Respiratory System Flashcards
respiratory system includes:
lungs/respiratory protein (gas exchanging unit)
ventilation mechanism
air passages
pleura divisions
parietal pleura- associated with the walls of the body cavity
visceral pleura- adheres to and covers the surface of the lung
parietal pleura
reflects off the body wall and forms a tubular covering for the structures entering and exiting the lungs
sleeve like covering and the structures form the root of the lung at the hilum of the lung (medial surface of the lung)
hilum
medial surface of the lung where blood vessels enter and exit
parietal pleura and visceral pleura are continuous here
pneumothorax
entry of air into the pleural cavity, results in collapse of the lung
hemothorax
blood in the pleural cavity
pleural effusion
accumulation of fluid in the pleural cavity
lungs: right and left
lungs- apex projects into the root of the neck
base- sits on the diaphragm
right lung- three lobes (superior, middle, inferior), two fissures (horizontal and oblique)
left lung- two lobes (superior and inferior) separated by an oblique fissure
duel blood supply of the lungs
- functional vessels- pulmonary arteries (deoxygenated blood) and pulmonary veins (oxygenated blood)
- nutrient vessels- bronchial arteries that carry oxygenated blood that nourished the tissues and lungs
function vessels
pulmonary arteries (deoxy) and pulmonary veins (oxy) do not run together
nutrient vessles
bronchiole arteries- nourish the tissues of the lungs (wall, pleura, connective tissue)
run together
pulmonary arteries
carry deoxygenated blood form the right ventricle
branches of pulmonary arteries travel alongside the branched of the bronchi and bronchioles down to the capillary level
pulmonary veins
blood that is oxygenated at the capillary level is carried in venules that form veins
four veins return oxygenated blood to the left atrium
pulmonary veins do not run alongside the pulmonary artery, they are located in the connective tissue segments of the lung
bronchial circulation
nutrient vessels
bronchial arteries are branches of the aorta
they provide nourishment to the connective tissues, walls of the bronchi and bronchioles and pleura
tissues of the respiratory system: cartilage
hyaline cartilage
c-shaped rings in the trachea
plates in bronchi become progressively smaller
tissues of the respiratory system: smooth muscle
regulates the diameter of the airway
tissues of the respiratory system: collagen fibers
type1- upper airways
type 3- lower airways- works with elastic fibers that allow for expansion of the respiratory system without over expansion
clinical: increase in collagen in the lungs
fibrosis- increase in collagen fibers
tissues of the respiratory system: elastic fibers
together form a network that allow expansion (limited) and recoil of the lung
extracellular proteins secreted by fibroblasts
work with collagen fibers
clinical: decrease in elastic fibers in the lung
emphysema
the respiratory system is functionally divided into two regions:
- conducting portion
2. respiratory portion
conducting portion of the lung
structure: varying levels of wall thickness with structures that warm, filter, humidify incoming air
location:
- outisde: nasal cavity, oral pharynx, pharynx, larynx, trachea, extra-pulmonary bronchi
- inside: bronchi, bronchioles, terminal bronchioles
function: conduct and condition air
respiratory portion of the lung
structure: thin walled for efficient gas exchange
location: only in the lungs (respiratory bronchioles and alveolar ducts and sacs
functions: gas exchange
respiratory epithelium- pseudostratified epithelium
trachea wall
mucosa (epithelium-
respiratory epithelium-pseudostratified epithelium, elastic rich lamina propria, no muscularis mucosae)
submucosa- tracheal submucosal or seromucous glands
adventitia/cartilage (cartilage is in C-shaped rings
tracheal epithelium (five cell types)
epithelium- pseudostratified
- ciliated cells
- mucous cells
- brush cells
- small granule cells (enteroendocrine cells)
- basal cell
ciliated cells
tracheal epithelium
maintain level pf periciliary fluid (layer of water and electrolytes)
cilia provide coordinated sweeping motion
forms mucous escalator allowing the cilia to beat
clears mucous coat
mucous cell
tracheal epithelium
mucinogen granules in cytoplasm
the mucus floats on a serous fluid (periciliary fluid)
cilia moves both serous and mucus toward the oral cavity
brush cells
tracheal epithelium
columnar cells with blunt microvilli
basal surface in synaptic contact with afferent nerve ending
specialized epithelial chemosensors
small granule cells (enteroendocrine cells)
tracheal epithelium
contain secretory granules
may function in reflexes
