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These slimy looking things are keeping you alive right now! The Circulatory & Respiratory Systems Getting stuff where it needs to go! What do these systems do? The circulatory and respiratory systems work together to bring oxygen and nutrients to and remove waste from working cells. Major Components of the Circulatory System: Blood Vessels Heart Blood Lymph Nodes Lymphatic Vessels The Heart The heart is the central organ of the cardiovascular system. It beats more than 2.5 BILLION times in an average life span! Heart Anatomy The septum vertically divides the heart into two sides. The right side pumps blood to the lungs, and the left side pumps blood to other parts of the body. Each side has an two chambers: The upper chambers are called atria (singular – atrium). The lower chambers are called ventricles. Blood flows from the atria to the ventricles. A simplified view of blood circulation through the heart: Blood Vessels There are three types of blood vessels: 1. 2. 3. Arteries Capillaries Veins They allow blood to travel in between the heart, lungs, and body tissues in one direction only. Arteries Arteries are the large, muscular vessels that carry blood away from the heart. (think: “Artery – Away”) Arteries have three main layers: 1. 2. 3. A layer of endothelial tissue on the inside A thick layer of smooth muscle tissue in the middle Connective tissue on the outside Capillaries Arteries branch off into smaller and smaller vessels, eventually branching into a network of tiny vessels called capillaries. The walls of capillaries are only one cell thick so that gases and nutrients can diffuse into and out of cells. Capillaries Capillaries are so thin that red blood cells must travel single file!! Veins Capillaries then merge to form larger and larger vessels, eventually forming veins. Veins carry blood back to the heart. Veins also have three layers: 1. 2. 3. Endothelial tissue on the inside A thin layer of smooth muscle tissue in the middle A layer of connective tissue on the outside. Veins Veins also have valves, which prevent blood from flowing backward. Because they only have a thin layer of muscle, veins rely on the squeezing of skeletal muscles to help them return blood to the heart. Some cross-section comparisons: Here’s what happens to your arteries when you eat too many cheeseburgers! The Lymphatic System The circulatory system also includes the lymphatic system, which returns fluids from the body tissues to the blood stream. The fluid is called lymph. Lymph vessels are similar to the heart in that they rely on the squeezing of skeletal muscle to help move the fluid inside, and have valves to prevent backflow. Lymphatic vessel with valve (V) Your body has a huge network of lymph vessels! On its way back to the bloodstream, lymph will pass through lymph nodes, which trap foreign particles, and play a role in fighting disease. Blood Blood is a liquid connective tissue that transports nutrients and gases through the body. Blood is composed of: Plasma (55%) Red Blood Cells (45%) White Blood Cells (<1%) Platelets (<1%) Plasma Plasma is a sticky, straw-colored fluid that’s 90% water. Substances like vitamins, minerals, amino acids, glucose, and hormones are dissolved in plasma. Red Blood Cells Also known as erythrocytes, red blood cells (RBCs) are formed in bone marrow. RBCs contain hemoglobin, which is the molecule that actually transports oxygen, and carbon dioxide. You have more than 30 trillion RBCs circulating in your body. 2 million of these die and are replaced every second! White Blood Cells Also known as leukocytes, these cells help to defend the body against disease. There are several different types of white blood cells that perform different jobs to help in body defense. Platelets Platelets are fragments of very large cells formed in the bone marrow. They congregate at the site of the wound, sticking together to form a plug that will eventually harden into a clot or scab. Major Components of the Respiratory System: Pharynx Larynx Trachea Bronchi Lungs Bronchioles Alveoli Diaphragm There are two kinds of respiration: External respiration is the exchange of gases between the atmosphere and the blood. Internal respiration is the exchange of gases between the blood and cells of the body. Anatomy of the Respiratory System Air passes from the atmosphere into: the mouth and nose, where it is moistened & filtered, the pharynx, the larynx, then the trachea, which branches into: two bronchi, each of which leads into a lung. The Lungs Each bronchus branches into smaller and smaller tubes, eventually branching into the smallest, which are called bronchioles. The bronchioles end in tiny air sacs called alveoli. The Lungs Alveoli A network of capillaries surrounds each alveolus. External gas exchange occurs between the air in the alveolus and blood in the capillaries. The structure of alveoli increases the surface area of the lungs, maximizing the amount of gas exchange that can occur. Gas exchange in the lungs Blood coming from the body is low in oxygen and high in carbon dioxide. Air in the alveoli is high in oxygen and low in carbon dioxide. These differing concentrations allow oxygen to travel from the air into the blood, and carbon dioxide to travel from the blood into the air. The Mechanism of Breathing “Breathing in” is called inspiration or inhalation. “Breathing out” is called expiration or exhalation. Inspiration When you take a deep breath, your chest expands and ribs move up and out. At the same time, the diaphragm flattens and pushes down on the abdomen. This increases volume and lowers air pressure, causing air to rush into the lungs. Expiration During expiration, the exact opposite process takes place. Diaphragm and ribs relax, reducing volume and increasing pressure. This forces air out of the lungs into the atmosphere. Here’s what smoking does to your lungs!