Investigation #3: Examining the direction of blood flow in the veins of the forearm.

Investigation #3:Investigation #3: Examining the direction of Examining the direction of

blood flow in the veins of the blood flow in the veins of the forearmforearm

ProcedureProcedure

CapillariesCapillaries• The finest type of The finest type of

blood vessels blood vessels connecting the connecting the arterioles and venulesarterioles and venules

• They reach all parts They reach all parts of the body of the body

• Very thin walls– Very thin walls– only one cell- only one cell-thickthick

• Lumen is only big Lumen is only big enough for one RBC enough for one RBC to pass through at to pass through at a time a time

• Allow materials to be Allow materials to be exchanged between exchanged between the blood and body the blood and body tissues, e.g. oxygen, tissues, e.g. oxygen, glucose, etc.glucose, etc.

Exchange of substances Exchange of substances between blood and body between blood and body

cells (Video)cells (Video)

Adaptations of capillaries Adaptations of capillaries for the exchange of for the exchange of

materialsmaterialsIn order for the diffusion of substances In order for the diffusion of substances

between blood and body cells to occur between blood and body cells to occur

more efficiently:more efficiently:• The capillary wall is only one-cell The capillary wall is only one-cell

thickthick• The cross-sectional area is very The cross-sectional area is very

large and thus blood flow is slowlarge and thus blood flow is slow• Large branching of the capillariesLarge branching of the capillaries

Investigation #4:Investigation #4: Examining the capillary Examining the capillary

flow in a fish’s tail fin flow in a fish’s tail fin

ProcedureProcedure

Location of Location of vesselvessel

Condition of Condition of bloodblood

Size of lumenSize of lumen

Presence of Presence of valves?valves?

Rate of blood Rate of blood pressurepressure

Presence of Presence of pulse?pulse?

Thickness of Thickness of wallwall

Direction of Direction of flowflow

CapillariesCapillariesVeinsVeinsArteriesArteries

Away from Away from heartheart

Towards Towards heartheart

From arteries From arteries to veinsto veins

ThickThick ThinnerThinner Only one-cell Only one-cell thickthick

YesYes NoNo NoNo

Highest Highest LowestLowest LowLow

NoNo YesYes NoNo

SmSmallall

LargeLarge Very smallVery small

OxygenatedOxygenatedDeoxygenatedDeoxygenatedNear art.: Oxy.Near art.: Oxy.Near vein: Deoxy.Near vein: Deoxy.

Deep under Deep under skinskin

Near surfaceNear surfaceNear all cellsNear all cells

Varicose VeinsVaricose Veins

Varicose VeinsVaricose Veins

• The result of The result of problems with valves problems with valves within the veins of within the veins of the leg the leg

• Blood is conducted Blood is conducted back into the leg back into the leg instead of up to the instead of up to the heart, causing blood heart, causing blood to accumulateto accumulate

• Pressure causes the Pressure causes the veins to bulge and veins to bulge and become visible become visible

Varicose VeinsVaricose Veins

ArteriosclerosisArteriosclerosis• The hardening and/or thickening of The hardening and/or thickening of

the blood vessel walls the blood vessel walls • Cholesterol and other fatty materials Cholesterol and other fatty materials

harden the walls by producing plaque harden the walls by producing plaque along the inner core of the vessels along the inner core of the vessels

• As the vessel walls become As the vessel walls become increasingly thicker, the increasingly thicker, the passageways through the vessels passageways through the vessels narrow narrow

• Result in decreased blood supply and Result in decreased blood supply and increased blood pressureincreased blood pressure

ArteriosclerosisArteriosclerosis

• Due to the arterial walls Due to the arterial walls becoming weaker and less becoming weaker and less elastic, the high blood pressure elastic, the high blood pressure may cause the arteries to burstmay cause the arteries to burst

• If the arteries are in the brain, If the arteries are in the brain, the brain cells will lack nutrients the brain cells will lack nutrients and oxygen, resulting in death and oxygen, resulting in death of the cells – this condition is of the cells – this condition is referred to as a referred to as a strokestroke

