PLATELETS / THROMBOCYTES



Biology 30SThe Circulatory System17653008191500ObjectivesBy the end of this unit students will be able to:Compare the structure of arteries, veins and capillaries.Relate the structure of the capillary to its role as the site of exchange in the circulatory system.Identify the anatomical components of the human heart and their related functions.Trace the pathway of blood flow through the human heart and associated vessels and organs.Identify factors responsible for the regulation of human heartbeat.Differentiate between the systolic and diastolic stages of the heartbeat. Identify types of heart diseases, define heart failure, and describe causes and treatments.Describe lymph nodes.Describe lymphatic pare the structure and functions of the lymphatic system to the blood circulatory system. Compare the structure, function and site of manufacture of the formed elements of the blood.Describe blood groups, including Rh.Describe the components of the blood clotting mechanism.Describe the role of the circulatory system in homeostasis.Describe the role of the circulatory system in immunity.Investigate selected blood disorders.Describe the body’s defense mechanisms for protection from foreign agents. Compare and contrast non-specific verses specific defenses.Describe the body’s response to allergens, vaccines, and viruses/bacteria. Outline the immune responseInvestigate and describe conditions/disorders that affect protection and/or control in the human body.INTRODUCTIONIntro Circ. Video: In humans, there is a single coordinated system for transport of fluids. This is the blood circulatory system and the lymphatic system associated with it. There is no special transport system for gases, as these are moved about dissolved or combined in the body fluids. The blood circulatory system of humans has three parts:Blood – the circulating fluidBlood Vessels – the transporting mediumHeart – the pumping stationPART ONE – BLOODThe average human adult has 5-6 litres of blood. Blood is composed of two parts: Plasma - a complex fluidCellular Components – erythrocytes, leucocytes, and plateletsBlood Video (Recap): BLOOD PLASMA:Yellowish thick fluid Makes up 55% of blood volumeConsists of:91.5% water7% organic proteins1.5% dissolved food, enzymes, vitamins, hormones, antibodies, waste products, inorganic salts and gasesAlso carries blood proteins which make up 7% of the plasma are of four types:Albumin (54%) – made in the liver and is important in maintaining blood pressureGlobulins (38%) – used in the body’s defense against diseaseFibrinogen (7%) – necessary for blood clottingProthrombin (1%) – necessary for blood clottingFunction of blood plasma:Carry nutrients (amino acids, fatty acids, simple sugars etc.)Carry gasses (nitrogen, oxygen, carbon dioxide)Carry mineral salts (calcium, sodium, potassium) and vitaminsCarry enzymes and hormonesCarry waste products (urea)RED BLOOD CELLS / ERYTHROCYTES:Appearance: have no nucleus when mature so there is more room for oxygen to be carried in the cell and hence around the body.small, round, biconcave shape (narrow in the center) for maximum surface area This shape gives the cell a large surface area through which oxygen can diffuseAlso ensures that all oxygen held in the cell is near the surface and can be exchanged quicklyAlso makes them flexible, easily squeeze through capillaries Origin:produced in red bone marrow and become filled with hemoglobin that pushes out the nucleuswhen worn out they are destroyed, and broken down in the liver and spleencontinually produced and die (life span 120 days)Number:5 million per cubic millimeterRBC make up 45% of blood more red blood cells than any other cell in the bodyFunction:Transport oxygen and small amount of carbon dioxide through the use of hemoglobin to and from the lungs to cellsRecall: oxygen + hemoglobin = oxyhemoglobin (bright red)Helps maintain a stable pH for the body (blood buffer = 7.2-7.4 stable pH)Problem with COcarbon monoxide bonds with hemoglobin and prevent oxygen from being circulated to organs, and cells.Carbon monoxide is produced by car emissions, and smoking23322712518500Watch video on Carbon Monoxide poisoning: WHITE BLOOD CELLS / LEUCOCYTES:Appearance:variety of colorless blood cellsirregular shaped cellscontain a nucleuscan reproduce by mitosiscontain no hemoglobinlarger than RBCcapable of their own movement outside blood stream (pseudopods)Origin:Formed in bone marrow and lymph nodesCan live for many months or yearsNumber:Less numerous than erythrocytes 5 – 10 thousand per cubic millimeterThere is approximately 1 white blood cell for every 600 red blood cells (makes up about 1% of the blood)Function:part of body’s defense system fight infections and prevent disease by ingesting foreign cells or substances and producing antibodiesTypes:There are two kinds of leucocytes:109220026506700Granular – lifespan of 2-14 days, produced by the bone marrowEosinophils – active in acidic environments and during allergic reactionsBasophils – active in basic environments also may aid in blood clot formationNeutrophils – active in neutral environments, very motileNon- granular – lifespan of 100-200 daysLymphocytes Produced in the lymph nodes and make antibodies which are involved with the immune response to small foreign proteinsMonocytesMade in red bone marrowAre mobile and phagocyticPLATELETS / THROMBOCYTESAppearance:not cells but tiny fragments of other cellseach platelet is surrounded by a membrane and is filled with thromboplastin irregular shapeno nucleusOrigin:made when small pieces of cytoplasm are pinched off the large cells which are found in bone marrow.Number:250, 000 platelets per cubic millimeter of bloodproduced at the rate of 200 billion a day live for average of 5-9 daysFunction:involved in blood clottingrepair of damaged blood vesselseach platelet is surrounded by a