3a Flashcards
why do organisms need exchange surfaces to their environment
- take in oxygen and nutrients
- excrete waste products like carbon dioxide and urea
-stay the same temp
why do single celled organisms not need exchange surfaces
as they are so small so everything can diffuse out directly and it is quick
why do multicelled organisms need exchange surfaces
cells can be deep in body
larger animals have a low surface area to volume ratio which isn’t enough for the substances they need
why does size affect heat exchange
larger surface area means it can lose it more easily as theirs more area for them to leave
if they have this they also need a high metabolism to stay warm
why does shape affect heat exchange
animals with a more comapct body have a small surface area relative to volume to reduce heat loss
but ones with less compact lose more heat. this depends on the enviroment
what are some examples of ways organisms have adapted to aid exchange
small desert mammals have kidney structure adaptations to produce less urine
high metabolic rates if cold regions
fur
elephants have large ears
hippos go in water
what are the 2 major gas exchange adaptations
large surface area
their thin so shorter diffusion pathway
what do single celled organisms have for gas exchange
large SA
thin surface
short diffusion pathway
what is a fish counterflow system
a special adaptation fish have to get lots of oxygen out of water with low o2 conc
how does the countercurrent system work
the water flows in the opposite direct to the blood flow. this maintains a large concentration gradient. conc of o2 is always higher in the water
what adaptations are their in the gills
gill filament which have a large SA
lamellae which are on filaments and increase SA
large blood supply
how do insects use trachea to exchange gases
A spiracle is an opening in the exoskeleton of an insect which has valves
It allows air to enter the insect and flow into the system of tracheae
Most of the time, the spiracle is closed to reduce water loss
Tracheae are tubes within the insect breathing system which lead to tracheoles (narrower tubes
how do dicotyledonous plants exchnage gas
the mesophyll cells in the leaf as they have a large surfaces area
gas moves in and out through pores called stomata
what do stomata do
open and close to aloow air in but reduce water loss
how do insects reduce water loss
they close their spiracles and have waterproof waxy cuticles
what do plants have to reduce water loss
stomata
what is the route of gas in the human body
mouth/nose to trachea to brochi to bronchioles to alveoli
describe the process of inspiration
external intercostal muscles and diapraghm contact
this makes the diaphragm flat
and the ribcage to move up and out
decreasing the pressure so air rushes in
what kidn of process is inspiration
active
describe the process of expirtation
external intercostal and diaphragm relax
ribcage moves downwards and inwards and diagram returns to dome shape
thorastic cavity volume reduced so pressure increases and air rushes out
where does gaesous exchange take place in the body
the alveoli
what adaptations are their in the alveoli
a thin membrane
large SA
lots of blood supply
how does gaseous exchange take place in the lungs
o2 diffuses across the alveolar epithelium then the capillary endothelium and then its in capillary and gets carried away
and co2 diffuses out
what is tidal volume
volume of air in each breath
what is the ventilation rate
number of breaths per minute
what is forced expiratory volume
max air that can be forced out in one second
what is forced vital capacity
volume of air that can be possible to force out of length after one deep breath in
what is pulmonary tuberculosis
when immune cells build a wall around bactiera in the lungs
infected tissue often dies and gas exchange is decreased
can also cause fibrosis
what is fibrosis
formation of scar tissue in the lungs
makes the lungs less able to expand
asthma
when airways become inflamed and irritated and the brochioles contact causing lots of mucus to be produced
stops airflow
emphysema
caused by smoking or air pollution
overall causes destruction of alveoli wall