ArteriosclerosisArteriosclerosis

BruiseBruise• Blood vessels are Blood vessels are

damaged or damaged or broken as the broken as the result of a blow to result of a blow to the skin the skin

• The raised area of The raised area of a bump or bruise a bump or bruise results from blood results from blood leaking from leaking from these injured these injured blood vessels into blood vessels into the tissuesthe tissues

The Human HeartThe Human Heart

• Muscular organ Muscular organ inside thorax inside thorax (between lungs) (between lungs)

• Weighs about 300gWeighs about 300g• Protected by Protected by

pericardium pericardium • Contracts and Contracts and

relaxes to pump relaxes to pump blood around the blood around the bodybody

Answers:Answers:• Aorta Aorta • Pulmonary Pulmonary

arteryartery• Left atriumLeft atrium• Left ventricleLeft ventricle• SeptumSeptum• Inferior venae Inferior venae

cavaecavae• Right Right

ventricleventricle• Right artriumRight artrium• Semilunar Semilunar

valvevalve• Superior Superior

venae cavaevenae cavae

External Structure of External Structure of HeartHeart

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Structures of the HeartStructures of the Heart• The heart is made up of 4 The heart is made up of 4

chambers – 2 chambers – 2 atriaatria (singular: (singular: atriumatrium) and 2 ) and 2 ventriclesventricles

• The atria have thinner walls than The atria have thinner walls than the ventricles, whereas the right the ventricles, whereas the right chambers have thinner walls than chambers have thinner walls than the left chambersthe left chambers

• The left chambers and the right The left chambers and the right chambers are separated by a chambers are separated by a septumseptum to prevent the mixing of to prevent the mixing of bloodblood

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Structures of the HeartStructures of the Heart

• The right atrium receives The right atrium receives DEOXYGENATED BLOODDEOXYGENATED BLOOD via the via the superior vena cavasuperior vena cava (blood from (blood from upper part of body such as head upper part of body such as head and arms) and and arms) and inferior vena cavainferior vena cava (blood from lower part of body (blood from lower part of body such as legs)such as legs)

• It receives blood from all parts of It receives blood from all parts of the body except for the lungsthe body except for the lungs

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Structures of the HeartStructures of the Heart

• The blood is pumped from the The blood is pumped from the right atrium into the right right atrium into the right ventricleventricle

• The right ventricle then pumps The right ventricle then pumps the the DEOXYGENATED BLOODDEOXYGENATED BLOOD to to the lungs via the the lungs via the pulmonary pulmonary arteryartery (remember: artery = (remember: artery = away from heart)away from heart)

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Structures of the HeartStructures of the Heart

• The left atrium receives The left atrium receives OXYGENATEDOXYGENATED BLOODBLOOD from the from the lungs via the lungs via the pulmonary veinspulmonary veins

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Structures of the HeartStructures of the Heart• The blood is pumped from the The blood is pumped from the

left atrium into the left ventricleleft atrium into the left ventricle• The left ventricle then pumps The left ventricle then pumps

the the OXYGENATED BLOODOXYGENATED BLOOD to all to all parts of the body via the aorta parts of the body via the aorta

• A huge pressure is needed to A huge pressure is needed to pump blood all over the body, pump blood all over the body, and therefore the left ventricle and therefore the left ventricle and aorta must be able to and aorta must be able to withstand the greatest pressurewithstand the greatest pressure

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Heart ValvesHeart ValvesHeart valves ensure that blood onlyHeart valves ensure that blood onlyflows in one direction:flows in one direction:• Tricuspid valveTricuspid valve – between the – between the

right atrium and right ventricle; right atrium and right ventricle; it is called “tricuspid” because it it is called “tricuspid” because it is made up of three flapsis made up of three flaps