membrane and filled with thromboplastinthe fragile membrane breaks easily if exposed to any environment other than the bloodwhen a wound is made and blood vessels are damaged, the platelets break down and thromboplastinogen is released into the blood plasma-3708406032500COMPONENTS OF BLOOD SUMMARYRED BLOOD CELLWHITE BLOOD CELLPLASMAPLATELETSAlso called?FunctionDescriptionIllustrationPercentage of Total BloodOriginAssociated DiseasesFUNCTIONS OF BLOOD1. Oxygen Transportred blood cells transport oxygenthey give blood its red colour because of their red pigment, hemoglobineach hemoglobin molecules consists of four heme groups attached to a central globin (protein) moleculethe iron in the hemoglobin has the ability to form a temporary union with oxygenone hemoglobin molecule can carry four oxygen molecules at once where the oxygen concentration is high, as in the lungs, hemoglobin combines with oxygen forming a bright red compound called oxyhemoglobinwhere the oxygen concentration is low as in most tissues the oxygen separates from the hemoglobin forming a dark purplish compound called deoxyhemoglobin2. Carbon Dioxide TransportCarbon dioxide is a waste product of cellular oxidation. It can be carried in the blood in one of three ways:carried in plasma in a dissolved statecarried by hemoglobinmajority is carried as the bicarbonate ion when carbon dioxide reacts with water, carbonic acid is formedcarbonic acid breaks down to from hydrogen ion and bicarbonate ion and is carried in the blood as ionswhen the bicarbonate ion reaches the lungs the reverse reaction occurs and the carbon dioxide is released and exhaled from the lungs3. Blood ClottingThis is a protective mechanism to prevent excessive blood lossPlatelets, also called thrombocytes, function in the clotting of blood and repairing of damaged blood vesselsPlatelets, prothrombin and fibrinogen are necessary for the clotting process. They are present in the plasma whether or not a blood vessel has been damaged. They are inactive unless a vessel wall is actually damaged.Dangers of Blood Clots in the Body:Blood clots that form in the body present potential danger for several reasons:Stop the flow of blood to vital organs, and cause cells to die due to oxygen starvationDecrease the flow of blood, and increase blood pressure (Embolisms are moving blood clots)Blocked blood vessels may rupture and cause internal hemorrhaging and death (Aneurysm)Steps to clotting:When a blood vessel is cut:Platelets that come in contact with the damaged tissue break, releasing thromboplastinogen and adhere to the broken vesselThey themselves become sticky to other platelets, which adhere to them and in turn become sticky to other platelets. A plug of platelets forms over the damaged area.After the initial plug is formed:The thromboplastinogen is activated to thromboplastin by an enzyme and several blood clotting factors.Thromboplastin is an enzyme that, in the presence of calcium ions, catalyzes the conversion of prothrombin to thrombinThrombin is an enzyme that catalyzes the conversion of the soluble fibrinogen to the insoluble fibrinFibrin consists of long, fibrous protein molecules that form a network across the opening in the blood vesselThe clot slows the flow of blood and eventually stops it if the amount of damage is not too greatNormally clots do not form in undamaged vessels. Circulating in the blood is an anticoagulant, heparin that normally prevents clotting in intact vessels. It does this by interfering with the conversion of fibrinogen to fibrinBLOOD CLOTTING VIDEO: 4. Defense against DiseaseThe body’s outer covering prevents the majority of disease organisms from entering; any that do must be destroyed immediately. Cellular DefenseLeucocytes are responsible for destroying the bacteriaWhen bacteria break through the outer defenses, the capillaries dilateThis causes inflammation and an increase in local temperatureLeucocytes are attracted to the area and begin engulfing the disease bacteriaThe leucocytes are killed while destroying the bacteria and accumulate in pockets with other dead tissue and plasma to form pusNeutrophils and lymphocytes are the most effective bacteria killing cellsChemical DefenseLymphocytes and monocytes produce antibodies that make an organism immune to an infectionForeign protein called antigen, when introduced to the body, triggers the production of antibodies to destroy itThe thymus gland is most important in antibody production during infancy and early childhood because it produces lymphocytesImmunity can either be natural or acquiredFunctions of Blood Video: BLOOD COMPONENTS PRACTICE QUESTIONS:List the functions of the blood. (4)Briefly describe the FOUR components of the blood. (4)Describe the function of each of the FOUR components of the blood. (4)Reorganize the events in each group in the order in which they would likely occur. Write 1 next to the first event, 2 next the event that would happen second, and so on. (2)_______Thromboplastinogen activates thromboplastin mixes with prothrombin and calcium to produce thrombin_______Fibrin forms the clot._______Injury occurs, and platelets rupture releasing thromboplastinogen_______Thrombin mixes with fibrinogen to produce fibrinExplain why red blood cells are the most numerous of the blood cells and why they have such a short life span. (2)Why are white blood cells the least numerous of the blood cells, and why do they have a longer life span. (2)BLOOD GROUPSHuman blood can be differentiated into four groups:Blood type ABlood type BBlood type ABBlood type OBlood types are determined by either the presence or absence of certain proteins found on the cell membranes of the red blood cells (antigens) and in the plasma part of the blood(antibodies) that cause AGGLUTINATION (clumping) of the red blood cells.Two of these antigens on the RBC are classified antigen A and