The Cardiovascular System (Hapara) PDF

The Cardiovascular System Lesson 4  Learning Goals Today I will… ❏ use appropriate terminology related to animal anatomy; ❏ explain the anatomy of the circulatory system and its function in transporting substances that are vital to health. The Cardiovascular System Made of blood, circulator...

The Cardiovascular System Lesson 4  Learning Goals Today I will… ❏ use appropriate terminology related to animal anatomy; ❏ explain the anatomy of the circulatory system and its function in transporting substances that are vital to health. The Cardiovascular System Made of blood, circulatory vessels (arteries, veins, capillaries) and the heart. An efficient system used for transporting materials within the body. Main Functions of the Circulatory System 1. Transports gases (from respiratory system), nutrients, and waste materials (from digestive system). 2. Regulates internal temperature and transports chemical substances that are vital to health. 3. Protects against blood loss from injury and against disease fighting microbes or toxic substances introduced into the body. Mammalian Circulatory System Contains 2 circuits: Pulmonary Circuit ○ low pressure circuit ○ carries blood to the lungs for gas exchange Systemic Circuit ○ high pressure system ○ carries blood to the body to deliver oxygen and nutrients and pick up waste The Structure of the Heart Made of cardiac muscle which allows for rhythmic contraction Atria fill with blood and relaxation without returning from fatigue. body/lungs. 4 chambers Ventricles receive blood Top = atria from atria and pump it Bottom = ventricles out to the body or lungs. Atria and ventricles are separated by the septum. The Four-Chambered Heart Right side of the heart receives oxygen-poor blood coming from the body. The vena cavae (sing: vena cava) open into the right atrium. Blood then flows into the right ventricle and out the pulmonary trunk into the pulmonary arteries. The oxygen-poor blood then goes to the lungs for gas exchange. *pulmonary arteries are the only arteries that contain oxygen-poor blood* The Four-Chambered Heart The left side of the heart receives oxygen-rich blood from the lungs and enters through the pulmonary veins to the left atrium. * these are the only veins in the circulatory system that carry oxygenated blood* Left atrium pumps blood into left ventricle and then exits to the body tissues through the aorta. Heart Valves The heart has 4 valves which ensure blood flows in the right direction. Atria and ventricles are separated from each other by the atrioventricular valves. ○ Right side = tricuspid valve (3 flaps) ○ Left side = bicuspid (mitral) valve (2 flaps) Semilunar valves are between the ventricle and large arteries which carry blood away from the heart. = semilunar valves = atrioventricular valves The Heart’s Electrical System The heart can beat on its own without input from the brain. The sinoatrial node (SA node) is the natural pacemaker of the heart. SA node generates an electrical impulse that spreads through the heart. It causes the heart beat to speed up, slow down, and coordinates electrical signals throughout the heart.  Cardiac Conduction System The Heart’s Electrical System Electrical signal starts in the right atrium, at the SA Node (sinoatrial node), and travels to the atria causing them to contract pumping blood into the ventricles. Then it goes to the AV node (atrioventricular node) between the atria and the ventricles. The signal moves to the ventricles through fibres inside the septum and ventricle walls called “bundle of His” and “Purkinje fibres”. This makes the ventricles contract – sending blood to the lungs and to the rest of your body. ECG https://pie.med.utoronto.ca/htbw/module.html?module=heart Heart Sounds Heart sounds are formed from the closing of the heart valves during the cardiac cycle. lub = tricuspid and mitral valves closing during ventricular contraction. DUB = pulmonary semilunar and aortic semilunar closing during atrial contraction. Blood Pressure (BP) The force of blood on arterial walls. Measured using a sphygmomanometer (sfig-mo-meh-NOM-uh-ter). Normal pressure is: Hypertension Forces the heart to work harder to pump the blood around the body. Can be caused by: ○ Kidney disease ○ Age ○ Diet ○ Physical activity level ○ Stress ○ Certain medications What is the Brain’s Role? Sensory information is gathered by the peripheral nervous system (PNS) and redirected to the central nervous system (CNS). The autonomic nervous system (ANS) sends signals to blood vessels and the heart. Blood Flow in Arteries Arteries carry blood away from the heart and have highly elastic walls which contract and expand as blood flows through. Smaller-diameter arteries, called arterioles, may also contract or relax causing: ○ vasoconstriction: diameter of blood vessels decrease ○ vasodilation: diameter of blood vessels increase Important in maintaining body temperature and responding to injury. Blood Flow in Capillaries Capillaries are the smallest blood vessels (1 cell thick, avg diameter of 8µm). Lack smooth muscle. Sphincter muscles are located before the capillaries. ○ If blood is not needed in a particular area, the sphincters contract to reduce blood flow. Blood Flow in Veins and Venules Veins are less thick and elastic than arteries and move blood towards the heart. Composed of smooth muscle, and one-way valves to return low pressure blood to the heart. Internal diameter is greater than arteries. Contraction of skeletal muscle also help push blood back to the heart. Blood Cellular (formed) component is 45% total blood volume and consists of RBCs, WBCs, and platelets. Fluid component is 55% total blood volume and is made of plasma. Plasma Plasma is ~90% water, with the remaining ~10% made up of ions, proteins, nutrients, wastes, and dissolved gases. Main proteins: ○ albumins: osmotic balance ○ globulins: transport lipids, cholesterol, and some fat-soluble vitamins and minerals ○ immunoglobulins: antibodies ○ fibrinogen: blood clotting Blood Cells Red Blood Cells (RBCʼs/Erythrocytes) Erythrocytes carry O2 to tissues and remove CO2 White Blood Cells (Leukocytes) Part of our immune system; fight pathogens Platelets (Thrombocytes) Initiate blood clotting Blood Colour