Human Respiratory Tract
Upper Respiratory Tract
nasal passages: warm, moisten, clean air
- turbinates (this bones) project into nasal passage to
increase surface area
- membrane secretes mucus (sticky and moist)
- blood capillaries provide heat
- cilia (tiny hairs) move mucus out of tract by beating in unison
pharynx: place that oral and nasal cavities join
epiglottis: closes off trachea when swallowing food
- thin, flexible, smooth, able to move
glottis: opening to trachea (allow air through to lungs)
larynx: voice box; produces sound
- made of cartilage (strength); two folds of membranes
stretched across trachea
- folds can change position; vibrate when air passes to
produce sound
- prevent food from entering trachea
trachea: carry air to lungs
- flexible, durable membrane; C-shaped pieces of cartilage
- cartilage rings hold airway open (even if unconcious)
- back of trachea can expand inwards (allow large food items
to pass) and rings allow neck to tilt
Lower Respiratory Tract
bronchi: carry air to each lung
- two tubes branch from trachea; cartilage rings and mucus
membrane still present
bronchioles: carry air to individual alveoli clusters
- smaller branches (become progressively smaller as move away
from bronchi)
- some cartilage
alveoli: site of gas exchange
- arranged as clusters (increase surface area)
- thin, flexible, moist membrane surrounded by blood
capillaries
- 500 million in adult lung
lung: site of gas exchange
- divided into lobes; left side has fewer lobes then right in
order to provide room for the heart
pleural membrane: decreases friction between lungs and cavity
wall during breathing
- double membrane with lubricating fluid between
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