antigen BThe two antibodies that correspond to antigens A and B are designated anti-A and anti-B.Agglutination is due to the combination of an antigen and its compliment antibody.For example: blood cells with antigen A will clump in the presence of anti-A antibodies.BLOOD TYPEANTIGENS ANTIBODIES TYPE AANTIGEN AANTIBODY BTYPE BANTIGEN BANTIBODY ATYPE ABBOTH A & BNEITHER A OR BTYPE ONEITHER A OR BBOTH A & B7328816667500Blood Group Video: BLOOD TYPINGIn blood typing, two serums are used: one has anti-A antibodies, the other anti-B antibodies. To one drop of blood a drop of serum is added; the two drops are mixed together and observed for evidence of agglutination or clumping. If clumping occurs with anti-A serum the person’s blood must have antigen A on the red blood cells. The person has blood type A.If clumping occurs with anti-B serum, the blood is type B because it has antigen B on the erythrocytes. If clumping occurs when a drop of blood is mixed separately with anti-A and anti-B serums, it must be AB because it contains both antigens A and B. If no clumping is evident, the type is O, because neither antigen A nor antigen B is present in the blood.3897091814300BLOOD TRANSFUSIONS:When large quantities of blood are transfused, the possible reaction of the donor’s antibodies with the recipient’s antigens must be considered Incorrect matching of blood could be fatal.Persons with type O are considered to be universal donors, as they contain no antigens to cause recipient’s antibodies to clump around “foreign antigens”Persons with type AB are universal recipients, as they contain no antibodies to attack donor’s antigens.Persons with type A cannot receive type B blood as type A has antigen A and antibodies B, antibodies B will attack “foreign antigen B” that it does not recognize, and cause clumping of the blood.Rh FACTORIn addition to the ABO antigens, there is another antigen on the red blood cells called the Rh antigen (named after the rhesus monkey in which the antigen was discovered).People who have the Rh antigen on their red blood cells are said to be Rh positive. (Rh+)People who do not have the Rh antigen on their red blood cells are said to be Rh negative (Rh-)7818674082100ERYTHROBLASTOSIS FETALIS: Rh factor can cause complications in some pregnancies.Problem occur only if the mother is Rh- and she is carrying an Rh+ baby.FIRST PREGNANCY:At birth the Rh+ baby’s blood mixes with the Rh- blood of the mother. The mother’s blood then makes anti-Rh+ antibodies.SECOND AND SUBSEQUENT PREGNANCIES:Should the mother become pregnant again, these antibodies will cross the placenta. If the new fetus is Rh+, the anti-Rh+ antibodies from the mother will destroy red blood cells in the fetus, endangering the fetus.TREATMENT:When the Rh+ fetus is 28 weeks old, and again shortly after birth, the Rh- mother is given a substance that removes the Rh antibodies from her blood. As a result her fetus will no longer be in danger.1012194376800Erythroblastosis Fetalis Videos: Bio30SPRACTICE QUESTIONS - BLOOD TYPE:Complete the following chart: (4)Blood type of RecipientBlood type of Possible DonorsABABOWhat blood type is the universal donor? Why would this type not cause clumping in other blood types? (2)What blood type is the universal recipient? Why would this type not be clumped by other blood types? (2)Can a type A recipient safely receive group B blood? Explain. (2)What is Rh factor? (1)If a mother has the Rh negative factor and her fetus is Rh positive, complications may result. Explain. (2)7.Reorganize the events in each group in the order in which they would likely occur. Write 1 next to the first event, 2 next the event that would happen second, and so on. (2)_______During the mother’s next pregnancy, Rh antibodies can cross the placenta and endanger the fetus. _______Mother is exposed to Rh antigens at the birth of her Rh+ baby_______Mother makes anti-Rh+ antibodies_______Baby inherits Rh+ from the father and the mother is Rh-.PART TWO – BLOOD VESSELSARTERIESArteries are blood vessels which carry blood away from the heart to various parts of the body.The large arteries branch many times to form smaller and smaller arteries. The smallest arteries are called arterioles.The aorta, the largest artery, is about 25 mm in diameter. Arterioles are about 0.2 mm in diameter.Artery walls are thick, strong and muscular and made of three tissue layers.The inner most layer is the endothelium – a smooth, thin sheet of tightly packed cells.The middle layer is made of elastic fibers and muscle fibers.The arteries outer most layer is made up of fibrous, connective material, nerves, and tiny blood vessels that nourish the artery’s walls. center850800Functions of the Arteries:Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, with the exception of the pulmonary and umbilical arteries.The arterial system is the higher-pressure portion of the circulatory system with the pressure varying between the peak pressure during heart contraction, called the systolic pressure, and the minimum, or diastolic pressure between contractions, when the heart expands and refills.The increase in arterial pressure during systole, or ventricular contraction, results in the pulse pressure which is an indicator of cardiac function.CAPILLARIESThe capillaries have very thin walls composed of a single layer of endothelial cells.The average diameter is 7/1000 mm – just wide enough to let red blood cells pass one at a time. The two outermost layers of the arteries disappear and the arterioles branch into a network of capillaries. There are approximately 100,000 km of capillaries in an adult.They provide a great deal of surface area that contacts other tissue; more than 6000 square meters allow for a great deal of exchange between blood and the tissues.The capillaries consist of epithelial tissue alone, the walls being only one cell thick.Substances