Circulation in AnimalsCirculation in Animals

Transport systems functionally Transport systems functionally connect the organs of exchange with connect the organs of exchange with body cells.body cells.Diffusion is too slow.Diffusion is too slow.By rapidly transporting fluid in bulk it By rapidly transporting fluid in bulk it

connects the aqueous environment of connects the aqueous environment of cells to organs of gas exchange.cells to organs of gas exchange.

Nutrients are absorbed and wastes are Nutrients are absorbed and wastes are taken away.taken away.

Invertebrate Nutrient and Gas Invertebrate Nutrient and Gas ExchangeExchange

Gastrovascular CavitiesGastrovascular CavitiesCnidarians, Planarians, and PoriferaCnidarians, Planarians, and PoriferaCirculation unnecessary because all Circulation unnecessary because all

cells are exposed to the environment.cells are exposed to the environment.

Cnirdarians

Open Circulatory Open Circulatory SystemsSystems Open circulatory system Open circulatory system

Blood bathes organs directlyBlood bathes organs directly Arthropods and most mollusksArthropods and most mollusks No distinction between blood and interstitial No distinction between blood and interstitial

fluid.fluid. Body fluid called hemolymph.Body fluid called hemolymph. Sinuses are spaces around organs.Sinuses are spaces around organs. One or more hearts pull blood in through One or more hearts pull blood in through ostia.ostia. Blood squeezed around the body through Blood squeezed around the body through

movement.movement.

Closed Circulatory Closed Circulatory SystemSystem

Blood is confined to vessel and distinct Blood is confined to vessel and distinct from interstitial fluid.from interstitial fluid.

Earth worms and higher animals.Earth worms and higher animals. Vertebrates have a cardiovascular system.Vertebrates have a cardiovascular system.

Atrium – top chamber of the heartAtrium – top chamber of the heart Ventricle- lower chamber of the heart.Ventricle- lower chamber of the heart. Arteries – direct blood away from the heart.Arteries – direct blood away from the heart. Veins direct blood to the heart.Veins direct blood to the heart. Capillary beds infiltrate each tissue.Capillary beds infiltrate each tissue.

Systemic circuitSystemic circuit – delivers blood to – delivers blood to the body.the body.

Pulmonary circuitPulmonary circuit – picks up blood – picks up blood from pulmonary organs and delivers from pulmonary organs and delivers it back to the heart.it back to the heart.

Fish HeartFish Heart

FishFishTwo chambersTwo chambersSingle circulation which means blood Single circulation which means blood

must travel through two capillary beds must travel through two capillary beds before it returns to the heart.before it returns to the heart.

Because pressure drops in the capillary Because pressure drops in the capillary bed, blood flow is much slower than in bed, blood flow is much slower than in other organisms.other organisms.

AmphibianAmphibian HeartHeart Three chambersThree chambers

Two atria and one ventricleTwo atria and one ventricle A ridge separates most of the oxygenated from A ridge separates most of the oxygenated from

the deoxygenated blood, however some mixing the deoxygenated blood, however some mixing does occur.does occur.

Double circulationDouble circulation Blood returns to the heart after picking up Blood returns to the heart after picking up

oxygen. Sustains a higher pressure.oxygen. Sustains a higher pressure. Pulmocutaneous circuit.Pulmocutaneous circuit. Pulmonary organs are the lungs and skin.Pulmonary organs are the lungs and skin.

ReptilesReptiles Three chambers clearly dividedThree chambers clearly divided Have a pulmonary circuitHave a pulmonary circuit

Mammalian HeartMammalian HeartTwo atria and two ventriclesTwo atria and two ventriclesDistinct separation of oxygen and Distinct separation of oxygen and

deoxygenated blood.deoxygenated blood.Double circulation with a pulmonary Double circulation with a pulmonary

circuit.circuit.

Mammalian Cardiac Mammalian Cardiac CycleCycle

Cardiac CycleCardiac Cycle - One complete pumping - One complete pumping and filling.and filling.

SystoleSystole – contraction phase of the cycle – contraction phase of the cycleDiastoleDiastole – relaxation phase of the – relaxation phase of the

cycle.cycle.Cardiac OutputCardiac Output – the volume of blood – the volume of blood

that the left ventricle pumps into the that the left ventricle pumps into the systemic circuit per minute.systemic circuit per minute.Depends on two factors:Depends on two factors:

Heart rate - rate of heart beat.Heart rate - rate of heart beat.Stroke volume – blood pumped from left Stroke volume – blood pumped from left

ventricle per contraction.ventricle per contraction.

Average stroke volume for humans is Average stroke volume for humans is 75 ml with a cardiac output of about 75 ml with a cardiac output of about 5.25 L/min. and an average pulse of 5.25 L/min. and an average pulse of 70 beats per minute.70 beats per minute.

