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2Circulatory SysCirculatory Systemstems
OutlineOutline
Transport in VertebratesTransport in VertebratesTransport in Transport in HumansHumans
HeartbeatHeartbeatVascular PathwaysVascular PathwaysBlood PressureBlood Pressure
BloodBloodComponentsComponentsClottingClottingTransport in Transport in InvertebratesInvertebratesOpen versus Closed Circulatory Open versus Closed Circulatory SystemsSystems
3Circulatory SysCirculatory SystemstemsTransport in HumansTransport in Humans
Human HeartHuman Heart
Cone-shaped Cone-shaped
Size of a fist-14cm long and 9cm wideSize of a fist-14cm long and 9cm wide
Inner surface is lined with Inner surface is lined with endocardiumendocardium
Thick muscular organ (special cardiac Thick muscular organ (special cardiac fibers)-fibers)-myocardiummyocardium
Lies within the Lies within the pericardiumpericardium, a thick , a thick membranous sac that secretes a lubricating membranous sac that secretes a lubricating liquid.liquid.
5Circulatory SysCirculatory Systemstems
Heart-lies behind the sternum and Heart-lies behind the sternum and between lungs.between lungs.
7Circulatory SysCirculatory Systemstems
Vascular PathwaysVascular Pathways
Human cardiovascular system includes Human cardiovascular system includes two major circular pathways:two major circular pathways:
Pulmonary CircuitPulmonary Circuit
Takes oxygen-poor blood to the lungs Takes oxygen-poor blood to the lungs and returns oxygen-rich blood to the and returns oxygen-rich blood to the heartheart
Systemic CircuitSystemic Circuit
Takes blood throughout the body from Takes blood throughout the body from the aorta to the vena cavathe aorta to the vena cava
9Circulatory SysCirculatory SystemstemsHuman Heart:Human Heart:
Gross AnatomyGross Anatomy
Septum separates heart into left & Septum separates heart into left & right halvesright halves
The heart has four chambersThe heart has four chambers
Upper two chambers are the atriaUpper two chambers are the atria
Thin-walledThin-walled
Receive blood from circulationReceive blood from circulation
Lower two chambers are the ventriclesLower two chambers are the ventricles
Thick-walledThick-walled
Pump blood away from heartPump blood away from heart
10Circulatory SysCirculatory SystemstemsHuman Heart:Human Heart:
ValvesValves
Valves open and close to control blood Valves open and close to control blood flow through heartflow through heart
Atrioventricular valves (between the Atrioventricular valves (between the atria and ventriclesatria and ventricles
TricuspidTricuspid
BicuspidBicuspid
Semilunar valves (between the Semilunar valves (between the ventricles and their attached vessels)ventricles and their attached vessels)
PulmonaryPulmonary
AorticAortic
13Circulatory SysCirculatory Systemstems
Transport in the VertebratesTransport in the VertebratesAll vertebrates have a Closed Circulatory All vertebrates have a Closed Circulatory SystemSystem
Heart pumps blood to capillariesHeart pumps blood to capillaries
Gases and materials diffuse to and from Gases and materials diffuse to and from nearby cellsnearby cells
Vessels return blood to heart without it Vessels return blood to heart without it contacting tissuescontacting tissues
Oxygen-poor blood never mixes with oxygen-Oxygen-poor blood never mixes with oxygen-rich blood (in humans)rich blood (in humans)
Vertebrate vessels:Vertebrate vessels: Arteries - Carry blood Arteries - Carry blood away away from heartfrom heart Arterioles – Lead to capillariesArterioles – Lead to capillaries Capillaries - Exchange materials with tissue Capillaries - Exchange materials with tissue fluidfluid
Venules - Lead to veinsVenules - Lead to veins Veins - Return blood to heartVeins - Return blood to heart
14Circulatory SysCirculatory Systemstems
Transport in HumansTransport in HumansBlood returning to heart from systemic Blood returning to heart from systemic circuitcircuit Enters right atriumEnters right atrium Right atrium pumps through tricuspid valve Right atrium pumps through tricuspid valve to right ventricleto right ventricle
Right ventricle pumps blood through Right ventricle pumps blood through pulmonary valve to the pulmonary circuitpulmonary valve to the pulmonary circuit
Blood returning to heart from pulmonary Blood returning to heart from pulmonary circuitcircuit Enters left atriumEnters left atrium Left atrium pumps through mitral valve to Left atrium pumps through mitral valve to left ventricleleft ventricle
Left ventricle pumps blood through aortic Left ventricle pumps blood through aortic valve to the systemic circuitvalve to the systemic circuit
16Circulatory SysCirculatory SystemstemsCardiac Cycle-70 beats/minCardiac Cycle-70 beats/min
100,000 x a day or 40 million x a year100,000 x a day or 40 million x a year
A single cardiac cycle is made up of A single cardiac cycle is made up of the events associated with one heart the events associated with one heart beat. Each cardiac cycle takes about beat. Each cardiac cycle takes about 8 tenths of one second.8 tenths of one second.
