Pulm Week 1 Flashcards
(243 cards)
The conducting airways consist of ___ dichotomous branching tubes starting with _____ and ending at _________. The first ____ branches are just for conduction
23
Trachea –> terminal bronchioles
16 (branch point 17 has alveolar tissue)
Gas exchange units begin distal to _________ and includes _______, _________, and _______
terminal bronchiole
respiratory bronchioles, alveolar ducts, alveoli
Type I Pneumocytes
simple squamous
95% of alveolar surface area, fuse with capillary endothelium for gas transfer
Type II pneumocytes
Secretory
- Produce surfactant → lower alveolar surface tension
- Can further differentiate into Type I to repair or replace them
Ventilation
air movement in and out of the lung
Respiration
gas exchange - exchange O2 and CO2 across the alveolar capillary membrane
-Heart and pulmonary circulation needed to provide blood flow to alveoli
Lung bud develops from _________ and branches multiple times into the ____________
embryonic gut tube endoderm
splanchnic mesenchyme
Lung bud develops from an out pouching between the ______ and ______ in a region called the _________
4th and 6th brachial arteries
Laryngotracheal groove
Pulmonary circulation develops from ________
mesenchyme
Stages of lung development (5)
1) Embryonic stage 4-7 weeks
2) Pseudoglandular stage 8-16 weeks
3) Canalicular stage 17-26 weeks
4) Saccular (Terminal Sac) Stave 26-36 weeks (term)
5) Alveolar Stage (Postnatal Stage) 36 weeks - 3 years
Embryonic stage
- foregut endoderm extends into surrounding mesenchyme
- 3 rounds of branching establish lung lobes
- to level os subsegmental bronchi
- begin to fill bilateral pleural cavities
- branching determined by mesoderm
Pseudoglandular stage
-14 rounds of branching form terminal bronchioles
Canalicular stage
- terminal bronchiole divides into 2+ respiratory bronchioles
- delineation of pulmonary acinus
- fetal “breathing” detected
- epithelial cell differentiation begins
- initial development of pulmonary capillary bed
- possible fetus can survive but respiratory distress trouble
Saccular stage
-Respiratory bronchioles subdivide to produce terminal sacs (these continue to develop well into childhood)
-Epithelial differentiation is hallmark
(Type II secretory cells –> surfactant production, fetal survival improves)
Alveolar Stage
- Lung grows and alveoli mature
- Septae thin
- Single capillary network in alveolar wall
- Gas exchange unit established (presence of true alveoli - 90% of 300 million appear after birth)
Pulmonary arteries (and arterioles) run with ______
bronchi (and bronchioles)
Pulmonary veins do not run with airways but are more peripheral
Lymphatics run near ______ and _____ to help cope with ________
pulmonary arteries and veins
extravascular lung water
Pulmonary arteries embryonic origin is the ________, whereas pulmonary veins originate from _________
6th aortic arce
outgrowths of left atrium
______ cells line the lungs
mesothelial
Branching pattern of conduction system
_______ → _______→ ___________→ _______ (how many on right vs. left)
trachea → primary bronchus → secondary bronchus → segmental bronchi (10 on the right, 8 on left)
Trachea differs from the bronchus in that is has no ___________ layer and no __________
no muscularis mucosa layer
no submucosal glands
Wall layers of bronchus from surface to deep (7)
1) Epithelium (ciliated cells, goblet cells, basal cells, neuroendocrine cells)
2) Basal lamina
3) Alveolar connective tissue
4) Musclaris Mucosa
5) Dense CT of submucosa
6) Hyaline cartilage
7) Adventitia
Epithelium in walls of broncus made up of what 4 types of cells with what functions?
1) ciliated cells (constantly move mucous up airway)
2) goblet cells (secrete mucus onto bronchial surface)
3) basal cell (stem cell for other cells in epithelium)
4) Neuroendocrine cells also present - do reflexive control of airway size
Alveolar connective tissue
- made up capillaries and nerve cells
- Contains leukocytes that wander around in loose CT
- Mucosal associated lymphoid tissue