoke damages cell lining.
- Smokers cough.
- COPD, emphysema, lung disease.
- Inhalation of smoke causes paralysis of the cilia.
What happens when blood acidity is high?
The brain sends impulses through the nervous system to increase breathing.
How is pulmonary ventilation controlled?
By the nervous system, which has two systems: sympathetic and parasympathetic.
What does the sympathetic nervous system do?
Prepares the body for exercise and increases breathing rate.
What does the parasympathetic nervous system do?
Lowers breathing rate.
Where is the respiratory centre located and what does it do?
Located in the medulla oblongata and controls the rate/depth of breathing using neural and chemical control
The Respiratory Centre (4 steps)
- Responds to changes in blood chemistry.
- These changes are detected by chemoreceptors.
- They send impulses to the inspiratory centre to increase ventilation until blood acidity returns to normal.
- Respiratory centre sends impulses down the phrenic nerve to stimulate more inspiratory muscles to increase breathing.
Order of neural/chemical control for inspiration
Receptors
Medulla oblongata
Phrenic nerve
Diaphragm, external intercostals, sternocleidomastoid, scalene, pectoralis minor
Order of neural/chemical control for expiration
Receptors
Medulla oblongata
Intercostal nerve
Abdominals, internal intercostals
Factors affecting neural control of breathing
- Mechanical factors: provide feedback to respiratory centre to increase breathing during exercise.
- Baroreceptors: a decrease in blood pressure in the aorta and carotid arteries = increased breathing.
- Stretch receptors: prevent over inflation of the lungs
What is adrenaline?
A natural stimulant which is the body’s activator and is released in response to exercise.
Where is adrenaline made?
Adrenal gland in the kidney
How does adrenaline work?
Just before exercise, the brain sends impulses to the renal glands which then pumps adrenaline into the blood, in anticipation of the increased need for O2 and CO2 exchange.
