cardiovascular system blood vessels. anatomy of blood vessels arteries carry blood from the heart to...

Cardiovascular SystemCardiovascular System

Blood VesselsBlood Vessels

Anatomy of Blood VesselsAnatomy of Blood Vessels

ArteriesArteries carry blood from the heart carry blood from the heart to the tissuesto the tissues


ArteriolesArterioles are small arteries that are small arteries that connect to capillariesconnect to capillaries


CapillariesCapillaries are the site of are the site of substance exchange between the substance exchange between the blood and body tissuesblood and body tissues


VenulesVenules connect capillaries to connect capillaries to larger veinslarger veins


VeinsVeins convey blood from the convey blood from the tissues back to the heart.tissues back to the heart.

ArteriesArteries

1.1. Tunica interna (intima) – innermostTunica interna (intima) – innermost

2.2. Tunica media – middle layerTunica media – middle layer

3.3. Tunica externa – outer layerTunica externa – outer layer

Tunica IntimaTunica Intima

Composed of;Composed of;

1.1. simple squamous epithelium simple squamous epithelium (endothelium)(endothelium)

2.2. Internal elastic membraneInternal elastic membrane

Tunica MediaTunica Media

Rich in smooth muscle and elastic Rich in smooth muscle and elastic fibersfibers

Tunica MediaTunica Media

Maintains elasticity and contractilityMaintains elasticity and contractility

Tunica ExternaTunica Externa

Rich in elastic and collagen fibersRich in elastic and collagen fibers

Functional Properties of Functional Properties of ArteriesArteries

1.1. ElasticityElasticity

2.2. ContractilityContractility

ElasticityElasticity

Due to the elastic tissue in the tunica Due to the elastic tissue in the tunica intima and mediaintima and media

ElasticityElasticity

Allows arteries to accept blood under Allows arteries to accept blood under great pressure from the contraction great pressure from the contraction of the ventricles of the ventricles

ContractilityContractility

Due to the smooth muscle in the Due to the smooth muscle in the tunica mediatunica media


Allows arteries to increase or Allows arteries to increase or decrease lumen sizedecrease lumen size


Sympathetic stimulation of alpha 1 Sympathetic stimulation of alpha 1 receptors on cutaneous arteries receptors on cutaneous arteries causes vasoconstrictioncauses vasoconstriction


Sympathetic stimulation of beta 2 Sympathetic stimulation of beta 2 receptors on arteries supplying receptors on arteries supplying skeletal muscle causes vasodilationskeletal muscle causes vasodilation

Elastic ArteriesElastic Arteries

Elastic Arteries – Large arteries with Elastic Arteries – Large arteries with more elastic fibers and less smooth more elastic fibers and less smooth musclemuscle


Example: aorta, sublcavian, and Example: aorta, sublcavian, and pulmonary arteriespulmonary arteries


Also called Also called conducting arteriesconducting arteries because they conduct blood from the because they conduct blood from the heart to medium sized arteriesheart to medium sized arteries

Muscular or distributing Muscular or distributing arteriesarteries

Medium sized and have a large Medium sized and have a large amount of smooth muscle and amount of smooth muscle and distribute blood to various parts of distribute blood to various parts of the bodythe body

Muscular or distributing Muscular or distributing arteriesarteries

Examples: brachial, femoral, and Examples: brachial, femoral, and popliteal arteriespopliteal arteries

ArteriolesArterioles

Very small arteries that deliver blood Very small arteries that deliver blood to capillariesto capillaries

CapillariesCapillaries

Connect arterioles and venulesConnect arterioles and venules


Microcirculation – flow of blood Microcirculation – flow of blood through the capillariesthrough the capillaries


Capillaries are found near almost Capillaries are found near almost every cell in the bodyevery cell in the body


Function – Permit the exchange of Function – Permit the exchange of nutrients and wastes between the nutrients and wastes between the blood and tissue cellsblood and tissue cells


