Respiratory system Flashcards
Conducting portion
Consists of; nasal cavity, nasopharynx (epiglottis), larynx, pharynx, trachea, bronchi, bronchioles and terminal bronchioles.
- functions to cleans and humidify the inspired air (conducting)
TUNICA MUCOSA
- respiratory epithelium; pseudostratified columnar ciliated
5 types of cells on a basement membrane;
1. ciliated columnar cells (250-300cilia)
2. goblet cells - filled with granules of mucin glycoproteins
3. brush cells - columnar type w sparse, blunt apical microvilli (chemosensory receptors)
4. granule cells (Kulchitsky cells) - part of diffuse neuroendocrine sys (DNES) - 100-300nm - serotonin!!!
5.Basal stem and progenitor cells
LPM - loose CT abundant with cells, elastic fibers and seromucous glands, MALT (mucosa associated lymphoid tissue - immune cells
Epiglottis
- structure projecting form the upper rim of the larynx; prevents food/fluid in
1.lingual surface- stratified squamous non-keratinized epithelium
2. laryngeal surface - pseudostratified columnar ciliated epith w goblet cells
- elastic cartilage
- LP; dense irregular CT
-seromuscous glands; mucous tubules, serous acini and serous demilunes +DUCTS) - most in laryngeal - lymph nodes at the basis
Larynx
4x4 cm passage between the pharynx and trachea
- wall reinforced by the hyaline cartilage
(thyroid, cricoid and inf, arytenoid cartilage) - small elastic cartilage
(epiglottis, cuneiform, corniculate and sup arytenoid cartilages)
*connected by lig.
–> airway maintained open w movment of the cartilage by skeletal muscles cause tension to lig = phonation
Laryngeal vestibule
- respiratory epith w goblet cells
- seromucous glands
- laryngeal tonsils - occasional lymphoid nodules in the LPM
Below the mucousa will project into the lumen forms folds separated by a ventricle!
False vocal cords - vestibular
- upper
- respiratory eptih
- seromucous glands
- lymphoid nodules
True vocal cords
- lower
- stratified squamous non-keratinized epith
- NO glands
- vocal ligament
*dense regular bundles of elastic CT
*supports the vocal cords
- vocal muscle
*striated muscle fibers
Phonation
- adduction of the vocal muscles
- narrows the intervening luminal space = rima glottidis!
- air form lung causes fold to vibrate
- larynx is larger in males than females
Trachea
10-12cm long, d=2.5-3cm
1- Tunica muscosa
- respiratory eptih
- LPM - loose CT
2.Elastic fiber layer
- T. submucosa
- loose CT
- seromucous glands
4.Hyaline cartilage
- 16-20 C-shaped rings
- rings open dorsally and are bridged by smooth muscle -> trachealis muscle and a fibroelastic tissue connected to the perichondrium
- T. adventitia
- loose CT
Func;
during swallowing the esophagus bulges into the trachea lumen and elastic fibers prevent form complete distention.
Lungs - Conducting portion -Bronchi
*trachea into primary bronchi –> secondary bronchi (2 at left lobe and 3 at the right lobe)–> tertiary (segmental) bronchi –> bronhiopulmonary segment –> bronchioles
BRONCHI
- 1-2mm
1.T muscosa
- resp epith + goblet cells
*as the d= decreases so does the height and number of goblet cells
LPM- loose CT + elastic fibers, lymphocytes + lymphatic nodules and MALT (more abundant as d= decreases)
- T Muscularis
- spiral smooth muscle bundles arranged w the elastic fibers (both increase and d-decreases) - T. submucosa
- loose CT
- seromucous glands (numb decrease as d-decreases)
4.Hyaline cartilage
- encircles the lumen and when bronchial diameter decreases it is replaced by these overlapping plates
- T. adventitia
- loose CT
Lungs - bronchioles
intrlobular airway d= 1mm or less
- T.mucosa
common bronchioles - resp epith + gobelt cells
terminal bronchioles - simple columnar/cuboida; ciliated epith w CLARA cells/exocrine –> nonciliated , dome-shaped apical ends w secretory granules
funct–>
1. secrete surfactant -lipoproteins and mucins
2. detoxification - of xenobiotic compound
3. antimicrobial pepetides and cytokines secretion ofr local immunity
4. stem cells -injury induced mitosis
+ mucous and ciliated cells, brush cells, DNES
- NO goblet cells
*ciliated epi lining = mucocilliary apparatus for clearing the debris
Respiratory bronchiole
simple cuboidal ciliated eptih. w CLARA cells (NO goblet cells)
*openings to the alveoli for gas exchange with simple squamous epith
*as d= decreases the numb of ciliated cells decrease but CLARA cells increase
- LPM- thin elastic fibers + smooth muscle forming folds of mucosa.
