Body weight is stable when average daily energy intake and output are equal. 

A cation is positive.

What is the red arrow pointing at?  

Name the specific structure pointed to by the black arrow.

Name the hole in the skull.

What specific structure is the black arrow pointing to?

This test tube is showing a positive result for salt. What is the test called?

Atrial depolarization causes the _________.

Decompensated shock is normally corrected by the body’s homeostatic mechanisms.

When the left ventricle contracts, the __________ valve closes and the __________ valve is pushed open.