Composed of a single layer of cells Composed of a single layer of cells (endothelium) and a basement (endothelium) and a basement membranemembrane


Two types;Two types;

1.1. Continuous Continuous

2.2. Fenestrated Fenestrated


Continuous – Continuous – composed of composed of endothelial cells endothelial cells that form a that form a continuous tube continuous tube that contains gaps that contains gaps between cells between cells called called intercellular intercellular cleftsclefts


Fenestrated Fenestrated capillaries – plasma capillaries – plasma membrane membrane contains small contains small porespores


Materials can cross the blood Materials can cross the blood capillary walls in four wayscapillary walls in four ways


Four Ways;Four Ways;

1.1. Intercellular cleftsIntercellular clefts

2.2. Trancytosis using pinocytic vesiclesTrancytosis using pinocytic vesicles

3.3. DiffusionDiffusion

4.4. Fenestrations Fenestrations

Intercellular cleftsIntercellular clefts

Open in response to histamine Open in response to histamine (released during inflamation) making (released during inflamation) making capillaries more leakycapillaries more leaky

Intercellular cleftsIntercellular clefts

This allows fluid and wbc, and This allows fluid and wbc, and antibodies to go from the antibodies to go from the bloodstream to the site of infectionbloodstream to the site of infection

PinocytosisPinocytosis

Large fats cross via pinocytosisLarge fats cross via pinocytosis

DiffusionDiffusion

Water, CO2, and O2 cross capillaries Water, CO2, and O2 cross capillaries by diffusionby diffusion

FenestrationsFenestrations

Allow small molecules such as water Allow small molecules such as water and electrolytes to get into the urineand electrolytes to get into the urine

FenestrationsFenestrations

Prevent large proteins and red cells Prevent large proteins and red cells from getting into the urinefrom getting into the urine

SinusoidsSinusoids

Discontinuous Discontinuous capillariescapillaries

SinusoidsSinusoids

Present in the liverPresent in the liver

SinusoidsSinusoids

Allow large molecules such as protein Allow large molecules such as protein and bilirubin to get from the and bilirubin to get from the bloodstream into hepatocytesbloodstream into hepatocytes

VenulesVenules

They are small vessels that are They are small vessels that are formed from the union of several formed from the union of several capillariescapillaries

VenulesVenules

Merges to form veinsMerges to form veins

VenulesVenules

Drain blood from capillaries into Drain blood from capillaries into veinsveins

VeinsVeins

Contain 60% of our blood volumeContain 60% of our blood volume

VeinsVeins

Consist of the same three tunics as Consist of the same three tunics as arteriesarteries

VeinsVeins

Have a thinner tunica intima and Have a thinner tunica intima and mediamedia

VeinsVeins

Thicker tunica externaThicker tunica externa

VeinsVeins

Thinner walled than arteries due to Thinner walled than arteries due to less elastic tissue and smooth muscleless elastic tissue and smooth muscle

VeinsVeins

Low pressure systemsLow pressure systems

VeinsVeins

Contain valves to prevent backflowContain valves to prevent backflow

VeinsVeins

Squeezing of the veins by muscles Squeezing of the veins by muscles and inspiration promote venous and inspiration promote venous returnreturn

Venous ReturnVenous Return

The volume of blood returning back The volume of blood returning back to the heart from the systemic veinsto the heart from the systemic veins

VeinsVeins

Vascular sinuses – veins with very Vascular sinuses – veins with very thin walls with no smooth muscle to thin walls with no smooth muscle to alter their diameteralter their diameter

Example: Coronary sinusExample: Coronary sinus

AnastomosesAnastomoses

Union of the branches of two or more Union of the branches of two or more arteries supplying the same regionarteries supplying the same region


Provide alternate routes for blood to Provide alternate routes for blood to reach a tissue or organreach a tissue or organ


Collateral circulation is the alternate Collateral circulation is the alternate flow of blood to a body part through flow of blood to a body part through an anastomosisan anastomosis


What is the importance of arteries What is the importance of arteries that anastomose?that anastomose?