- T. muscularis
- cirular smooth muscle
- No serousmeous glands and hyaline cartilage
3.T. adventitia
- loose CT
Alveolar ducts
distal ends of the resp bronchioles branch to
- lined by the openings of the alveoli
- simple squamous epith
LP- thin w strand of smooth muscle around each opening and a matrix of elastic and collagen fibers supporting both
Alveolar sacs
- clusters if alveoli forming the ends of the ducts distally
LP- very thin, network of elastic and reticular fibers around the openings and alveolus + capillary network
Alveoli
- sac like invagination of d= 200 um
- spongy structure of the lungs
- app. 200 million in adult lung and internal SA=75m^2
- exchange of O2w CO2 around capillaries
Interalveolar speta
- between each alveoli
- scattered fibroblasts and extracellular matrix = elastic and reticular fibers
*elastic - allow for expansion and contraction
*reticular - preventing the collapse
- richest network of capillary in body
also supported by the fibers
-macrophages and leukocytes
Blood-air barrier
separates the air in alveoli from the capillary blood
made up of 3 layers ~0.1-1.5um
1. 2-3 highly attenuate, thin cells lining the alveolus (type 1)
2. fused basal laminae of cells and the capillary endothelial cells
- thin but continuous and not fenestrated
- pinocytotic vescles
3. thin endothelial cells
Alveolar pores (of kohn)
10-15um in diameter
penetrate the septa and connect neighboring alveoli
-equalize air pressure
- collateral circulation of the bronchiole is obstructed
Pneumocytes
Type 1
- thin attenuated cells lining the alveolar surfaces (95%)
- FLAT SIMPLE SQUAMOUS EPIT
- pinocytotic vesicle- turnover of surfactant and removal of particles
- desmosomes + tight junctions –> prevent leakage of tissue fluid
Type 2 - spetal cells (5%)
- cuboidal cells bound to type 1 through tight junctions + desmosomes
- occur in groups of 2-3 where 2+ alveolar wall unite
- rest on the basal lamina
- divide after injury and provide projenitor cells for type 1 cells
- round nuclei and cytoplasm with many vesicles
–> lamellar bodies = membrane - bound granules (1-2um) closely staked membrane lamella (can be considered markers for type 2 cells)
- lipids, phospholipids, proteins rleased at the apical surface and spreads over the inner alveolar surface = pulmonary surfactant –> lowers the surface tension to prevent collapse at exhalation and lowers inspiratory force at inflation
*surfactant components
- DPPC = dipalmitoylphosphatidylcholine
- cholesterol
- proteins;
SP-A - hydrophilic glycoprotein
SP-D - innate immune protection
SP-B AND C - maturation of DPPC
Embryo
- surfactant appears in the last week of gestation as type 2 cells and diff into lamellar bodies.
Alveolar macrophages/DUST cells
- in the alveoli and spta
- monocytes migrate from the microvasulature to lung tissue –> phagocytose erythrocytes lost form damage capillaries
- darker than type 2 cells due to dust, carbon and iron
- after phagocytosis
- migrate to the mucocilliary apparatus
*lymphatic drainage - remain at the septa CT
Alveolar lining fluid + bronchial muscus = bronchoalveolar fluid
- bacteriostatic w lysosomes and agents produced by CLARA CELLS, type 2 cells + dust cells
Regeneration
- Inhalation of toxins kills type 1 and 2 cells
- death of one increased mitotic activity in the remaining type 2 cells = become both cells
- Clara cells can also be stimulates to be divided and form alveolar cells
