Gas Exchange Flashcards
Explain how fish are adapted to gas exchange
Gill lamellae have a large surface area for gases to diffuse over. Very short diffusion distance through the walls of the lamellae. Lamellae have an extensive network of blood capillaries.
Countercurrent exchange system - blood with low oxygen conc passes into capillaries of lamellae. Oxygen diffuses from the water into the bloodstream. Oxygen rich blood passes out of lamellae and leaves the gills. Direction of blood and water are opposite so always maintains a steep conc gradient for oxygen
How are mammals adapted for efficient gas exchange?
Walls of trachea contain cartilage - prevents the walls from collapsing
Walls of trachea are lined with ciliated epithelial cells - have cilia which move the mucus to the throat
and goblet cells - produce mucus to trap dust
Alveoli - large amounts provide large surface area for diffusion of gases. Wall of alveoli are one cell thick - short diffusion pathway. Extensive capillary network - ensures a steep conc gradient for oxygen
Explain the process of inhalation
The external intercostal muscles contract and shorten. Pulls the ribs up and out. Diaphragm contracts causing it to flatten. The volume of the thorax increases which reduces the pressure in the lungs and so air is drawn in and into the alveoli. Energy is required
Explain the process of exhalation.
External intercostal muscles relax and return to their original length. Diaphragm also relaxes and moves up back to its usual shape. This reduces the volume of the thorax and the lungs which causes the pressure to be greater than atmospheric pressure and so air is pushed out. Does not require energy.
How do stomata control the rate of transpiration?
Guard cells determine if stomata are open or closed.
Light - stomata are open as light triggers solutes (potassium ions) to be transferred into the guard cells - lowers the water potential causing water to love into the cells by osmosis making them turgid which causes a curved shape allowing them to open
Dark - stomata close to reduce water loss
What is the difference between transpiration and transpiration stream
Transpiration - loss of water vapour via the stomata by diffusion
Transpiration stream - movement of water from the roots to leaves
Describe the mechanism for the absorption of amino acids in the ileum
Facilitated diffusion of amino acid into the cell
Co transport
Sodium ions are actively transported from cell to blood
Creating a sodium ion concentration gradient
Facilitated diffusion of amino acid into blood
