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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
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What is the components of inspired air?
- o2 - 21%
- nitrogen- 78%
- co2- 0.04%
- water vapour (variable)
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what are the components of expired air?
- o2- 16%
- nitrogen- 78%
- co2- 4%
- water vapour (to saturation)
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how many sinuses are there within the skull?
4
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what are the 3 functions of the nose?
- Warming the air we breathe in
- filtering and cleaning of air
- humidification
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How many tonsils are there?
5
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what are the tonsils role?
help in immune response
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what are the 3 parts of the pharynx?
- Nasopharynx
- oropharynx
- laryngopharynx
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What are the 3 functions of the pharynx?
- passageway for air and food
- resonating chamber for speech sounds
- houses tonsils
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How long is the pharynx?
12-14 cm
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Where does the pharynx extend down to?
cricoid cartilage of the larynx
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What is the pharynx lined with and what is it composed of?
- mucous membrane
- skeletal muscle
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where does the nasopharynx lie?
behind nasal cavity and is superior to the soft palate
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what does the nasopharynx contain?
orifices of auditory tubes that open into the middle ear
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Where does the oropharynx extend?
from the level of the soft palate to level of hyoid bone
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what two systems cross over at the oropharynx?
respiratory and digestive
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Where does the laryngopharynx start?
level of the hyoid bone
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what does the larynx connect?
laryngopharynx with trachea
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Where does the larynx lie?
- in midline of the neck
- anterior to the C3 through to C6
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What are the 3 single cartilages in the larynx?
- thyroid
- epiglottis
- cricoid
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what is the paired cartilage in the larynx?
arytenoid
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what are the 5 functions of the larynx?
- production of sound
- speech
- 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
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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.
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What is the thyroid cartilage?
- forms anterior wall of the larynx
- connected to hyoid bone by thyrohyoid membrane
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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.
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what is the space between the vocal cords called?
Glottis
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What is the structure of the trachea?
16-20 incomplete C shaped rings
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Where does the trachea extend down to?
larynx to T5
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How long is the trachea?
about 10-11 cm
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What is the outer layer of the trachea composed of?
fibrous and elastic tissue
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What is the middle layer of the trachea composed of?
cartilage and smooth muscle
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What is the inner layer of the trachea lined with?
ciliated columnar epithelium containing goblet cells
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What do the C shaped rings provide?
semi ridged support to stop the trachea collapsing with the pressure changes
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Where does the trachea terminate?
Carina at T5
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What happens to the trachea at Carina?
bificates into R and L bronchus
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What are the 4 functions of the trachea?
- Support and patency
- mucociliary escalator
- cough reflex
- warming, humidifying and filtering air
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What is the difference between the R and L bronchus?
R primary is more vertical/ shorter & wider than the L
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Which bronchus is an aspirated object more likely to go down?
Right primary bronchus
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What happens to the primary bronchus when entering the lungs?
primary divide into the secondary (lobar) bronchi
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what do the bronchi progressively subdivide into?
secondary bronchi- tertiary bronchi- bronchioles- terminal bronchioles
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what are the wider passages of the bronchi called?
conducting airways (walls too thick for gas exchange)
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what is the extensive branching of the bronchis from the trachea commonly known as?
the bronchial tree
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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
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As the bronchi divide, what are the structural changes to the smooth muscle?
- replaces cartilage in smaller airways
- allows airway diameter to increase/decrease
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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
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Once inside the lobes of the lungs, what o the bronchi progressively sub divide into?
bronchioles
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What do the bronchioles sub divide into?
- Terminal bronchioles
- respiratory bronchioles
- alveolar ducts
- alveoli
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Where are the lungs situated?
- Either side of the mediastinum
- within the thoracic cavity
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How many lobes does the right lung have?
3
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How many lobes does the left lung have?
2
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What is the lung described to have?
- apex
- base
- costal surface
- medial surface
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Where is the hilum on the lungs?
medial surface
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What are the lungs & interior of thoracic cavity lined by?
two layers of serous membrane- the pleura
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What is the inside layer of the thoracic cage called?
Parietal pleura
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What is the layer that covers the lungs called?
visceral pleura
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What is the space between the parietal pleura and the visceral pleura called?
pleural space
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What is the pleura?
Serous membrane which surrounds each lung
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What separates the visceral and parietal pleura?
serous fluid
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What pleura is attached to the lung?
visceral pleura
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What lines the wall of the thoracic cavity?
parietal pleura
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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
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What are the two circulation systems in the lungs?
pulmonary and systemic
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What is pulmonary circulation?
process of deoxygenated blood being sent to the lungs to get oxygen via the pulmonary trunk
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What is ventilation?
Gases are exchanged between the atmosphere & the alveolus
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The pressure inside the alveoli with respect to the atmosphere is changed by what?
changes in the size of the lungs
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what is the diaphragm?
sheet of muscle that separates the thoracic from the abdominal cavities
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What shape is it when it is relaxed?
dome shaped
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diaphragmatic activity is responsible for what percentage of air entry?
75%
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What direction do the intercostal muscles pull the rib cage in inspiration?
upwards and outwards
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Where does the gas exchange take place in the lungs?
- alveoli
- walls of the alveolar ducts
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What is the anatomical dead space?
- volume of air that does not take part in gas exchange
- 150 ml
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What is tidal volume?
- the amount of air exchanged with each breath
- approx 500mls
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How do you work out minute volume?
tidal volume x breathing rate per minute
500mls x 15 bpm = 7.5L
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What is partial pressure?
The pressure of a specific gas in a mixture
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Where do gases move to?
from a high pressure to low pressure
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What is diffusion?
a movement of a solute from a high concentration to a low concentration through a semi permeable membrane
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What is external respiration?
exchange of gases between the alveoli and the blood in the alveolar capillaries
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What is internal respiration?
exchange of gases between blood in the capillaries and the body cells.
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Where does the voluntary control of respiration originate?
cerebral cortex
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Where does the autonomic nervous control of respiration originate?
- the respiratory centre
- group of nerves in the medulla
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What is the chemical control of respiration?
chemoreceptors
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What do chemoreceptors detect?
changes in the partial pressures of o2 and co2 in the blood and CSF
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where are the central chemoreceptors located?
- in the respiratory centre
- also respond to changes in pH
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Where are the peripheral chemoreceptors located?
- in arch of aorta
- bifurcation of common carotids
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What is a normal breathing rare for an adult?
12-20
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