lung embryology snd defence Flashcards
whats the first part of the respiratory zone
respiratory bronchioles
whats the rule of the respiratory zone
to produce surfactant
4 stages of lung maturation
- pseudoglandular stage (6-16 weeks)
- canalicular stage (16-26 weeks)
- saccular stage (26 weeks - birth)
- alveolar stage (32 weeks-8 years)
pseudoglandular stage
creation of bronchial tree
canalicular stage
bronchial and terminal bronchiole lumen becomes larger
at least 2 respiratory bronchioles at 24 weeks
saccular stage
type II alveolar cells produce surfactant which stops alveoli collapsing
what is the role of surfactant
reduced surface tension and prevents alveolar collapse
in what 3 ways is amniotic fluid cleared at birth
- through nose and mouth by vaginal wall pressure
- into pulmonary circulation
- into pulmonary lymphatics
what lines the respiratory airways
pseudostratified ciliated columnar epithelium
what a common pathogen seen in CF patients
pseudomonas aeruginosa
what are the precursors to macrophages
monocytes
the optimum height of ASL for efficient clearance
7 micrometers
whats the primary embryology al original of respiratory tract epithelium
endoderm
what germ layer gives rise to the connective tissue and smooth muscle of lungs
mesoderm
what stimulates the production of surfactant by type II pneumocytes
glucocorticoids
what propels the mucus along the respiratory tract in the mucocilliary escalator
ciliary muscle
which cell type secretes the mucus that traps inhaled particles in the resp tract
goblet cells
what are the accessory muscles of forced inhalation
sternocleidomastoid,scalene, pectoralis minor
what is the strongest muscle of forced exhalation
rectus abdominus
pneumotaxic centre - upper pons
regulates and fine tunes breathing
apneustic centre - lower pons
signals for inspiration to occur- longer, deeper breaths
respiratory mechanoreceptors
in walls of bronchi and bronchioles, prevent over inflation of lungs
hering-brewer reflex
- stretching of walls (air coming in) activates mechanoreceptors
- impulses sent from receptors to DRG via vagus nerve
- inspiration stops
- expiration starts, reduces stretch, inactivates receptors, vagus stops sending signals
- inspiration starts
where are peripheral chemoreceptors found
in bifurcation of carotid artery and arch of aorta
where are central chemoreceptors located
on surface of medulla, exposed to CSF
ventilation
how much air gets from inhaled air to alveoli
perfusion
how much air from alveoli gets across into capillaries
shunt
perfusion of poorly ventilated alveoli eg pneumonia, acute asthma
physiological dead space
ventilation of poorly perfused alveoli eg COPD, pulmonary embolism
whats the main area of the brain used for voluntary breathing
cerebral cortex
tidal vol
amount of air in/out of lungs in single inspiration/expiration
functional residual capacity
vol air that remains in lungs at end of normal respiration