During each cardiac cycle pressure During each cardiac cycle pressure changes occur within the chambers changes occur within the chambers of the heart as they relax and of the heart as they relax and contract.contract.
As the chambers relax, they fill with As the chambers relax, they fill with blood, diastole. When the chambers blood, diastole. When the chambers contract, this is called systole.contract, this is called systole.
17Circulatory SysCirculatory Systemstems
Cardiac cycleCardiac cycle
When the AV-opens-blood When the AV-opens-blood flows into the ventricles flows into the ventricles from the atria (semilunar from the atria (semilunar valves are closed).valves are closed).
Atrial contraction results Atrial contraction results from a series of events from a series of events beginning with the spread beginning with the spread of nerve impulses from the of nerve impulses from the SA-node across the walls SA-node across the walls of the atria. of the atria.
Ventricular filling is Ventricular filling is completed by atrial completed by atrial systole. systole.
Impulses from the AV-node Impulses from the AV-node travels along the travels along the ventricular conduction ventricular conduction fibers leading to fibers leading to contraction of the contraction of the ventricles. ventricles.
18Circulatory SysCirculatory Systemstems
HeartbeatHeartbeat
In ventricular systole, In ventricular systole, increased pressure forces increased pressure forces the AV valves closed, the AV valves closed, “Lub” semilunar valves “Lub” semilunar valves open and blood is ejected open and blood is ejected from the ventricles. from the ventricles.
Ventricular diastole, Ventricular diastole, pressure in the ventricles pressure in the ventricles decrease and blood in the decrease and blood in the aorta and pulmonary aorta and pulmonary flows back toward the flows back toward the chambers, causing these chambers, causing these valves to close “dub”. valves to close “dub”.
Ventricular pressure falls Ventricular pressure falls below that of the atria, below that of the atria, AV valves open and cycle AV valves open and cycle begins again.begins again.
19Circulatory SysCirculatory Systemstems
HeartbeatHeartbeat
Electrocardiogram (ECG) Fluids contain Electrocardiogram (ECG) Fluids contain ions that conduct electrical currents, ions that conduct electrical currents, electrodes placed on the skin are electrodes placed on the skin are connected to a instrument that detects connected to a instrument that detects electrical changes of the myocardium.electrical changes of the myocardium.
P- Atrial depolarization/systoleP- Atrial depolarization/systole
QRS- Ventricular depolarizationQRS- Ventricular depolarization
T-wave- Ventricular repolarizationT-wave- Ventricular repolarization
20Circulatory SysCirculatory Systemstems
Conduction System of the HeartConduction System of the Heart
21Circulatory SysCirculatory Systemstems
One way venous valvesOne way venous valves
During muscle contraction, venous diameter decreases, and venous pressure rises. The increase in pressure forces the flow toward the heart.
22Circulatory SysCirculatory Systemstems
Cross Section of a Valve in a VeinCross Section of a Valve in a Vein
23Circulatory SysCirculatory Systemstems
Blood PressureBlood PressureThe beat of the heart supplies pressure The beat of the heart supplies pressure that keeps blood moving in the arteriesthat keeps blood moving in the arteriesSystolic Pressure results from blood Systolic Pressure results from blood forced into the arteries during ventricular forced into the arteries during ventricular systolesystole
Diastolic Pressure is the pressure in the Diastolic Pressure is the pressure in the arteries during during ventricular diastolearteries during during ventricular diastole
Skeletal muscle contraction pushes blood Skeletal muscle contraction pushes blood in the veins toward the heartin the veins toward the heart
Blood pressureBlood pressureNormally measured with a Normally measured with a sphygmomanometer on the brachial arterysphygmomanometer on the brachial artery
Expressed in the form: Systolic “over” Expressed in the form: Systolic “over” DiastolicDiastolic
24Circulatory SysCirculatory Systemstems
Transport in InvertebratesTransport in Invertebrates
Small aquatic animals with no circulatory Small aquatic animals with no circulatory systemsystemMay rely on external water in May rely on external water in gastrovascular cavity to service cellsgastrovascular cavity to service cells
Roundworms and other pseudocoelomatesRoundworms and other pseudocoelomatesUse a fluid-filled body cavity as a means of Use a fluid-filled body cavity as a means of transporting substancestransporting substances
