The process of gas exchange is called ______________.
respiration
Respiratory surfaces must be thin and __________ for diffusion of O2 and CO2.
moist
A ________________ cavity in cnidarians and flatworms serves as a circulatory system.
gastrovascular
Fish and amphibians use _______ to promote gas exchange.
gills
___________ waters holds more oxgen than still water.
turbulent
The __________ system of insects provides direct exchange between the air and body cells.
tracheal
Insects use tiny _______ tubes to deliver oxygen to each cell.
branching
Insects also use their respiratory system to ________.
molt
Air is ___________ and easier to move.
lighter
The 1st tetrapods on land diverged into _______ major lineages.
three
Birds and mammals have higher metabolic rates and more _______ lungs.
complex
____________ helps transport CO2 and assists in buffering blood.
hemoglobin
In the lungs, blood picks up _________ and drops off CO2.
OXYGEN
_______ controls centers in the brain sense and respond to CO2 levels in the blood.
Breathing
__________ occurs wehn the diaphragm relaxes and moves upward.
exhalation
__________ occurs when the diaphragm muscles contract and moves downward.
inhalation
In mammals, air is inhaled through the nostrils into the ______ cavity.
nasal