Sorry babe i don't get your question if your question is "how does the body use food" then your answer is this (when you eat, your body breaks down all of the starches, sugars, fats, etc. from food that you eat, and uses that from the food you just ate for ENERGY so you can stay alive) so long story short your body uses food for ENERGY....but if that wasn't your question then i'm sorry i don't know
Tolerance can in fact cause an overdose, because the greater tolerance you can get the more of a certain substance your body will need eventually leading your body to take more than it can handle leading to overdose and death.
right side:
Blood enters the heart through two large veins, the inferior and superior vena cava emptying oxygen-poor blood from the body to the right atrium.
atrium contracts, blood flows from your right atrium into your <em>right ventricle</em> through the open tricuspid valve.
ventricle contracts, blood leaves the heart through the pulmonic valve, into the <em>pulmonary artery</em> and to the lungs where it is oxygenated.
left side:
<em>pulmonary vein</em> empties oxygen-rich blood from the lungs into the <em>left atrium</em>.
contracts, blood flows from your left atrium into your <em>left ventricle </em>
ventricle contracts, blood leaves the heart through the aortic valve, into the<em> aorta </em>and to the body.
veins carry blood to the heart ( deoygenated blood)
Arteries carry blood from heart ( oxygen rich blood)
Capillaries connects them.