• Bicuspid valveBicuspid valve – between the left – between the left atrium and left ventricle; it is atrium and left ventricle; it is called “bicuspid because it is called “bicuspid because it is made up of only two flapsmade up of only two flaps

Heart ValvesHeart ValvesHeart valves ensure that blood Heart valves ensure that blood

onlyonly

flows in one direction:flows in one direction:

3) Semilunar valve3) Semilunar valve – found at the – found at the base of the aorta and the base of the aorta and the pulmonary arteries; it is called pulmonary arteries; it is called “semilunar” because it looks “semilunar” because it looks like a half-moonlike a half-moon

Heart ValvesHeart Valves

Valve opened – Valve opened – blood flows throughblood flows through

Valve closed – Valve closed – Blood flow is blockedBlood flow is blocked

Heart ValvesHeart Valves

Opened valveOpened valveClosed valveClosed valve

Heart ValvesHeart Valves

Chordae Tendineae Chordae Tendineae

• The valves are The valves are attached to attached to chordae tendineaechordae tendineae (heart tendons) (heart tendons) which are attached which are attached to to papillary papillary musclesmuscles

• The strings The strings prevent the valves prevent the valves from turning from turning inside-outinside-out

Cardiac MusclesCardiac Muscles• Make up the wall of the heartMake up the wall of the heart• Muscles that are never tiredMuscles that are never tired• Throughout life, the muscles contract Throughout life, the muscles contract

some 70 times per minute, pumping some 70 times per minute, pumping about 5 liters of blood each minute about 5 liters of blood each minute

• The cells are joined end-to-endThe cells are joined end-to-end• Each cell has a single nucleus Each cell has a single nucleus • Cardiac muscles are controlled Cardiac muscles are controlled

involuntarily (contract on their own involuntarily (contract on their own rhythmically)rhythmically)

Cardiac CycleCardiac Cycle

• Sequence of events taking place in Sequence of events taking place in the heart during ONE heartbeatthe heart during ONE heartbeat

• One cycle lasts for about 0.8 secondOne cycle lasts for about 0.8 second• The pumping action of the heart is The pumping action of the heart is

carried out by the contraction and carried out by the contraction and the relaxation of the atria and the relaxation of the atria and ventriclesventricles

• Contraction of the heart – Contraction of the heart – SYSTOLESYSTOLE• Relaxation of the heart - Relaxation of the heart - DIASTOLEDIASTOLE

3 3 Stages of Cardiac Stages of Cardiac CycleCycle

• Atrial systoleAtrial systole (0.1 second) (0.1 second)• Ventricular systoleVentricular systole (0.3 (0.3

second)second)• DiastoleDiastole (0.4 second) (0.4 second)

Total cardiac cycle: 0.8 secondTotal cardiac cycle: 0.8 second

Atrial SystoleAtrial Systole• Just prior to atrial contraction, both Just prior to atrial contraction, both

the atria and ventricles are relaxed the atria and ventricles are relaxed • The semilunar valves connecting the The semilunar valves connecting the

ventricles to the major arteries are ventricles to the major arteries are closed closed

• The valves in the venae cavae and The valves in the venae cavae and pulmonary veins are forced to close by pulmonary veins are forced to close by the high blood pressure in the atriathe high blood pressure in the atria

• However, the atrioventricular However, the atrioventricular (bicuspid/tricuspid) valves that (bicuspid/tricuspid) valves that connect the atria to the ventricles are connect the atria to the ventricles are open open

Atrial SystoleAtrial Systole• Blood flows continually from the veins Blood flows continually from the veins

into the atria, filling these chambers into the atria, filling these chambers • Some of this blood passes through the Some of this blood passes through the

open atrioventricular valves to the open atrioventricular valves to the ventricles ventricles

• When the atria contract, they force the When the atria contract, they force the remaining blood contained in them to remaining blood contained in them to flow into the ventricles flow into the ventricles

• By the end of atrial contraction, the By the end of atrial contraction, the ventricles contain a full supply of blood ventricles contain a full supply of blood while the atria contain virtually nonewhile the atria contain virtually none

