export_resp 12 Flashcards
ventilation
air exchange between atmosphere and alveoli
what are the pulmonary defenses?
mucus, cilia, immune cells
breakdown of airways
trachea - bronchi - bronchioles - terminal bronchioles - respiratory bronchioles - alveolar ducts - alveolar sacs
where does gas exchange occur in the lungs?
respiratory bronchioles, alveolar ducts, alveolar sacs
what secrete mucus?
goblet cells and mucus-secreting glands
what cells secrete surfactant?
type II on alveoli
pleural sac
double-walled structure surrounding each lung
intrapleural space
- space between lung and thoracic wall
- contains intrapleural fluid
elastic recoil
tendency for lungs to want to pull in
transpulmonary pressure (Ptp)
difference in P between alveolar P and intraplural P
-pushed outward on lung wall
transrespiratory pressure (Prs)
pressure diff between alveolar P and atmospheric P
-determines airflow
transmural pressure across chest wall (Pcw)
P difference between intraplural P and atmospheric P
-F pushing on chest wall
inspiratory muscles
diaphragm, external intercostals
expiratory muscles (when not passive)
abs, internal intercostals
how does diaphragm cause inspiration?
diaphragm contract –> inc thoracic volume –> dec thoracic P –> inspiration
tests to measure lungs
- amount of air lungs can hold
- residual volume
vital capacity
amount of air in lungs after max inhale and exhale
tidal volume
amount of air inhaled/exhaled during relaxed breathing
residual volume
amount of air in lungs after max expiration
-keeps alveoli inflated
functional residual capacity
amount of air in lungs after relaxed expiration
what is anatomic dead space?
volume in airways left over from preceding breath
what type of breath increases alveolar ventilation?
deep breath
tidal volume
volume per breath
alveolar ventilation
tidal volume minus dead space
alveolar dead space
no blood or air supply
what determines volume of air moved during ventilation?
1) Ptp
2) compliance (lung elasticity)
2) airway resistance
low lung compliance=
- stiff
- difficult to expand
- high surface tension (low surfactant)
emphysema
-high compliance (floppy) lung
what determines compliance?
1) elastic lung tissue
2) surface tension
what causes surface tension?
forces acting on water at surface of alveoli
surfactant
- phospholipids and proteins
- secreted by type II cells
-lowers surface tension
what determines airway resistance?
size of airway
what determines flow rate?
- pressure
- resistance*
as number of airways inc, total resistance ____
decreases (even though individual airways increase)
why doesnt resistance limit air flow?
- lateral traction (pulled open when alveoli expand)
- pranspulm pressure (acts outward and pulls them open)
what signals to airway resistance?
- inc parasymp and inflammation
- dec by CO2 and epinephrine
when is resistance greatest?
expiration and low lung volumes
what increases mucus secretion and airway contractions?
- parasym
- paracrines (hisamine)
what causes airway dilation?
- epinephrine
- PCO2 in alveoli
asthma effects
- elasticity
- surface tension
-resistance
asthma therapies
- reduce inflammation
- bronchiodilators
emphysema
- destroyed alveolar walls (dec surface area)
- airway collapse
- destroyed pulmonary capilalries
- inc resistance (dec recoil and lateral traction)
bronchitis
- excessive mucus
- inflammation
-inc resistance
COPD
emphysema and bronchitis
fibrosis
- inc connective tissue stiffens lungs
- unable to expand alveoli
- lung volumes dec
- inc diffusion distance
- R unchanges/slight dec
