Respiratory Histology Flashcards
What is the conducting part of the respiratory system and what structures does it contain?
Carries and conditions air
Nasopharynx, trachea, bronchi, bronchioles
What is the respiratory part of the respiratory system and what structures does it contain?
Exchanges O2 for CO2
Alveoli in lungs
What is respiratory epithelium?
Lines the conducting part of the respiratory system
- pseudostratified epithelium
- ciliated cells (columnar)
- secretory cells (goblet cells) - produce mucus
- sensory cells - initiate coughing
- basal cells - in the base of the epithelium, renew it
- brush cells with microvilli
What is the role of ciliated cells?
Sweep the mucus layer up to the epiglottis, beat it up into the oesophagus and then down into the stomach
- cleaning cycle
- smoking destroys cilia
What are the layers of the trachea?
Mucosa (respiratory epithelium and lamina propria), sub-mucosa (glands and connective tissue), adventitia (contains cartilage and outer layer of connective tissue)
What is the pathway of the airway structures?
Trachea –> bronchi (2L, 3R) –> bronchioles (when there is no cartilage left, loses goblet and ciliated columnar cells, gains Clara cells)
What are Clara cells?
Columnar to cuboidal with short microvilli, secrete surfactant to keep the airways open (destroy surface tension)
What are the first respiratory structures?
Alveoli from the respiratory bronchioles
What is the structure of the alveolus?
Thin walled pouches made of mostly simple squamous epithelium
- walls contain many pulmonary capillaries (form a dense, anastomosing network of vessels for exchange of gas)
- individual alveoli are connected by pores –> gas can go through
What is the interalveolar septum and what is its function?
Sits between alveoli
- contains reticular and elastin fibres to pull the alveoli open
- pores allow air to equilibrate
- elastin fibres keep alveoli from collapsing, as does positive air pressure
What are type 1 pneumocytes?
Provide the majority of the SA for alveoli –> provide the exchange surface
- simple squamous epithelium
- tight junctions limit ECF leakage
- prominent basal lamina
What are type 2 pneumocytes?
Cuboidal cells, lamellar bodies contain surfactant that is secreted
Stem cells - can turnover and give rise to new type 1 or type 2
What is the blood-gas barrier?
Exchange of gas takes place across the type 1 pneumocyte and the endothelial cell of the capillary
Layer of mucus and surfactant –> type 1 pneumocyte –> basal lamina –> connective tissue –> basal lamina –> endothelial cell –> plasma and then to RBC
What are intra-alveolar macrophages?
Beyond the type 1 pneumocyte - out of the body
Phagocytose particles that get past previous barriers
When they die go back inside and are swept away by cilia
What defines a bronchiole?
When there is no cartilage left
- loses goblet cells and ciliated columnar cells and gains Clara cells
