Circulatory System PDF

Circulatory System January 7, 2025 10:08 AM Pipes - Arteries - Veins - Capillaries Arteries - Large thick walled elastic vessels - Carry blood away from heart - Blood in arteries is normally oxygenated - Arteries become gradually smaller - Very small, thin arteries are c...

Circulatory System January 7, 2025 10:08 AM Pipes - Arteries - Veins - Capillaries Arteries - Large thick walled elastic vessels - Carry blood away from heart - Blood in arteries is normally oxygenated - Arteries become gradually smaller - Very small, thin arteries are called arterioles (these lead to capillaries) Capillaries - Thin, hair-like structures - Walls are composed of single cells - Blood cells roll slowly through capillaries, one after another - Slow flow so enough time for materials to be exchanged between capillary and cells and tissues it supplies - Waste, oxygen, carbon dioxide, nutrients, hormones, ions all pass between the capillary and the cells - Large beds of capillaries supply tissues and organs, reaching every cell Veins - Capillaries drain into larger vessels, called venules - These, in turn, become bigger and drain into veins - Veins are large, floppy vessels which carry blood back to the heart - Blood in veins is normally deoxygenated - Two largest veins: inferior vena cava and superior vena cava - Both carry blood back to the heart Blood - Blood is a tissue with a variety of cells and functions Biology Page 1  - Blood is a tissue with a variety of cells and functions - Include red blood cells, white blood cells (leukocytes) and platelets (pieces of cells) - Includes plasma, the fluid in which cells are suspended Parts of the Heart - A protective layer called the pericardium surrounds the heart - There is nervous and connective tissue in the heart - Nervous tissue is involved in the beating of the heart - Connective tissue is involved in creating the blood vessels that supply the heart with its own blood supply 4 chambers of the heart - Deoxygenated blood flows into the Vena Cavas - Then enters the Right atrium - Blood then flows into the Right Ventricle, which contracts, ejecting blood into lungs - Blood returns from lungs (now rich in oxygen) - It enters the Left Atrium, where it collects - Blood then travels to the Left Ventricle - It is ejected out to the body via the Aorta (an artery) Heart Diseases - Coronary Artery Disease: coronary arteries provide blood to heart muscle tissue, and plaque build up can partially block them - Heart attack: coronary arteries become completely blocked (no oxygen or nutrients to heart muscles), the heart stops pumping and heart tissue starts to die Lymphatic System - Drains the interstitial fluid - This is the fluid that lies between the cells - Drains into small lymphatic vessels, which accumulate into ducts - Eventually the fluid flows back to the heart and come back to the Right Atrium via the Vena Cava Biology Page 2