Circulation Chapter 37-1

Circulatory System Functions: Functions: –Transports oxygen, nutrients, hormones and waste products to and from body cells –All materials pass into and out of the blood vessels via diffusion Consists of: Consists of: –Heart, arteries, veins and capillaries

The Heart The size of your fist Made of four chambers –T–Two atria (The heart receives blood into these) –T–Two ventricles (Blood leaves the heart through these)

Blood Flow in the Heart Blood enters the heart through the atria (plural for atrium) Blood enters the heart through the atria (plural for atrium) When the heart contracts, blood is forced into the ventricles When the heart contracts, blood is forced into the ventricles –Valves prevent backwash –Movement of blood through the body is unidirectional

Pulmonary Circulation The circulatory system is divided into two separate systems The circulatory system is divided into two separate systems The right side of the heart pumps blood to the Pulmonary circulation (lungs) The right side of the heart pumps blood to the Pulmonary circulation (lungs) –This blood leaves the heart oxygen poor, picks up Oxygen at the lungs and returns to the heart oxygen rich

Systemic Circulation Blood that leaves the left side of the heart is part of the Systemic circulation (body). Blood that leaves the left side of the heart is part of the Systemic circulation (body). –This blood leaves the heart loaded with oxygen, drops it off at the tissues (ex: muscles, organs etc.) and returns to the heart oxygen poor

The two systems combined

The heartbeat Your heartbeat is not controlled by the nervous system directly Your heartbeat is not controlled by the nervous system directly A small patch of cardiac muscle cells (Sinoatrial node) on the right atrium starts each heart contraction A small patch of cardiac muscle cells (Sinoatrial node) on the right atrium starts each heart contraction –Called the “pacemaker” of the heart Each contraction starts on the right atrium and spreads across the heart to the left atrium and then to the ventricles Each contraction starts on the right atrium and spreads across the heart to the left atrium and then to the ventricles

Blood vessels Arteries (Largest blood vessels, biggest one is AORTA): Arteries (Largest blood vessels, biggest one is AORTA): –Blood leaves the heart through these –They have thick smooth muscular walls and actively push blood along Veins (Slightly smaller than above, biggest one is VENA CAVA): Veins (Slightly smaller than above, biggest one is VENA CAVA): –Blood returns to the heart through these –They have thinner walls and less muscle and cannot push blood –They have valves that prevent blood from backwashing Capillaries (Smallest blood vessels): Capillaries (Smallest blood vessels): –One cell thick –The bridge between arteries and veins –This is where diffusion takes place

Path of Blood through the body Blood starts in the Left Ventricle Blood starts in the Left Ventricle –Leave through the Aorta –Is carried through smaller and smaller arteries to organs and tissues until it reaches the… Capillaries Capillaries –At the capillaries, gases (O2 and CO2) exchange as well as nutrients and water) –Blood continues onto the … Veins Veins –Blood returns to the body through veins which become larger and larger until they reach the Vena Cave –The Vena Cava dumps blood into the Right atrium Blood is then moved into the Right Ventricle and out the Pulmonary Artery on the way to the lungs Blood is then moved into the Right Ventricle and out the Pulmonary Artery on the way to the lungs –Arteries get smaller and smaller until they reach the capillaries of the lungs where O2 and CO2 diffuse –Blood then returns through bigger and bigger veins to the heart until they reach the Pulmonary Vein which dumps blood into the Left Atrium and finally into the Left Ventricle where we started

Blood through the Body

Problems with the Circulatory System Heart disease is the #1 cause of death of women in America Most heart diseases come from Atherosclerosis, which is fatty plaque deposits that build up in the walls of arteries –C–C–C–Caused by diet, lack of exercise and/or not brushing teeth enough! High blood pressure (hypertension) –R–R–R–Results in weakened heart and arteries which may lead to heart attack or other complications

Problems Continued Heart Attack: Heart Attack: –Atherosclerosis that occurs in the coronary arteries (arteries that give blood to the heart itself) may prevent the heart from receiving oxygen. Without oxygen, the heart muscle begins to die. Stroke: Stroke: –Blood clots may form as a result of atherosclerosis. Some of these clots may break free and travel to the brain, getting stuck in a blood vessel. This starves part of the brain of oxygen and results in a stroke PREVENTION OF CIRCULATORY PROBLEMS: PREVENTION OF CIRCULATORY PROBLEMS: –Exercising regularly keeps your muscles healthy and blood flow open. Eating a diet low in fats and excess carbs prevents the formation of fatty plaques in your arteries. Not smoking is a huge step to prevention.