Ventricular SystoleVentricular Systole

• The ventricles begin to contract, the The ventricles begin to contract, the pressure within them quickly exceeds pressure within them quickly exceeds that within the atria, forcing the that within the atria, forcing the atrioventricular valves to close atrioventricular valves to close (First heart sound: “lub”)(First heart sound: “lub”)

• As ventricular contraction continues, As ventricular contraction continues, the pressure within the ventricles the pressure within the ventricles reaches a point where it exceeds that reaches a point where it exceeds that in the aorta and the pulmonary in the aorta and the pulmonary arteries arteries

Ventricular SystoleVentricular Systole• At this point, the semilunar valves At this point, the semilunar valves

open, and the blood from the ventricles open, and the blood from the ventricles is ejected through these valves into is ejected through these valves into the aorta and pulmonary arterythe aorta and pulmonary artery

• At about the same time that the At about the same time that the ventricles enter systole, the atria begin ventricles enter systole, the atria begin to relax to relax

• Blood flows into the left atrium from Blood flows into the left atrium from the pulmonary veins and into the right the pulmonary veins and into the right atrium from the superior and inferior atrium from the superior and inferior vena cavae vena cavae

DiastoleDiastole• The ventricles start to relax and the The ventricles start to relax and the

pressure within the ventricles decreases pressure within the ventricles decreases • Once the ventricular pressure becomes Once the ventricular pressure becomes

lower than the pressure in the aorta and lower than the pressure in the aorta and the pulmonary artery, the semilunar the pulmonary artery, the semilunar valves close valves close (Second heart sound: “dup”)(Second heart sound: “dup”)

• As the ventricles fully relax, the As the ventricles fully relax, the ventricular pressure becomes lower than ventricular pressure becomes lower than the pressure in the atria. This allows the the pressure in the atria. This allows the atrioventricular valves to openatrioventricular valves to open

DiastoleDiastole

• Because the ventricles are now in Because the ventricles are now in diastole and the atrioventricular diastole and the atrioventricular valves are open, some of the blood valves are open, some of the blood that has been flowing into the atria that has been flowing into the atria flows through the open valves into flows through the open valves into the ventricles. The ventricles the ventricles. The ventricles reach about 80% of their capacity reach about 80% of their capacity before the atria begin to contract before the atria begin to contract and the cardiac cycle is repeatedand the cardiac cycle is repeated

Cardiac CycleCardiac Cycle

Blood PressureBlood Pressure• Blood pressure is a Blood pressure is a

measurement of the measurement of the force applied to the force applied to the walls of the arteries walls of the arteries as the heart pumps as the heart pumps blood through the blood through the body. The pressure body. The pressure is determined by the is determined by the force and the force and the amount of blood amount of blood pumped, and the pumped, and the size and flexibility of size and flexibility of the arteriesthe arteries

Blood PressureBlood Pressure

• Systolic blood pressureSystolic blood pressure - the - the maximum pressure exerted when the maximum pressure exerted when the heart contractsheart contracts

• Diastolic blood pressureDiastolic blood pressure - the pressure - the pressure in the arteries when the heart is at in the arteries when the heart is at rest rest

• Generally, in adults, the systolic Generally, in adults, the systolic pressure is approximately 120 mmHg, pressure is approximately 120 mmHg, and the diastolic pressure is and the diastolic pressure is approximately 70 to 80 mmHg approximately 70 to 80 mmHg

• The contraction The contraction of the atria of the atria causes a rise in causes a rise in pressure pressure

• The pressure The pressure pushes any pushes any blood left in blood left in the atria into the atria into the ventriclesthe ventricles

• As the ventricles As the ventricles contract the contract the ventricular pressure ventricular pressure begins to rise begins to rise

• As soon as the As soon as the ventricular pressure ventricular pressure surpasses the atrial surpasses the atrial pressure the A-V pressure the A-V valves close (1)valves close (1)

