Functional Functional Organization of Organization of

the the Cardiovascular Cardiovascular

SystemSystem

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ObjectivesObjectives Describe the functional organization of cardiovascular Describe the functional organization of cardiovascular

systemsystem List the functions of cardiovascular system.List the functions of cardiovascular system. Describe the main function of arteries, capillaries and Describe the main function of arteries, capillaries and

veinsveins Describe the flow of blood through the chambers of the Describe the flow of blood through the chambers of the

heart and through the systemic and pulmonary heart and through the systemic and pulmonary circulations.circulations.

Compare and contrast the systemic and pulmonary Compare and contrast the systemic and pulmonary circulation.circulation.

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Functional Organization of Functional Organization of CardiovascularCardiovascular system system

CARDIOVASCULAR SYSTEM

HEART(PUMP)

VESSELS(DISTRIBUTION

SYSTEM)

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Functions of the Functions of the Cardiovascular systemCardiovascular system

Transport of nutrients, oxygen, and hormones to cells throughout the body and removal of metabolic wastes (carbon dioxide, nitrogenous wastes, and heat).

Protection of the body by white blood cells, antibodies, and complement proteins that circulate in the blood and defend the body against foreign microbes and toxins. Clotting mechanisms are also present that protect the body from blood loss after injuries.

Regulation of body temperature, fluid pH, and water content of cells.

System circulates blood throughout the System circulates blood throughout the body.body.

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THE HEARTTHE HEART

Anatomy of the heartAnatomy of the heart Hollow, muscular organ Hollow, muscular organ

about the size of a about the size of a clenched fistclenched fist

Positioned between two Positioned between two bony structures – bony structures – sternum and vertebraesternum and vertebrae

(CPR)(CPR)

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Heart: Two sided pumpHeart: Two sided pump

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Heart: 2 separate pumps (an atrium & a ventricle) Rightpumps blood through lungs Left pumps blood through peripheral circulationAtrium: weak primer pump for the ventricleVentricle: the main pumping force Rt. Ventricle Lt. ventricle Pulmonary circulation Systemic circulation

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Blood Flow Through and Pump Action Blood Flow Through and Pump Action of the Heartof the Heart

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Pulmonary circulation systemic circulation

Starts at right Starts at right ventricleventricle

Ends at left atriumEnds at left atrium

Receives blood Receives blood from right side of from right side of heartheart

Carries blood Carries blood between heart and between heart and lungslungs

Blood perfusing the Blood perfusing the lungs is partially lungs is partially deoxygenateddeoxygenated

All blood flows All blood flows through lungsthrough lungs

Low pressure, low Low pressure, low resistanceresistance

Starts at left ventricleStarts at left ventricle

Ends at right atriumEnds at right atrium

Receives blood from Receives blood from left side of heartleft side of heart

Carries blood Carries blood between heart and between heart and other organ systemsother organ systems

Blood perfusing the Blood perfusing the organ systems is organ systems is oxygenatedoxygenated

Part of the blood go Part of the blood go to different organ to different organ systemssystems

High pressure, high High pressure, high resistanceresistance

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Atrioventricular (AV) valves (Tricuspid & Atrioventricular (AV) valves (Tricuspid & mitral)mitral) Prevent backflow of blood from Prevent backflow of blood from

ventricles into atria during ventricular ventricles into atria during ventricular emptyingemptying

Chordae tendinaeChordae tendinae Fibrous cords which prevent valves Fibrous cords which prevent valves

from being evertedfrom being everted Papillary muscles Papillary muscles

Heart Valves cont..Heart Valves cont..Heart Valves cont..Heart Valves cont..

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Semilunar valves (Aortic and pulmonary valves)Semilunar valves (Aortic and pulmonary valves) Lie at juncture where major arteries leave ventriclesLie at juncture where major arteries leave ventricles Prevented from everting by anatomic structure and Prevented from everting by anatomic structure and

positioning of cuspspositioning of cusps No valves between atria and veinsNo valves between atria and veins

ReasonsReasons Atrial pressures usually are not much higher than Atrial pressures usually are not much higher than

venous pressuresvenous pressures Sites where vecavae enter atria are partially Sites where vecavae enter atria are partially

compressed during atrial contractionnaecompressed during atrial contractionnae

Heart Valves cont..Heart Valves cont..Heart Valves cont..Heart Valves cont..

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The fibrous skeleton of the The fibrous skeleton of the heartheart

Serves 3 roles:Serves 3 roles: A mechanical base: A mechanical base:

atria anchored atria anchored above and above and ventricles belowventricles below

Perforated by 4 Perforated by 4 apertures, each apertures, each containing a valvecontaining a valve

Insulates the Insulates the ventriclesventricles

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Blood vesselsBlood vessels

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ArteriesArteriesStructure of arterial wallStructure of arterial wall

Plentiful of elastic Plentiful of elastic fibers….high fibers….high compliancecompliance

Function: Rapid transit passage-ways for blood from heart to tissuesPressure reservoir

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ArterioleArteriole Very small artery that Very small artery that delivers blood to capillariesdelivers blood to capillaries

StructureStructure Very little elastic tissue but thick layer of smooth muscleVery little elastic tissue but thick layer of smooth muscle

FunctionFunction Regulating blood flow from arteries to capillaries by regulating Regulating blood flow from arteries to capillaries by regulating

resistance according to tissue metabolic needs.resistance according to tissue metabolic needs.

Contraction of smooth muscle (vasoconstriction) decrease Contraction of smooth muscle (vasoconstriction) decrease arteriole diameter increase resistance decrease blood arteriole diameter increase resistance decrease blood flowflow

Relaxation of smooth muscles (vasodilation) increase Relaxation of smooth muscles (vasodilation) increase arteriole diameter decrease resistance increase arteriole diameter decrease resistance increase blood flowblood flow

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CapillariesCapillaries Microscopic vessels that Microscopic vessels that connectsconnects arterioles to venules arterioles to venules StructureStructure

Single wallSingle wall layered vesseles (endothelial cells) layered vesseles (endothelial cells) Undergoes extensive branchingUndergoes extensive branching

Function:Function: Exchange Exchange of nutrients and wastes between blood and tissue cellsof nutrients and wastes between blood and tissue cells

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VeinsVeins Carry blood Carry blood from tissues to heartfrom tissues to heart

Structure:Structure: Thin wallThin wall Less smooth muscle and considerable Less smooth muscle and considerable

amount of collagenamount of collagen Less elastic fibersLess elastic fibers

Function:Function: Passage waysPassage ways back to heart back to heart Blood reservoir Blood reservoir (capacitance vessels)(capacitance vessels)

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