Exercising increases stroke volume Exercising increases stroke volume because the heart beats more because the heart beats more efficiently.efficiently.More blood pumped to the systemic More blood pumped to the systemic

circuit per contraction.circuit per contraction.

The “Lub The “Lub Dub”Dub” Atrioventricular valvesAtrioventricular valves

Separate atria from ventricles.Separate atria from ventricles. Semilunar valvesSemilunar valves

Present at both exits of the heart.Present at both exits of the heart. Heart MurmurHeart Murmur

Defect in the valves.Defect in the valves. ““Lub” Lub”

Recoil of blood against closed atrioventricular Recoil of blood against closed atrioventricular valves.valves.

““Dub”Dub” Recoil of blood against closed semilunar valvesRecoil of blood against closed semilunar valves

Maintaining the BeatMaintaining the Beat Sinoatrial NodeSinoatrial Node

Located in the right atrium near the Superior Located in the right atrium near the Superior Vena Cava.Vena Cava.

Sets the tempo for contraction.Sets the tempo for contraction. Stimulates atrium to contract in unison.Stimulates atrium to contract in unison. Orchestration of muscle cells accomplished Orchestration of muscle cells accomplished

through intercalated discs.through intercalated discs. Perkunji FibersPerkunji Fibers

Transmit electrical signal.Transmit electrical signal. 0.1 second delay allows atria to completely 0.1 second delay allows atria to completely

empty before the ventricles contractempty before the ventricles contract

Maintaining the Maintaining the BeatBeat

Atriovenricular NodeAtriovenricular NodeCauses the ventricles to contract.Causes the ventricles to contract.

Factors That Affect Heart RateFactors That Affect Heart RateBody temperatureBody temperature

11oo F increase increases heart rate by 10 F increase increases heart rate by 10 beats/min.beats/min.

ExerciseExerciseHormonal stimulation.Hormonal stimulation.

Epinephrine –speeds up heart rate.Epinephrine –speeds up heart rate.

ArteriesArteries

Thicker wallsThicker wallsOuter wall connective tissue with elastic Outer wall connective tissue with elastic

fibersfibersMiddle layer smooth muscle – peristalsisMiddle layer smooth muscle – peristalsisInner wall – Inner wall – Endothelium Endothelium , composed of , composed of

smooth flat cells to reduce resistance to smooth flat cells to reduce resistance to blood flow. blood flow.

VeinsVeins

Thinner than arteries.Thinner than arteries.Valves to prevent back flow.Valves to prevent back flow.Blood moves through by muscle Blood moves through by muscle

contractions.contractions.Virtually all pressure from ventricular Virtually all pressure from ventricular

contraction is gone.contraction is gone.

CapillariesCapillaries Lack outer and middle layers.Lack outer and middle layers.

Basement membrane with endothelial layer.Basement membrane with endothelial layer. Designed for gas and nutrient exchange Designed for gas and nutrient exchange

between blood and interstitial fluid.between blood and interstitial fluid. Blood flows 1000 times slower than in Blood flows 1000 times slower than in

arteries and veins due to a large surface arteries and veins due to a large surface area. area. Facilitates gas exchange.Facilitates gas exchange.

Pressure drops dramatically in capillary Pressure drops dramatically in capillary bedsbeds

Blood PressureBlood Pressure Hydrostatic pressure pushes blood through Hydrostatic pressure pushes blood through

blood vessels.blood vessels. Systole Systole – pressure due to ventricular – pressure due to ventricular

contraction.contraction. Arteries stretch because blood flows out much Arteries stretch because blood flows out much

more quickly than it can leave the artery.more quickly than it can leave the artery. Diastole – pressure due to the arterial wall Diastole – pressure due to the arterial wall

”snapping back”.”snapping back”. Next contraction occurs before all blood has Next contraction occurs before all blood has

left the artery and maintains pressure flow.left the artery and maintains pressure flow.

Blood pressure determined by:Blood pressure determined by:Cardiac outputCardiac outputPeripheral resistancePeripheral resistance

Contraction of atrioles creates peripheral Contraction of atrioles creates peripheral resistance.resistance.

Contractions triggered by stress, hormones, Contractions triggered by stress, hormones, and nicotine.and nicotine.

Exercise increases cardiac output and dialates Exercise increases cardiac output and dialates atrioles to supply blood to the muscles.atrioles to supply blood to the muscles.

Giraffes and probably dinasaurs have Giraffes and probably dinasaurs have valves and sinuses in their brain and neck valves and sinuses in their brain and neck to prevent a stroke while bending down to prevent a stroke while bending down for a drink.for a drink.

