CirculationCirculationChpt. 44Chpt. 44

Transportation, cardiac cycle, Transportation, cardiac cycle, evolution of advanced systemsevolution of advanced systems

Oxygen and nutrients obtained Oxygen and nutrients obtained for simple organisms by for simple organisms by diffusion diffusion

cnidarians and flatworms – cnidarians and flatworms – bodies only 2 cells thickbodies only 2 cells thick

Development of multi-layer Development of multi-layer tissuestissues

Oxygen and nutrients Oxygen and nutrients transported in liquid via transported in liquid via circulatory systemcirculatory system

Open – mollusks, arthropods, Open – mollusks, arthropods, no distinction between circulating no distinction between circulating

fluid and fluid of body tissuesfluid and fluid of body tissues Called hemolymphCalled hemolymph

Closed – blood enclosed in Closed – blood enclosed in vessels, transport away and vessels, transport away and back to a pump (heart)back to a pump (heart)

Some invertebrates (annelids)Some invertebrates (annelids)

Vertebrate Circulatory SystemsVertebrate Circulatory Systems

TransportationTransportation Respiratory, nutritive, Respiratory, nutritive,

excretoryexcretory

RegulationRegulation Hormone transportHormone transport Temperature regulation Temperature regulation

(vasoconstriction/dilation, (vasoconstriction/dilation, countercurrent heat countercurrent heat exchange)exchange)

ProtectionProtection Blood clottingBlood clotting Immune defenseImmune defense

BloodBlood Composed of fluid plasmaComposed of fluid plasma

Interstitial fluid originates from plasma Interstitial fluid originates from plasma Matrix in which blood cells and Matrix in which blood cells and

platelets are suspendedplatelets are suspended Metabolites, wastes, hormonesMetabolites, wastes, hormones Ions Ions Proteins – carriers and clottersProteins – carriers and clotters

Red Blood Cell/ErythrocytesRed Blood Cell/Erythrocytes Oxygen transport, 45% of bloodOxygen transport, 45% of blood Doughnut shaped – increases surface Doughnut shaped – increases surface

areaarea Hemoglobin – pigmentHemoglobin – pigment

Develop from stem cellsDevelop from stem cells Plasma oxygen levels decrease, bone Plasma oxygen levels decrease, bone

marrow creates moremarrow creates more Mammalian – no nucleus, removed as Mammalian – no nucleus, removed as

ageage

White blood cells and plateletsWhite blood cells and platelets Immunological defensesImmunological defenses

Less than 1% of bloodLess than 1% of blood Larger, have nuclei, not confined to bloodLarger, have nuclei, not confined to blood Several types, each have specific jobSeveral types, each have specific job

Platelets – pieces of megakaryocytesPlatelets – pieces of megakaryocytes Injury – smooth muscle contracts, Injury – smooth muscle contracts,

constrictionconstriction Platelets accumulate, stick to each other via Platelets accumulate, stick to each other via

fibrinfibrin

Blood vesselsBlood vessels

Blood leaves heart via Blood leaves heart via arteries which branch to arteries which branch to reach organs, reach organs,

Finest branches are Finest branches are arterioles, enters arterioles, enters capillariescapillaries

Collected in venules led Collected in venules led to veinsto veins

Arteries, veins = same basic Arteries, veins = same basic structurestructure

Innermost = endothelium, Innermost = endothelium, elastic fibers, smooth elastic fibers, smooth muscle, connective tissue muscle, connective tissue layerlayer

Too thick to permit Too thick to permit exchangeexchange

Capillaries = only Capillaries = only endotheliumendothelium

Diffusion, filtration, Diffusion, filtration, transporttransport

Arteries and arteriolesArteries and arterioles Transport blood away from Transport blood away from

heartheart Larger arteries = more elastic Larger arteries = more elastic

fibersfibers Smaller = thick smooth muscleSmaller = thick smooth muscle Vast “tree” = frictional Vast “tree” = frictional

resistanceresistance Narrower vessel = more resistance Narrower vessel = more resistance

to flowto flow Regulated by constriction and Regulated by constriction and

dilationdilation Precapillary sphincters – limits heat Precapillary sphincters – limits heat

loss in coldloss in cold

Exchange in capillariesExchange in capillaries

Sufficient pressure needed to pump against Sufficient pressure needed to pump against resistanceresistance

