module 3.1 Flashcards
whats the alveoli
tiny folds in the lung epithelium to increase sa
whats the bronchi and bronchioles
smaller airways leading into the lungs
whast the diaphragm
a layer of muscle beneath the lungs
what are the intercostal muscles
muscles between the ribs. contraction of the external intercostal muscles raise the ribcage
whats the trachea
the main airway leading to the back of the mouth to the lungs
ventilation
the refreshing of air in the lungs, so that there is a higher oxygen conc. in the blood, and a lower co2 conc.
where does the exchange of gasses take place?
the alveoli
what must the lungs maintain to ensure gas diffusion can continue
a steep gradient
adaptations of the alveoli (general)
- large sa
- thin layer of moisture
- thin barrier for molecules to diffuse across (animal cells don’t have cell walls)
where does oxygen diffuse from
from the alveoli to the blood in the capillaries
what are the 5 adaptations that reduce the distance gasses have to diffuse- gas exchange
- the alveolus is one cell thick
- the capillary wall is one cell thick
- both walls consist of squamous cells ( flattened or very thin)
- the capillaries are in close contact with the alveolus wall
- the capillaries are so narrow that the red blood cells are squeezed against the capillary wall making them closer to the air in the alveoli and reducing the rate of flow.
what helps maintain a steep concentration gradient in the lungs
a good blood supply:
- the blood system transports co2 from the tissues to the lungs, this ensures the conc of the co2 in the blood is higher than that in the air of the alveoli thus co2 diffuses into alveoli
- blood also transports oxygen away from the lungs, this ensures the conc of o2 in the blood is kept lower than that of the alveoli so that o2 diffuses into the blood
what does ventilation ensure?
- the conc of o2 in the air of the alveolus remains higher than that in the blood
- the conc of co2 in the alveoli remains lower than that in the blood
whats inspiration
inhaling
whats expiration
exhaling
what occurs during inspiration
- the diaphragm contracts to move down and become flatter- this displaces the digestive organs downwards
- the external intercostal muscles contract to raise the ribs
- the volume of the chest cavity increases
- the pressure in the chest cavity is increased
- air is moved into the lungs
what occurs during expiration
- the diaphragm relaxes and is pushed up by the displaced organs underneath
- the external intercostal muscles relax and the ribs fall; the internal intercostal muscles can contract to help push air out more forcefully- this usually only happens during exercise or coughing and sneezing
- the volume of the chest cavity decreases
- the pressure in the lungs increases and rises above the pressure in the surrounding atmosphere
- air is moved out the lungs
what happens to the elastic fibres in the alveoli during inspiration and expiration
during inspiration the walls stretch and then recoil to help push out air during expiration
what are the airways (trachea, bronchi and bronchiole’s) lined with
lined by ciliated epithelium which contributes to keeping the lungs healthy- goblet cells in the epithelium release mucus which traps pathogens, the cilia then moves the mucus up to the top of the airway.
what do the trachea and bronchi have/ are supported by- what does this allow for
- supported by rings of cartilage which prevent collapsing during inspiration- they are C-shaped which allow for flexibility and space for food to pass down the oesophagus
state things about bronchioles
- narrower than bronchi
- larger ones may have cartilage but smaller ones wont
- wall is comprised mostly of smooth muscle and elastic fibres