• The rapid closing of The rapid closing of the valves causes a the valves causes a rise in pressure in rise in pressure in the atria the atria

• The pressure in The pressure in the ventricle the ventricle continue to continue to increase increase rapidly rapidly

• The pressure The pressure quickly rises to quickly rises to a point above a point above that of in the that of in the aorta/pulmonaraorta/pulmonary artery (2)y artery (2)

• The aortic and The aortic and pulmonary valves pulmonary valves are forced open are forced open and blood flows and blood flows into the aorta and into the aorta and pulmonary arterypulmonary artery

• When the When the ventricular ventricular pressure becomes pressure becomes lower than the lower than the aortic/pulmonary aortic/pulmonary pressure, the aortic pressure, the aortic and pulmonary and pulmonary valves are forced valves are forced to close (3)to close (3)

• When the When the ventricular ventricular pressure drops pressure drops below that of the below that of the atrial pressure, atrial pressure, the A-V valves the A-V valves open (4)open (4)

• The blood The blood pressure which pressure which has slowly built up has slowly built up in the atria causes in the atria causes blood to quickly blood to quickly flow into the flow into the ventriclesventricles

• Cycle is repeated Cycle is repeated

Effects of exercise on pulse Effects of exercise on pulse raterate

• Increased blood flow to skeletal musclesIncreased blood flow to skeletal muscles• Increased blood flow to heart musclesIncreased blood flow to heart muscles• Increased blood flow to skinIncreased blood flow to skin• In other words, pulse rate will increase In other words, pulse rate will increase

when we exercise when we exercise • The more vigorous the exercise, the The more vigorous the exercise, the

faster the pulse rate (why?)faster the pulse rate (why?)• A greater pulse rate leads to a longer A greater pulse rate leads to a longer

recovery timerecovery time (why?) (why?)

Effects of exercise on pulse Effects of exercise on pulse raterate

• We can use a data logger to We can use a data logger to measure a person’s pulse ratemeasure a person’s pulse rate

• A pulse rate sensor is clipped A pulse rate sensor is clipped to the person’s ear lobe or the to the person’s ear lobe or the tip of the index fingertip of the index finger

• The pulse rate will be shown The pulse rate will be shown on a computeron a computer

Control of Heart BeatControl of Heart Beat• The heartbeat (heart rate) is normally The heartbeat (heart rate) is normally

governed by the frequency of governed by the frequency of electrical signals which are generated electrical signals which are generated by the heart's natural by the heart's natural pacemakerpacemaker

• Electrical signal from the pacemaker Electrical signal from the pacemaker stimulate the cardiac muscles to stimulate the cardiac muscles to contractcontract

• The rate of heart rate can be changed The rate of heart rate can be changed by the action of nerves and hormonesby the action of nerves and hormones

• If the natural pacemaker fails to If the natural pacemaker fails to work, artificial pacemaker may be work, artificial pacemaker may be inserted into the heartinserted into the heart

Blood CirculationBlood Circulation

The blood circulation in humans is The blood circulation in humans is a a double circulationdouble circulation. It consists . It consists of:of:

• Pulmonary circulationPulmonary circulation – – circulation through the lungs and circulation through the lungs and the heartthe heart

• Systemic circulationSystemic circulation – circulation – circulation through the heart and the rest of through the heart and the rest of the bodythe body

The Double CirculationThe Double Circulation

QuestionsQuestions

• What happens during the What happens during the pulmonary circulation?pulmonary circulation?

• What happens during the What happens during the systemic circulation?systemic circulation?

• What is the advantage of What is the advantage of having a double circulation?having a double circulation?