in the blood and substances in the body tissue are exchanged only across the capillary endothelium, and not across the walls of arteries and veins.34671010795000Functions of the CapillariesCapillaries function in a group, or a capillary bed, which is an interweaving network of capillaries. The more active a cell is the more capillaries that are needed to supply the proper blood flow and exchange of materials. These blood vessels are microscopic, but their presence is viewable at times. When a person blushes, this occurs in the capillaries and turns the cheeks red. This is partially possible because the wall of the capillary is only one cell thick.VEINSAlthough blood is forced into the arteries under pressure, by the time it reaches the capillaries this pressure is very low.Since the blood pressure in the veins is less than 1/10 of the pressure in the aorta it is obvious that another mechanism must be present for getting blood back to the heart.350393055118000Capillaries reunite to form venules, which join to form larger and larger veins, having progressively thicker layers of muscle and elastic fibers and connective tissue.The structure of a vein is similar to that of an artery, except the middle section containing muscle and elastic fiber is thinner because there is very little blood pressure in it.Veins act as low resistance channels for the flow of blood from the tissues back to the heart.The veins depend largely on the pressure exerted on them by surrounding tissues to return blood to the heart.Most veins, particularly in the arms and legs have one –way valves that prevent the backflow of blood into the capillaries. While standing a person unconsciously contracts muscles in his legs to force blood through the leg veins. When blood is not being forced forward in the vein the valve closes to prevent blood from flowing backwardsFunctions of the VeinsVeins serve to return blood from organs to the heart. Veins are also called "capacitance vessels" because most of the blood volume (60%) is contained within veins. Standing or sitting for a prolonged period of time can cause low venous return from venous pooling. Jet pilots wear pressurized suits to help maintain their venous return and blood pressure.The difference between veins and arteries is their direction of flow (out of the heart by arteries, returning to the heart for veins), not their oxygen content. One Exception:Pulmonary arteries carry deoxygenated blood from the heart to the lungs to pick up oxygen.Pulmonary veins carry oxygenated blood from lungs to the heart to be pumped to the rest of the body. Blood Vessels Video: A Comparison of Arteries and Veins and CapillariesArteryVeinCapillariesFunction Oxygenated/Deoxygenated BloodStructureVolume and PressureValvesSmaller Blood vesselsBlood MovementPART THREE – THE HUMAN HEARTThe adult heart is about the size of a large fist and has a mass of approximately 300 grams. The heart is a tough muscular organ which beats about 72 times and pumps 5 litres of blood every minute. Pumping over 7000 litres of blood each day, 35 million litres in the life time of a grade 11 student, your heart provides the vital force for the circulatory system. The human heart is really two pumps working side by side. A thick wall of muscle, called the septum, separates the hearts right and left sides.Each side is divided into two chambers: the atrium and the ventricle.The upper chambers, the atria, collect blood returning to the heart through veins. The think muscles of their walls push blood a short distance to the lower chambers, the ventricles. The thick, muscular walls of the ventricles contract forcefully, pushing blood out of the heart to the lungs and body through arteries.1091565825500The Human Heart Video: OF THE HEART:FOUR CHAMBERS: two upper chambers called ATRIA two lower chambers called VENTRICLESTHE SEPTUMThe right and left sides of your heart are divided by an internal wall of thick muscular tissue called the septum. The septum prevents blood from mixing between ventricles.VALVES in the Heart:There are two sets of valves (4 individual valves) located within the heart. Function is to move blood in one direction through the heart.1st set - ATRIO-VENTRICULAR VALVES (AV valves):located between the atria and ventriclesflaps of tissue are supported by tiny tendons or connective tissue to muscles that pull the flaps open.when blood fills the cavity, the valves close Right AV valve contains 3 flaps and is called the TRICUSPID valveLeft AV valve contains 2 flaps and is called the BICUSPID valve (AKA MITRAL Valve)2nd set - SEMI-LUNAR VALVES:42862506540500these valves resemble little pockets or half moonsflaps of tissue located in the arteries that leave the ventriclesoperate by pressure alone (no muscular control)prevents the back-flow of blood into the heart from the aorta and pulmonary arterieseach valve consists of three half moon cusps attached to the arterial wallsFound at the opening of the pulmonary artery is the PULMONARY SEMI-LUNAR VALVEFound at the opening of the aorta is the AORTIC SEMI-LUNAR VALVEValves open and close by blood pressure pushing against them. BLOOD FLOW THROUGH THE HEART AND BODYBlood from any body tissue other than the lungs returns to the heart through either one of two veins: superior vena cava and inferior vena cava. The superior vena cava drains blood from the arms, head and upper part of the body. The inferior vena cava drains the lower part of the body and legs. Having come from living and therefore respiring tissues, the blood in these veins is called deoxygenated blood, has a low oxygen content and a high carbon dioxide content. Deoxygenated blood passes from the superior and inferior vena cava into the right atrium of the heart. A contraction of the atrium forces blood into the lower chamber, the right ventricle. The atrioventricular (AV) valve between