The Respiratory System Flashcards
What are the upper respiratory tract structures
Nasal cavity
Pharynx
Nasopharynx
Oropharynx
Laryngopharynx
Larynx
What are the lower respiratory tract structures
Trachea
Bronchi
Bronchioles
Alveolar sacs
Alveoli
Describe the nasal cavities
Chambers internal nose through which air inhaled, warmed, humidified as moves further into the nasal cavities
Describe the scroll-shaped bones (nasal cavities)
Nasal conchae, protrude and form spaces through which air passes
Conchae swirl air around allowing time to humidify, warm and clean air before it enters lungs
Describe the epithelial cilia and mucous membrane line inside nasal cavities
Seromucous and other glands produce mucous that along with cilia traps unwanted large particles which we cough out and swallow
Describe the pharynx and oropharynx
Air and food have shared pathway so risk of choking
When breathing epiglottis stays up and air passes freely between laryngopharynx and larynx
Larynx connects lower part of pharynx, the laryngopharynx to the trachea
When eating glottis closes and epiglottis folds backward to cover the entrance larynx so food and liquid don’t enter trachea
Swallowing coordinated by neurons in brainstem
What are the functions of upper respiratory tract
Warming
Humidifying
Filtering particles
Smell
Speech
Describe the trachea
Fibro - cartilaginous tube
Extends from lower border of larynx to division into right and left main bronchi at the carina
C shaped cartilage
Posteriorly trachealis muscle
What is a bronchogram
When an X- ray or CT scan is completed after injection of a radio- opaque dye
Describe the right main bronchus
Wider
Shorter
More vertical than the left
Foreign body entering the trachea more likely to get stuck in the right main bronchus
Describe the pleura and pleural cavity
Pleura consists of a closed sac of serous membrane, one for each lung which contains a small amount of pleural fluid
Membrane of ballon is a single membrane, but when fist pushed ballon it is effectively coated in two membranes with water in between, so fist can slide around but not get wet and sac remains enclosed. So the lung can expand and recoil within the pleural sac lubricated by pleural fluid
Describe the pleural membrane
Although it’s described as two sheets, the visceral and the pleural membrane, the description refers to whether the layer is the outer or inner one : it is still all one membrane
The pericardium forms a similar arrangement around the heart allowing it to beat without friction
Describe how bronchi divides
Bronchioles
Terminal bronchioles
Respiratory bronchioles
Alveolar ducts
Alveoli
Describe the divisions of the lower respiratory tract
Air in the conducting zone = anatomical dead space
From nostril up to the start of the respiratory bronchioles
Volume of conducting airways = 150mls (approx 30% tidal volume)
No alveoli in this zone
So no gas exchange in this stretch
Describe alveoli
Vast surface area
Type I cells (squamous) cover 90% of surface area and permit gas exchange with capillaries
Type II cells (cuboidal) cover 10% of surface area and produce surfactant
Numerous macrophages line alveolar surface (phagocytose particles)
Describe the protection of lungs against infection
Epithelial lining of the respiratory tract
Pseudo stratified epithelium with cilia and goblet cells lines the airways from the nasal cavity to the largest bronchioles
Column shaped cells with cilia
Goblet cells between columnar cells
Further down respiratory tree there is less prevalent number of cilia and goblet cells
At alveolar level goblet cells or cilia could impede gas exchange so infection defence relies on antibodies, phagocytes and macrophages
Describe mucoiliary escalator
Mucous secreted by goblet cells and glands
Dust and other particles are deposited on the mucous layer
There is synchronous regular beating of cilia of the mucous membrane wafts mucous adhered particles up towards the pharynx mucous is then coughed up or swallowed
Describe intercostal muscles in respiration
11 pairs of intercostal muscles occupying the spaces between the 12 pairs of ribs, they are arranged in two layers, the external and internal intercostal muscles and are supplied by the intercostal nerves
Explain the external intercostal muscles in respiration
These extend downwards and forwards from the lower border of the rib above to the upper border of the rib below
They lift the rib cage upwards and outwards in inspiration
Explain internal intercostal muscles in respiration
These extend downwards and backwards from the lower border of the rib above to the upper border of the rib below, crossing the external intercostal muscle fibres at right angles
They are used when expiration becomes active as in exercise