What is the primary anatomical difference that marks the dividing line between the conducting zone and the respiratory zone of the respiratory tract?
A) the absence of goblet cells
B) the presence of macrophages
C) the presence of smooth muscle and the absence of cartilage
D) the absence of cartilage
E) the thickness of the walls surrounding the air spaces
Ans: E) the thickness of the walls surrounding the air spaces
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From an evolutionary point of view, what important process occurs when a young male baboon leaves the troop that he was born in to join another troop?
What sequence of events leads to the perception of a visual scene?
I. In response to light, retinal dissociates from rod and cone photopigments, hyperpolarizing the photoreceptor cells and leading to activation of bipolar neurons. II. Action potentials are propagated through ganglion cells, whose axons project to the occipital lobe of the brain. III. In response to light, rod and cone photoreceptors depolarize, causing increased release of neurotransmitter and activation of bipolar neurons. A. I then III B. III then II C. III then I then II D. I then II then III E. I then II
The ____________________ is the noncellular structure between an epithelium and the underlying connective tissue. Fill in the blank(s) with the appropriate word(s)
What explanation can you give for why the sodium-potassium pump does not run out of ions to move in or out of the cell?
A. The cell continuously produces more ions to replace those moved by the pump, maintaining a constant supply. B. Leak channels are always open, allowing the passage of sodium ions (Na+) and potassium ions (K+) across the membrane. C. Many of the ions moved in or out then diffuse passively back through the membrane in the opposite direction.