Every cell is within 100 micromteres of a Every cell is within 100 micromteres of a capillarycapillary

Capillaries 1 millimeter long, 8 micro in diameterCapillaries 1 millimeter long, 8 micro in diameter Slightly wider than erythrocyte, must be flexibleSlightly wider than erythrocyte, must be flexible

Although narrow, number means greatest total area than any Although narrow, number means greatest total area than any vesselvessel

Blood has more time in capillaries, Blood has more time in capillaries, releases/pick-upreleases/pick-up

Loses pressure and velocity, is under low pressure in veinsLoses pressure and velocity, is under low pressure in veins

Venules and veinsVenules and veins

Venules-veins-heartVenules-veins-heart Less muscle because Less muscle because

less pressureless pressure Can expand to hold Can expand to hold

additional bloodadditional blood Skeletal muscles can Skeletal muscles can

contract to move blood contract to move blood back to heart – venous back to heart – venous pumppump

One way back to heart, One way back to heart, venous valvesvenous valves

Lymphatic SystemLymphatic System

Closed – all vessels connected with anotherClosed – all vessels connected with another Some water and solutes do filter through capillaries to form Some water and solutes do filter through capillaries to form

interstitial fluidinterstitial fluid Supplies tissue cells with oxygen and nutrientsSupplies tissue cells with oxygen and nutrients

Exits near arteriolar end where pressure is higher, re-Exits near arteriolar end where pressure is higher, re-enters by osmosis (oncotic pressure)enters by osmosis (oncotic pressure)

Lymphatic is open, returns rest of fluid to cardiovascularLymphatic is open, returns rest of fluid to cardiovascular Capillaries, vessels, nodes, organs including spleen and thymusCapillaries, vessels, nodes, organs including spleen and thymus Activate some white blood cellsActivate some white blood cells

Circulatory and respiratory Circulatory and respiratory adapatationsadapatations

Large body size and locomotion of animals Large body size and locomotion of animals possible because of coevolution of possible because of coevolution of systemssystems

Needed more efficient Needed more efficient

ways to transportways to transportCirculation and respirationCirculation and respiration

linkedlinked

Fish heartFish heart

Early chordates had Early chordates had simple tubular heartssimple tubular hearts

Gills of fish required Gills of fish required chamber-pump heartchamber-pump heart

Peristaltic sequence, Peristaltic sequence, heartbeat initiated by heartbeat initiated by electrical impulseelectrical impulse

Gills oxygenate blood, Gills oxygenate blood, but looses pressure but looses pressure developed by heart developed by heart contractioncontraction

Amphibian/reptilianAmphibian/reptilian Lungs – blood is oxygenated then Lungs – blood is oxygenated then

returned to heartreturned to heart Two circulations – pulmonary – heart/lungsTwo circulations – pulmonary – heart/lungs

Systemic – heart/bodySystemic – heart/body Separates oxygenated from deoxygenatedSeparates oxygenated from deoxygenated

Right atrium – receives deoxygenated Right atrium – receives deoxygenated from systemicfrom systemic

Left atrium receives oxygenated from Left atrium receives oxygenated from lungslungs

Little mixing in ventricleLittle mixing in ventricle Oxygenated blood to aorta, major arteryOxygenated blood to aorta, major artery

One ventricle with incomplete One ventricle with incomplete separationsseparations

Separation of pulmonary and systemic is Separation of pulmonary and systemic is incompleteincomplete

