Lecture 15 Flashcards
What are the components of the lower respiratory tract
Larynx, Trachea, Bronchi, Bronchioles, Alveoli
What are the functions of the lower respiratory tract?
Conduct air to and from the site of gas exchange, complete cleaning, warming and humidifying of air, providing a barrier between the air and blood and a large surface area for gas exchange
What is the larynx?
The initial passageway (beyond the pharynx) is for air only. Is anterior the the oesophagus and runs from the hyoid bone to the trachea.
What does the anterior portion of the larynx contain?
Contains cartilage to protect and maintain an open airway. Plus the epiglottis
What is the epiglottis?
A piece of cartilage that closes over the airway when swallowing to stop the entry of food
What does the posterior portion of the larynx contain?
The glottis, vocal folds and vestibular folds
What is the glottis?
The voice box
What are the vocal folds?
The ‘true’ vocal cords. Passing air causes vibrations which cause sound waves. Used for normal phonation. Testosterone affects cartilage and muscle which can result in longer, thicker folds and therefore a deeper voice.
What are the vestibular folds?
The ‘false’ vocal cords. Superior to vocal folds. Prevent foreign object entry to the glottis and can produce very deep sounds
What is the trachea?
A long, U-shaped tube that connects your larynx (containing voice box) to your lungs
Where is the trachea?
Anterior to the oesophagus between the larynx and primary bronchi
What is the function of the trachea?
To maintain a patent airway and clean, warm and humidify air (lined with respiratory epithelium)
How does the trachea maintain a patent airway?
With C-shaped cartilage rings where the ends are connected by bands of smooth muscle that contract for coughing. Also contains many elastin fibres in lamina propria and submucosa
What is the name for the smooth muscles connecting the cartilage in the trachea?
Trachealis
What is the mucociliary escalator?
It runs along the trachea and removes debris escalating it to the pharynx to be swallowed and broken down by stomach acid. Contains; mucus from goblet cells and mucus glands, epithelia and cilia
What are the lobes of the lungs?
3x on right and 2x on left
Why does the left lung only have 2x lobes?
To accommodate for the heart
What is the hilum?
Where the bronchi and blood vessels enter the lungs
What is the apex of the lungs?
The superior regions
What is the costal surface of the lungs?
The lateral surface, against the ribs
What is the base of the lungs?
Inferior regions, sitting on the diaphragm
What are the components of the bronchial tree?
Trachea -> primary bronchi -> secondary bronchi -> tertiary bronchi -> many branches -> terminal bronchioles
What are the components of the primary bronchi?
Respiratory epithelium, cartilage and complete smooth muscle rings
What are the components of the secondary and tertiary bronchi?
Respiratory epithelium begins to decrease in height, and goblet cell number decreases. Contains cartilage plates
What are the components of the bronchioles?
<1mm, Cuboidal epithelium, no cartilage but thick smooth muscles for bronchoconstriction and dilation
What are the componenets of the terminal bronchioles?
<0.5mm each supplies a pulmonary lobule
What are the alveoli?
Air sacks of ~150 million per lung. Cover most of lung volume with their massive surface area.
What component of the alveoli make them optimal for gas exchange?
The simple squamose epithelium on a thin basement membrane and the external surface being covered in a fine network of pulmonary capillaries
What are pneumocytes?
Lung epithelial cells
What are the types of pneumocytes?
Type 1 squamose and type 2 cuboidal
What are the type 1 squamose pneumocytes?
Forms the respiratory membrane/blood-air barrier with capillary wall and shared basement membrane
What are the type 2 cuboidal pneumocytes?
Scattered amongst type 1. Secrete surfactant, a complex lipoprotein that reduces the surface tension of alveolar fluid
What do the roaming macrophages do in the alveoli?
Remove debris that makes it to alveoli as there is no mucus membrane