Occlusion of an end artery interrupts Occlusion of an end artery interrupts the blood supply to a whole segment the blood supply to a whole segment of an organ, producing necrosis of of an organ, producing necrosis of that segmentthat segment

Blood PressureBlood Pressure

Pressure exerted on the walls of a Pressure exerted on the walls of a blood vesselblood vessel


In a clinical sense, it refers to In a clinical sense, it refers to pressure in arteriespressure in arteries


BP=CO X TPRBP=CO X TPR


Systolic and Diastolic fluctuations in Systolic and Diastolic fluctuations in the pressure are only seen in the the pressure are only seen in the arteries and arteriolesarteries and arterioles

Systolic PressureSystolic Pressure

Peak pressure in the arteries with Peak pressure in the arteries with each cardiac cycle during ventricular each cardiac cycle during ventricular contractioncontraction

Systolic PressureSystolic Pressure

Due to the stroke volume being Due to the stroke volume being ejected into the aortaejected into the aorta

Diastolic PressureDiastolic Pressure

Lowest pressure in the arteries with Lowest pressure in the arteries with each cardiac cycleeach cardiac cycle

Diastolic PressureDiastolic Pressure

Force of blood recorded during Force of blood recorded during ventricular relaxationventricular relaxation


Young adult male = 120/80 mm Hg Young adult male = 120/80 mm Hg (8-10 mm Hg less in a young adult (8-10 mm Hg less in a young adult female)female)

ResistanceResistance

Depends on three variables;Depends on three variables;

1.1. Blood viscosityBlood viscosity

2.2. Vessel lengthVessel length

3.3. Blood Vessel RadiusBlood Vessel Radius

Blood ViscosityBlood Viscosity

Increased viscosity increases Increased viscosity increases resistanceresistance

Vessel lengthVessel length

Increased length increases resistanceIncreased length increases resistance

Blood Vessel RadiusBlood Vessel Radius

Increased radius decreases Increased radius decreases resistanceresistance

Systemic vascular resistanceSystemic vascular resistance

Total peripheral resistance (TPR)Total peripheral resistance (TPR)

Systemic vascular resistanceSystemic vascular resistance

All of the vascular resistance offered All of the vascular resistance offered by systemic blood vesselsby systemic blood vessels

Mean Arterial PressureMean Arterial Pressure

MAP = Diastolic Pressure X MAP = Diastolic Pressure X 1/3(systolic pressure – diastolic 1/3(systolic pressure – diastolic pressure)pressure)


MAP = CO X TPRMAP = CO X TPR


Factors that increase BPFactors that increase BP increase SVincrease SV increase HRincrease HR constrict the blood vessels constrict the blood vessels

(increases resistance)(increases resistance)


Factors that decrease BPFactors that decrease BP Decrease CODecrease CO Dilate the arteriesDilate the arteries

Cardiovascular CenterCardiovascular Center

A group of neurons in the medulla A group of neurons in the medulla that regulate heart rate, contractility, that regulate heart rate, contractility, and blood vessel diameterand blood vessel diameter


CV receives input from higher brain CV receives input from higher brain regions and sensory receptors regions and sensory receptors (baroreceptors and chemoreceptors)(baroreceptors and chemoreceptors)


Sympathetic impulses along Sympathetic impulses along cardioaccelerator nerves increase cardioaccelerator nerves increase heart rate and contractilityheart rate and contractility


Parasympathetic impulse along Parasympathetic impulse along vagus nerves decrease heart ratevagus nerves decrease heart rate


The sympathetic division also The sympathetic division also continually sends impulses to smooth continually sends impulses to smooth muscle in blood vessel walls via muscle in blood vessel walls via vasomoter nerves resulting in a vasomoter nerves resulting in a moderate state of tonic moderate state of tonic vasoconstrictionvasoconstriction