Amphibians can diffuse extra oxygenAmphibians can diffuse extra oxygen

Mammalian and BirdsMammalian and Birds Four chambered heartFour chambered heart

Two atria and two ventriclesTwo atria and two ventricles Right Right atriumatrium receives deoxygenated blood, delivers to receives deoxygenated blood, delivers to

right ventricle, which right ventricle, which pumpspumps to blood to lungs to blood to lungs Left atrium receives oxygenated blood from lungs, Left atrium receives oxygenated blood from lungs,

delivers to left ventricle, which delivers to left ventricle, which pumpspumps blood to body blood to body Occur simultaneously – increased efficiencyOccur simultaneously – increased efficiency Closed system – same amount of blood pumped by both Closed system – same amount of blood pumped by both

ventricles at same timeventricles at same time More pressure generated by left ventricleMore pressure generated by left ventricle

Sinus venosus – pacemaker Sinus venosus – pacemaker site of heartbeat impulsesite of heartbeat impulse

Major chamber in fishMajor chamber in fish Reduced through amphibians, Reduced through amphibians, reptilesreptiles Mammals/birds no longer Mammals/birds no longer separate chamber – tissue remains separate chamber – tissue remains in right atrium – sinoatrial (SA) in right atrium – sinoatrial (SA) nodenode

Cardiac cycleCardiac cycle Two separate pumping Two separate pumping

systems within one organsystems within one organ Two pairs of valvesTwo pairs of valves

Atrioventricular (AV) valves – Atrioventricular (AV) valves – guard openings between atria guard openings between atria and ventriclesand ventricles

Ttricuspid valve = exit Ttricuspid valve = exit of right atriumof right atrium

Bicuspid valve = exit Bicuspid valve = exit of left atriumof left atrium

Semilunar valves – guard Semilunar valves – guard openings between ventricles openings between ventricles and arteriesand arteries

Pulmonary – right ventricle Pulmonary – right ventricle to lungsto lungs

Aortic – left ventricle to bodyAortic – left ventricle to body Valves open and close during Valves open and close during

cardiac cycle cardiac cycle rest (diastole) and contraction rest (diastole) and contraction

(systole)(systole)

Blood returns to resting heart (diastole)Blood returns to resting heart (diastole) Deoxygenated blood into right atriumDeoxygenated blood into right atrium Oxygenated blood into left atriumOxygenated blood into left atrium

Ventricles contract (systole)Ventricles contract (systole) AV valves close (lub), push semilunar valves openAV valves close (lub), push semilunar valves open Ventricles relax, semilunar close (dub)Ventricles relax, semilunar close (dub)

http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_pumping.html

Veins and arteriesVeins and arteries

Pulmonary arteries to Pulmonary arteries to lungslungs

Veins back to heartVeins back to heart

AortaAorta Superior vena cavaSuperior vena cava Inferior vena cavaInferior vena cava

Electrical excitationElectrical excitation

Heart contains specialized autogenic Heart contains specialized autogenic depolarizing cellsdepolarizing cells

Spreads from SA node to atria to ventriclesSpreads from SA node to atria to ventriclesRecorded on EKGRecorded on EKGLargest peak is polarization of ventriclesLargest peak is polarization of ventricles

http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_electrical.html

Blood Flow and Blood PressureBlood Flow and Blood Pressure Cardiac output has normal Cardiac output has normal

resting rate (5L/minute)resting rate (5L/minute) Increases during exercise Increases during exercise

(25L/min)(25L/min) Vasoconstriction/dilation direct Vasoconstriction/dilation direct

extra blood to important areasextra blood to important areas Increased blood pressure = Increased blood pressure =

increase in heart rate or increase in heart rate or vasoconstrictionvasoconstriction Can be regulated by hormones Can be regulated by hormones

to increase blood volumeto increase blood volume

Blood Volume RegulationBlood Volume Regulation

ADH – antidiuretic, prevent dehydrationADH – antidiuretic, prevent dehydrationAldosterone – vasoconstrictionAldosterone – vasoconstrictionAtrial Natriuretic Hormone – release Na+ Atrial Natriuretic Hormone – release Na+

and waterand waterNitric Oxide – gas acts as a hormone - Nitric Oxide – gas acts as a hormone -

vasodilationvasodilation