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
what keeps the alveoli inflated?
lung surfactant
what happens to the ribcage during inspiration?
it moves upwards and outwards
what happens to the diaphragm during inspiration?
it flattens and lowers
what do the external intercostal muscles do during inspiration?
contract
what happens to the pressure in the thorax during inspiration?
the raising of the ribcage and lowering of the diaphragm increases the volume of the thorax which lowers the pressure
what happens to the pressure in the thorax during inspiration?
the raising of the ribcage and lowering of the diaphragm increases the volume of the thorax which lowers the pressure
how does air move into the thorax during inspiration?
the atmosphere pressure is higher than in the thorax so air moves down the pressure gradient and into the thorax
what happens to the ribcage during expiration?
it moves downwards and inwards
what happens to the diaphragm during expiration?
it raises
what do the external intercostal muscles do during expiration?
they relax causing the ribcage to lower
what happens to the pressure in the thorax?
the lowering of the ribcage and raising of the diaphragm reduces the volume in the thorax which increases the pressure
how does air move out of the thorax in expiration?
the pressure of the atmospheric air is lower than the pressure in the thorax. air moves down the pressure gradient and out of the thorax.
is inspiration active or passive?
active as the external intercostal muscles need to contract
is expiration active or passive?
passive
what happens when you forcibly exhale?
the intercostal muscles contract causing the ribcage to move down quicker which rapidly increases the pressure in the thorax
is forced expiration active or passive?
active as the internal intercostal muscles need to contract
