The exchange of substances with their environment Flashcards
Larger organisms have a more complex transport system because..
..they are more active and have a higher metabolic rate
Why is O2 absorbed rapidly in single celled organisms?
They only have a cell-surface membrane so a very short diffusion distance so more rapid
What is the gas exchange system in insects?
Tracheal system: spiracles - tracheae - tracheoles
What is the gas exchange system in fish?
Gills: gill filaments - lamellae (countercurrent system)
What is meant by a countercurrent exchange system?
Blood and water flow in the opposite direction so blood will always meet water will a high % of O2 in so O2 will diffuse into the blood
What is the gas exchange system of a plant?
Leaf: stomata surrounded by guard cells - mesophyll cells with chloroplasts plus air spaces throughout the mesophyll layer
What is the gas exchange system in humans?
Lungs: mouth - trachea - bronchi - bronchioles - alveoli
What happens during inhalation?
External intercostal muscles contract, internal intercostal muscles relax, rib cage moves up and out, diaphragm contracts (flattens), the volume inside the thorax cavity increases, the pressure inside the thorax cavity decreases and air moves in
What happens during exhalation?
External intercostal muscles relax, internal intercostal muscles contract, rib cage moves down and in, diaphragm relaxes (domes), the volume inside the thorax cavity decreased, the pressure inside the thorax cavity increases and air moves out
What is the equation for pulmonary ventilation rate?
PVR = Tidal volume x Breathing rate
Or.. 60/cycle time (s)
Define pulmonary ventilation rate:
Total volume of air that is moved into the lungs during one min
Define: tidal volume
Volume of air taken in at each breath when the body is at rest
Define: breathing rate
number of breaths taken in one minute
What is a spirometer used for?
Used to measure air capacity in the lungs
How are the alveoli of the lungs adapted for efficient gas exchange?
Lined with epithelial cells - thin (one cell thick), large SA, flattened red blood cells (maintains steep concentration gradient
