Blood Vessels

Tidbits your blood vessels are hollow tubes that circulate your blood If you took all of the blood vessels out of an average child, and laid them out in one line, the line would be over 60,000 miles long! An adult's vessels would be closer to 100,000 miles long!

3 Types of Blood Vessels Arteries Veins Capillaries

1. Arteries Carry blood away from the heart Carry oxygenated blood with one exception

Arteries The walls of arteries (left) are thicker than that of veins (right) Arteries are tough on the outside and smooth on the inside. An artery actually has three layers: outer layer of tissue muscular middle (elasticity helps move blood along) inner layer of epithelial cells

Movement of Blood Through Arteries Arteries are located deep near the bones (with a few exceptions) Arterial blood is pumped by the heart under high pressure Pulse (= heart rate) The contraction of the artery keeps pace with the beat of the heart. Blood pressure blood flowing through the arteries because it has a higher pressure than the blood in the veins uses two numbers; systole(under pressure) and diastole(minimum pressure). The walls of arteries are thicker than that of veins

Major Arteries of Circulation Aorta Largest artery in the body Leaves from the left ventricle of the heart Regions Ascending aorta Aortic arch Thoracic aorta Abdominal aorta —passes through the diaphragm into the abdominopelvic cavity

Vessels of the Aortic Arch Brachiocephalic Left common carotid Left subclavian

Arterial Supply of the Brain Internal carotid arteries divide into Anterior and middle cerebral arteries These arteries supply most of the cerebrum

2. Capillaries walls are only one cell layer thick some allow for only one RBC to pass at a time allow for exchanges between blood and tissue Arteriole- small branch of artery leading into a capillary. Venule- small branch of vein receiving blood from a capillary

Veins Carry blood to the heart Carry deoxygenated blood (with one exception) The walls of veins are thinner, however the lumen is larger Veins are more superficial near the skin (with a few exceptions) Veins are under low pressure

Movement of Blood Through Veins Larger veins have valves to prevent backflow Veins use the “milking” action of muscles to help move blood

Major Veins of Circulation Vena Cava Largest vein in the body Returns blood to the right atrium Regions Superior vena cava drains the head and arms Inferior vena cava drains the lower body