Neural Regulation of Blood Neural Regulation of Blood PressurePressure

BaroreceptorsBaroreceptorsChemoreceptorsChemoreceptors

BaroreceptorsBaroreceptors

Pressure-sensitive sensory neurons Pressure-sensitive sensory neurons that monitor stretching of the walls that monitor stretching of the walls of blood vesselsof blood vessels


If blood pressure falls, the If blood pressure falls, the baroreceptor reflexes;baroreceptor reflexes;

accelerate heart rateaccelerate heart rate increase force of contractionincrease force of contraction promote vasoconstrictionpromote vasoconstriction


If pressure increases above normal, If pressure increases above normal, the reflexes cause;the reflexes cause;

decrease in sympathetic tonedecrease in sympathetic tone increase in parasympathetic toneincrease in parasympathetic tone

Hormonal RegulationHormonal Regulation

Renin leads to the formation of Renin leads to the formation of angiotensin IIangiotensin II


Angiotensin II causes;Angiotensin II causes;

1.1. VasoconstrictionVasoconstriction

2.2. Secretion of aldosterone, which Secretion of aldosterone, which leads to sodium and water retentionleads to sodium and water retention


Epinephrine and norepinephrine Epinephrine and norepinephrine increase CO and cause increase CO and cause vasoconstrictionvasoconstriction


ADH causes water retention and a ADH causes water retention and a little vasoconstrictionlittle vasoconstriction


Nitric oxide from the endothelial cells Nitric oxide from the endothelial cells causes vasodilationcauses vasodilation


Cortisol keep our arteries sensitive to Cortisol keep our arteries sensitive to vasoconstricting hormonesvasoconstricting hormones

ShockShock

Is an inadequate CO that results in Is an inadequate CO that results in failure of the CV system to deliver failure of the CV system to deliver adequate amounts of O2 and adequate amounts of O2 and nutrients to meet the metabolic nutrients to meet the metabolic needs of body cellsneeds of body cells

ShockShock

Could result in;Could result in; dysfunction of cellular membranesdysfunction of cellular membranes abnormal cellular metabolismabnormal cellular metabolism cellular deathcellular death

Types of ShockTypes of Shock

5 main types5 main types

Hypovolemic ShockHypovolemic Shock

Due to decreased blood volumeDue to decreased blood volume

Cardiogenic ShockCardiogenic Shock

Due to poor heart functionDue to poor heart function

Vascular ShockVascular Shock

Due to inappropriate vasodilationDue to inappropriate vasodilation

Obstructive ShockObstructive Shock

Due to obstruction of blood flowDue to obstruction of blood flow

Neurogenic shockNeurogenic shock

Due to decreased sympathetic Due to decreased sympathetic outflowoutflow

Homeostatic ResponseHomeostatic Response

Activation of renin-angiotensin-Activation of renin-angiotensin-aldosterone systemaldosterone system


Secretion of ADHSecretion of ADH


Activation of the sympathetic division Activation of the sympathetic division of the ANSof the ANS

Circulatory RoutesCirculatory Routes

SystemicSystemicPulmonaryPulmonaryHepatic PortalHepatic PortalFetalFetal

Hepatic Portal CirculationHepatic Portal Circulation

Collects blood from the veins of the Collects blood from the veins of the pancreas, spleen, stomach, pancreas, spleen, stomach, intestines and gallbladder and directs intestines and gallbladder and directs it into the hepatic portal vein of the it into the hepatic portal vein of the liver before it returns to the heartliver before it returns to the heart

Hepatic Portal CirculationHepatic Portal Circulation

Enables nutrient utilization and blood Enables nutrient utilization and blood detoxification by the liverdetoxification by the liver

cardiovascular system blood vessels. anatomy of blood vessels arteries carry blood from the heart to...

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