Respiratory System Flashcards
What are the functions of the respiratory system?
- air conduction/gas exchange
- phonation (talking)
- olfaction (smell)
- heat regulation
- air conditioning (temp and moisture)
- protection
- acid-base regulation
- hormone conversion
Describe the functions and components of the Conductive system
- composed of nasal cavity, pharynx, larynx, trachea, and bronchi
- brings air to the respiratory portion
- cleanses, moistens, and warms incoming air
- hair and secretions in nasal cavity trap particulate matter
Describe the functions and components of the Transitional system
- composed of terminal bronchioles lined by club cells, non-ciliated secretory cells, and a few ciliated cells
- a transition zone between the conducting and gas exchange areas
Describe the function and components of the Gas Exchange system
- composed of respiratory bronchioles and alveoli
- alveoli lined by epithelial type 1 and type 2 pneumonocytes
- where gas exchange occurs
What is the path of airflow?
nasal cavity > nasopharynx > larynx > trachea > bronchi > bronchioles > respiratory bronchioles > alveolar ducts > alveolar sacs > alveoli
What are the specific and non-specific defense mechanisms?
Non-Specific: mucous trapping, mucocilliary clearance, phagocytosis, air turbulance
Specific: antibody production, cell-mediated immunity
Explain the lining epithelium of the Conductive system
pseudostratified ciliated, columnar epithelium, with secretory goblet cells and submucosal cells
What are the three regions of the nasal cavity?
- vestibular region
- respiratory region
- olfactory region
Describe the vestibular region of the nasal cavity
- external part of the nasal cavity
- cutaneous mucous membrane, hair, and glands
- lined with stratified squamous keratinized epithelium
Describe the respiratory region of the nasal cavity
- largest region
- lined with pseudostratified columnar ciliated epithelium with goblet cells
- contains mucocilliary apparatus and Chonchae turbinates
What are the Conchae Turbinates?
projections from the lateral wall that narrow the lumen of the nasal cavity and increase the area of contact of inhaled air with mucous membrane
Describe the Mucociliary Apparatus
- pseudostratified ciliated columnar epithelium with goblet cells
- movement of cilia removes mucus with trapped inhaled particles
- a cleaning apparatus
Describe Goblets cells: locations, functions, and features
- present from nasal cavity to the level of large bronchioles
- all cells in contact with basement membrane
- secrete mucinogen that traps particulate matter
- hyperplasia and metaplasia (lose cilia) in smokers
Describe the Olfactory epithelium
- much thicker than respiratory epithelium
- no goblet cells
- specialized sensory cells: olfactory neurons, sustentactular cells, stem/basal cells
Describe the Olfactory region
- located in dorsal part of nasal cavity
- lamina propria contains serous olfactory glands and non-myelinated axons of olfactory neurons
- rich in venus plexuses (swell bodies)
What is the functions of the Vomeronasal Organ?
- chemoreception, sexual behavior
- smelling pheromones
Describe the Larynx
- includes cartilage, vocal folds, skeletal muscle
- initial part lined by stratified squamous epithelium
- after the vocal chords, lining changes to pseudostratified ciliated columnar epithelium
Describe the Trachea
- lined by ciliated pseudostratified columnar epithelium
- serous glands in the lamina propria/submucosa
- rings of hyaline cartilage incomplete in mammals, complete in birds
- contain goblet cells
Describe the Bronchi
- trachea bifurcates into two bronchi
- lined by ciliated pseudostratified columnar epithelium
- smooth muscle surrounds lamina propria, then connective tissue with mixed bronchial glands and plates of hyaline cartilage
What are the general features of Bronchioles?
- lack cartilage and glands
- subdivided into terminal and respiratory bronchioles
- Clara/Club cells bulge into lumen
Describe Terminal Bronchioles
- lined by ciliated cuboidal cells with few to no goblet cells
- muscularis mucosae present
Describe Respiratory Bronchioles
- function is gas exchange and conduction
- lined by ciliated cuboidal epithelium which become flattened distally
- have incomplete muscularis muscosae
- subdivide into alveolar ducts
What are the functions of Clara/Club cells?
- source of surfactant-like substance which aids in maintaining patency of airway
- metabolize airborne toxins, may have immune function
Describe the Alveolar Ducts
- part of the exchange system
- empty into alveolar sacs and alveoli
- walls composed of alveoli lined with simple squamous epithelium
- edge surrounding each opening of alveoli contains smooth muscle
Describe Alveolar Sacs
- site of gas exchange
- no smooth muscle
- lined by pneumocytes type 1 and 2
Describe the Alveolar Septum + Interstitium
- contains fibroblasts and capillaries
- dust cells = macrophages that migrate through pores
- collagen type III present in alveolar wall
- collagen type I present in conducting airways
- elastic fibers present, allow lungs to stretch
Describe Type 1 Pneumocytes
- forms walls of alveoli
- 95% of alveolar surface area
- gas permeability, prevent fluid passage
- not mitotic
Describe Type 2 Pneumocytes
- 5% of alveolar surface area
- secretory cells: produce surfactant via lamellar bodies (granules)
- can be mitotic: produces types 1 and 2
What is Surfactant and what is its function?
- mono-molecular layer of phospholipoprotein
- reduces surface tension: reduces effort needed to inflate alveoli, so prevents alveolar collapse
- constantly produced by type II pneumocytes
- cortisol stimulates production in fetus prior to parturition
What are the components of the Air-Blood Barrier
- vascular epithelium
- basement membrane of the endothelial cells
- basement membrane of type I pneumocytes
- cytoplasm of type I pneumocyte covered by surfactant
What is the pathway of oxygen into the blood stream?
oxygen in alveolar air > surfactant and cytoplasm of type I alveolar cell > basal lamina of type I cell and basal lamina of endothelial cell > cytoplasm of endothelial cell > capillary RBCs
Describe the Pleura of the Respiratory system
- composed of simple squamous epithelial cells (mesothelial cells)
- visceral pleura covers the lungs and is continuous with the parietal pleura
