exchange surfaces Flashcards
how does surface area affect the need for an exchange surface?
small organisms have a large surface area in comparison to their column which means their surface area is large enough for the exchange of substances and means there is a shorter diffusion distance
How does metabolic rate affect the need for an exchange surface?
large organisms have a higher metabolic rate so require additional adaptations to increase efficiency of exchange
what is the route air takes during ventilation?
trachea –> bronchi –> bronchioles –> alveoli
How is the trachea adapted for exchange?
the trachea has c shaped rings of cartilage for support and to ensure that it does not collapse when pressure decreases. it is also lined with ciliated epithelium cells which contain goblet cells. also there is smooth muscle within trachea walls which allows muscle to contractiont if there are harmful substances detected
what are goblet cells?
goblet cells release mucus which traps dust and pathogens which then get swept up the mouth and is removed by ciliated epithelium cells.
what are the adaptations of alveoli
these are located at the end of the bronchiole and are the site of gas exchange. oxygen diffuses from the alveoli into the blood in the capillaries and carbon dioxide diffuses from the capillaries to the alveoli. alveoli are small and there are lots of them which creates a very large surface area for gas exchange. in addition the alveolus cells are one wall thick which reduces the diffusion distance. also each alveolus is surrounded by a good supply of blood from the capillaries which maiantisn the concentration gradient.
what is ventilation?
this is the mechanism of breathing which maintains the concentration gradient for gas exchange at the alveoli
summarise inspiration
external intercostal muscles contract –> ribs are raised –> volume in chest cavity increases –> pressure in chest cavity falls –> o2 moves into the lungs
summarise expiration
external intercostal muscles relax –> ribs fall –> internal intercostal muscles contract to push air –> volume of chest cavity is decreased –> pressure in lungs increases –> air moved out the lungs
what is a spirometer
a device that measures lung volumes by measuring the movement of air in and out of the lungs as a person breathes
what is vital capacity
the maximum volume of air an individual can inhalee and exhale during a deep breath
what is tidal volume
The air inhaled (peaks) and exhaled (troughs) when at rest
what is the structure and function of gills within fish?
most fish have 5 pairs of gills covered by a non plate called the operculum, each gill consists of two rows of gel filaments (primary lamellae) attached to a bony arch. these are very thin and folded into secondary lamellae meaning they have a large surface area. they are surrounded by blood capillaries to create a short diffusion distance
why do fish have to use a counter current flow mechanism for exchange?
water has a lower dissolved oxygen concentration than 02 in the atmosphere so for fish to be able to maintain the concentration gradient for diffusion they need to use this mechanism. the water flows over the gill in the opposite direction to the flow of blood in the capillaries to ensure the gradient is maintained across the entire length of the gill lamellae
how does gas exchange occur in insects?
air enters a pore called the spiracle and is transported into the blood via the trachea which divides into tracheal. these tracheal are open ended containing trachea fluid. gas exchange occurs between the air in the trachea and the tracheal fluid
