A&P 2 Lab 4 AP lab4

Circulatory System-Blood Flow Tracings Circulatory system- how the blood from the heart is circulated throughout the body. General blood flow through the body after it leaves the heart follows a mapping system. From the heart, it flows through arteries, then capillaries, and comes back to the heart by way of veins. BLOOD  VESSELS IN THE CIRCULATORY SYSTEM: Arteries- referred to as efferent blood vessel in the circulatory system o They always carry blood away from the heart. o Typically carry oxygenated blood. (except in the pulmonary artery) o 1. Conducting arteries:  very large arteries and typically exit from the heart  They have the need/ability to expand when the heart beats so they withstand the splurge. So, with every heartbeat, blood surges out of the heart into these large vessels.  To do this, they must have a layer of elastic tissue that gives it the ability to stretch and recoil when the heart is relaxing.  EX: aorta and pulmonary trunk o Atherosclerosis- when arteries age and stiffen because plaque builds up in the arteries, they loose that elasticity and the ability to stretch when blood surges into them.  It results in an increase in pressure in those vessels which can lead to an aneurism- a weak point in a artery and with each heartbeat, that little thin walled area will pulsate and it can further and further weaken and eventually rupture which can lead to death or stroke. o 2. Distributing arteries:  A.k.a. medium or muscular arteries  They are direct branches from the conducting arteries  Have a very thick muscular wall (up to 40 layers of smooth muscle)  The muscular wall in a distributing artery makes up 75% of the arterial wall itself.  EX: brachial artery, femoral artery (named for area where they are distributing their blood) o 3. Resistance arteries:  A.k.a. small arteries  Too numerous to name o 4. Metarterioles:  Very short vessels that will link the arteriole system to the capillaries. AFTER BLOOD FLOWS THROUGH THE ARTERIAL SYSTEM, IT THEN FLOWS INTO A SERIES OF CAPILLARY BEDS.