exchange surfaces Flashcards
epithelial tissue found in lungs and airways
squamous epithelium and ciliated
how do alveoli create an effiecient exchange surface
wall is one cell thick so shorter diffusion pathway
squamous cells provide shorter pathway
elastic so recoil which helps ventillation and maintains conc gradient
lots of alveoli increase surface area
small size/folds of alveoli increase sa v ratio
good blood supply maintains high conc gradient
tidal volume
is the volume of air inhaled in each breath during regular breathing
vital capacity
the maximum volume of air inhaled or exhaled in one breath
whys it not possible to expel all air from lungs
thorax cant be completely compressed alveoli are held open by elastic fibres
smooth muscle
constricts bronchus
elastic fibres
allow alveoli to recoil to expel air
capillaries
deliver o2 and remove co2 maintains a steep concentration gradient
why should air sacs be refreshed
to increase the pressure of oxygen in the air sac so the concentration of oxygen is higher than that in the blood . it also decreases partial pressure of oxygen in the air sac so the concentration of co2 in the ar sac is lower than that in the blood.
spirometer
person blocks nose and breathes normally through mouth.Measure the height of the waves produced and calculate a mean. When you breathe in the lid goes down and when you breathe out the lid goes up.
effective gas exchange
squamous epithelium provides short diffusion pathway rbc transport co2 and o2 from the exchange surface to alveoli ciliated cells waft mucus to prevent pathogen from entering alveoli cartilage hold airways open smooth muscle constrict and control diameter of airways
why is expiration passive
as it doesnt use muscle contraction as rib cage falls due to gravity and lungs recoil because they contain elastic tissue.
vital capacity measurement what should subject do
the subject should breathe in deeply as possible and then force out as much air as possible.
insect trachea vs mammalian trachea
Insect tracheae differ from animal trachea as mammals have just one trachea and insects have multiple tracheae, mammal tracheas have a much larger diameter than insect tracheae, in mammals the trachea has cartilage to support it, whereas insect tracheae are supported by chitin, mammals have C-shaped ‘rings’ of supporting tissue (cartilage), whereas insects have spiral supporting tissue (chitin), mammal tracheas are longer, mammal tracheas branch into bronchi whereas insect tracheae branch into tracheoles, a mammal trachea has smooth muscle / goblet cells / ciliated epithelium, and insect tracheae do not.
hows a steep concentration gradient maintained in the lungs
By the continuous flow of blood in capillaries to the alveoli in the lungs
• This results in more oxygen being taken away from the lungs and more carbon
dioxide being brought to the lungs
