Ketchum Flashcards
Cellular (biochemical) respiration
Deals w/gaseous exchange within cell.
O2 taken up by complex enzymatic process.
CO2 formed as waste and diffuses out of cell.
External respiration
Occurs at level of blood cells
- rid themselves of CO2 from body cells
- recharge with O2 from atmosphere
Conduction portion of lung
Includes: nasal cavity, nasopharynx, larynx, trachea, bronchi, bronchioles.
Function: conduct air; removing particulates; warming, cooling, humidification of air
Respiratory epithelium
ciliated pseudostratified columnar epithelium w/ goblet cells glands in lamina propria smooth muscle elastic fibers cartilage cilia, glands & cartilage gradually disappear smooth muscle increases epithelium becomes cuboidal
Trachea characteristics
Hollow rigid tube, 1.1 cm x 2.5 cm diameter
Respiratory epithelium
pseudo-stratified columnar, with cilia & goblet cells
rests on a thick BM
lamina propria
contains thin, fibrous layer
elastic fibers condense
forms elastic membrane
submucosa
beneath elastic membrane of lamina propria
contains seromucous glands
Tracheal Characteristics
C-shaped cartilage “rings” deep to submucosa
16-20 “rings” composed of hyaline cartilage “rings “
smooth muscle span prongs of cartilag
Primary Bronchus
trachea divides at carina
right and left branches called primary (1°) or main bronchi
histologic structure nearly identical to trachea
following exceptions:
horseshoe-shaped cartilage of trachea
replaced by cartilage plates of irregular shape
smooth muscle
more prominent & encircles lumen
composed of right & left spirals
Bronchi
1°bronchi enter lung tissue at hilus
bronchi ramify
give rise to different orders of bronchial tree
lobar or large (secondary, 2°) bronchi
2 branches on left lung, 3 on right lung
segmental or small (tertiary, 3°) bronchi
8 to 10 branches on each lung
Bronchioles
become bronchiole when caliber of bronchial tube <1mm
occurs when:cartilage plates no longer present
bronchioles undergo branching up to 20 generations
final stage known as terminal bronchiole
Terminal bronchioles
as branching occurs, bronchiole gradually changes
epithelium changes from pseudostratified columnar to simple columnar
two types of columnar cells present
ciliated cells
club cells (non-ciliated secretory cells) smooth muscle increases
elastic fibers increase
called “terminal” because they are the termination of the conducting system
Club Cells of Terminal Bronchioles
club cells (non-ciliated secretory cells)
secrete products which protect bronchiolar epithelium:
Clara cell secretory protein (CCSP)
solution similar to lung surfactant
engulf and break down toxins via cytochrome P-450
serve as progenitor cell population to regenerate ciliated epithelial cells
Function of cilla
Mechanical host defense
Removal of particulate matter
Respiratory region of Lung
site of gaseous exchange between air & blood
consists of:
respiratory bronchioles
alveolar ducts
alveolar sacs
alveoliRespiratory bronchioles
arises from terminal bronchiole
200mm in diameter
simple epithelium
low columnar to cuboidal with no cilia
becomes squamous in alveolus
characterized by presence of alveoli
(singular, alveolus)Branches of Respiratory Bronchioles
branches into:
alveolar duct
2-3 elongate branches of respiratory bronchiole
atrium
space between alveolar duct & alveolar sac
alveolar sacs (saccules)
alveolar duct ends in 2-3 alveolar sacs
alveolus
single outpocketing
Alveoli
alveolus
75m to 300m in diameter
thin-walled polyhedral structures
walls are delicate and contain elastic fibers
Alveolar pores
allows air to flow between adjacent alvioli
small, slit-like openings between adjacent alveoli
10m to 15m diameter in large alveoli
pores equalize inter-alveolar pressure
pores equalize inter-alveolar pressure
can prevent atelectacsis
allow alternate pathway for ventilation (in obstruction)
may permit spread of infection
Cells of Alveolar Wall
alveolar wall consists of five different types of cells described in two groups surface cells type I alveolar cell type II alveolar cell intramural cells endothelial cells fibroblasts (CT cells) smooth muscle cells
Type I epithelial (alveolar) cell
Second most common alveolar cell and covers 90% of alveolar surface.
Cytoplasm attenuated to form alveolar lining
Have little or no endoplasmic reticulum
Type II alveolar cell
More numerous than type I but only covers 5-10%.
Large round cell, may protrude from alveolar wall.
Lamellar bodies contain globular surfactant.
Type II avleolar cells produce Surfactant
phospholipid material
released and spread over surface of squamous cell
thin coating acts as surface tension reducing agent
by reducing surface tension
prevents collapse of alveolus during expiration
Intramural cells of alveolar wall
capillary endothelial cells (nuclei are most numerous)
fibroblasts (CT cells)
occasionally observe smooth muscle cells
Alveolar Macrophages
dust cells free of alveolar wall contain phagocytosed material in cytoplasm also known as heart failure cells derived from monocytes
Alveolar Membrane
O2 exchange between alveolus & RBC’s largely by ‘passive transport“
alveolar membrane a multilayered barrier 0.3-0.7m thick
consists of: attenuated cytoplasm of type I cell (0.05m) BM between type I cell & endothelium (0.15m) attenuated cytoplasm of endothelium (0.25um)
Gas exchange and physiologic shunt
Mean pulmonary artery pressure = 15 mm Hg
Mean systemic pressure = 100 mm Hg
Shunt- transfer of deoxygenated blood from the venous circulation to the arterial circulation
