Gas Exchange Flashcards
(36 cards)
How does an organism size relate to its surface area to volume ratio?
The larger the organism, the lower the surface area to volume ratio.
Describe the gas exchange mechanism in Fftworms
Flat and so have a larger suface area to volume ratio compared to spherical organisms
short diffusion paths
Describe the gas exchange mechanism in ameoba
Large surfsce area to volume ratio
Thin cell membrane and so has a short diffusion distance
Gas excahneg via simple diffusion across cell membrane to supply oxygen for respiration and remove carbon dioxide.
Describe the gas exchange mechanism in earthworms
Cylindrical and so has a small surface area to volume ratio
Respiratory surface is skin which remains moist by secreting mucus.
Low metabolic rate and sp has a low oxygen requirement
Good blood suplly maintaining steep diffusion gradient at the respiratpry surface.
Define metabolic rate
The rate of energy expenditure by the body.
Explain how a fishs gills are adapted for gas exchange
Describe the process of ventilation in bony fish
- Mouth opens, bucaal cavity floor lowers, Volume of buccal cavity increases and pressure decreses while the operculum remains closed water is pulled in
- Mouth closes, buccal cavity floor contracts and raises. Water is forced across gills
- pressure in the gill cavity increases and forces rhe operculum open, water leaves via the operculum.
What is the purpose of ventilation in bony fish?
Ventilation in a bony fish allows
water to be passed continuously
across the gills even when the fish
is resting
Define counter current flow
Blood and water flow in
opposite directions across the gill plate. Blood always meets water with a high oxygen content and thus maintains a concentration gradient for the efficient diffusion of oxygen into the blood. Diffusion occurs across the entire gill plate.
Why is counter current flow more effecient than parallel flow?
Counter current flow increases
the efficiency of diffusion
by maintaining a steep
concentration gradient across the
whole gill filament. Blood always
meets water with relatively high
oxygen content.
Define parallel flow
Blood and water flow in the same direction across the gill plate and so the oxygen concentration is not maintained and instead an equilibrium is reached between the water and the blood. Diffusion does not occur across the entire gill plate.
Describe the process of inspiration in mammals
- Intercoastal mucles contract, ribs move up and out
- Outer then inner pleural membrane is pulled outwards following the ribs, decreasing pressure in the pleural cavity (negative pressure breathing)
- Diaphragm, contacts and flattens increasing thoracic volume and decreasing pressure in the lungs to below atmospheris pressure, drawing air in.
Describe the process of expiration in mammals
- Intercoastal mucles relax, ribs move down and in
- Pleural membrane is pulled inwards, increasing pressure in the pleural cavity
- Diaphragm relaxes and concaves decreasing thoracic volume and increasing pressure in the lungs to above atmospheris pressure, forcing air out.
Describe the respiratory surface of gas exchange for amphibians
For an inactive amphibian gas exchange occurs across mooist skin.
When an amphibian is active, gas exchange occurs across simple lungs or hollow sacs. High surface area due to folding.
The
tadpole stage uses gills.
Describe the respiratory surface of gas exchange for reptiles
Gaseous exchange occurs exclusively in sac-like lungs with complex folding. Reptiles have ribs, but no diaphragm. Ventilation is aided by the movement of the ribs by the intercostal muscles.
Describe the respiratory surface of gas exchange for birds
Birds are warm-blooded and have a high respiration rate. Bird lungs are small and compact, composed of numerous branching air tubes called bronchi. The smallest air tubes, the parabronchi end in large, thin walled air sacs which help in ventilation and have an extensive blood capillary network. Ventilation of the lung is brought about by movement of the ribs. During flight the action of the wing muscles ventilates the lungs.
Describe the process of ventilation in insects
1.Abdomen expands and the spiracles open at the thorax but close at the abdomen. Air enters the tracheal system.
2. Abdomen compresses and the spracles at the thorax close but open at the abdomen. Air leaves the tracheal system.
This occurs during activity.
Describe the journey of gas during gas exchange in insects
Gas exchange in insects occurs through paired holes, called spiracles, running along the side of the body. The spiracles lead into a system of branched, chitin lined airtubes called tracheae. The spiracles can open and close like valves; this allows gaseous exchange to take place and reduces water loss.
What is the purpose of the fluid in the pleural cavity?
Prevents friction and acts as a lubricant
What is surfactant?
A fluid that lines the alveoli to reduce surface tension and prevent them from collapsing during exhalation.
How are aveoli adapted for gas exchange?
Squamous epithelia cells are 1 cell thick providing a short diffusion path.
Surrounded by surfactant providing moisture for gases to dissolve.
Large surface area to volume ratio
Extensive capillary network providing a good blood supply and maintaining a steepconcentration gradient.
Describe the structure and function of the larynx
Hollow tube at the top of the trachea involved in breathing and phonation.
What is the function of the waxy cuticle?
Reduces water loss from the leaf surface by evaporation
What is the function of the upper epidermis?
Transparent cells which allow light to pass to the mesophyll tissue. The epidermal cells also synthesise and secrete the waxy cuticle.
