Alveoli Flashcards
(14 cards)
How does gaseous exchange occur between the alveoli and capillaries?
1
Upon inhalation the alveoli fill with oxygen
2
De-oxygenated blood (from pulmonary artery) is in the capillaries.
Why is there a concentration gradient in the capillaries/alveoli?
the alveoli contain a high conc of oxygen but low conc of CO2 whilst the blood in the capillaries contain CO2 and have a lack of oxygen
3
Oxygen diffuses down its concentration gradient into the blood and binds with the haemoglobin to form oxyhaemoglobing
4
CO2 diffuses down its concentration gradient from the blood to the alveoli to be breathed out
5
The now oxygenated blood returns to the heart to be pumped around the body to respiring cells
6
The blood has a higher conc of O2 than the cells so the oxygen diffuses into the cells and the cells have a higher conc of CO2 than the blood cells so CO2 diffuses into the blood
the blood is now de-oxygenated so
the cycle repeats
How does having alveoli lead to more efficient gas exchange by diffusion?
They increase the SA
How do capillaries affect the alveoli’s surface area?
capillaries cover 70% of the outside of an alveoli which again provides a large SA for gases to diffuse across.
How are alveoli adapted to provide a large SA for gaseous exchange?
.they’re small and so have a larger SA:V ratio
.there are also a lot of them which means they have a large SA
How else are they adapted for efficient diffusion?
.They’re lined with a thin film of moisture which gases dissolve in, resulting in a smaller diffusion path
. the walls of capillaries & alveoli are 1 cell thick so there’s a short diffusion path
.they also have a good supply of blood and are ventilated which provides a conc gradient for diffusion
What is the calculation for breathing rate?
(no. of breaths) ÷ no. of mins = breaths per min
