HUMAN CIRCULATORY SYSTEM

Circulatory SystemsOpen system vs. closed systemBoth have a pumpOpen system has no blood vessels to hold bloodClosed system has blood contained within vessels

Circulatory systemsThe simplest of organisms do not have a circulatory systemRely on diffusion/osmosis for regulation

Circulatory systemsOther simple organisms rely on the flow of water to exchange nutrients and wastes

Open vs. Closed Circulatory systems

Closed circulatory systemsVary in complexity

Human Heart

Cardiac muscle

Structure of the heart wall

Structure of the heart wall

HUMAN CIRCULATORY SYSTEM

Artery and Veinstructural comparison

ArteryWalls are thickMuscularElastic, so they can stretch when heart contractsMust withstand higher pressure than veins

Atherosclerosis

VeinThin-walled (less muscle, less elastic tissue)Contain VALVES to prevent back-flow

CapillariesBlood vessels with the smallest diameter and thinnest walls

Capillary BedsExchange of carbon dioxide, oxygen, and nutrients occurs in the capillary beds

BLOOD PRESSUREMeasurement of both the pressure under which the heart contracts (systole), as well as the pressure under which the heart fills (diastole)

BLOOD PRESSUREBlood pressure is checked in your arm, using a sphygmomanometer

Blood PressureThe pressure generated by your heart can be measured in your arm because the pressure is transmitted through the muscular, elastic arteries

Blood PressureMeasured in mm HgReported as two numbers:systolic pressurediastolic pressure

Systolic blood pressurePressure transmitted when the left ventricle contractsIt is the pressure under which the blood is being forced out of the left ventricle into the aorta

Diastolic blood pressureIs the filling pressure of the heart

Sounds of Korotkoff

Sounds of KorotkoffSounds of Korotkoff (are caused by turbulence in arterial blood flow.A well-trained examiner can hear 5 different Korotkoff sounds, which vary slightly in qualityThe first and fifth Korotkoff sounds are used to define blood pressure

Pulse Points

Blood PressureGenerally measured over the brachial artery

Why is blood pressure important?Blood pressure must remain in a normal range so that tissues can receive adequate blood flow in order to exchange gases, nutrients, and wastes efficiently

HYPERTENSIONElevation in blood pressureFairly common: about 30%almost 1 in 3 adults!HTN more common in African AmericansObese people

HypertensionHigh blood pressure can damage the heart and blood vesselsIncreases the chances of having a strokeCause is multi-factorialCan be treated with medication; sometimes with diet and exercise alone

Regulation of blood pressure

Conduction System of the Heart

ElectrocardiogramUseful tool for studying the conduction of impulses through the heart

ElectrocardiogramP wave represents depolarization of the atriumQRS complex represents depolarization of the ventriclesT wave represents repolarization (recharging for the next beat

Normal Electrocardiogram

ECG abnormalitiesAfter a myocardial infarction (heart attack, MI), the damaged areas of the heart no longer have normal conduction of impulsesResults in a change in the normal waveforms

ECG abnormalities

ECG abnormalities

ECG abnormalitiesAtrial fibrillation

ECG abnormalitiesAcute myocardial infarction (heart attack)

COMPOSITION OF BLOODBlood is made up of a fluid portion and a cellular portion

PLASMAMade up of water, proteins, ions, amino acids, sugarsCarries carbon dioxide (released from tissues)Carries nutrients from the digestive system, hormones

Cells in the BloodErythrocytes: Red Blood Cells, RBCs

ErythrocytesContain hemoglobinA proteinTransports Oxygen

ErythrocytesHemoglobin structure

ErythrocytesLive about 120 daysProduced in the bone marrowProductions is regulated by a hormone from the kidneys-erythropoetin

Blood CellsLeukocytes = White Blood CellsFunction in the immune systemForm a second line of defense against bacteria and virusesLarger than RBCs

LeukocytesGranulocytesNeutrophilsBasophilsEosinophilsLymphocytesMacrophages

GranulocytesNeutrophilGreatest in numberHas a segmented nucleusFunctions in bacterial infectionsShort-lived

Neutrophils

BasophilAlso a granulocyteVery few in numberFunction is not completely understoodContain granules that are important in immune response

EosinophilGranulocyte containing very large granulesImportant in allergiesFew in number (far less than neutrophils but more than basophils)

Eosinophil

LymphocytesImportant in immune systemMaking of antibodiesFighting viral infectionsHas a large, dark-staining nucleus

Lymphocyte

MacrophagesPhagocytes: engulf and destroy cellular debris and bacteria/virusesLifespan is months to yearsLarger than a lymphocyte

Macrophage

Other Blood ComponentsPlateletsInvolved in blood coagulation (clotting)Sticky; form a plug at the site of bleedingSmall and numerousBlood clotting is a very complex processInvolves many proteins (factors)Cascade event

Platelets

PlateletsWhat protein forms the threads that trap the platelets when forming a clot??

Blood disordersANEMIA: qualitative or quantitative reduction in hemoglobinMost common is iron deficiency anemiaCaused by low levels of iron: causes may be dietary, chronic blood loss from gutVitamin B6, folic acid deficienciesAplastic anemia

Hemoglobin

Iron Deficiency Anemia

Iron Deficiency anemiaUnusual symptomsGlossitisPica: geophagia (compulsive eating of dirt), pagophagia (compulsive eating of ice)

Iron Deficiency anemiaBlood smear

Iron Deficiency anemia: treatmentTreatment depends on the causeIron supplementDietary changesIn severe cases, blood transfusion

Sickle Cell anemiaInheritable disorder (co-dominance)Mutation in the hemoglobin molecule (HgbS)RBCs form a sickle shapeReduces oxygen carrying capacity of the bloodAfrican descentConfers resistance to malaria

Sickle Cell anemia

Sickle Cell CrisisCaused by a variety of things: stress, fever, illness, alcohol & drug use, dehydrationCauses severe pain in tissues, bones, jointsCan be life-threatening

Sickle Cell CrisisSymptoms due to sickle cells blocking capillary flowTreatment: fluids, pain medicine, other treatments for specific problems (i.e. heart attack, stroke, blindness)