Gas Exchange Flashcards
How do single called organisms gain the oxygen they require for respiration?
Diffusion across cell membrane.
Surface area is huge compared to the volume.
What are spiracles?
Holes in the abdomen of insects. Used to let air into the tracheoles.
What is the advantage to the insect in opening and closing the spiracles?
Conserve water when closed
How does the countercurrent exchange system maximise oxygen absorbed by fish?
Blood and water flow in opposite directions across the gas exchange surface in fish.
Water containing the highest concentration of oxygen meets blood already containing some oxygen
Maintains a steep concentration gradient across the whole lamellae.
How is surface area:volume ratio calculated.
Surface area / volume
Why is countercurrent an advantage for gas exchange?
Water containing the highest concentration of oxygen meets blood already containing some oxygen
Allows diffusion across the whole gas exchange surface
What is the function of stomata?
Open to increase the rate of diffusion of air into the leaf.
Explain why plants only open stomata during day time.
Maximise the amount of carbon dioxide entering the leaf.
Close at night to prevent water loss.
Give 3 adaptation shown by the alveolus to increase rate of diffusion.
Large surface area.
Short diffusion distance created by flattened cell making up the epithelium.
Blood capillary close to gas exchange surface.
Large concentration gradient - maintained by ventilation of lungs.
Describe how a human breathes in.
Diaphragm contracts and moves downwards (flattens). External intercostal muscles contract. Internal intercostal muscle relax Ribs move out and up. Volume in thorax increases. Pressure in thorax decreases. Air is sucked into the lungs.
What is the equation for pulmonary ventilation rate is:
What is the pulmonary ventilation when the breathing rate is 15 breathes per minute and the tidal volume is 1.5 litres.
tidal volume X breathing rate
22.5
What does tidal volume mean?
The volume of air breathed in with each breath when the body is at rest.
Explain how gills are adapted for efficient gas exchange.
Lamellae provide a large surface area for diffusion to happen
Thin squamous epithelium so has a short diffusion distance
Counter current flow maintains concentration gradient across whole length of lamellae.
List the structures that air passes through in a human
Nose/mouth Trachea Bronchus Bronchioles Alveoli
Describe the trachea and its function in the mammalian gas exchange system
Wide tube supported by C-shaped cartilage to keep air passage open
Lined by ciliated epithelium cells which move mucus towards the throat to be swallowed
Explain the adaptations shown by alveoli for efficient gas exchange
Large surface area for diffusion
Squamous epithelium for a short diffusion distance
Rich blood supply - maintains concentration gradient and a short diffusion distance, preventing lung infections
Carries air to the bronchi
Describe the pathway of an oxygen molecule from the alveolus to the blood
Diffuses across single squamous cell of the alveolar epithelium
Diffuses across the single squamous cell of the capillary endothelium
What happens to the surface area:volume ratio as an organism gets larger?
Gets smaller
Needs to develop an efficient exchange surface
What is Fick’s law?
Diffusion = SA X Concentration gradient/diffusion distance
Describe the process of gas exchange in insects
Gases move in and out of the tracheae through the spiracles
Diffusion gradient allow oxygen to diffuse into body tissue and carbon dioxide to diffuse out
Contraction of muscles (abdominal pumping) allows mass movement of air in and out
Name and describe the two main features of a fish gas exchange system
Gill -
Describe and explain how a human breathes out
External intercostal muscle relax Internal intercostal muscle contract Ribs move down and in Diaphragm relaxes and becomes domed Volume of thorax decreases Pressure in thorax increases Air is forced out of the lungs
How is the volume of a cube calculated?
Volume = length x width x height
How is the surface area of a cube calculated
Surface area = 6 (length x width)
