The Cardiovascular System

The Cardiovascular System

Formation of Endocardial Tube 3 1.5 . , 2 . , .

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5-6 . // , 2 . Z /T / . , .

Angiogenetic cell clusters extend in an arc around the head end of the ventral opening of the yolk sac. Initially //, this means that the angiogenetic cell clusters (and the blood vessel that forms from them) have the pattern of a "horseshoe" if viewed from a dorsal or ventral perspective.

The brain grows at an incredible rate. It grows so fast that it makes the head bend around under the embryo's body.

This is why the heart winds up on the VENTRAL SIDE of the body.

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EndocardiumMyocardiumEpicardia

*Layers of pericardium and heart wall

Walls of the ventricles:Left wall is thicker!

/cor, cardio, heart, /Basis cordisBasis apexFacies sternocostalisFacies diaphragmaticaFacies pulmonaris Sulcus coronariusSulcus interventercularis anteriorSulcus interventercularis posterior

*Hearts position in thorax

*Hearts position in thoraxIn mediastinum behind sternum and pointing left, lying on the diaphragmIt weighs 250-350 gm (about 1 pound)Feel your heart beat at apex

(this is of a person lying down)

Anterior View of a Pig Heart

*

4 atrium dexter ventriculus dexter atrium sinister ventriculus sinister

.

Septum interatriale septum interventriculare

Ostium atrioventriculare dexter Valva atrioventricularis dexter / tricuspidalis/- cuspis posterior- cuspis anterior cuspis septalis

Ostium trunci pulmonalisValvula trunci pulmonalis - Lunula valvularis semilunaris noduli valvularum semilunarium /aranthi/

Ostium atrioventerculare sinisterValva atrioventeculari sinistrum /mitralis, s.bicuspitlis/

Ostium aortaeValva aortaeValva semulunaris dexterValva semilunaris sinisterValva posterior noduli valva semilunris

*Function of AV valves

*Function of semilunar valves(Aortic and pulmonic valves)

Functions:A closed system of the heart and blood vesselsThe heart pumps bloodBlood vessels allow blood to circulate to all parts of the bodyThe function of the cardiovascular system is to deliver oxygen and nutrients to and remove carbon dioxide and other waste products from the bodies tissues.

Blood Vessels: TypesTaking blood to the tissues and backArteries (large, thickest walled, carry blood away from heart, blood is moved by the pumping of the heart)Arterioles (smaller, thinner walled, carry blood away from heart, blood is moved by pumping of the heart)Capillaries (smallest, thinnest vessels, one cell layer thick, site of exchange of materials between the blood and body tissues)Venules ( thinner walled vessels, carry blood back towards heart)Veins (thin walled vessels, large lumen, have valves present which keep blood moving in one direction, blood is moved by milking action due to the contraction of skeletal muscles.

Structure of VesselsThree layers (tunics)Tunic intima /interna/Endothelium 1. endothelium- 2. membarana basalis 3. stratum subendotheliale 4. membara elastica interna Connictive tissueInterna elastic membarana

Tunic mediaInvoluntary musculi fibraMembara elastica interna

Tunic externaMostly fibrous connective tissueControlled by sympathetic nervous system

a.elastotypico /aorta, pulmonary arter/ a.mixtotypica / a.caroticum, a.subclavicula a. myotypica / /

Vein Tunica interna Tunica media Tunica adventitia

v.myotypica . . . . - v.fibrotypica / , , , /

Tunica intima

Tunica media

Tunica externa (adventicia)

Tunica intima

Tunica media

Tunica adventicia

Extremely thin tunica media in a vein.

Blood Movement Through Veins

Blood Circulation: Pulmonary and Systemic PathwaysCO2 is given off bythe blood into the lungsand O2 is picked up by the blood from thelungs.O2 is given off bythe blood and and CO2 is picked up by the blood from thebodys tissue.

