what are the 3 functions of the respiratory system?
- Extract o2 from the atmosphere and transfer it to the blood
- excrete water vapour and co2
- ventilate the lungs
What is the components of inspired air?
- o2 - 21%
- nitrogen- 78%
- co2- 0.04%
- water vapour (variable)
what are the components of expired air?
- o2- 16%
- nitrogen- 78%
- co2- 4%
- water vapour (to saturation)
how many sinuses are there within the skull?
what are the 3 functions of the nose?
- Warming the air we breathe in
- filtering and cleaning of air
How many tonsils are there?
what are the tonsils role?
help in immune response
what are the 3 parts of the pharynx?
What are the 3 functions of the pharynx?
- passageway for air and food
- resonating chamber for speech sounds
- houses tonsils
How long is the pharynx?
Where does the pharynx extend down to?
cricoid cartilage of the larynx
What is the pharynx lined with and what is it composed of?
- mucous membrane
- skeletal muscle
where does the nasopharynx lie?
behind nasal cavity and is superior to the soft palate
what does the nasopharynx contain?
orifices of auditory tubes that open into the middle ear
Where does the oropharynx extend?
from the level of the soft palate to level of hyoid bone
what two systems cross over at the oropharynx?
respiratory and digestive
Where does the laryngopharynx start?
level of the hyoid bone
what does the larynx connect?
laryngopharynx with trachea
Where does the larynx lie?
- in midline of the neck
- anterior to the C3 through to C6
What are the 3 single cartilages in the larynx?
what is the paired cartilage in the larynx?
what are the 5 functions of the larynx?
- production of sound
- protection of the lower respiratory tract during swallowing
- provides a passageway for air from the pharynx to the trachea
- continues the process of humidifying, filtering and warming inspired air
what is the epiglottis and where is it attached?
- elastic cartilage attached to anterior rim of thyroid
- leaf shaped, moves up and down like a trap door.
What is the thyroid cartilage?
- forms anterior wall of the larynx
- connected to hyoid bone by thyrohyoid membrane
what happens if food or fluid get past the epiglottis and into the trachea?
cough reflex which gets rid of the food or fluid from the respiratory tract.
what is the space between the vocal cords called?
What is the structure of the trachea?
16-20 incomplete C shaped rings
Where does the trachea extend down to?
larynx to T5
How long is the trachea?
about 10-11 cm
What is the outer layer of the trachea composed of?
fibrous and elastic tissue
What is the middle layer of the trachea composed of?
cartilage and smooth muscle
What is the inner layer of the trachea lined with?
ciliated columnar epithelium containing goblet cells
What do the C shaped rings provide?
semi ridged support to stop the trachea collapsing with the pressure changes
Where does the trachea terminate?
Carina at T5
What happens to the trachea at Carina?
bificates into R and L bronchus
What are the 4 functions of the trachea?
- Support and patency
- mucociliary escalator
- cough reflex
- warming, humidifying and filtering air
What is the difference between the R and L bronchus?
R primary is more vertical/ shorter & wider than the L
Which bronchus is an aspirated object more likely to go down?
Right primary bronchus
What happens to the primary bronchus when entering the lungs?
primary divide into the secondary (lobar) bronchi
what do the bronchi progressively subdivide into?
secondary bronchi- tertiary bronchi- bronchioles- terminal bronchioles
what are the wider passages of the bronchi called?
conducting airways (walls too thick for gas exchange)
what is the extensive branching of the bronchis from the trachea commonly known as?
the bronchial tree
As the bronchi divide what are the structural changes to the cartilage?
- Larger airways have rigid cartilage.
- No cartilage at bronchiolar level- would prevent gas exchange
As the bronchi divide, what are the structural changes to the smooth muscle?
- replaces cartilage in smaller airways
- allows airway diameter to increase/decrease
As the bronchi divide, what are the structural changes to the epithelial lining?
- Ciliated epithelium is gradually replaced with non- ciliated epithelium
- goblet cells disappear
Once inside the lobes of the lungs, what o the bronchi progressively sub divide into?
What do the bronchioles sub divide into?
- Terminal bronchioles
- respiratory bronchioles
- alveolar ducts
Where are the lungs situated?
- Either side of the mediastinum
- within the thoracic cavity
How many lobes does the right lung have?
How many lobes does the left lung have?
What is the lung described to have?
- costal surface
- medial surface
Where is the hilum on the lungs?
What are the lungs & interior of thoracic cavity lined by?
two layers of serous membrane- the pleura
What is the inside layer of the thoracic cage called?
What is the layer that covers the lungs called?
What is the space between the parietal pleura and the visceral pleura called?
What is the pleura?
Serous membrane which surrounds each lung
What separates the visceral and parietal pleura?
What pleura is attached to the lung?
What lines the wall of the thoracic cavity?
What does the serous fluid in between the parietal and visceral pleura do?
- reduces friction
- allows them to slide easily over one and other during breathing
What are the two circulation systems in the lungs?
pulmonary and systemic
What is pulmonary circulation?
process of deoxygenated blood being sent to the lungs to get oxygen via the pulmonary trunk
What is ventilation?
Gases are exchanged between the atmosphere & the alveolus
The pressure inside the alveoli with respect to the atmosphere is changed by what?
changes in the size of the lungs
what is the diaphragm?
sheet of muscle that separates the thoracic from the abdominal cavities
What shape is it when it is relaxed?
diaphragmatic activity is responsible for what percentage of air entry?
What direction do the intercostal muscles pull the rib cage in inspiration?
upwards and outwards
Where does the gas exchange take place in the lungs?
- walls of the alveolar ducts
What is the anatomical dead space?
- volume of air that does not take part in gas exchange
- 150 ml
What is tidal volume?
- the amount of air exchanged with each breath
- approx 500mls
How do you work out minute volume?
tidal volume x breathing rate per minute
500mls x 15 bpm = 7.5L
What is partial pressure?
The pressure of a specific gas in a mixture
Where do gases move to?
from a high pressure to low pressure
What is diffusion?
a movement of a solute from a high concentration to a low concentration through a semi permeable membrane
What is external respiration?
exchange of gases between the alveoli and the blood in the alveolar capillaries
What is internal respiration?
exchange of gases between blood in the capillaries and the body cells.
Where does the voluntary control of respiration originate?
Where does the autonomic nervous control of respiration originate?
- the respiratory centre
- group of nerves in the medulla
What is the chemical control of respiration?
What do chemoreceptors detect?
changes in the partial pressures of o2 and co2 in the blood and CSF
where are the central chemoreceptors located?
- in the respiratory centre
- also respond to changes in pH
Where are the peripheral chemoreceptors located?
- in arch of aorta
- bifurcation of common carotids
What is a normal breathing rare for an adult?