the two chambers prevents the backward flow of blood from the ventricle to the atrium. This valve, commonly called the tricuspid valve, consists of three flaps of tissue that together form a more or less funnel-shaped arrangement, the narrow end extending into the ventricle. The pressure of the blood in the atrium forces the valve open, but when pressure develops in the ventricle, the pressure pushes the flaps against each other, effectively closing the opening. A contraction of the right ventricle can force blood out only though the pulmonary trunk, the only artery departing from the right ventricle. Another valve, the pulmonary semilunar valve, between the right ventricle and the pulmonary trunk prevents backflow of blood. Shortly after leaving the right ventricle, the pulmonary trunk branches into the two pulmonary arteries, each of which serves a different lung. In the capillaries of the lungs, deoxygenated blood releases the carbon dioxide received from the body tissues and receives a fresh supply of oxygen. After passing through the lungs, oxygenated blood returns to the heart by way of the pulmonary veins, which enter the left atrium. Contraction of this chamber forces blood into the left ventricle. Another AV valve, known as the mitral valve, between the left atrium and left ventricle prevents the backflow into the left atrium. Contraction of the left ventricle forces blood into the aorta, the largest artery of the body. The aortic semilunar valve prevents backflow into the left ventricle when the ventricle relaxes. The branches of the aorta carry oxygenated blood to all parts of the body except the lungs. In the brain, a muscle, a gland, or some other organ the oxygenated blood becomes deoxygenated blood as it releases its oxygen and accepts carbon dioxide from the tissues. The venules and veins that drain capillaries carry deoxygenated blood to either the superior vena cava or inferior vena cava, both of which return blood to the right atrium of the heart. In the human circulatory system, there are two prominent blood circuits: the pulmonary system and the systemic system.The pulmonary system is concerned with the passage of blood from the heart through the lungs and back to the heart.The systemic system is concerned with the passage of blood from the heart and all other organs (except the lungs) and back to the heart. One complete cycle of the flow of blood through the systemic circuit takes about 90 seconds. The two-circuit arrangement is an efficient circulatory pattern that avoids the mixing of oxygenated and deoxygenated blood. -163830-2476500THE CARDIAC CYCLE (THE HEARTBEAT)Each heartbeat requires approximately eight tenths of a second, although this varies with age, exercise, state of health, and emotion. Unlike other striated muscles, the heart requires no nervous stimulation to contract. A heart continues to beat if all nerve connections to it are severed. However the nerves serving the heart do control the rate at which it beats.A single beat of the heart consists of a contraction of the atria followed by a contraction of the ventricles and a period of relaxation of all four chambers of the heart.Contractions are called systoles, and relaxations are called diastoles.An atrial systole lasts one eight of a second, and permits blood to flow from the atria into the ventricles. It is followed by an atrial diastole, lasting seven eights of a second, which allows blood from the inferior vena cava and the superior vena cava and the pulmonary veins to enter the atria. The beginning of the atrial diastole coincides with the beginning of the ventricular systole, which lasts three eights of a second and forces blood into the pulmonary arteries and the aorta. The ventricular diastole lasts through the atrial systole of the next beat. For half of the beat (half a second) all the chambers of the heart relax. The contraction of the heart muscles of the atria and ventricles is initiated by a mass of specialized cells known as the sinoatrial node (SA node). The SA node is located in the posterior wall of the right atrium, near the entrance of the superior vena cava. The SA node is called the pacemaker because it produces the impulse that starts each heartbeat. The nerve impulse spreads quickly over both atria, causing the atrial muscles to contract. The impulse reaches a second node, the atrioventricular node (AV node), located in the septum between the ventricles but in contact with the lower portion of the right atrium. The stimulation of the AV node causes never impulses to be sent down the bundle of nerve fibres, known as the Bundle of His. The Bundle of His branches into a pair of nerve fibres going down the septum with one going around the base of each ventricle. The impulse started in the SA node and picked up by the AV node reaches the muscles of the ventricles and causes them to contract.THE HEART CYCLE:Each heartbeat has two basic parts: diastole (di-AS-toe-lee, or relaxation) and atrial and ventricular systole (SIS-toe-lee, or contraction).SYSTOLE: is the contraction of the heart muscle and blood is being pumped out(emptying of blood)high pressureDIASTOLE:is the relaxation of the heart muscle and blood is flowing into the heart (filling with blood)low pressureSystole or DiastoleWhat is occurring?