mammalian gas exchange Flashcards
why do single celles organisms have a high SA:V ratio
-allows simple diffusion
-large surface area allows for maximum absorption of nutrients and gases and secretion of waste products
-small volume means short diffusion distance
what happens to surface area and volume when organisms increases in size
their SA:V decreases
so longer diffusion distance and less surface area for absorption and secretion
what do larger organisms have
-higher metabolic rate
-smaller surface area:volume ratio
-longer distance from the outside of the organism to the middle of it
-require adaptations to increases efficiency of exchange across their surfaces
adaptations of trachea
-c shaped rings of cartilage for support
-ciliated epithelium with goblet cells to get rid of pathogens with mucus and removed them
-smooth muscle within the walls.
adaptations of bronchi
-both have cartilage within their walls for support and to keep the tubes open
adaptations of alveoli
-larger surface area from a large number of alveoli
- short diffusion distance as alveoli walls are very thin and made up of squamous epithelial cells
-maintains steep concentration gradient so each alveolus is surrounded by a network of capillaries
what does ventilation maintain
the steep concentration gradient for gas exchange at the alveoli
what is vital capacity
the max volume of air an individual can inhale and exhale during a deep breath
what is tidal volume
the air inhaled (peaks) and exhaled (troughs) when at rest
equation for ventilation rate
ventilation rate = tidal volume * breathing rate
adaptations of bronchioles
-do not need to be kept open therefore mostly have smooth muscle and elastic fibres to contract and relax easily during ventilation
describe inspiration process
-external intercostals contract pulling ribs up and out
-diaphragm contracts and flattens
-volume of the thoracic cavity increases
-air pressure outside the lungs is higher than air pressure inside so air moved in to rebalance
describe the process of expiration
-external intercostals relax bringing ribs down and in
-diaphragm relaxes into dome shape
-volume of thoracic cavity decreases
-air pressure inside the lungs is higher than the pressure outside so air moves out to rebalance
during exercise internal intercostals contract aswell to pull ribs in with force
how does a spirometer
measures lung volume
-a person breathes into an airtight chamber which leaves a trace on a graph which shows the volume of the breaths