granules secrete into underlying connective tissue and release hormone into the blood supply
basal cell
tracheal epithelium
stem cell for individual cell replacement in the epithelium
metaplasia in the human respiratory system
pathogenesis (inhaled irritants- smoking)
pseudostratified respiratory epithelium changes to stratified squamous non-keratinized epithelium as a protective mechanism
removal of mucous impaired
marked increase in the size of mucus secreting glands of the submucosa
individual must cough to clear secretions (smokers cough)
bronchi wall
mucosa- pseudostratified epithelium (same cells as trachea)
muscularis- regulates the diameter of the airway
submucosa- glands present
adventitia/cartilage- plats smaller with decreasing diameter
bronchial submucosal glands
key concepts of the trachea:
- plates of cartilage instead of rings- become smaller toward the bronchioles
- a layer of smooth muscle, the muscularis is found below the mucosa layer
- increase in elastic fibers
bronchioles (overview)
airways less than 1mm
embedded in CT of the lung
divided into terminal bronchioles (conducting airways) and respiratory epithelium (function as sites of gas exchange
epithelium- simple columnar to simple cuboidal
no cartilage
key points on bronchioles
- cartilage plates and glands are absent
- thick layer of smooth layer present
epithelium changes- ciliates cells reduce in number and club cells (clara cells) increase when proceeding to respiratory zone
Club cells (clara cells)- of the bronchioles
structure: simple columnar, non-ciliated, dome-shapes apical aspect projects into the lumen
function- detoxify harmful compounds in the air, secrete a lipoprotein (surfactant) that prevents luminal adhesion
mitotically active stem cell
location: bronchioles
respiratory bronchioles
first region where gas exchange takes place
wall interrupted with alveoli
club cells and some cilia cells (club cells dominate)
alveoli
site of gas exchange
alveoli cells
lined by type 1 and type 2 pneumocytes
alveolar ducts
smooth muscle disappears at the end of the duct
elastic and collagen fibers are only support for alveoli
alveolar sac
spaces surrounded by clusters of alveoli
type 1 pneumocytes
in the wall of the alveoli
structure: squamous, attenuated cells
function- provide barrier of minimal thickness that is permeable to gases
type 2 pneumocyte
also called septal cells
structure: rounded cells, apical cytoplasm, contains lamellar bodies (frothy appearance)
function: undergo mitosis to regenerate themselves and type 1 pneumocytes, continuously produce surfactant to prevent collapse of the alveoli
interalveolar septum (thick and thin portions)
thin: site of blood-air barrier, houses the capillary for gas exchange
thick: pulmonary interstitium- composed of collagen fibers, elastic fibers, capillaries, lymph vessels, fibroblasts, mast cells, alveolar macrophages
blood- air barrier (respiratory membrane)
four components:
- layer of surfactant
- alveolar epithelium (type 1 pneumocyte cytoplasm)
- fused basement membranes of the alveolar cell and endothelial cell
- endothelial cell
alveolar pore (pores of Kohn)
functions: equalizing pressure in the alveoli, enable collateral ventilation, allow macrophage migration
tight junctions between the alveolar cells (type 1 and 2)
defense mechanisms in the respiratory system
- nose and trachea (nasal hairs and capillary bed in nasal cavity and serous-mucus bed
- mucociliary escalator (transport
mucociliary escalator
traps and removes debris, bacteria and particles and toxic substances from distal to proximal
components:
-cilia
-serous fluid (periciliary fluid)
-mucous layer (produced by mucous cells and submucosal glands)
-alveolar macrophages- at distal level can trap particles and can travel to where the cilia are; but can also burrow into CT where die and stick (i.e. black lung)
lung development
lung= bud of endoderm layer
embryonic stage- day 22- 6/8weeks
endoderm derived
gives rise to epithelium lining, the larynx, trachea, bronchi, bronchioles proximally, parenchymal cells distally
splanchnic mesoderm derived
gives rise to cartilage, muscle, and connective tissue components, vascular network
stage of development
- embryonic
- pseudoglandular
- canalicular
- terminal saccular stage
- alveolar stage
embryonic stage
respiratory diverticulum forms (22 days to 6/8 weeks)
pseuglandular stage
branching to form terminal bronchioles (6-16 weeks)
canalicular stage-
respiratory bronchioles form (16-26 weeks)
terminal saccular stage
mature capillary-epithelium interface (26 weeks- birth)
alveolar stage
increase in respiratory bronchioles and alveoli (32 weeks- birth/post natal)
BALT/MALT
bronchial associated lymph tissue
