Overview of the Pulm System/Lung Development Flashcards
Functions of the lung
1) gas exchange= constantly survey in and out environ
1) extraction of O2 from enviro
2) eliminate CO2 from lungs
3) endocrine and immune organ
Proper gas exchange requires which organs
1) lung, chest wall, resp muscles for movement
2) heart and pulm circulation for flow
3) central and peripheral receptors to control and match ventilation/perfusion
problem in obstructive airway disease
1) impede gas flow in and out of alveoli
problem in restrictive disease
alter ventilation-perfusion matching
barrier for gas exchange
problem in pulmonary vascular disease
impair gas transfer
–> right heart failure
Pleural space created by (2)
1) inner lining of chest wall (parietal pleura)
2) outer lining of lung
(visceral pleura
what separates pleura
thin fluid (lubricant)
what happens if air enters pleural space
pneumothorax
what happens if fluid enters pleural space
pleural effusion
where are 5 lobes
2 upper lobe
2 lower lobe
right middle lobe
what supplies lobes
lobar bronchi and pulm arteries
what do pulm veins and lymphatics drain from
drain from the acini
which structures are part of lung’s conducting airways
1) trachea
2) bronchi
3) bronchioles
which structures part of lung’s gas exchange units
1) respiratory bronchioles
2) alveolar ducts
3) alveoli
conducting airway is defined by a series of ___
dichotomously branching tubes
the first 16 of the 23 airways are ___
conducting (conduit for gas transfer to and from respiratory exchange units)
structures that make up airway wall
1) inner mucosal surface (epithelial cells, cilia, goblet)
2) smooth muscle layer
3) outer connective tissue layer
what are structures within inner mucosal surface
1) epithelial cells
2) cilia
3) goblet cells
___ changes as generation increases
morphology of the airway wall
how does airway wall morphology change from bronchi to bronchioles
loss of cartilage in outer tissue layer
what do bronchitis and bronchietasis refer to
diseases of airway with cartilage
what do bronchiolitis refer to
diseases of bronchioles or non-cartilagenous airways
ventilation
air movement in and out of lung
respiration
gas exchange
exchange O2 and CO2 across alveolar capillary movements
conducting airways do not ___
exchange gas
“anatomic deadspace”
what does deadspace refer to?
parts of lungs that don’t exchange gas
What are the gas exchange regions
allow efficient diffusion of O2 and CO2 across alveolar and capillary walls
what is the gas exchange region also known as
acinus
where does acinus begin?
1) distal to terminal bronchiole
what are components within gas exchange region
1) respiratory bronchiole
2) alveolar ducts
3) alveoli
2 different cell types in alvoelar epithelial cells
1) squamous lining cells = type 1 cells = pneumocytes (simple squamous)
2) secretory cells = type II cells
describe type 1 cells of lung
95% of alveolar surface area
fuse with capillary endothelium to create thin membrane for transfer
what do type 1 cells fuse to create?
capillary endothelium to create thin membrane for gas transfer
what cells are injured in ARDS
type 1 cells
if type 1 cells are injured what disease
ARDS
functions of type II cells
1) repair/replace injured type 1 pneumocytes
2) secrete surfactant (lower alveolar surface tension)
what do type II cells secrete
surfactant (lower alveolar surface tension
pulmonary arteries (and arterioles) run with the ___
bronchi (and bronchioles)
PULMONARY VEINS ARE MORE PERIPHERAL
at what interface does gas exchange occur
across capillary-alveolar interface
where do lymphatics run?
what is their function?
run near pulm arteries and veins
help with extravascular lung water
lung development
what do lungs develop from? when?
fxn of that structure
lung bud of gut tube endoderm at week 4 from outpouch between 4th and 6th brachial arches (laryngotracheal groove)
instructs formation of notochord, heart, blood vessel
creates 2 tubes- digestive & respiratory
which layer do lungs develop from?
gut endoderm
where does pulmonary circulation develop from?
surrounding mesenchyme off lung bud branching
what happens day 26- 6 weeks
embryonic
foregut endoderm invade splanchnic mesenchyme
3 rounds of branching –> lung lobes
(asymmetric –> dichotomous (proximal tracheobronchial tree) –> subsegmental bronchii –> fill bilateral pleural cavities
____ forms lung lobes
3 rounds of branching
when does this happen
foregut endoderm extends into surrounding mesenchyme
3 rounds of branching –> lung lobes
days 26- 6 weeks
what happens 6 to 16 weeks
pseudoglandular
lung descend into thorax
pleuroperitoneal foramen closens
14 rounds of branching form terminal bronchioles
glandular cells = columnar rather than glandular
finished formation of conducting airways (down to #16)
–> splanchnic mesenchyme –> forms cartilage, smooth muscle cells and mucous glands
when does this happen
14 rounds of branching form terminal bronchioles
6 - 16 weeks
what happens between 16-28 weeks (canalicular)
form terminal bronchiole that divides into 2+ respiratory bronchioles
develop pulm capillary bed
expand airspaces
surfactant production begins
when does this happen
terminal bronchiole divides into 2+ respiratory bronchioles
surfactant production begins
16-28 weeks
what happens 28-36 weeks (saccular)
EPITHELIAL CELL DIFFERENTIATION –> TYPE 1 AND 2
respiratory bronchioles subdivided –> terminal sacs (develop into childhood)
distal growth and branching of terminal saccules
when does this happen
respiratory bronchioles dubdivided –> terminal sacs (develop into childhood)
28-36 weeks
what happens 36 week- early childhood (4-6 yrs)
alveolar
secondary septal
form true alveoli
septae thin
fusion of double capillary network
establish gas exchange unit
when does this happen
lung grows and alvoeli mature
septae thin
single capillary network in alv wall
establish gas exchange unit
36 week to early childhood (4-6 yrs)
what happens during week 4 of embryology
Epithelial cells of primitive foregut invade the splanchnic mesenchyme
Primitive lung bud develops from an outpouching between the 4th and 6th brachial arches
(Laryngotracheal groove)
when does this happen?
Epithelial cells of primitive foregut invade the splanchnic mesenchyme
Primitive lung bud develops from an outpouching between the 4th and 6th brachial arches
(Laryngotracheal groove)
3 weeks
what happens during week 5 of embryology
right and left lung bud push into primordial pleural cavity (pericardioperitoneal)
a
a
embryonic lung branching determined by ___
mesoderm
at branch points epithelial cell division stopped and collagen produced
at developing buds, growth factor produced to induce epithelial mitosis
when is fetal breathing detected
17-26 weeks gestation
type 1 cells are fusion of ___ and ___ basal lamina
epithelial and endothelial
a
a
when do type II pneumocytes appear?
at 6 month and start secreting surfactant
what happens during month 7
Respiratory bronchioles proliferate
Alveolar ducts and sacs
branching pattern determined by ___
mesoerm
what happens at branch points in branching?
epithelial cell division stops
collagen produced
what happens at developing buds in branching?
growth factors produced to induce epithelial mitosis
othe rmesodermal and epith factors stabilize and develop airways
