Functional Organization Functional Organization of the Cardiovascular of the Cardiovascular

SystemSystem

ObjectivesObjectives Describe the functional organization of Describe the functional organization of

cardiovascular systemcardiovascular system List the functions of cardiovascular system.List the functions of cardiovascular system. Describe the main function of arteries, Describe the main function of arteries,

capillaries and veinscapillaries and veins Describe the flow of blood through the Describe the flow of blood through the

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

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

Functional Organization of Functional Organization of Cardiovascular systemCardiovascular system

CARDIOVASCULAR SYSTEM

HEART(PUMP)

VESSELS(DISTRIBUTION

SYSTEM)

Blood

Functions of Cardiovascular Functions of Cardiovascular System:System:

I. Primary (main) function of the heart:I. Primary (main) function of the heart:

♥♥ Acts as a muscular pump:Acts as a muscular pump: in order to maintain adequate level of blood in order to maintain adequate level of blood

flow flow throughout CVS by pumping blood under throughout CVS by pumping blood under

press into press into vascular system.vascular system.

♥♥ Responsible for the mass movement of fluid Responsible for the mass movement of fluid in in

body.body.

Functions of Cardiovascular System Functions of Cardiovascular System (continued)(continued)

II. Secondary functions:II. Secondary functions: 1. Transportation:1. Transportation: delivers Odelivers O22 to tissues, & brings back CO to tissues, & brings back CO22 to lungs. to lungs. carries absorbed digestion products to liver & carries absorbed digestion products to liver &

tissues.tissues. carries metabolic wastes to kidneys to be excreted.carries metabolic wastes to kidneys to be excreted. distribution of body fluids. distribution of body fluids.

2. Regulation:2. Regulation: Hormonal: carries hormones to target tissues to produce Hormonal: carries hormones to target tissues to produce

their effects.their effects. Immune: carries antibodies, leukocytes (WBCs), Immune: carries antibodies, leukocytes (WBCs),

cytokines, & complement cytokines, & complement to aid body defense mechanism against pathogens.to aid body defense mechanism against pathogens. Protection: carries platelets, & clotting factors to aid Protection: carries platelets, & clotting factors to aid

protection of the bodyprotection of the body in blood clotting mechanism.in blood clotting mechanism. Temperature: helps in regulation of body temperature, Temperature: helps in regulation of body temperature,

by diverting blood by diverting blood to cool or warm the body.to cool or warm the body.

Anatomy of the heart:Anatomy of the heart:

Positioned between two bony structures – sternum and vertebrae

(CPR)

Hollow, muscular organ.Hollow, muscular organ.

Heart: Two sided pumpHeart: Two sided pump

Vena cavapulmonary veins

Pulmonary trunk

(Aorta)

AtriumAtrium: weak primer pump for the ventricle: weak primer pump for the ventricleVentricleVentricle: the main pumping force: the main pumping force Rt. Ventricle Lt. ventricleRt. Ventricle Lt. ventricle Pulmonary circulation Systemic circulationPulmonary circulation Systemic circulation

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

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

Valves of the heart:Valves of the heart:♥ 2 atrioventricular (AV) valves: ■ One way valves. ■ Allow blood to flow from atria into ventricles. ■ Tricuspid (Rt) & Mitral (Lt).

♥ 2 semilunar valves : ■ One way valves. ■ At origin of pulmonary artery & aorta. ■ Pulmonary (Rt) & Aortic (Lt). ■ Open during ventricular contraction.

Heart ValvesHeart Valves One way flow in One way flow in

heart is ensured by heart is ensured by heart valvesheart valves

Valves open & Valves open & close passivelyclose passively

-- open open by by forward P by bloodforward P by blood

- - closeclose by by backward P by backward P by bloodblood

Atrioventricular Valve Atrioventricular Valve FunctionFunction

Semilunar Valve Semilunar Valve FunctionFunction

No valves between atria No valves between atria and veinsand veins ReasonsReasons

Atrial pressures Atrial pressures usually are not usually are not much higher than much higher than venous pressuresvenous pressures

Sites where venae Sites where venae cavae enter atria cavae enter atria are partially are partially compressed during compressed during atrial contractionatrial contraction

The fibrous skeleton of the The fibrous skeleton of the heartheartServes 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

Vascular TreeVascular Tree Closed system of vesselsClosed system of vessels Consists of Consists of

ArteriesArteries Carry blood away from heart to tissuesCarry blood away from heart to tissues

ArteriolesArterioles Smaller branches of arteriesSmaller branches of arteries

CapillariesCapillaries Smaller branches of arteriolesSmaller branches of arterioles Smallest of vessels across which all exchanges Smallest of vessels across which all exchanges

are made with surrounding cellsare made with surrounding cells VenulesVenules

Formed when capillaries rejoinFormed when capillaries rejoin Return blood to heartReturn blood to heart

Veins Veins Formed when venules mergeFormed when venules merge Return blood to heartReturn blood to heart

ArteriesArteries

Structure 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

Arteries as a Pressure Arteries as a Pressure ReservoirReservoir

Arterioles (resistance vessels)Arterioles (resistance vessels) Very small arteries that Very small arteries that

delivers blood to delivers blood to capillariescapillaries

StructureStructure Very little elastic tissue Very little elastic tissue

but thick layer of smooth but thick layer of smooth musclemuscle

Function Function Regulating Regulating blood flow from arteries blood flow from arteries to capillaries by to capillaries by regulating resistance regulating resistance according to tissue according to tissue metabolic needs.metabolic needs.

CapillariesCapillaries Microscopic vessels that Microscopic vessels that connectsconnects

arterioles to venulesarterioles to venules StructureStructure

Single wallSingle wall layered vessels layered vessels (endothelial cells)(endothelial cells)

Undergoes extensive branchingUndergoes extensive branching Maximized surface area and Maximized surface area and

minimized diffusion distanceminimized diffusion distance Velocity of blood flow through Velocity of blood flow through

capillaries is relatively slowcapillaries is relatively slow Provides adequate exchange Provides adequate exchange

timetime Function:Function:

Exchange Exchange of nutrients and wastes of nutrients and wastes between blood and tissue cellsbetween blood and tissue cells

Capillaries cont.Capillaries cont.

Under resting conditions many capillaries are not Under resting conditions many capillaries are not openopen

Capillaries surrounded by precapillary sphinctersCapillaries surrounded by precapillary sphincters Contraction of sphincters reduces blood flowing into Contraction of sphincters reduces blood flowing into

capillaries in an organcapillaries in an organ Relaxation of sphincters has opposite effectRelaxation of sphincters has opposite effect

VeinsVeins Carry blood Carry blood from tissues to from tissues to

heartheart

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

considerable amount of considerable amount of collagencollagen

Less elastic fibersLess elastic fibers

Function:Function: Passage waysPassage ways back to back to

heartheart Blood reservoir Blood reservoir

(capacitance vessels)(capacitance vessels)