External Coverings of the HeartPericardium a double serous membraneVisceral pericardiumNext to heartParietal pericardiumOutside layerSerous fluid fills the space between the layers of pericardium

External Coverings of the Heart

External Structure of the Heart

Great Vessels of HeartAorta (largest blood vessel in the body)Leaves left ventricle carries oxygenated blood to all parts of the bodyPulmonary arteriesLeave right ventricle carries deoxygenated blood to the lungsVena cava (Superior and Inferior)Enters right atrium, Superior vena cava brings deoxygenated blood from the upper part of the body and the inferior vena cava brings deoxygenated blood from the lower part of the bodyPulmonary veins (four)Enter left atrium brings oxygenated blood from the lungs

Coronary Blood SupplyBlood in the heart chambers does not nourish the myocardiumThe heart has its own nourishing circulatory systemCoronary arteriesCardiac veinsBlood empties into the right atrium via the coronary sinus

Internal Structures of the Heart: Heart WallThree layersEpicardiumOutside layerThis layer is the parietal pericardiumConnective tissue layerMyocardiumMiddle layerMostly cardiac muscleEndocardiumInner layerEndothelium

Internal Structures of HeartRight and left side act as separate pumpsFour chambersAtriaReceiving chambersRight atriumLeft atriumVentriclesDischarging chambersRight ventricleLeft ventricleThe valves allow blood to flow in only one directionFour valvesAtrioventricular valves between atria and ventriclesBicuspid valve (left)Tricuspid valve (right) Semilunar valves between ventricle and arteryPulmonary semilunar valveAortic semilunar valve

Internal Structures of the Heart

The Hearts Pace Maker: Regulation of HeartbeatSpecial tissue sets the paceSinoatrial nodePacemakerAtrioventricular nodeAtrioventricular bundleBundle branchesPurkinje fibersContraction is initiated by the sinoatrial nodeSequential stimulation occurs at other autorhythmic cells

ECG: ElectrocardiagramThis graph shows the electrical changes which occur when the muscles of the heart wall depolarize and repolarize.

ECG: ElectrocardiogramThe first little upward notch of the EKG tracing is called the "P wave." The P wave indicates that the atria (the two upper chambers of the heart) are contracting to pump out blood. The next part of the tracing is a short downward section connected to a tall upward section. This next part is called the "QRS complex." This part indicates that the ventricles (the two lower chambers of the heart) are contracting to pump out blood to the body.

ECG: ElectrocardiogramThe next short upward segment is called the "ST segment." The ST segment indicates the amount of time from the end of the contraction of the ventricles to the beginning of the rest period before the ventricles begin to contract for the next beat. The next upward curve is called the "T wave." The T wave indicates the resting period of the ventricles.

Cardiac Cycle

Atria contract simultaneouslyAtria relax, then ventricles contractSystole = contractionDiastole = relaxationCardiac cycle events of one complete heart beatMid-to-late diastole blood flows into ventriclesVentricular systole blood pressure builds before ventricle contracts, pushing out bloodEarly diastole atria finish re-filling, ventricular pressure is low

Cardiac Cycle

Cardiac Cycle: Valves

PulsePulse pressure wave of blood as it passes through an arteryMonitored at pressure points where pulse is easily palpated

Blood PressureMeasurements by health professionals are made on the pressure in large arteriesSystolic pressure at the peak of ventricular contractionDiastolic pressure when ventricles relaxPressure in blood vessels decreases as the distance away from the heart increasesHuman normal range is variableNormal140110 mm Hg systolic8075 mm Hg diastolicHypotensionLow systolic (below 110 mm HG)Often associated with illnessHypertensionHigh systolic (above 140 mm HG)Can be dangerous if it is chronic

BloodThe only fluid tissue in the human bodyClassified as a connective tissueLiving cells = formed elementsNon-living matrix = plasmaColor rangeOxygen-rich blood is scarlet redOxygen-poor blood is dull redpH must remain between 7.357.45Blood temperature is slightly higher than body temperature

