Flashcards in Gas Exchange- Humans and Lung disease Deck (27)
what is the epiglottis
flap of cartilage
closes over the entrance to the trachea
What is the trachea
has a cilitated liningto beat upwards are sweap mucuos out.
has rings of cartilage to keep the airway open
name the other compenents of the gas exchange
How does air flow in?
diaphragm contracts and is flat
external intercostal muscles contract
ribs move up and out
ribcage pulls on the pleural membrane
reduces the pressure in the alveoli
air rushes in
How does air flow out?
Internal intercostal muscles contract
ribs move in and down
volume of the thoratic cavity decreases
increased pressure in the thoratic cavity and lungs
air flows out
What is a spirometer?
used to measure and record volumes of inspired and expired air.
How does oxygen get into the blood?
How is the alveoli adapted for diffusion?
short diffusion distance- one flattened epithelial cell thick
Folds- increase surface area
Has its own capillary network to maintain a gradient as new blood is always flowing through.
Advantages to humans of an internal gas exchange surface
reduces water loss
maintains a moist gas exchange surface.
What is the diaphragm?
a tough membrane attached by muscles to inner wall of the chest.
when muscles of the diaphragm contract, the domoe flattens.
as volume of chest increases, the air pressue inside the lungs decreases and becomes slightly lower than air pressure outside, air moves down the presure gradient.
Lungs rocoil from being stretched (at rest)
as external intercostal muscles relax, the elastic fibres recoil and squeeze air out.
Internal intercostal muscles contract and pull ribs back down.
internal intercostal muscles pull ribcage down as far as possible to empty the lungs of more air than when at rest.
What is residual volume?
air that is not expired.
Which artery takes blood to the alveoli?
which vein takes blood away from the alveoli?
What happens at the alveoli?
CO2 diffuses into the alevoli out of the blood.
02 diffuses out of the alevoli into the blood.
Why is there never a 0% CO2 concentration in the alveoli?
Because diffusion requires a gradient, so an equilibrium is found.
Why does oxygen bind to haemoglobin?
because haemoglobin has a high affinity for oxygen.
What does tobacco smoke contain?
nicotine and carbin monoxide.
What is a retrospective study?
collecting data from the past, it is unreliable because people may have forgotten details .
What is a prospective study?
collecting data as it accumulates.
Takes a lot of time.
What do you need to consider when analysing a health risk study?
1. the number of people investigated.
2. identify the different levels of exposure to the health risk.
3. asses whether the control group were matched.
4. asses whether the differences are sufficiently large to indicate a factor as a risk.
5. see if tests have been done to see if stat. sig.
What does incidence mean?
The number of cases that occur in a particular group of people in a given time.
What does mortality rate mean?
number of deaths per number of population per year from a cause.
How is relative risk calucated?
finding the ratio between incidences with factor to incidences without factor.