gas exchange in humans (topic 11) Flashcards
what are some adaptations of the breathing system
gas exchange surfaces have:
have a large surface area
are thin
have a good blood supply
have good ventilation with air.
what are the main structures that compose the breathing system
lungs, diaphragm, ribs, intercostal muscles (internal and external), larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries
what is the order of air going into your body for gas exchange?
nose/mouth → larynx → trachea → bronchi → bronchioles → alveoli
describe the trachea
A tube made of cartilage that allows ventilation to the lungs from the mouth and nose. they support the airway and help keep it open
describe the thorax
The chest cavity that protects some of the main internal organs such as the heart and lungs. Muscle contractions in the thorax allows for ventilation.
explain what happens to the thorax when breathing in
the volume of the thorax increases
the pressure inside decreases and becomes less than the pressure outside
air is pushed into the lungs.
explain what happens to the thorax when breathing out
the volume of the thorax decreases
the pressure inside increases and becomes more than the pressure outside
air is pushed out of the lungs.
what are the changes in the volume of the thorax caused by
contraction and relaxation of the diaphragm
contraction and relaxation of the intercostal muscles resulting in movement of the ribs
explain movement of breathing system when breathing in
diaphragm- contracts
internal intercostal muscles relax
external intercostal muscles contract
ribcage moves upwards and outwards
explain movement of breathing system when breathing out
diaphragm- relaxes
internal intercostal muscles contract
external intercostal muscles relax
ribcage moves downwards and inwards
what are the percentages of gases in inspired air
21%- oxygen
0.04%- carbon dioxide
water vapour- variable
78%-nitrogen
what are the percentages of gases in expired air
16%- oxygen
4%- carbon dioxide
water vapour- always high
79%- nitrogen
compare the percentage comopositon of gases in expired and inspired air
compared with inspired air, expired air has:
less oxygen- oxygen used by cells for aerobic respiration
more carbon dioxide- a waste product of respiration
more water vapour- moisture evaporates from the cells of the gas exchange surface.
how can you test for carbon dioxide
use limewater- turns milky white if present
briefly what happens to your rate and depth of breathing when excerising
- rate and depth increases, however after stopping this levels gradually drop
explain why the body increases in rate and depth of breathing while exercising
-cells of the body respire more during physical activity, provides energy needed by the muscles.
-increased rate of respiration produces more carbon dioxide, waste product
-increasing concentration of carbon dioxide in blood, detected by brain, triggers body to respond by increasing the rate and depth of breathing to expel the carbon dioxide from body.
-also increases oxygen obtained.
why must breathing system have protecting methods as well
because air that you breathe in through your nose or mouth may contain pathogens and other particles
how does body protect against possible pathogens and particles in air
as you breathe in through your nose air is moistened warmed and filtered
hairs in nose help filter dust
specialised cells eg. goblet cells and ciliated cells
explain role of goblet cells
produce mucus which lines trachea, these pathogens and particles are trapped in mucus
explain role of cilliated ells
they line surfaces of nose, trachea, bronchi, bronchioles, specialised cells with very thins structures called cilia, sweep mucus out of breathing system to the throat, carries any trapped pathogens or particles away from the breathing system