Whole Blood Composition

Blood: PlasmaComposed of approximately 90 percent waterIncludes many dissolved substancesNutrientsSalts (metal ions)Respiratory gasesHormonesProteins : Albumin regulates osmotic pressure, Clotting proteins help to stem blood loss when a blood vessel is injured, Antibodies help protect the body from antigens Waste products

Blood: Formed ElementsErythrocytes = red blood cellsLeukocytes = white blood cellsThrombocytes or Platelets = cell fragmentsFormed in red bone marrow (hematopoiesis)

Blood: Formed Elements

Blood: Formed Elements

Blood: Formed Elements

HemostasisStoppage of blood flowResult of a break in a blood vesselHemostasis involves three phasesPlatelet plug formationVascular spasmsCoagulation

Hemostasis: Platelet Plug FormationCollagen fibers are exposed by a break in a blood vesselPlatelets become sticky and cling to fibersAnchored platelets release chemicals to attract more plateletsPlatelets pile up to form a platelet plugPositive Feed-back Mechanism

Hemostasis: Vascular SpasmsAnchored platelets release serotoninSerotonin causes blood vessel muscles to spasmSpasms narrow the blood vessel, decreasing blood loss

Hemostasis: CoagulationInjured tissues release thromboplastinPF3 (a phospholipid) interacts with thromboplastin, blood protein clotting factors, and calcium ions to trigger a clotting cascadeProthrombin activator converts prothrombin to thrombin (an enzyme)Thrombin joins fibrinogen proteins (water soluble) into hair-like fibrin (insoluble in water)Fibrin forms a meshwork (the basis for a clot)

Forming Blood Cloterythrocytesthrombocytesfibrin

Diseases and Disorders of the Cardiovascular SystemMyocardial infarction: Commonly called a heart attack.. It is due to the blockage of an coronary artery which supplies the myocardium. The cardiac muscle dies and the heart doesnt function properly because of this. It can be due to the formation of deposits of cholesterol and lipids called plaques, blood clots called thrombus, or an embolism which is a blood clot that forms somewhere else in the body, breaks free and lodges in a coronary artery stopping the flow of blood. Angina pectoralis is a sharp pain radiating into the left arm and /or neck accompanied by a feeling of pressure within the chest.. This is a classic symptom of problems with blood flow to the heart muscle itself.

Diseases and Disorders of the Cardiovascular SystemAtherosclerosis: Is commonly called hardening of the arteries. The arteries began to loose their elasticity due to aging and the formation of plaques in their walls. They narrow and reduce blood supply to regions of the body particularly the brain and heart.

Diseases and Disorders of the Cardiovascular SystemAneurysm: An aneurysm is a weakened area within the wall of an artery or arteriole. Because of the high pressure, the vessel wall balloons out and can rupture when the wall becomes stretched too thin. This leads to a serious internal hemorrhage.

Diseases and Disorders of the Cardiovascular SystemArrhythmia: Arrhythmia is due to the irregular beat of the heart. It may be due to damage to the SA or AV node, or the myocardium itself. It is commonly treated with medications or by the implantation of an artificial pace-maker. Bradycardia indicates that the heart is beating too slow and tachycardia indicates the heart is beating too fast.

Diseases and Disorders of the BloodHemophilia: Is a genetic disorder that is due to the fact that there is a clotting factor missing necessary for clot formation to stop bleeding. These individuals can bleed to death from simple injuries or bruising of the body. The most prevalent form is more common in males than females because it is carried on the X chromosome of the female (sex-linked).

Diseases and Disorders of the BloodLeukemia: Is a cancer of the bone marrow which produces blood cells. There are many different forms of this disease depending upon which type of blood stem cells are involved. However, the cells typically do not mature and inhibit the production of other types of blood cells necessary for survival.Noamal Bone Marrow AML Bone Marrow

Diseases and Disorders of the BloodAnemia: Anemia is due to the lack of Erythrocytes or low levels of hemoglobin in erythrocytes, or abnormal erythrocytes (sickle cell). This inhibits the proper transport of oxygen in the body. There are several forms of anemia

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