Gas exchange Flashcards
Where are the lungs?
the thorax
What are the 3 steps when breathing in?
1- Intercostal muscles and diaphragm contract
2-thorax volume increases
3-this decreases pressure, drawing air in.
What are the 3 steps when breathing out?
1- Intercostal muscles and diaphragm relax
2-thorax volume decreases
3-this increases pressure, forcing air out.
where does gas exchange take place in ?
Alveoli-oxygen diffuses into the blood and carbon dioxide diffuses out of the blood.
adaptations of alveoli for gas exchange ( SA)
- Lots of alveoli provide a very large surface area thus increasing the rate of diffusion
adaptations of alveoli for gas exchange ( blood)
Alveoli also have a good blood supply as they are covered in lots of capillaries; this makes sure that the concentration gradient is maintained as red blood cells that have collected oxygen flow away from the lungs and red blood cells that need oxygen keep arriving.
adaptations of alveoli for gas exchange (wall)
Alveoli have very thin walls that are only one cell thick; this reduces the distance the gases have to diffuse so that the rate of diffusion increases
why do alveoli have moist lining?
for gases to dissolve in
why are alveoli’s walls permeable?
so gases diffuse across easily
why do alveoli’s have a good blood supply?
to maintain conc. gradient
why are alveoli’s wall only i cell thick
so diffusion can happen faster
What does smoking do to alveoli?
damages the walls inside the alveoli- reducing the SA for gas exchange - leading to emphysema
what does the tar in cigarettes do?
( cilia)
damages cilia in lungs+ trachea- chest infections more likemy
what do the cilia do?
these hairs ( along with mucus) catch dust + bacteria before they reach the lungs.
the cilia also help to keep the trachea clear by sweeping mucus back towards the mouth
what does tar in cigarettes do ( bronchi)
Irritates bronchi/bronchioles
