BILL

The Circulatory System Blood Flow Heart Blood Pressure Blood Flow Lymphatic System Respiratory System

The Heart  About the size of your fist  Pump that forces blood through vessels with regular contractions  Pericardium – outside tough protective covering of the heart

The Heart  4 chambers of the heart  Atria (2) – upper chambers, thin walled chambers that collect blood from moving in from veins  Ventricles (2) – lower chambers, thick muscular walls that build up enough pressure to pump blood to lungs/body

The Heart  Septum – separates L and R side of the heart and prevents mixing of oxygen rich (L side) and oxygen poor (R side) blood

The Heart  Blood flow in heart controlled by 4 valves  Atrioventricular Valves (2) – allow blood from atria to ventricles R Side – Tricuspid Valve (3 flaps) L Side – Bicuspid Valve (2 flaps) or Mitral Valve  Semilunar Valves (2) – allow blood to move from ventricle to pulmonary artery, or from ventricle to aorta

The Heart

Blood Vessels  Pulmonary Arteries – carries blood from right ventricle to lungs  Pulmonary Veins – carries blood from lungs to left atria  Aorta – carries blood from left ventricle to the rest of the body  Superior/Inferior vena cava – veins that carry blood from the body back to the right atria

The Heart  Heart is a “double pump”  Right side sends oxygen poor blood to lungs (carbon dioxide rich)  Left side sends oxygen rich blood to body (carbon dioxide poor)

Blood Flow through Heart

The Heart – Blood Flow  Pair of side-by-side pumps each consisting of two chambers  Two possible routes Pulmonary circulation – blood flow from right side of heart to lungs and back Systemic Circulation – blood flow from left side of heart to body cells and back

Blood Flow through Heart

Pulmonary Circulation  Oxygen poor blood collects in right atrium, and flows through right AV valve into the right ventricle  Once ventricle full, in begins to contract, causing: Right AV valve closes to prevent backflow Blood pressure increases inside right ventricle, opening right semilunar valve Blood is pumped through pulmonary artery to lungs to gain oxygen and back to heart into left atrium

Blood Flow through Heart

Systemic Circulation  Blood flows from lungs to the let atrium through the left AV valve into ventricle  Once ventricle fills, it begins to contract causing: Closure of left AV valve to prevent backflow Increase in blood pressure inside ventricle, opening left semilunar valve Blood pumps into aorta, leaving the heart and traveling to the body

Circulation  Right and left sides of heart act in unison  Both atria contract at same time, both ventricles contract at same time  Closing of the valves causes “lub dub” sound of heart beat

Heart Rate – “lub-dub” sound of heart valve opening and closing (can be heard with a stethoscope)  Myogenic Muscle Contraction – spontaneous contraction/relaxation of cardiac muscle without nervous system control  Diastole – relaxed heart  Systole – contraction of the heart

Sinoatrial (SA) Node (“Pacemaker”) Specialized group of cells in R atria that produce small electrical current, signaling for the atria to contract and keeps contracting (recorded on an ECG – Electrocardiogram)

Atrioventricular Node (AV node)  Specialized mass of tissue that receives signals from SA node and sends the signal for ventricular contraction  Occurs roughy 0.1 seconds after signal is received

Heart Rate Control  During Exercise, heart rate increases due to increased demand for oxygen/removal of CO 2  As CO 2 levels rise, area in brain called the Medulla senses increase and sends a signal to SA node through the cranial nerve, called a cardiac nerve, to increase in HR  HR increases the rate of contractions

Heart Rate Control  As CO 2 levels decrease after exercise, Medulla senses decrease and sends a signal to SA node through the cranial nerve, called vagus nerve, to decrease HR  SA node returns to normal pace of contractions

Heart Rate Control - Chemicals  Heart rate is also influenced by chemicals  During periods of excitement/stress, adrenal glands secrete adrenaline  Causes SA node to fire more frequently and increase heart rate

Blood Pressure  Pulse – alternate expansion (high pressure) and relaxation (low pressure) of an artery

Blood Pressure  Normal Resting Blood Pressure – 120/80 (systolic/diastolic)  When ventricles contract – high blood volume into arteries (high pressure)  When heart is relaxed, less volume in arteries so pressure decreses