Gas Exchange in the Gas Exchange in the CapillariesCapillaries

OO22 and CO and CO2 2 diffuse down their gradient.diffuse down their gradient. Hydrostatic pressure on the atriole end Hydrostatic pressure on the atriole end

forces 80 % of the fluid out into the tissues.forces 80 % of the fluid out into the tissues. Large proteins and blood cells left behind Large proteins and blood cells left behind

increases the osmolarity of the blood.increases the osmolarity of the blood. Causes fluid to move back into the Causes fluid to move back into the

capillaries at the venule end.capillaries at the venule end. Fluid that doesn’t make it back into the Fluid that doesn’t make it back into the

cappilarie(15%) is returned to the blood cappilarie(15%) is returned to the blood through the lymphatic system.through the lymphatic system.

Lymph VesselsLymph Vessels Lymph fluid composition about the same Lymph fluid composition about the same

as interstitial fluid.as interstitial fluid. Moves through the body by squeezing of Moves through the body by squeezing of

skeletal muscles and peristalsis.skeletal muscles and peristalsis. Valves prevent back flow.Valves prevent back flow. Lypmph returns fluid that has leaked out Lypmph returns fluid that has leaked out

in capillary beds to the circulatory system in capillary beds to the circulatory system near the right atrium.near the right atrium.

Lymph contains white cells that attack Lymph contains white cells that attack bacteria and viruses.bacteria and viruses.

PlasmaPlasmaComposition of PlasmaComposition of Plasma

90% H90% H22O, inorganic salts(electrolytes) O, inorganic salts(electrolytes) PH about 7.4PH about 7.4Plasma proteinsPlasma proteins

BuffersBuffersFibrinogen(clotting)Fibrinogen(clotting)Proteins that escort lipids which are Proteins that escort lipids which are

insoluble in water.insoluble in water.HormonesHormonesViscosity proteinsViscosity proteins

Kidneys maintain electrolytes.Kidneys maintain electrolytes.

ErythrocytesErythrocytes Biconcave for more surface area.Biconcave for more surface area. Lack mitochondria and nuclei – more room for Lack mitochondria and nuclei – more room for

hemoglobin.hemoglobin. 250 million molecules of hemoglobin per cell.250 million molecules of hemoglobin per cell. Generate ATP through anaerobic metabolism.Generate ATP through anaerobic metabolism. Kidneys produce Kidneys produce erythropoietinerythropoietin to stimulate to stimulate

the function of RBC’s.the function of RBC’s. Hemoglobin also binds NO to relax capillaries.Hemoglobin also binds NO to relax capillaries.

RBC’S, Neutrophils

Blood PressureBlood Pressure Hydrostatic pressure pushes blood through blood Hydrostatic pressure pushes blood through blood

vessels.vessels. Highest during ventricular contraction.Highest during ventricular contraction.

During During systolesystole blood is pushed out into the artery faster blood is pushed out into the artery faster than it can leave the artery.than it can leave the artery.

During During diastolediastole artery “snaps back” and creates residual artery “snaps back” and creates residual pressure in the arteries to continue pushing blood pressure in the arteries to continue pushing blood through.through.

Blood pressure is determined by Blood pressure is determined by cardiac outputcardiac output and and peripheral resistanceperipheral resistance..

Stress contracts blood vessels and raises blood Stress contracts blood vessels and raises blood pressure.pressure.

Exercise causes atrioles to dialate causing more Exercise causes atrioles to dialate causing more blood to flow in. A drop in pressure occurs and blood to flow in. A drop in pressure occurs and the cardiac output increases to compensate.the cardiac output increases to compensate.

Cardiovascular Cardiovascular DiseaseDisease

ThrombusThrombus – blood clot. – blood clot. EmbolusEmbolus – when clot breaks off and moves – when clot breaks off and moves

elsewhere in the body.elsewhere in the body. When a clot blocks a coronary artery – When a clot blocks a coronary artery –

myocardial infarctionmyocardial infarction.. AtheroschlerosisAtheroschlerosis – plaques form on the – plaques form on the

inner wall of the artery.inner wall of the artery. ArterioschlerosisArterioschlerosis – when plaques harden – when plaques harden

through calcification.through calcification. Angina PectorisAngina Pectoris – heart pain that signals – heart pain that signals

that theheart is not getting enough that theheart is not getting enough oxygen.oxygen.

HypertensionHypertensionHigh Blood PressureHigh Blood Pressure

Causes chronic abuse of the Causes chronic abuse of the endothelium and encourages plaque endothelium and encourages plaque formation.formation.

Narrows the lumen of the blood vessels Narrows the lumen of the blood vessels and reduces elasticity of blood vessels.and reduces elasticity of blood vessels.

Can compromise aterial walls and Can compromise aterial walls and increase risk for embolisms and increase risk for embolisms and anuerisms.anuerisms.

Plaque Build-Up in Blood Vessels

Counter Current Exchange

AlveoliAlveoli