Fluid-filled cavity can also act as a Fluid-filled cavity can also act as a hydrostatic skeleton hydrostatic skeleton
Animals that have a rigid skeletonAnimals that have a rigid skeletonMay still rely on body fluids for the May still rely on body fluids for the purpose of locomotionpurpose of locomotion
Bivalves pump hemolymph into the foot Bivalves pump hemolymph into the foot for digging into mudfor digging into mud
26Circulatory SysCirculatory SystemstemsOpen vs. ClosedOpen vs. Closed
Invertebrate CirculationInvertebrate Circulation
Two types of circulatory fluids:Two types of circulatory fluids:Blood - contained within blood vesselsBlood - contained within blood vesselsHemolymph - flows into hemocoelHemolymph - flows into hemocoel
Open Circulatory SystemOpen Circulatory SystemHeart pumps hemolymph via vesselsHeart pumps hemolymph via vesselsVessels empty into tissue spacesVessels empty into tissue spaces
30Circulatory SysCirculatory SystemstemsComparison of Circulatory Comparison of Circulatory
PathwaysPathwaysFish - Blood flows in single loopFish - Blood flows in single loop
Single atrium and single ventricleSingle atrium and single ventricle
Amphibians - Blood flows in double Amphibians - Blood flows in double looploop
Two atria with single ventricleTwo atria with single ventricle
Other vertebrates - Blood flows in a Other vertebrates - Blood flows in a double loopdouble loop
Heart divided by septum into separate Heart divided by septum into separate sidessides
31Circulatory SysCirculatory SystemstemsBlood:Blood:
Homeostasis FunctionsHomeostasis Functions
Transports substances to and from Transports substances to and from capillaries for exchange with tissue capillaries for exchange with tissue fluidfluid
Guards against pathogen invasionGuards against pathogen invasion
Regulates body temperatureRegulates body temperature
Buffers body pHBuffers body pH
Maintain osmotic pressureMaintain osmotic pressure
Clots prevent blood/fluid lossClots prevent blood/fluid loss
32Circulatory SysCirculatory Systemstems
Red Blood CellsRed Blood Cells
Small, biconcave disksSmall, biconcave disks
Lack a nucleus and contain hemoglobinLack a nucleus and contain hemoglobin
Hemoglobin containsHemoglobin contains
Four globin protein chainsFour globin protein chains
Each associated with an iron-containing Each associated with an iron-containing hemeheme
Manufactured continuously in bone Manufactured continuously in bone marrow of skull, ribs, vertebrae, and marrow of skull, ribs, vertebrae, and ends of long bonesends of long bones
33Circulatory SysCirculatory Systemstems
White Blood CellsWhite Blood Cells
Most types larger than red blood cellsMost types larger than red blood cells
Contain a nucleus and lack hemoglobinContain a nucleus and lack hemoglobin
Important in inflammatory responseImportant in inflammatory response
Neutrophils enter tissue fluid and Neutrophils enter tissue fluid and phagocytize foreign materialphagocytize foreign material
Lymphocytes (T Cells) attack infected Lymphocytes (T Cells) attack infected cellscells
Antigens cause body to produce Antigens cause body to produce antibodiesantibodies
35Circulatory SysCirculatory Systemstems
PlateletsPlatelets
PlateletsPlatelets
Result from fragmentation of Result from fragmentation of megakaryocytesmegakaryocytes
Involved in coagulationInvolved in coagulation
Blood clot consists of:Blood clot consists of:
PlateletsPlatelets
Red blood cellsRed blood cells
All entangled within fibrin threadsAll entangled within fibrin threads
37Circulatory SysCirculatory Systemstems
Capillary ExchangeCapillary Exchange
Capillaries very narrow – Tiny RBCs Capillaries very narrow – Tiny RBCs must go through single filemust go through single file
Wall of capillaries very thin to Wall of capillaries very thin to facilitate diffusion of nutrients, facilitate diffusion of nutrients, gasses and wastesgasses and wastes
Oxygen and nutrients exit a capillary Oxygen and nutrients exit a capillary near the arterial endnear the arterial end
Carbon dioxide and waste molecules Carbon dioxide and waste molecules enter a capillary near the venous endenter a capillary near the venous end
40Circulatory SysCirculatory Systemstems
ReviewReview
Transport in InvertebratesTransport in InvertebratesOpen versus Closed Circulatory Open versus Closed Circulatory SystemsSystems
Transport in VertebratesTransport in VertebratesTransport in HumansTransport in Humans
HeartbeatHeartbeatVascular PathwaysVascular PathwaysBlood PressureBlood Pressure
Cardiovascular DisordersCardiovascular DisordersBloodBlood
ComponentsComponentsClottingClotting
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