Structures (outgrowths from the body) that create a large surface area over which gas exchange occurs.
Chitin-lined tubes in insects that permeate their bodies. Oxygen enters (or CO2 exits) through spiracles (openings).
Covers the trachea when an animal is swallowing, preventing the entrance of solid and liquid material.
In humans, the trachea branches into two ____, which enter the lungs and then repeatedly branch, forming narrower tubes called (______).
Each bronchiole branch ends in a small sac called an ____, which is surrounded by blood-carrying capillaries.
Vessels moving away from the heart (closed circulatory system). Branch into (_____)
Portions of the heart (left and right) which pump out the blood into the arteries. Have thicker walls.
___valve prevents between blood from moving backward into the the atria when the ventricles (left and right) contract.
___valve prevents backflow of blood into the ventricle after the ventricles relax (connects the ventricles and the aorta on the left side and the ventricles and the pulmonary trunk on the right side).
SA (sinoatrial) (or pacemaker)
___node, located in the upper wall of the right atrium, spontaneously initiates the heart/cardiac cycle by simultenously contracting both atria and also by sending a delayed impulse that stimulates the AV (atrioventricular) node
In the ___ phase, blood is forced through the pulmonary arteries and aorta. Occurs when the ventricles CONTRACT.
Blood moves through the ___ due to the movements of adjacent skeletal muscles which squeeze the blood vessels (not because of the contractions of the heart).
The ___ system is a second network of capillaries and veins through which some interstitial fluids (fluids that bathes/surrounds the cells) and wastes return to the circulatory system. Acts as a filter (with lymph nodes to be cleaning filters and ward against infection).