Pulmonary Exam I Flashcards
Majority of resistance to breathing is within the first ____ generations
10
- cross sectional area increases farther down the bronchial tree
How many generations make up the conducting zone?
0-16
- starts from the trachea (0) and ends at the terminal bronchioles (16)
Where is cartilaginous support found in the airway?
trachea and subsegmental bronchi (4-9)
Conducting Airway Layers
(picture)
Ciliated pseudostratified epithelia
Cilia
propel debris and foreign particles toward glottis
- found in conducting zone
- moves mucus 2cm/min
- works with Nexin
Goblet Cells
produce mucus in conducting zone
- 100 mL of mucus a day
- viscoelastic
- deforms and spread when force is applied to it
- innervated by parasympathetic NS (Vagus)
Clara Cells
secretory in bronchioles and beyond
- conducting zone
- proteins, inflammatory modulators
Mast Cells
contains inflammatory mediators of conducting zone
- histamine, lyosomal enzymes, met.
Bronchial Glands
exocrine glands controlled by the parasympathetic NS
Respiratory Bronchiole
- squamous cell
- some ciliated
- no goblet cells or smooth muscle
- alveoli in walls
Alveolar Ducts
- walls made of alveoli
- each opens into 10-15 alveoli
When do you stop making alveoli?
8-10 years old
Approximately how many alveoli are in an adult?
300 million
- up to 280 billion pulmonary capillaries
- SA for gas exchange is about 70m2
Pore of Kohn
holes in the walls of adjacent alveoli
- allows air to move between alveoli
Type I Alveolar Cells
really flat squamous epithelia
- 250 um wide
Type II Alveolar Cells
manufacture and store sufactant
- contains phospholipids
- decrease surface tension of alveolus
Canals of Lambert
openings to a second respiratory bronchiole
Pathway for Gas Exchange
- oxygen inside alveolus
- surfactant
- type I cell (wall)
- basement membrane
- interstital space
- capillary wall (endothelium)
- plasma
- erythrocyte
Inhalation
expanding chest generates negative pressure
- Diaphragm and external intercostals
Accessory muscles of inhalation
sternocleidomastoid, scalenes, and pectoralis
Muscles of Exhalation
abdominals and internal intercostals
Pleural space
virtual space that contains fluid to reduce friction
- links motion of chest wall and lungs
- negative pressure
Resting position of chest wall
negative intrathoracic pressure is required to keep it from expanding to its resting position
- usually greater than its dimensions in vivo
What keeps the chest wall from expanding further?
negative pleural pressure
Transmural pressure
unequal pressures on either side of structure define expanion or compression
Pinside - Poutside
- positive: forces that expand of increase volume
- negative: collapsing forces or decrease volume
- zero value: unstressed, resting position
End Expiration and During Inspiration
(pictture)
Respiratory compliance
lung and thoracic cage are in series
1/total = 1/lung + 1/chest wall
- for a supine paralyzed patient:
- 1/0.85 = 1/1.5 + 1/2
Normal value of lung compliance
150 mL/cmH2O
(1. 5 k/kPa)
* stiff lungs have a low compliance
Compliance curve of lung
(picture)
Factors in elastic recoil of lung
Mainly the surface tension at the alveolar gas-liquid interface
some from tissue elastic forces of lung and chest wall
LaPlace’s Law
P = 2T/R
Pulmonary surfactant
produced by type II and stored in lamellar bodies
- 90% lipids
- 10% proteins
- albumin and globulin
- 2% surfactant proteins
- Mono or multi- layer structure
- 5-30 dynes/cm
- compaired to 72 in water
Surfactant deficiency
decreases compliance of lungs
- needs a greater inflation pressure to keep alveoli open
- areas of atelectasis
- fluid filled alveoli
Functional Residual Capacity
when outward expansion of chest wall counter balances the collapsing force of the lungs
- resting equilibrium point
Normal value of thoracic cage compliance
200mL/cmH2O
FRC as a function of body position
(picture)
FRC in disease states
(picture)
Which generation of bronchi have the highest total resistance?
5th-7th
PNS stimulation of bronchial smooth muscle
constriction and secretions
What constricts the airway?
- Paraysmpathetic stimulation
- acetylcholine
- histamine
- leukotrienes
- thromboxane A2
- serotonin
- alpha agonists
- decrease PCO2 in small airways
What dilates the airway?
- sympathetic stimulation
- Beta receptors
- Beta-2 agonists
- nitric oxide
- increase PCO2 in small airways
- decreased PO2 in small airways
Abdominal contraction effects in forced exhalation
- increase:
- intrathoracic pressure
- pleural pressure
- alvevolar pressure
Dynamic compression of airway
- amount able to be forced out is independent of effort
- increase in pleural pressure is transmitted to airway and alveoli
- flow limitation