A4 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 and out of the tracheoles.
What is the advantage to the insect in 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 reduce water loss.
Name structures labelled A, B and C
A = trachea
B = bronchiole
C = diaphragm
Expalin how 3 adaptation shown by the alveolus increases rate of diffusion.
Large surface area.
Short diffusion distance created by flattened cell making up the epithelium.
Blood capillary close to gas exchange surface to decrease diffusion distance
Large concentration gradient - maintained by ventilation of lungs and flow of blood.
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.
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 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
The diagram show a gill arc. Name sructure A
Gill filament
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
The picture shows one of the openings on the side of an insects abdomen.
Name the structure and state its function
Spiracle
Allows air to diffuse into the tracheae
Closes to reduce water loss
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
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)
List the structures through which air travels into an insect.
Atmosphere –> spiracle –> tracheae –> tracheole
In mammals as the surface area to volume ratio increase what happens to the rate of heat loss?
Increases
Large surface area losing heat.
Small volume replacing heat
Explain why a mouse has a high metabolic rate.
Large surface area to volume ratio
Loses heat rapidly
Needs high metabolic rate to release heat
To maintain body temperature
What does countercurrent flow mean and why is it an advantage in a fish gill?
Blood and water flow in opposite directions
Maintains a steep concentration gradient across the gill lamellae
