1-Respiratory Flashcards
Two functional divisions of the lungs
1) Conducting portion
2) Respiratory portion
Conducting portion(function, location, function)
- Structure: varying levels of wall thickness
- Location: parts inside and outside lungs
- Function: conduct and condition(filter,heat,humidify)
Conducting portions parts
Outside lungs: nasal cavity to extrapulmonary bronchi
Inside lungs: Bronchi, bronchioles, terminal bronchioles.
Respiratory portion(function, location, function)
Structure-Thin walled gas exchange
Location: Only in lungs
Function: gas exchange
Respiratory portion parts
Respiratory bronchioles, Alveolar ducts and sacs
Types of circulation in the lungs
- Pulmonary
- Bronchial
Bronchial circulation
- Branches off the aorta
- provides nourishmnt ot the CT, walls of the bronchi and bronchioles, and pluera
- Vein-deoxy
- artery-oxy
Pulmonary circulation
- Blood from right ventricle(RV)
- 100% of blood
- Arteries- DEOXY blood from RV. Arteries follows the branches of the bronchi and bronchioles down to capillaries.
- Veins- Carry OXY blood from capillaries to the left atrium. does not run with the arteries. Located in CT of the lung. 2 veins per lung
Main histological components of respiratory system
- Cartilage
- Smooth muscle
- Collagen fibers
- Elastic fibers
Emphysema
- Enlargement of the airspaces after the terminal bronchioles and dstruction of the walls without fibrosis
- COPD
- Enzymatic degradation of elastin
- most common cause is cigarette smoking
Pleura
- Serous memebrane
- Parietal- associated withe the walls of the body cavity
- Viseral- adheres to and cover lung surface
Turbinates or Conchae(structure, function and location)
Structure: Bony shelf like projections lined with pseudostratified epithelium. Well vascularized
Function: Increase Surface area
Location:lateral walls of the nasal cavities
Trachea layers
- Mucosa(elastic rich lamina propria, no muscularis mucosae)
- Submucosa
- Adventitia/ C-shaped Cartilage become progressively smaller
Tracheal epithelium and other associated cells
- Pseudostratified epithelium
- Ciliated cells
- Mucous cells
- Brush cells
- small granule cells( enteroendocrine cells)
- Basal cells
Ciliated cells
- Maintain level of periciliary fluid (water and electrolytes)
- Each cell has 250 cilia that provide coordinated sweeping movement
- forms “mucociliary escalator”
- Clears mucous coat
Mucous cells
Mucinognn granues in cytoplasm
Mucous floats on the periciliary fluid
Brush cells
- Columnar cells with blunt microcilli
- Basal surface in synaptic contact with afferent nerve ending
- receptor cell
Small granule cells(enteroendocrine cells)
- Contain secretory granules
- many function in reflexes
Basal cell
Stem cell of individual cell replacement in the epithelium
Metaplasia in respiratory system
Pseudostratified epithelium changes to stratified squamous non-keratinized epithelium
-Harder to remove mucous
-mucous build up in the lumen of respiratory tree
mucus secreting glads get bigger
- must cough to clear secretions
-Inhaled irritants such as smoking cause it.
- reversible if irritant eliminated
Bronchi wall layers
- Mucosa- same epithelium as trachea
- Muscularis-reguates diameter of airway
- Submucosa- glands present
- Adventitia/cartilage-Plates smaller with decreasing diameter
Intrapulmonary bronchus
- Plates of cartilage become plates and get smaller
- Muscularis is found
- More elastic fibers
Bronchioles
- 1mm or less
- embedded in CT of the lungs so they diameter changed with lung volume
- Terminal-non respiratory or Respiratory-sites of gas exchange
- pseudostratified to simple columnar to simple cuboidal epithelium
- gradual changes
Bronchiole special feature
- No cartilage
- Lack submucosal glands
- thick layer of smooth muscle
- ciliated cells decrease and club cells increase
Club cells(or Clara)(structure, function and location)
- Simple columnar dome shaped, apical aspect poke into lumen
- Detox harmful compounds in the air
- secrete a lipoprotein that prevents luminal adhesion
- Mitotically active stem cell
- In bronchioles
Repiratory bronchioles
- First region of gas exchange
- Wall is interupted by alveoli
- mostly club cells
Aleoli(function and cells)
Site of gas exchange
-Lined with type I & II pneumocytes occasional brush cells
Alveoar ducts
Smooth muscle disappears at the end of the duct
elastic and collagen are the only support for alveoli
Alevolar sacs
Spaces surrounded by clusters of alveoli
Type I pneumocyte(structure function,location)
-Structure: squamous, attenuated cells, many organelles clusted by nucleus while cytoplasm is spread for gas exchange
Function: provide a barrier of minimal thickness for gas exchange
Location- 95% of surface area of the alveolus
Type II pneumocytes(septal cell)(structure function,location)
Structure: rounded cells apical cytoplasm contains lamellar bodies
Location:Typically found in corners occupy 5% f surface area
Function: Undergo mitosis to regenerate themselves and type I pneumocytes. Also continuously produce surfactant to prevent alveolar collapse
Interalveolar septum-thin region
- site of air-blood barrier
- house capillaries that function in gas exchnage
Interalveolar septum-thick region
Composed of collagen, elastic fibers, capillaries, lymphatic vessels, fibroblasts, mast cells, alveolar macrophages
Blood-air barrier
-Layer of surfactant
-alveolar epithelium(Type I pneumocytes)
-Fused basement membrane of he alveolar and epithelial cells
-endothelial cells
All type I and type II pneumocytes have desmosomes and occluding junctions
Alveolar Pores(Pores of Kohn
- Equilizing pressure in alveoli
- enable collateral ventilation
- allow macrophage migration
Defense mechanisms
- Nose and trachea
- Mucocilliary escalator (traps and moves debris towards the nasopahrynx
- Alveolar macropages(dust cells)