Pulmonary CirculationPulmonary Circulation• Deoxygenated blood is carried Deoxygenated blood is carried

from the body cells to the right from the body cells to the right side of the heart via the venae side of the heart via the venae cavaecavae

• Blood is pumped from the heart to Blood is pumped from the heart to the lungs via the pulmonary artery the lungs via the pulmonary artery

• Blood drops off carbon dioxide and Blood drops off carbon dioxide and picks up oxygen at the lungspicks up oxygen at the lungs

• Oxygenated blood is returned to Oxygenated blood is returned to the left side of the heart via the the left side of the heart via the pulmonary veinpulmonary vein

Systemic CirculationSystemic Circulation

• Oxygenated blood is pumped from the Oxygenated blood is pumped from the left side of the heart to all parts of the left side of the heart to all parts of the body (except the lungs) via the aortabody (except the lungs) via the aorta

• When the blood reaches a particular When the blood reaches a particular organ, oxygen and nutrients are organ, oxygen and nutrients are dropped off whereas carbon dioxide and dropped off whereas carbon dioxide and other wastes are picked upother wastes are picked up

• The venae cavae carries deoxygenated The venae cavae carries deoxygenated blood back to the right side of the heart blood back to the right side of the heart

Advantage of a Double Advantage of a Double CirculationCirculation

• Since the oxygenated blood is Since the oxygenated blood is returned to the heart first, it returned to the heart first, it can be pumped to the rest of can be pumped to the rest of the body under a high pressurethe body under a high pressure

• The high pressure allows blood The high pressure allows blood (containing oxygen/nutrients (containing oxygen/nutrients and carbon dioxide/wastes) to and carbon dioxide/wastes) to be transported rapidly be transported rapidly

Coronary Heart Disease Coronary Heart Disease

• Coronary heart disease develops when Coronary heart disease develops when one or more of the coronary arteries one or more of the coronary arteries that supply blood to the heart become that supply blood to the heart become narrower than they used to be narrower than they used to be

• This happens because of a buildup of This happens because of a buildup of cholesterol and other substances in cholesterol and other substances in the wall of the blood vessel, affecting the wall of the blood vessel, affecting the blood flow to the heart muscle the blood flow to the heart muscle

• Many people experience chest pain or Many people experience chest pain or discomfort from inadequate blood flow discomfort from inadequate blood flow to the heartto the heart

Coronary Heart DiseaseCoronary Heart Disease

As coronary heart disease develops, As coronary heart disease develops, more damage to the heart occurs and more damage to the heart occurs and the following conditions may develop:the following conditions may develop:

• If the heart is not getting enough If the heart is not getting enough oxygen, a person may experience pain oxygen, a person may experience pain or discomfort in the chest known as or discomfort in the chest known as angina angina

• If blood flow to any part of the heart is If blood flow to any part of the heart is completely blocked, the cells in that completely blocked, the cells in that part of the heart begin to die, causing part of the heart begin to die, causing a a heart attackheart attack

Coronary Heart DiseaseCoronary Heart Disease

Treatments:Treatments:• Coronary bypass operationCoronary bypass operation - -

rerouting the blood flow rerouting the blood flow around the obstructed part of around the obstructed part of the artery the artery

• AngioplastyAngioplasty - widen narrowed - widen narrowed or blocked arteries using an or blocked arteries using an inflated ballooninflated balloon

Lymphatic Lymphatic SystemSystem

Tissue fluidTissue fluid LymphLymph

Lymph vesselsLymph vesselsLymph nodesLymph nodes

Lymphatic SystemLymphatic System

Lymphatic SystemLymphatic System

Tissue FluidTissue Fluid• Tissue cells are bathed in tissue Tissue cells are bathed in tissue

fluidfluid• Serves as the medium for the Serves as the medium for the

exchange of materials between exchange of materials between the blood and the cellsthe blood and the cells

• Its composition is similar to that Its composition is similar to that of plasma (contains glucose, of plasma (contains glucose, amino acids, minerals, etc.)amino acids, minerals, etc.)