-both atria contract to finish filling the ventricles-ventricle muscles relax-heart is passively filling with blood again as blood is returned to heart by the veins-AV valves are open and SL valves are closed (“dub”)-both atria are at rest-ventricle muscles are contracting simultaneously-AV valves are closed and SL valves are open (“LUB”)-blood passes into aorta and pulmonary arteryELECTROCARDIOGRAM (EKG or ECG)Video: What is an ECG? If you’ve ever seen the heart test called an EKG (electrocardiogram), you’ve seen a graphical picture of the electrical activity of your heart.center1836300The P wave is a record of the electrical activity through the upper heart chambers (atria). The QRS complex is a record of the movement of electrical impulses through the lower heart chambers (ventricles). The ST segment corresponds to the time when the ventricle is contracting but no electricity is flowing through it. The ST segment usually appears as a straight, level line between the QRS complex and the T wave. The T wave corresponds to the period when the lower heart chambers are relaxing electrically and preparing for their next muscle contraction.Electrical signals within the heart can be measured and recorded by a machine called an ELECTROCARDIOGRAPH. This recording is then shown as an electrocardiogram. An EKG is a technological device that monitors the heart’s electrical activity.The EKG is an important tool used in diagnosing abnormal heart rhythms or patterns. Each peak or valley in the EKG tracing represents a particular electrical activity that takes place during a heartbeat.WHAT IS AN ARRHYTHMIA?An arrhythmia (also referred to as dysrhythmia) is an abnormal rhythm of the heart, which can cause the heart to pump less effectively.Arrhythmias can cause problems with contractions of the heart chambers by:not allowing the chambers to fill with an adequate amount of blood because the electrical signal is causing the heart to pump too fast.not allowing a sufficient amount of blood to be pumped out to the body because the electrical signal is causing the heart to pump too slowly or too irregularly. In any of these situations, the body may not receive enough blood because the heart cannot pump out an adequate amount with each beat as a result of the arrhythmia's effects on the heart rate.?Videos: Arrhythmias Tachycardia – heart beats too fastBrachycardia – heart beats too slow FIBRILLATION:Is the condition that results when the heart goes into arrest and is in a state of rapid quivering In this situation, the pacemaker cells are sending electrical signals faster than the heart can respond. Therefore the heart can only be restored to normal beating by means of defibrillation.DEFIBRILLATION: Is the delivery of an external current into the heart muscle. This “shock” stops the uncontrolled electrical activity and allows the heart’s normal pacer to take over.What is a defibrillator and how does it work Video: NERVOUS SYSTEM CONTROL OF THE HEART:the pacemaker (SA node) controls the rate of the heartbeat, a portion of the brain called the MEDULLA OBLONGATA regulates the rate of the pacemaker, speeding or slowing its nerve impulses.if the heart beats too fast, sensory cells in the arteries (aorta) near the heart become stretched. These cells send a signal, via the nervous system, to the medulla oblongata, which in turn sends a signal to slow down the pacemaker.if the heart slows down too much, blood pressure in the arteries drops, signaling the medulla oblongata to speed up the pacemaker and increase heart rate.Afferent nerves convey impulses toward the brain, specifically the autonomic nervous system centered in the medulla oblongata .Efferent nerves convey impulses from the brain outward carrying messages to regulate heartbeat Autonomic nervous system (controls involuntary actions) is composed of both sympathetic nerves, and parasympathetic nerves.-sympathetic nerves act to increase heart rate-parasympathetic nerves act to slow down heart rate.chemical receptors in the blood vessels are sensitive to oxygen or carbon dioxide levels and stimulate various nerves to affect heart rate. These inform the nervous system of the changes in oxygen content in the blood and stimulate the appropriate nerves.HOMEOSTASIS AND HEARTBEAT CONTROL:3810146685RECEPTORS(Sensory cells in arteries become stretched and detect fast heart rate)RESPONSE(Pacemaker slows down and heart rate decreases)STIMULUS(fast heart rate)EFFECTOR(Impulses are received in heart and heart muscle beats slower)REGULATORY CONTROL CENTER (Medulla Oblongata)00RECEPTORS(Sensory cells in arteries become stretched and detect fast heart rate)RESPONSE(Pacemaker slows down and heart rate decreases)STIMULUS(fast heart rate)EFFECTOR(Impulses are received in heart and heart muscle beats slower)REGULATORY CONTROL CENTER (Medulla Oblongata)FACTORS AFFECTING HEART RATE:EMOTIONS:Fear, excitement, shock, anger, tension will all cause an increase in heart rateCHEMICALS:Carbon monoxide will slow down the heartExcess carbon dioxide will increase heart rateExcess oxygen will increase heart rateNicotine, caffeine will increase heart rateAlcohol will slow down heart rateHormones such as adrenaline will increase both force and rate of the heart beatAdditional Factors Affecting Heart Rate:Gender, age, Body Positioning, physical trainingEffects of ADRENALINE AND NORADRENALINE on heart rate: (also called epinephrine and norepinephrine)when the body is in danger or is threatened, adrenaline and noradrenaline are released from the adrenal glands these hormones causes the sympathetic nerves to act on heart rate and breathing rate are both increasedthis is called the “fight or flight” response as it prepares the body to either face the fear or evade danger.once the danger has passed, the body returns to normal resting levels controlled by the parasympathetic nerves.THE CIRCULATORY SYSTEM’S ADJUSTMENT TO EXERCISE:The circulatory system adjusts in various ways to changes in physiological conditions. These adjustments are controlled by negative feedback mechanism, which bring conditions in the body back to normal range.As exercise begins, the nervous system sends impulses to the adrenal glands to release adrenaline (epinephrine) into the blood stream.Effects:blood vessels in the skin and abdominal organs constrict, decreasing blood supply to these organs and sending blood to areas of more active circulation. This in effect increases the volume of