Respiratory system Flashcards
What does the upper respiratory tract consist of?
Nasal cavity, pharynx, larynx
What does the pharynx divide into?
Nasopharynx, oropharynx, laryngopharynx
What does the lower respiratory tract consist of?
Primary bronchi. secondary bronchi, tertiary bronchi, bronchioles, alveoli
Where does the apex of the lungs sit
Slightly above the clavicles
Where does the base of the lungs sit?
Rests on the diaphragm
How many lobes does the right lung have?
Three lobes
How many lobes does the left lung have?
Two lobes and is 10% smaller
Where does the trachea extend to?
From the larynx to the primary bronchi in the thoracic cavity, is anterior to the oesophagus
What does the mucosal lining in the trachea consist of?
Ciliated pseudostratified epithelium, containing goblet cells
What type of muscle is in the trachea?
Smooth and elastic muscle making it very flexible
What is the carina?
Branch point of the trachea into the bronchi
What triggers coughing?
The mucosa at the carina as it is extremely sensitive and triggered when a foreign object touches it
What is in the primary bronchi?
Rings of C-shaped cartilage, right bronchus is wider, shorter and more vertical
What does the secondary bronchi do?
Supples the lobes of each lung, rings of cartilage are replaced with strips
What does the tertiary bronchi do?
Supply the segments within the lobes of each lung
What do the bronchioles do?
Connect the tertiary bronchi (conduction zone) to the respiratory bronchioles, alveolar ducts and alveoli
What are the alveoli lined with?
Simple squamous epithelium to optimise diffusion
What is the main gas exchange structure of the respiratory tract?
Alveoli
What does surfactant do?
Prevents a thin watery liquid from lining the surface of alveoli exerting a force called surface tension
Why is surfactant important?
If the lining of pure water the surface tension would cause the alveoli to collapse inwards between breaths, but the surfactant reduces this surface tension, also reduces the energy needed to expand the lungs
What does lung tissue consist of?
Mostly air spaces, elastic connective tissue
What is each lung enclosed by?
Pleural membrane (serous membrane)
What does the visceral and parietal pleura line?
Visceral pleura covers the lungs
Parietal pleura lines the wall of the thoracic cavity
What pressure gradient does air move?
From an area of high pressure to low pressure
for air to move into the lungs we need to create low pressure, for air to move out we need to create high pressure
What nerve stimulates the diaphragm to contract?
Phrenic nerve, this movement increases the height of the thoracic cavity (responsible for 75% of the change of volume and pressure)
What nerve stimulates the external intercostal muscles to contract?
Intercostal nerve, this movement pulls the sternum and ribcage (superiorly swinging the ribs outwards)
Why do the lungs expand when the thoracic cavity expands?
Parietal layer is fixed to the chest wall, visceral layer adheres to the lungs, the fluid between them makes them adhere to each other
What causes the diaphragm and external intercostal muscles to relax?
When the phrenic and intercostal nerves stop sending impulses
What do the lungs recoil?
Because they have extensive elastic tissue
What factors affect the rate of airflow and ease of breathing?
Surface tension in the alveoli, compliance of the lungs, airway resistance
What is lung compliance?
The ease with which the lungs and thoracic wall can be expanded
What is lung recoil?
The tendency of the lungs to return to the resting state after inspiration
What causes airway resistance?
Friction between the air and air passages
The exchange of gases between the alveoli and capillaries in the lungs is
external respiration
A factor which promotes external respiration is
a short diffusion distance between alveolus & the capillary
carbon dioxide is mostly transported in the blood
as bicarbonate ions
the most powerful respiratory stimulant is
Rising CO2 in the blood
The test that measures HCO3- and calculates pH, and measures PCO2 & PO2
is the arterial blood gas
In children …
the airways that are much narrower than adults & more seriously affected by oedema/secretions/ bronchoconstriction
Haemoglobin releases oxygen more readily to tissues that are
Low in pH
the airway(s) that dilate under the influence of the sympathetic nervous system are
The bronchioles
Quiet exhalation involves
elastic recoil of the lungs
