Respiratory Histology Flashcards
What is the function of the turbinate bones?
To moisturise and heat the air that you breath in
Where are the sensory nerve endings for smell?
The olfactory epithelium
What is the function of the epiglottis?
To divert food from the airway
What is the function of the larynx?
Keeps fluid from getting into airways and also for phonation
What type of epithelium is respiratory epithelium?
Pseudostratified epithelium
What kinds of cells are present in the respiratory epithelium?
Ciliated cells, goblet cells, basal stem cells, brush cells, serous cells, small granule cells
What is the function of ciliated cells?
They make up about 30% of the epithelium and have cilia that can be controlled and move to move mucous up the airways
What is the function of goblet cells?
They make up about 30% of the epithelium and secrete mucous
What is the function of basal stem cells?
They make up another 30% and are stem cells which continually divide to produce new ciliated cells and goblet cells
What is the function of brush cells?
Brush cells are very few cells of the epithelium and have a brush layer rather than cilia - may have a sensory role
What is the function of serous cells?
Very few cells of the epithelium - have an unknown secretory role
What is the function of the small granule cells?
Very few cells of the epithelium - have an endocrine role and may also be sensory
What protective mechanisms do the airways have against dust and fungal and bacterial spores?
Mucous covered walls, cilia, intra-alveolar macrophages
What are the three layers of the trachea?
Mucosa, submucosa, adventitia
What makes up the mucosa?
The respiratory epithelium and the lamina propria
What makes up the submucosa?
connective tissue with serous and mucous glands
What makes up the adventitia?
Cartilage and a thin layer of connective tissue
How many orders of branching are there between the trachea and the alveoli?
23
What is the structure of the bronchus?
Initially similar to the trachea but changes as it gets smaller
When is the bronchus called the intrapulmonary bronchi?
When the cartilage rings become cartilage plates
Where does the smooth muscle run when the cartilage becomes plates?
Between the lamina propria and the submucosa (technically part of the submucosa)
When does the airway become classified as a bronchiole?
When there is no more cartilage - at approximately 1mm in diameter
At what stage of the branching is the bronchiole?
15 of 23
How do the cells change as you get further down the airways?
There are fewer goblet cells and fewer ciliated columnar cells and get more Clara cells
What are Clara cells?
Columnar to cuboidal cellos which have microvilli and secrete surfactant
What is surfactant?
A glycoprotein which breaks surface tension to resist the collapse of fine tubes
When is the airway classified as a terminal bronchiole?
At the final level of the conducting system when there are no goblet cells - only Clara cells with a few cuboidal epithelial cells with cilia and one or two layers of smooth muscle
What do the terminal bronchioles give rise to?
Respiratory bronchioles
What are the features of respiratory bronchioles?
Cuboidal to squamous epithelium that gives rise to alveolar ducts
What is the structure of the alveoli?
200 micrometer holes separated by inter alveolar septa lined with simple squamous epithelium
What are the inter alveolar septum made of?
Reticular fibres, elastin fibres, pores and contains pulmonary capillaries
What prevents the alveoli from collapsing?
The radial arrangement of the connective tissue
What are the two types of cells in alveolar epithelium?
Type I and type II pneumocytes
What are type I pneumocytes?
The epithelial cells between the air and the capillary - have a thick basal lamina and tight junctions to prevent fluid leaking
What are type II pneumocytes?
The cuboidal cells at the junctions of the inter alveolar septum whose role it is to secrete surfactant and they are also stem cells
What makes up the blood gas barrier?
Type I pneumocyte, basal lamina, connective tissue, basal lamina, endothelial cell, plasma
What are the two fates of intra-alveolar macrophages?
Go up airway to ciliated part to get pushed back up and then down to the stomach or take up permanent residence in the alveolar wall
What type of cells make up the surface of pleura?
Squamous epithelium
