Do Now  What artia/ventricles of the heart have oxygenated blood?  Why do you think that oxygenated/non- oxygenated blood are separated?

Circuits  Travel in two loops (circuits)  Pulmonary Circuit: Heart  Lungs  Heart  Systemic Circuit: Heart  Body  Heart

CIRCUITS & PATHWAYS

Blood Vessels  Two types  Arteries (move away from heart)  Veins (move towards heart)

Three Layers of Blood Vessels  Tunica interna: innermost layer.  Prevents blood from clotting  Tunica media: middle layer.  Muscles, move blood  Tunica externa: Outermost layer.  Connective tissue  Connects blood vessel to surrounding tissue.

Size of vessels  At first, there are only a few arteries leaving the heart (they are large)  They start to branch off into smaller arterioles  Arterioles then branch to smaller capillaries Arteries  arterioles  capillaries Highway  boulevard  street

Size of vessels  Same with veins…  Capillaries  Veinule  Veins

Capillaries??  This is where arterioles and veinules meet – the SITE OF GAS EXCHANGE in the blood!  Thin walls  Diffusion is force responsible for these exchanges

Travel Essay – QUIZ GRADE  Start as a blood cell.  Start in the heart as low-oxygen blood  and explain your trip around the body (you may choose where you travel to) and back to the heart  You MUST mention…  The four chambers of the heart  The major veins and arteries  Smaller blood vessels you go through  What is exchanged and where