• However, plasma proteins and However, plasma proteins and RBC’s are too big to pass into the RBC’s are too big to pass into the tissue fluidtissue fluid

Tissue FluidTissue Fluid

• Due to the high pressure of Due to the high pressure of blood at the arterial end, some blood at the arterial end, some plasma in the blood is forced plasma in the blood is forced out through the capillary wall out through the capillary wall into the spaces among the into the spaces among the tissue cells, forming tissue tissue cells, forming tissue fluidfluid

Tissue FluidTissue Fluid

• At the venous end, blood At the venous end, blood pressure has greatly decreased. pressure has greatly decreased. Also, water potential of the Also, water potential of the tissue fluid is higher than that of tissue fluid is higher than that of blood because of the lack of blood because of the lack of plasma proteinsplasma proteins

• Therefore most of the tissue fluid Therefore most of the tissue fluid will return back to the bloodwill return back to the blood

Tissue FluidTissue Fluid

• Tissue fluid also helps to Tissue fluid also helps to regulate blood pressureregulate blood pressure

• If blood pressure is too high, If blood pressure is too high, more fluid will be moved out of more fluid will be moved out of the capillaries the capillaries

• If blood pressure is too low, If blood pressure is too low, less fluid will be moved out of less fluid will be moved out of the capillariesthe capillaries

Lymph VesselsLymph Vessels• Thin-walledThin-walled• Blind-endedBlind-ended• Small lymph capillaries join into larger Small lymph capillaries join into larger

lymph vesselslymph vessels• Fluid inside the lymph vessels (lymph) Fluid inside the lymph vessels (lymph)

moves forward due to the contraction moves forward due to the contraction of surrounding skeletal musclesof surrounding skeletal muscles

• Lymph vessels, like veins, contain Lymph vessels, like veins, contain valves to prevent backflowing of valves to prevent backflowing of lymphlymph

Lymph VesselsLymph Vessels

• Tissue fluid that is not returned to Tissue fluid that is not returned to the capillaries are collected into the capillaries are collected into the lymph vesselsthe lymph vessels

• Lymph in lymph vessels is drained Lymph in lymph vessels is drained into the lymphatic duct and then into the lymphatic duct and then into a large vein near the neck into a large vein near the neck region. Thus all the tissue fluid is region. Thus all the tissue fluid is eventually returned to the eventually returned to the circulatory system circulatory system

Lymph NodesLymph Nodes

• Swellings/filters along lymph Swellings/filters along lymph vessels that produce and store vessels that produce and store white blood cellswhite blood cells

• Viruses, bacteria, cancer cells Viruses, bacteria, cancer cells and other unwanted and other unwanted substances are trapped and substances are trapped and killed by the white blood cells killed by the white blood cells at the lymph nodesat the lymph nodes

What are the functions What are the functions of lymphatic system? of lymphatic system?

• Collects and carries excess tissue Collects and carries excess tissue fluid back to the blood stream fluid back to the blood stream (What happen if the lymph (What happen if the lymph vessels in an organ are blocked?)vessels in an organ are blocked?)

• It consists of lymph nodes for It consists of lymph nodes for filtering unwanted substances. filtering unwanted substances. Lymph nodes also produce white Lymph nodes also produce white blood cells (What type of WBC’s blood cells (What type of WBC’s are produced by the lymph are produced by the lymph nodes?)nodes?)

What are the functions What are the functions of lymphatic system? of lymphatic system?

3) 3) It transports absorbed fats from It transports absorbed fats from lacteals in the small intestine to lacteals in the small intestine to the blood streamthe blood stream

Blocking of Lymph Blocking of Lymph VesselsVessels

• Blocking of lymph vessels and leading Blocking of lymph vessels and leading to the swelling in tissues – to the swelling in tissues – edemaedema

• Due to the accumulation of tissue Due to the accumulation of tissue fluid fluid

• Reasons causing lymph vessels Reasons causing lymph vessels blockage – injury, inflammation, blockage – injury, inflammation, infection, etc.infection, etc.

• ElephantitisElephantitis – lymph vessels are – lymph vessels are blocked by roundworms that are blocked by roundworms that are transmitted by mosquitoestransmitted by mosquitoes