blood available.Vasodilation of small arterioles and capillaries in the muscle and the heart, increasing blood supply to these organs.This trade off of blood supplies helps to maintain the blood pressure in the whole body.stimulates faster breathing rate, and heartbeat rate, speeding up both delivery of extra oxygen to the muscles and removal of wastes.excess heat is removed from the body by the dilation of blood vessels in the skin, allowing extra heat to be given off to the environment.BLOOD PRESSUREBlood pressure is determined mainly by: the rate and force of the heartbeat the volume of blood pumped at each stroke the resistance of the blood vessels to the flow of blood.The thick, muscular walls of the arteries are elastic, and expand to accommodate this great pressure by the blood. As the ventricles relax, the pressure decreases.Blood pressure is the force that the blood exerts on the blood vessels when the heart beats (systolic pressure) and when the heart is at rest (diastolic pressure)Blood pressure rises and falls as the heart contracts and then relaxes.Muscles in the walls of a blood vessel may contract or relax, changing the vessel’s diameter, and this changes the blood pressure by making it harder or easier for blood to pass through the vessel.The narrower the vessel, the greater the resistance, and so the speed of blood flow drops very low in capillaries.SYSTOLIC PRESSURE:Blood pressure rises sharply when the ventricles contract, pushing blood through the arteries.systolic pressure indicates the force with which the left ventricle pushes bloodThe high pressure is called SYSTOLIC PRESSURE (greatest pressure)DIASTOLIC PRESSURE:Blood pressure then drops dramatically as the ventricles relax.diastolic pressure indicates the elasticity of the blood vessels, and is useful in diagnosing hardening of the arteriesThe lowest pressure occurs just before the ventricles contract again and is called DIASTOLIC PRESSURE (resting pressure)The usual blood pressure reading is 120/ 80. 120 represents the systolic pressure (contracting) and 80 represents the diastolic pressure (resting)HOW DOES BLOOD FLOW BETWEEN ARTERIES, CAPILLARIES AND VEINS?ARTERIES:As blood flows through the arteries, there is a little drop in pressure. Blood pressure accounts for the flow of blood in the arteries and arterioles. There is a large drop in pressure when the blood reaches the arterioles. CAPILLARIES:At the capillary ends of the arterioles there are rings of muscles that control the blood flow through the capillaries. The capillaries are the most numerous blood vessels in the body.Blood flow must slow down to allow time for exchange of substances between blood in the capillaries and the surrounding tissues.VEINS:By the time blood reaches the veins, pressure is very low. It is too low to return to the heart from the lower parts of the body.Blood flow in the veins is helped by the squeezing action of the skeletal muscles as the body moves and one way valves. center1143000-1009650-7620000REGULATION OF BLOOD PRESSURELow blood pressure reduces your capacity to transport blood. High blood pressure can weaken an artery and eventually lead to rupturing of the blood vessel. Special BLOOD PRESSURE RECEPTORS are located in the walls of the aorta and the carotid arteries (found in neck). These receptors are sensitive to high pressures.LOWERING BP: When blood pressure exceeds the acceptable levels, the receptors send a message to the brain.Afferent nerves message travels to the medulla oblongata, which is the blood pressure regulator found at the stem of the brain.Efferent nerves transmit nerve messages from the brain to the autonomic nervous system. The sympathetic nerve is inhibited, and the parasympathetic nerve is stimulated. Arterioles dilate, increasing the flow of blood from the artery. Heart rate and stroke volume decrease, and as a result, the decreased cardiac output slows the movement of blood into the arteries and lowers blood pressure.INCREASING BP:When blood pressure is below the acceptable levels, adjustments are made by the sympathetic nerve. Without nerve information from the pressure receptors of the aorta or the carotid arteries, the sympathetic nerve in not inhibited. Under the influence of the sympathetic nerve, cardiac output increases, arterioles constrict, and decreased outflow raise blood pressure to normal levels.-566233126871RECEPTORS(Sensory cells in aorta and carotid artery detect high blood pressure)RESPONSE(Blood Pressure decreases)STIMULUS(High Blood Pressure)EFFECTOR(Muscles relax and blood vessels dilate = vasodilation)REGULATORY CONTROL CENTER (Medulla Oblongata)00RECEPTORS(Sensory cells in aorta and carotid artery detect high blood pressure)RESPONSE(Blood Pressure decreases)STIMULUS(High Blood Pressure)EFFECTOR(Muscles relax and blood vessels dilate = vasodilation)REGULATORY CONTROL CENTER (Medulla Oblongata)VARIATIONS IN BLOOD PRESSURE DUE TO INTRINSIC FACTORS:Amount of Blood injury or hemorrhage will cause loss of blood internally or externally and will decrease b.p.Heart Rate faster heart rate will increase b.p.Size of Blood Vessels Change in blood vessel size due to chemicals, hormones act as vasodilators, and vasoconstrictorsVASOCONSTRICTION: occurs in arterioles, where vessels become smaller (decrease diameter) which increases b.p. Caused by fear (pale), sicknessVASODILATION: occurs in arterioles, where vessels become wider (increase in diameter) which decreases b.p. Caused by embarrassment (blushing- red)Elasticity of the Blood Vessel ability to expand and relax through blood surges decreases with age leading to an increase in b.p.Resistance from the arteries due to narrowing or hardening, or blockages will increase the blood pressure as arteries have less stretch and a decrease in blood flow also occurs as less blood is able to move through a smaller opening.Distance from