OPTION 2_ Circulatory System Reading 7th grade science q1 week 3

1. 09-21-2020 I will demonstrate understanding of the Levels of Organization I will be an inquirer by investigating the structure and function of the Circulatory System REMINDERS: DAILY AGENDA • Warm-up: Heart Rate • Lab Safety Contract • Syllabus • Pre-learning activity • Circulatory System Video and Notes • Matching Levels of Organization • Stemscopedia slides • Ultimate Athlete Slide 2 Warm Up: Heart Rate Warm-up in Google Classroom

2. Circulatory System The circulatory system is the system of vessels and organs through which blood flows and nutrients are transported throughout the body. It is also known as the cardiovascular system. What is the Circulatory System? • The primary function of the circulatory system is to keep blood flowing throughout the body in order to fight diseases and maintain homeostasis (healthy internal balance). • According to the US National Library of Medicine, the circulatory system is made up of three independent systems: the cardiovascular, pulmonary, and systemic systems. • The cardiovascular system consists of the heart. • The pulmonary system consists of the lungs. • The systemic system consists of the arteries, veins, coronary vessels, and portal vessels.

3. Circulatory System • Pulmonary circulation occurs when blood is oxygenated through the lungs. • Systemic circulation occurs when oxygenated blood is sent throughout the body. • The main parts of the circulatory system are the heart, the blood, and the blood vessels. • The heart sends blood through the blood vessels to cells. • Blood transports oxygen, carbon dioxide, amino acids, blood cells, hormones, and other gases throughout the body. • Blood consists of red blood cells, white blood cells, platelets, and plasma. The Cycle • The heart beats 60 to 100 times per minute. • Blood is sent throughout the body with every heartbeat. • Blood begins to circulate when the heart relaxes between two heartbeats. • The blood then releases oxygen and nutrients to the cells and takes on carbon dioxide and other waste. • The deoxygenated blood returns to the heart after transporting nutrients and oxygen. • The heart pumps blood back to the lungs to pick up more oxygen, then the cycle repeats. Source: Bryan Brandenburg / Wikimedia Commons / CC BY-SA 4.0

4. Circulatory System The Heart • The heart has two top and two bottom chambers. • The two top chambers are called right atrium and left atrium, which are divided by a wall called the interatrial septum. • The two bottom chambers are called right ventricle and left ventricle, which are divided by a wall called the interventricular septum. • The right and left atriums receive the blood entering the heart. • The right and left ventricles pump blood out of the heart. • The top and bottom chambers are divided by atrioventricular valves. • There are four types of atrioventricular valves: the aortic valve, the pulmonic valve, the tricuspid valve, and the mitral valve. • The aortic valve separates the aorta from the left ventricle. • The pulmonic valve separates the pulmonary artery from the right ventricle. • The tricuspid valve separates the right ventricle from the right atrium. • The mitral valve separates the left ventricle from the left atrium. Systemic Circulation • Arteries carry blood away from the heart. • The main artery is called the aorta, which carries the blood to the body. • The pulmonary artery carries blood to the lungs.

5. Circulatory System • Arteries branch into small pathways called arterioles which then branch into capillaries. • Capillaries are tiny thin-walled blood vessels that merge into smaller veins called venules which then merge into larger veins. • Veins carry blood back to the heart. • There are two major veins that empty into the right atrium of the heart: the superior vena cava and the inferior vena cava. • The superior vena cava drains the areas above the heart. • The inferior vena cava drains the areas below the heart. A Heartbeat • Electrical signals in the heart prompts the heart to beat. • Two nodes are important in sending and relaying these signals: the sinus node and the atrioventricular node. • Found in the wall of the right atrium, the sinus node is the pacemaker of the heart. • The sinus node sets the rate of the heartbeat by sending electrical impulses that make the atria contract. • The atrioventricular (AV) node receives these impulses which make the ventricles contract. • One heartbeat is made up of two phases: the sistole and the diastole. • During systole, the ventricles contract and blood is pumped into the aorta. • During diastole, the ventricles relax and get filled with blood to flow from the atria in preparation for the next heartbeat.

6. Circulatory System Circulatory Diseases • Circulatory diseases are classified into cardiovascular diseases (affecting the cardiovascular system) and lymphatic diseases (affecting the lymphatic system). • Cardiovascular diseases are the leading cause of death in the United States according to the American Heart Association. • Arteriosclerosis is one of the top common diseases, which occurs when the walls of the arteries are thickened and stiffened by fatty deposits such as fat and cholesterol. • Strokes occur when blood vessels going into the brain are blocked. • Hypertension, also known as high blood pressure, is a circulatory disease that can cause kidney complications, a heart attack, or a stroke. • Peripheral arterial disease (PAD) occurs when there is a blockage or narrowing within an artery. • Diseases that concern the heart are treated by cardiologists. • Operations on the heart are done by cardiothoracic surgeons. • Operations on the vascular system are done by vascular surgeons. A Healthy Heart • To keep your heart and the rest of your circulatory system healthy, you have to get enough exercise, eat a well-balanced and nutritious diet, not smoke, and get regular medical check-ups.