Apresentação em tema: "The Circulatory System"— Transcrição da apresentação:
1The Circulatory System The Heart, Blood Vessels, Blood Types
2The Closed Circulatory System Humans have a closed circulatory system, typical of all vertebrates, in which blood is confined to vessels and is distinct from the interstitial fluid.The heart pumps blood into large vessels that branch into smaller ones leading into the organs.Materials are exchanged by diffusion between the blood and the interstitial fluid bathing the cells.
3The Cardiovascular System Three Major Elements – Heart, Blood Vessels, & Blood1. The Heart- cardiac muscle tissuehighly interconnected cellsfour chambersRight atriumRight ventricleLeft atriumLeft ventricle
5Pathway of the blood Superior Vena Cava Right Atrium Tricuspid Valve Right VentriclePulmonary Semilunar ValveLungsPulmonary VeinBicuspid ValveLeft VentricleAortic Semilunar ValveAortaTo the bodies organs & cells
6Circuits Pulmonary circuit Systemic circuit The blood pathway between the right side of the heart, to the lungs, and back to the left side of the heart.Systemic circuitThe pathway between the left and right sides of the heart.
7The Cardiovascular System 2. Blood Vessels -A network of tubesArteriesarterioles move away from the heartElastic FibersCircular Smooth MuscleCapillaries – where gas exchange takes place.One cell thickServes the Respiratory SystemVeinsVenules moves towards the heartSkeletal Muscles contract to force blood back from legsOne way valuesWhen they break - varicose veins form
9The Cardiovascular System 3. The BloodPlasmaLiquid portion of the blood. Contains clotting factors, hormones, antibodies, dissolved gases, nutrients and waste
10The Cardiovascular System The BloodB. Erythrocytes - Red Blood CellsCarry hemoglobin and oxygen. Do not have a nucleus and live only about 120 days.Can not repair themselves.
11The Cardiovascular System The BloodC. Leukocytes – White Blood cellsFight infection and are formed in the bone marrowFive types – neutrophils, lymphocytes, eosinophils, basophils, and monocytes.
12The Cardiovascular System The BloodD. Thrombocytes – Platelets.These are cell fragment that are formed in the bone marrow from magakaryocytes.Clot Blood by sticking together – via protein fibers called fibrin.
13Disorders of the Circulatory System Anemia - lack of iron in the blood, low RBC countLeukemia - white blood cells proliferate wildly, causing anemiaHemophilia - bleeder’s disease, due to lack of fibrinogen in thrombocytesHeart Murmur - abnormal heart beat, caused by valve problemsHeart attack - blood vessels around the heart become blocked with plaque, also called myocardial infarction
14Cardiovascular System Unit 9 – The HeartCardiovascular SystemThe Heart
15Functions of the Heart Generating blood pressure Routing blood Heart separates pulmonary and systemic circulationsEnsuring one-way blood flowHeart valves ensure one-way flowRegulating blood supplyChanges in contraction rate and force match blood delivery to changing metabolic needs
16Size, Shape, Location of the Heart Size of a closed fistShapeApex: Blunt rounded point of coneBase: Flat part at opposite of end of coneLocated in thoracic cavity in mediastinum
19Heart Wall Three layers of tissue Epicardium: This serous membrane of smooth outer surface of heartMyocardium: Middle layer composed of cardiac muscle cell and responsibility for heart contractingEndocardium: Smooth inner surface of heart chambers
29Heart SkeletonConsists of plate of fibrous connective tissue between atria and ventriclesFibrous rings around valves to supportServes as electrical insulation between atria and ventriclesProvides site for muscle attachment
30Cardiac MuscleElongated, branching cells containing 1-2 centrally located nucleiContains actin and myosin myofilamentsIntercalated disks: Specialized cell-cell contactsDesmosomes hold cells together and gap junctions allow action potentialsElectrically, cardiac muscle behaves as single unit
32Electrical Properties Resting membrane potential (RMP) presentAction potentialsRapid depolarization followed by rapid, partial early repolarization. Prolonged period of slow repolarization which is plateau phase and a rapid final repolarization phaseVoltage-gated channels
33Action Potentials in Skeletal and Cardiac Muscle
35Refractory PeriodAbsolute: Cardiac muscle cell completely insensitive to further stimulationRelative: Cell exhibits reduced sensitivity to additional stimulationLong refractory period prevents tetanic contractions
36ElectrocardiogramAction potentials through myocardium during cardiac cycle produces electric currents than can be measuredPatternP waveAtria depolarizationQRS complexVentricle depolarizationAtria repolarizationT wave:Ventricle repolarization
37Cardiac Arrhythmias Tachycardia: Heart rate in excess of 100bpm Bradycardia: Heart rate less than 60 bpmSinus arrhythmia: Heart rate varies 5% during respiratory cycle and up to 30% during deep respirationPremature atrial contractions: Occasional shortened intervals between one contraction and succeeding, frequently occurs in healthy people
39Cardiac CycleHeart is two pumps that work together, right and left halfRepetitive contraction (systole) and relaxation (diastole) of heart chambersBlood moves through circulatory system from areas of higher to lower pressure.Contraction of heart produces the pressure
42Heart Sounds First heart sound or “lubb” Second heart sound or “dupp” Atrioventricular valves and surrounding fluid vibrations as valves close at beginning of ventricular systoleSecond heart sound or “dupp”Results from closure of aortic and pulmonary semilunar valves at beginning of ventricular diastole, lasts longerThird heart sound (occasional)Caused by turbulent blood flow into ventricles and detected near end of first one-third of diastole
44Mean Arterial Pressure (MAP) Average blood pressure in aortaMAP=CO x PRCO is amount of blood pumped by heart per minuteCO=SV x HRSV: Stroke volume of blood pumped during each heart beatHR: Heart rate or number of times heart beats per minuteCardiac reserve: Difference between CO at rest and maximum COPR is total resistance against which blood must be pumped
46Regulation of the Heart Intrinsic regulation: Results from normal functional characteristics, not on neural or hormonal regulationStarling’s law of the heartExtrinsic regulation: Involves neural and hormonal controlParasympathetic stimulationSupplied by vagus nerve, decreases heart rate, acetylcholine secretedSympathetic stimulationSupplied by cardiac nerves, increases heart rate and force of contraction, epinephrine and norepinephrine released
47Heart Homeostasis Effect of blood pressure Baroreceptors monitor blood pressureEffect of pH, carbon dioxide, oxygenChemoreceptors monitorEffect of extracellular ion concentrationIncrease or decrease in extracellular K+ decreases heart rateEffect of body temperatureHeart rate increases when body temperature increases, heart rate decreases when body temperature decreases
51Effects of Aging on the Heart Gradual changes in heart function, minor under resting condition, more significant during exerciseHypertrophy of left ventricleMaximum heart rate decreasesIncreased tendency for valves to function abnormally and arrhythmias to occurIncreased oxygen consumption required to pump same amount of blood