Gas Exchange Flashcards
Gas exchange
Intake of oxygen and release of carbon dioxide
How does gas diffuse?
They diffuse down a concentration gradient (high to low)
Partial pressure
Part of atmospheric pressure caused by one gas
There is more gas at the surface of the Earth than at the top. T or F?
True
Which holds more oxygen at sea level, water or air?
Water holds 30x less oxygen than air
Respiratory surfaces
Sites of gas exchange
What allows for fast gas diffusion?
Wide, thin surface
What are the types of exchange surfaces?
Epidermis, trachea, gills, and lungs
Epidermis
Skin; is a respiratory site for smaller animals allowing them to breathe through skin; Ex: amphibians, annelids, lophotrochozoans
Trachea
System of tubes and sacs that distribute air, from external openings, throughout the body; does not require linkage w/ circulatory system; Ex: arthropods
Gills
Type of respiratory surface that allows for ventilation; large, highly vascularized area that water moves over to transfer oxygen; Ex: salamander, crayfish, fish
Ventilation
Movement of respiratory medium over the respiratory surface
How do gills use countercurrent exchange to extract oxygen?
Water moves over gills. As water gets close to the blood vessels, O2 diffuses from water to blood. The vessel containing the O2 rich blood sends oxygenated blood to the rest of the body, while the deoxygenated blood that is carried from the heart to the gradient (due to fish only exhibiting single circulation) where it can be oxygenated via countercurrent exchange.
Lungs
Internal respiratory exchange surface; bronchus branches into bronchioles and then into alveoli covered w/ capillaries; pulmonary artery brings deoxygenated blood from the heart to the lungs where it gets oxygenated and sent back to the heart and later to the rest of the body via the pulmonary vein
Capillaries
Small blood vessels that cover alveoli
Alveoli
Tiny air sacs do the lungs that allow for rapid gas exchange
What are the three modes of ventilation?
Buccal pump, tidal respiration, and flow through respiration
Buccal pump
Forces air over gills/lungs via positive pressure (our heart operates like this but not our lungs); essentially pumping to another chamber by muscle contractions; squeeze throat=force lungs into air, squeeze lungs=expels air; Ex: amphibians and sharks
Tidal respiration
Muscle contractions draw in air via negative pressure (we do this); reduce pressure by expanding the volume of lungs (using diaphragm) forces air into lungs
Flow through respiration
Inhale air and travels to posterior air sacs then then inhale again to go to lungs and inhale again to go to anterior air sacs; air travels in one direction; lungs only encounter fresh, oxygen-rich air; 2 cycles of inhaling and exhaling to oxygenate the body; most efficient among vertebrates, almost as efficient as fish; Ex: birds
Partial pressure gradients
Cause gases to diffuse into and out of the circulatory system; uses approx. 40 mm Hg of O2 from air
Which is not an example of a respiratory exchange surface?
Gills
Lungs
Skin
Air sacs
Air sacs
Respiratory pigments
Reversible bind oxygen; hemoglobin in vertebrates is red due to iron; hemocyanin in arthropods and molluscs is blue due to copper (used to see if vaccines are safe); annelids have hemerythrin (purple) and chlorocruorin (green)
Can animals survive w/ no hemoglobin?
Yes, icefish do not have red blood cells or hemoglobin. They are able to survive due to have large hearts, blood volumes
and more mitochondria. More importantly, they live in cold water which holds more oxygen than warm water.
