7.2 Flashcards
why do mammals need a specialised exchange surface?
they are big so have a small SA:V ratio
they have a high metabolic rate as mammals are very active
therefore they need a lot of oxygen and need to remove a lot of CO2
how is the nasal cavity adapted for gaseous exchange?
- has a large surface area
- good blood supply
- contains hair which stop dust and bacteria
how is the trachea adapted for gaseous exchange?
- contains cartilage
- contains ciliated epithelium and goblet cells
what does cartilage do?
prevents the trachea from collapsing
what does ciliated epithelium do?
contains goblet cells which secrete mucus which trap dust and bacteria
epithelium contains cilia which waft the mucus away from the lungs
what does the trachea divide into?
two bronchi
do bronchi contain cartilage?
yes
what do bronchi divide into?
many bronchioles
do bronchioles contain cartilage?
no
what are bronchioles lined with?
flattened epithelium which allows for gas exchange
what does the smooth muscle in the bronchioles do?
constrict and relax to control the amount of air which reaches the lungs
how do the alveoli have a large surface area?
there are so many alveoli which provide a large SA:V ratio for efficient gas exchange
how do the alveoli have thin layers?
the alveoli have walls lined with squamous epithelial cells which are 1 cell thick and provide a short diffusion distance which means faster diffusion
how do the alveoli have a good blood supply?
capillaries surrounding the alveoli provide a constant flow of blood and allows for a steep concentration gradient for CO2 and O2 to allow for gas exchange?
how do the alveoli have good ventilation?
breathing maintains a steep concentration gradient to keep gas exchange occuring
