3.1- Exchange Flashcards
why do organisms need exchange surfaces?
- Cells need to take in oxygen (aerobic respiration) and nutrients
- They also need to excrete waste products ( CO2 and urea)
- most organisms need to stay at roughly the same temperature and release heat
describe the relationship between the size of an organism or structure and its SA:V ratio
SMALLER the organism, GREATER the SA:V ratio
LARGER the organism, SMALLER the SA:V ratio
how does size affect heat exchange?
Depends on SA
- e.g. animals with a larger volume, has a smaller SA, makes it harder to lose heat
how does shape affect heat exchange?
COMPACT shape have a SMALL SA - minimising heat loss
LESS COMPACT shape-> LARGE SA -> INCREASE heat loss
describe how the change to body shape and adaptations allow organisms to survive in hot/cold environments
- Animals with a high SA:V ratio tend to lose more water
(e.g. desert animals have kidney structure adaptations so they produce less urine) - HIGH metabolic rates, small animals in a cold environment eat large amounts of high energy foods
- SMALLER mammals may have thick layers of fur or can hibernate
- Elephants in hot regions have developed large flat ears to INCREASE SA -> lose more heat
Describe the adaptations of gas exchange surfaces of a single-celled organism
- release and absorb gases via diffusion on their outer surface
- LARGE SA, thin surface and a short diffusion pathway (oxygen can occur in biochemical reactions)
- DO NOT need a gas exchange system
Adaptations of gas exchanges surfaces in the trachael system
Large network so INCREASE in SA:V ratio
-
Spiracles are pores on the surface of the insect where gases enter and leave
(can be opened and closed to prevent water loss and allow a conc gradient to build up) - Tracheae -> network of tubes gases move through - containing strengthened rings to ensure they do not collapse -> continous movement of gases
Tracheoles- smaller branched tubes, thin, permeable walls so direct diffusion so a short diffusion pathway
- the ends have a LOW O2 conc but a HIGH CO2 conc
Adaptations in gas exchange across the gills of the fish
** COUNTER CURRENT SYSTEM**
- each gill is made of thin plates called gill filaments -> BIG SA for gas exchange
- Gill filaments are covered in lots of tiny structures called LAMELLAE - which INCREASE SA but also have lots of blood capillaries and a thin layer to speed up diffusion
- Blood flows in one direction and water flows the opposite way -> maintains a HIGH conc gradient
(oxygen in water ALWAYS have a HIGHER conc)
adaptations in gas exchange of the leaves in dicotyledonous plants
-MESOPHYLL (main gas exchange surface- mesophyll cells inside the leaf) -> LARGE SA
- Gases move in and out of the leaf in the epidermis called the STOMATA
> through the stoma is surrounded by two guard cells, which can open and close for gas exchange
describe the gross system of the human respiratory system
Lungs
Trachea- flexible tube supported by rings of cartilage (prevents from collapsing)
Bronchi- two divisions of the trachea, each leading to a lung -> produces mucus and cilia
Bronchioles- series of branching subdivisions of the bronchi, walls made of muscle lined with epithelial cells
Alveoli- air sacs with a diameter of 100-300 um
what are the essential features of the alveolar epithelium?
Large surface area - many alveoli are present in the lungs with a shape that further increases surface area.
· Thin walls - alveolar walls are one cell thick providing gases with a short diffusion distance.
· Moist walls - gases dissolve in the moisture helping them to pass across the gas exchange surface.
· Permeable walls - allow gases to pass through.
· Extensive blood supply - ensuring oxygen rich blood is taken away from the lungs and carbon dioxide rich blood is taken to the lungs.
· A large diffusion gradient - breathing ensures that the oxygen concentration in the alveoli is higher than in the capillaries so oxygen moves from the alveoli to the blood. Carbon dioxide diffuses in the opposite direction.
Structural and functional compromises between the opposing needs for efficient gas exchange and the limitation of water loss shown by Terrestrial insects and xerophytic plants
hairs in their epidermis to trap moist air around the stomata prevents loss of water
· Sunken stomata in pits capable of trapping moist air. Lowers the concentration gradient of water between the air and the leaf, lessening the tendency for water to evaporate away.
· Lower number of stomata to lessen sites where water can escape.
· waxy cuticle to reduce evaporation
describe the role of internal and external intercostal muscles and the diaphragm within INSPIRATION
Breathing in (inspiration)
- External intercostal muscles contract, internal intercostal muscles relax (antagonistic)
- Moving ribcage up and out
- Diaphragm muscles contract → flatten/move down diaphragm
- Increasing volume in thoracic cavity / chest
- Decreasing pressure in thoracic cavity
- Atmospheric pressure higher than pressure in lungs
- Air moves down pressure gradient into lungs
- (Active process)
describe the role of internal and external intercostal muscles and the diaphragm within EXPIRATION
Breathing out (expiration)
- Internal intercostal muscles contract, external intercostal muscles relax (antagonistic)
- Moving ribcage down and in
- Diaphragm relaxes, moves upwards
- Decreasing volume in thoracic cavity
- Increasing pressure in thoracic cavity
- Atmospheric pressure lower than pressure in lungs
- Air moves down pressure gradient out of lungs
- (Passive process)
what is tidal volume?
volume of air in each breath