BILL  Explain how the heart beats? (5 marks)  SA node fires (electrical) signal throughout walls of atria to begin cycle; causing atria to undergo systole; SA signal reaches atrioventricular node; which spreads signal throughout; causing ventricles to undergo systole; atrioventricular valves slap shut; causing "lub" sound; after ventricles are emptied semilunar valves close; causing "dub" sound; atrioventricular valves open; ventricles begin diastole and start filling; all four chambers are in diastole and filling; when atria filled and ventricles 70% filled cycle has ended;

Closed System with Three Types of Blood Vessels  Arteries  Veins  Capillaries

Arteries – carry blood Away from the heart to organs and tissues  Thick, muscular, elastic walls  Blood at High Pressure as it travels through artery  Branch off into smaller arterioles (the smallest arteries) in tissues and organs

Capillaries – connect arteries to veins  So small (1 cell thick), red blood cells must go through single file  Dissolved nutrients, wastes, oxygen, etc exchanged between blood and body cells as blood flows through capillaries

Veins – return blood to the heart from the body organs and tissues  Thin and slightly elastic for large diameters because of low pressure  Flap-like valves in veins allow blood to flow in one direction only (toward the heart)  Venules – smallest veins

Varicose Veins Vein walls become stretched and valves do not work properly causing blood to build up in vein

Plasma – liquid part of blood (nonliving)  Transports nutrients, wastes, Hormones, etc  Mostly water (90%)

Red Blood Cells (RBCs) - Erythrocytes  Red in color – hemoglobin  Transport dissolved substances (oxygen, carbon dioxide, nutrients, wastes, etc)  No nucleus

Red Blood Cells  Smaller than white blood cells  More numerous than white blood cells (2-5 million per mm 3 of blood)  Made by bone marrow and live for about 120 days

Red Blood Cell Disorders  Anemia – too few RBCs or insufficient amount of hemoglobin causing body to not receive enough oxygen  Sickle Cell Anemia – caused by abnormal shaped hemoglobin

White Blood Cells (WBCs) - Leukocytes  AKA phagocytes and lymphocytes  Colorless  Helps fight infection and protect the body from disease causing organisms  Move on their own like amoebas (pseudopods) and through circulatory system

White Blood Cells  Have a nucleus  Larger than RBCs  Less numerous than RBCs (5,000-10,000) – you have more WBCs in your body when you have an infection and less when you are healthy

White Blood Cells  Made by bone marrow and lymphatic tissue  Leukemia – cancer of cells that make WBCs

Platelets  Help to clot blood and begin the healing process  Blood cell fragments (250, ,000)  Live for 7 days

Blood Clotting – platelets stick together to damaged/torn area and seal the “leak”  If wound is more serious  clotting process takes over 1. Platelets release thromboplastin (enzyme) 2. Thromboplastin converts prothrombin (plasma protein) into thrombin 3. Thrombin converts fibrinoogen into fibrin 4. Fibrin forms a network of strands that trap RBCs and platelets to form clot 5. Once the healing is complete, plasmin (enzyme) dissolves the fibrin clot

Blood Clot

Clotting Problems  Hemophilia – hereditary disease with inability to clot blood  Clotting when not needed  heart attack or stroke

Blood – liquid tissue that transport, regulates, and protects  Transports – oxygen, carbon dioxide, nutrients, wastes, etc  Regulates – absorbs heat, maintains pH and water balance, etc  Protects – defense against pathogens

BILL  Distinguish between the following: Red Blood Cells, White Blood Cells, Platelets  RBCs – small cells with no nucleus, composed of protein hemoglobin, transport dissolved nutrients  WBC – larger cells with a nucleus, help fight infections in the body and protects body from infectious diseases  Platelets – blood cell fragments help to clot blood and begin healing process

Lymphatic System  Lymphatic system – a network of vessels, nodes, and organs that collects fluid that is lost by the blood and returns it back to the circulatory system  Fluid that is lost is called lymph

Lymph Nodes  Lymph Nodes – act as filters, trapping bacteria and other microorganisms that cause disease  When there are large numbers of microorganisms trapped in the lymph nodes, they become enlarged (swollen)

Lymphatic System  As blood circulates, some blood leaks into surrounding tissues  This helps maintain movement of nutrients and salts from the blood into the tissues  Between 3-4 liters of fluid leaks from the circulatory system per day and if the leaks go unchecked, the body would swell