Transcript File
Lesson 15 February 8th, 2011 THE CIRCULATORY SYSTEM BODY SYSTEMS WORKING TOGETHER MAINTAINING A STEADY STATE Our body systems function in a way to maintain homeostasis, which means “steady state.” An acceptable range of physical and chemical conditions in which body cells, tissues, and organs can operate efficiently. To keep the body within this acceptable range, different organ systems must work together to maintain homeostasis in the body. CIRCULATORY SYSTEM The Circulatory system is the transport system for the body and has four principle functions: Two parts to the Circulatory system 1. Pulmonary circuit Right side of the heart Pumps blood to the lungs where blood picks up oxygen and returns to the left side of the heart. CIRCULATORY SYSTEM Two parts to the Circulatory system 2. Systemic circuit Left side of the heart Pumps blood through arteries to the whole body, they deliver oxygen and other materials. CIRCULATORY SYSTEM THE CIRCULATORY SYSTEM HAS AND HAS FOUR PRINCIPLE FUNCTIONS 1. 2. 3. 4. Transportation of oxygen and carbon dioxide Distribution of nutrients and transport of wastes Maintenance of body temperature Circulation of hormones THE CIRCULATORY SYSTEM - STRUCTURE Three main components 1. 2. 3. A fluid which transports materials (blood) A system of blood vessels through which the fluid moves. A pump that pushes the fluid through the body (heart) HEART STRUCTURE The mammalian heart consists of a double pump separated by a wall of muscle called the Septum. The pump on the right powers the pulmonary circuit and the pump on the left powers the systemic circuit. HEART STRUCTURE Each side contains: Atrium – (plural atria) receive blood from veins and pump it into the ventricles. Ventricle - Pump blood to distant tissues. Valves prevent blood from flowing backwards through the system. ATRIOVENTRICULAR VALVES Tricuspid valve located on the right side of the heart Bicuspid Valve located on the left side of the heart. The Atriums contract together as do the ventricles. When the valves close they create a sound. This is why you heart has a lubb dubb sound. BLOOD VESSELS Arteries are blood vessels that carry blood away from the heart. Thick walls Layers of muscle and connective tissue The Aorta leads from the left ventricle and branches into the many arteries. BLOOD VESSELS To distribute blood to as many tissues as possible, the arteries branch into smaller vessels called arterioles, which branch into capillaries. Blood cells are exchanged at the capillary level. Capillaries flow into venules which then lead to veins which go back to the heart. BLOOD VESSELS Blood flow is greatly reduced in the veins but must return to the heart. To help blood flow back to the heart veins contain valves that prevent the blood from flowing backwards. Skeletal muscles also contribute to pumping the blood back to the heart by squeezing the veins during muscle contraction. THE RESPIRATORY SYSTEM • All animals exchange gases with their surroundings. Animals take in oxygen gas and release carbon dioxide is the process of respiration. The oxygen is used to react with nutrients in the mitochondria to release energy. Since we cannot store gases very well in our bodies we are continually exchanging gases with the atmosphere. THE HUMAN RESPIRATORY SYSTEM Air usually enters the reparatory system through your nostrils where the following occurs: The nasal and oral cavities join at the back of the mouth to form the Pharynx. Air passes from the pharynx, through the trachea. THE HUMAN RESPIRATORY SYSTEM The trachea contains the larynx (voice box) Air from the trachea moves into two Bronchi (singular bronchus) From there it goes into smaller tubes called bronchioles bronchioles continue to branch until they reach a dead end of tiny air sacs called alveoli This is where gas exchange actually happens. Each lung contains around 150 million which creates a huge about of surface area A network of capillaries surround each cluster of alveoli – – – The blood entering the network is low in oxygen concentration and a high carbon dioxide concentration. CO2 is diffused out of the blood and O2 diffuses into the blood. The blood leaves the capillaries rich in O2 SYSTEMS THAT AID IN CLEANING THE AIR WE BREATHE. Dust and foreign particles are trapped and filtered by tiny hairs and mucus in the nose Goblet cells which produce mucus are located on the trachea, bronchi and bronchioles. The mucus traps bacteria, dust, pollen, which is then carried out of the lungs by cilia. This is known as the bronchial escalator HOW WE BREATHE Breathing involves two stages. 1. Inspiration –(inhaling) – air is moved into the lungs • 2. Expiration – (exhaling) – air is forced out of the lungs. Air moves in and out of the lungs due to a change in pressure. Air will always move from an area of high pressure to an area of low pressure. INSPIRATION In order to decrease the air pressure in our lungs two things happen. 1. The diaphragm contracts and moves down ward The diaphragm is a sheet of muscle at the bottom of the ribcage. INSPIRATION 2. The external intercostals muscles contract and the ribcage moves upwards and out. This results in an increase in volume and a decrease in pressure. Air rushes into the lungs The autonomic nervous system controls inspiration and expiration by nerve impulses SMOKING AND LUNG CANCER Lung cancer is one of the most dreaded but most preventable diseases. The number one cause of lung cancer is cigarette smoke. SMOKING AND LUNG CANCER It kills around 18 000 people per year in Canada It is related to around 87% of all lung cancers responsible for 30% of all cancer deaths Between 10,000-20,000 people die each day from smoking (worldwide stat) SMOKING AND LUNG CANCER The smoke irritates the cells in the bronchi and bronchioles This causes the cells to secrete more mucus A single cigarette can cause cilia to stop moving for hours. DISORDERS OF THE RESPIRATORY SYSTEM Bronchitis Inflammation or swelling of the bronchi and bronchioles. Caused by viral or bacterial infection or by chemicals from smoking. Narrowing air passages plus extra mucus make breathing more difficult. Coughing is a reflex to help clear the pathways. BRONCHIAL ASTHMA 3 million Canadians suffer from it. Usually caused by allergic reaction to a foreign substance Excess mucus is produced Muscles surrounding the bronchi and bronchioles spasm making it difficult to breath. Inhalers (puffers) cause the bronchi and bronchioles to increase in diameter. QUESTIONS: HOMEWORK How is the respiratory system related to the circulatory system? Where does the diffusion of gases occur in the respiratory system? How does Inspiration occur? How does the inflammation of the bronchi and bronchioles affect breathing? What are the main functions of the circulatory system? If shown a blood vessel attached to the heart. How could you tell if it was an artery or a vein? What is the only artery that carries deoxygenated (used blood) blood away from the heart? What special feature do veins have that help to bring blood back to the heart and prevent pooling in the legs? A LOOK AT BREATHING – LAB – HAND IN When you breathe, you move about 500 mL of air in and out of your lungs. Usually we are not aware of our breathing. What can you learn about how you breathe if you concentrate on your breathing?