heart: artery distance from heart also decreases blood pressure. As blood passes into smaller vessels and the distance from the heart becomes greater, the blood pressure becomes greatly reduced.Viscosity (thickness) of the Blood depends upon the balance between the red blood cells and the amount of plasmaShock: primary caused by nervous disordersecondary caused by a great loss of bloodAnaphylactic- caused by antibody-antigen reaction which decreases the heart action, and causes an allergic reaction.EXTRINSIC FACTORS WHICH AFFECT BLOOD PRESSURE:Stress, hardening of the arteries, overweight, fatty diet, nicotine, cardiovascular diseases all can lead to elevated blood pressures Alcohol can lead to low blood pressureExercise, diet low in fat, healthy life style can regulate blood pressure.HOW TO MEASURE BLOOD PRESSURE:blood pressure is measured with a sphygmomanometer (blood pressure cuff)24288757239000Units of measure: millimeters of mercury or mmHgEach time the heart contracts, the sound is heard. A gauge measures the pressure that the blood exerts during ventricular contractions called systolic pressure. Diastolic pressure is measured when the heart is relaxing.HIGH BLOOD PRESSURE or HYPERTENSION: Is higher than average blood pressure, and occurs when the force or tension of the blood in the walls of the arteries increases.High BP = 140 + 90 +CAUSE: Anything that abnormally overloads the heart such as: atherosclerosis (hardening of the arteries), stress and nervous tension, can all increase the risk of CORONARY HEART DISEASE (heart attack) High blood pressure can also cause shortness of breath, and kidney failure, and strokeLOW BLOOD PRESSURE or HYPOTENSION:Is lower than average blood pressure, and occurs when the force of blood within the artery walls is weak.Low BP = 100 - 60 -Low blood pressure can lead to slight or even severe oxygen deprivation to the brain. Standing for long periods of time may be difficult. STETHOSCOPES:Doctors used to check the heart by simply putting an ear on the patient's chest. However, that was a bit embarrassing for many people. So in 1817, a French?doctor named Rene Laennec began using a hollow wooden tube for the task. The idea caught on, and by the early 1900s, the stethoscope had evolved into its present form with rubber tubes and a metal bell on the end. An acoustic medical device for listening to the internal sounds of an animal or human body. It is often used to listen to lung and heart sounds. listens for two sounds--a "lub," followed by a "dub." The "lub" is the sound of the first set of heart valves closing; the dub is the second set closing. In-between the lub and dub, the heart should be quiet. If it isn't, there might be a problem.also listens for a whoosh or gurgle heard in-between the lub and dub. This is called a murmur. Murmurs can be caused by a rough edge on a valve. A murmur may tell your doctor that some blood is leaking backward with every beat.It is also used to listen to intestines and blood flow in arteries and veins. In combination with a sphygmomanometer, it is commonly used for measurements of blood pressure. CIRCULATORY SYSTEM END OF UNIT PRACTICE QUESTIONS:Blood Vessels– Fill in the blanks by naming the artery or vein in question. Artery/VeinFunctionBlood vessel carrying oxygenated blood to the legsBlood vessel carrying deoxygenated blood away from the headLarge blood vessel located in the armBlood vessel carrying blood to the kidneysBlood vessel carrying blood from the lungs to the heartBlood vessel carrying blood from the intestinesBlood vessel carrying blood to the liverLargest blood vessel in the bodyTwo blood vessels that drain the upper and lower regions of the body andcarry blood directly to the heart Large artery in the neckThe only vein in the body that carries oxygenated bloodThe only artery in the body that carries deoxygenated bloodList three ways in which the circulatory system maintains homeostasis in the human body. Be SPECIFIC!Distinguish between an artery and a vein structurally. Trace the pathway, in point form, taken by a red blood cell as it passes from the lungs to the aorta of the heart. Include valves.What is the function of the heart? Describe how the structure of the heart is related to its function.Explain why the heart is called a double pump.Why does the left ventricle contain more muscle than the right ventricle?Name and explain the different in the two sets of valves found in the heart.What would happen if a person had a hole in their septum? Label the diagram of the heart below.4655820444817502000046843953427095020000472249539789100200004713605289750502000036290254999990476948518313400200004625340418465020000370803105708020000-572471505572020000-3554353705915020000-3390901922780020000241203114319502000010852631330764-5501054501857020000-2863364044657020000-133936315370302000039973254997269Electrical impulses are sent out under the control of what part of the brain?Explain what an EKG tells you. What is an arrhythmia?Describe how adrenaline affects the body, and heart rate.List four factors that could affect heart rate, include how they affect heart rate.State three factors that determine blood pressure levels.Explain why the blood pressure changes periodically in the aorta and the small arteries, but not in the capillaries and veins. How do blood pressure regulators detect and respond to high blood pressure. Discuss systolic and diastolic pressure. Discuss four intrinsic factors that affect blood pressure. Compare vasodilation vs vasoconstriction. Discuss any two extrinsic factors that affect blood pressure. How is blood pressure values stated? What is hypertension? Hypotension? At what values is blood pressure considered to be “high” and “low”. What effect would exercise have on a person systolic and diastolic pressure? ................
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