12.1- The Function of Circulation SBI3U1

Did you know?  Your heart is about the size of your fist  The heart beats about x a day  The heart functions with blood vessels that are the combined length of the circumference of the Earth.

Main Functions of the Circulatory System 1. Transportation of gases, nutrient molecules, and waste materials 2. Regulates internal temperature and transports chemical substances vital for health 3. Protects against blood loss from injury and disease- causing microbes

Major Components of the Circulatory System 1)Heart: muscular organ that pumps blood through the body 2)Blood vessels: system of hollow tubes through which blood moves Ie. Arteries, veins, capillaries 3)Blood: fluid that transports nutrients, oxygen, carbon dioxide, and many other materials

Open vs. Closed Circulatory Systems  OPEN Blood flows freely within the body cavity and makes direct contact with organs and tissues.  Examples: insects  CLOSED Blood is kept physically contained within vessels. The blood follows a continuous fixed path of circulation and is confined to a network of vessels that keeps the blood separate.  Examples: earthworms, birds, humans

The Human Heart  Located slightly to the left middle of chest  Size of your fist  Composed of cardiac muscle  Contracts and relaxes rhythmically/involuntarily

Structure of the Heart  The heart consists of four chambers; 2ventricles & 2 atria  The left and right chambers are separated by a septum.

Chambers of the Heart: Atria Right Atrium  Receives blood returning to the heart via superior/inferior vena cava  Deoxygenated blood from the body Left Atrium  Receives blood via the pulmonary veins  Oxygenated blood from the lungs

Chambers of the Heart: Ventricles Right Ventricle  Receives blood from the right atrium  Pumps deoxygenated blood to the pulmonary artery Travels to the lungs to get oxygen Left Ventricle  Receives blood from the left atrium  Pumps oxygenated blood to the aorta  Carries it to the body

Valves of the Heart  4 valves: bicuspid( mitral), tricuspid, aortic semilunar valve, pulmonary semilunar valve  The valves prevent the back flow of blood.

Blood Vessels UNIT 4 Chapter 12: The Circulatory System Section 12.1 Arteries (largest): carry blood away from the heart are elastic Veins : carry blood to the heart have one-way valves to keep blood moving forward Capillaries( smallest): exchange of materials between blood and cells occurs one cell thick

Arteries of the Heart Pulmonary Artery- carries deoxygenated blood to the lungs Aorta - carries oxygenated blood away from the heart to the rest of the body (largest artery)

Veins of the Heart Inferior Vena Cava – carries deoxygenated blood from bottom of body to the heart Superior Vena Cava – carries deoxygenated blood from top of body to the heart Pulmonary Vein – carry oxygenated blood from the lungs to the left atrium

The Mammalian Circulatory System UNIT 4 Chapter 12: The Circulatory System Section 12.1 Pulmonary circulation: pumps blood through one circuit between the heart and the lungs Systemic circulation: pumps blood between the heart and the rest of the body. Cardiac circulation: The movement of blood through the heart is called

Components of Blood  Plasma Consists of water, dissolved gases, nutrients, Proteins, waste materials  White Blood Cells  Red Blood Cells

Red Blood Cells and Their Functions Red blood cells (erythrocytes) - transports oxygen -Hemoglobin carries oxygen and carbon dioxide (in small amounts) -Mature erythrocytes do not have a nucleus. -There are between 500 and 1000 red blood cells for every white blood cell. UNIT 4 Chapter 12: The Circulatory System Section 12.1 NOTICE THE BI-CONCAVE SHAPE

White Blood Cells and Their Functions White blood cells (leukocytes) -approx.1% of the total volume of blood. -fight infections and cancer. Examples: 1)neutrophils (most abundant), 2)eosinophils (in mucus) 3)basophils (attract phagocytes) 4)lymphocytes (produce antibodies) 5)monocytes (circulate and destroy bacteria). UNIT 4 Chapter 12: The Circulatory System Section 12.1

Platelets and Their Function Platelets (thrombocytes) membrane-bound fragments of cells (no nuclei) -form blood clots -when injured, they rupture, release chemicals, and form thromboplastin. UNIT 4 Chapter 12: The Circulatory System Section 12.1

Steps in Clotting Blood  Copy steps into your notes (point form): pg. 485

The Functions of Blood: TRANSPORT UNIT 4 Chapter 12: The Circulatory System Section 12.1 Blood in capillaries of the small intestines absorbs nutrients during digestion. Blood absorbs glucose and amino acids made in other parts of the body and sends them to the liver. Blood transports chemicals and gases from and for the respiratory system. Blood transports and removes waste products of cellular processes, such as mineral ions.

The Functions of Blood: Temperature Regulation Temperature is regulated by changing the volume of blood flowing near the skin. Blood vessels can either expand (vasodilation) to release heat or contract (vasoconstriction) to conserve heat. UNIT 4 Chapter 12: The Circulatory System Section 12.1

Counter-Current Heat Exchange This system helps maintain a steady temperature in the core of the body. Deep arteries and veins entering and leaving the body’s extremities lie adjacent to one another, so warmer blood that flows from the body core to the extremities exchanges heat with the cooler blood returning from the extremities to the body core. UNIT 4 Chapter 12: The Circulatory System Section 12.1

Homework 1) Read and make notes ) Complete pg. 481 #1-6 3) Label the diagram of the heart