Open circulationOpen circulation This is where blood does This is where blood does

not stay within vessels.not stay within vessels. Low blood pressureLow blood pressure It passes through large It passes through large

blood spaces called a blood spaces called a sinus/haemocoel and sinus/haemocoel and comes in direct contact comes in direct contact with cellswith cells

Eg. insectsEg. insects

The Human cardiovascular systemThe Human cardiovascular system Consists of:Consists of: BloodBlood Blood vessels Blood vessels HeartHeart As the blood always remains As the blood always remains

within vessels it is called a within vessels it is called a closedclosed circulatory system.It does not circulatory system.It does not come in direct contact with body come in direct contact with body cellscells

Advantages: higher blood Advantages: higher blood pressure maintained,faster flow of pressure maintained,faster flow of oxygen & nutrientsoxygen & nutrients

Can be more responsive to Can be more responsive to change and direct blood to where change and direct blood to where it is needed by constriction & it is needed by constriction & dilation of vesselsdilation of vessels

Single Single circulationcirculation

Blood pressure Blood pressure reduced after flowing reduced after flowing through the tiny through the tiny capillaries of the gillscapillaries of the gills

Slow flow to the rest Slow flow to the rest of the bodyof the body

Limits rate of delivery Limits rate of delivery of oxygen and of oxygen and nutrients to tissues nutrients to tissues

Limits activity levelsLimits activity levels

Double CirculationDouble Circulation The blood passes through the heart The blood passes through the heart

TWICETWICE on each circuit of the body on each circuit of the body This means the pressure can be This means the pressure can be

increased again after the lungs to increased again after the lungs to ensure faster delivery of materials to ensure faster delivery of materials to tissues(mammals are active and also tissues(mammals are active and also have to maintain body temperature)have to maintain body temperature)

Body-heart-lung-heart-body.Body-heart-lung-heart-body. Circulation to the lungs is the Circulation to the lungs is the

PULMONARY CIRCULATION PULMONARY CIRCULATION Circulation to the body is theCirculation to the body is the

SYSTEMIC CIRCULATION SYSTEMIC CIRCULATION at a at a higher pressure than pulmonary to higher pressure than pulmonary to avoid damaging delicate capillariesavoid damaging delicate capillaries

The advantage of double The advantage of double circulation is to maintain circulation is to maintain higher blood pressure in higher blood pressure in the circulatory systemthe circulatory system

In single circulation the In single circulation the blood only passes blood only passes through the heart ONCE through the heart ONCE on each circuiton each circuit

Eg FishEg Fish Disadvantage is lower Disadvantage is lower

blood pressure in blood pressure in systemic circulationsystemic circulation

Blood VesselsBlood Vessels ArteriesArteries(smaller = arterioles)-carry (smaller = arterioles)-carry

blood away from the heartblood away from the heart VeinsVeins(smaller = venules)-carry (smaller = venules)-carry

blood back to the heartblood back to the heart CapillariesCapillaries-tiny,thin walled vessels -tiny,thin walled vessels

connect arteries & veinsconnect arteries & veins

Artery StructureArtery Structure

Arteries transport blood away from the Arteries transport blood away from the heart at high pressure to the tissuesheart at high pressure to the tissues

The The properties properties of the artery wall adapt of the artery wall adapt it for its it for its functionfunction : :

Artery –Structure & Artery –Structure & functionfunction

Artery Artery structurestructure

PropertyProperty FunctionFunction

EndotheliumEndothelium

EndotheliumEndothelium- the inner lining of the artery - the inner lining of the artery made up of squamous epithelial cells. made up of squamous epithelial cells. Flat and Flat and smoothsmooth to minimise to minimise friction friction as blood flows.It is as blood flows.It is folded and can unfold when the artery stretchesfolded and can unfold when the artery stretches

LumenLumen(blood space)- this is (blood space)- this is smallsmall to to maintain maintain high blood pressurehigh blood pressure

Artery wallArtery wall – this is thick & strong – this is thick & strong as it as it contains the protein contains the protein collagencollagen to to withstand the withstand the high blood pressure(120mm Hg or 16 kPa)high blood pressure(120mm Hg or 16 kPa)

It contains It contains elastic fibres(protein elastin)-elastic fibres(protein elastin)- allows them to allows them to give give when blood is forced when blood is forced through them- so more in walls nearer the through them- so more in walls nearer the heart. heart.

Then they Then they recoilrecoil they give the they give the blood an blood an extra push.extra push.This also helps even out blood This also helps even out blood flow(though you can still feel a pulse)flow(though you can still feel a pulse)

Both contain Both contain smooth muscle tissuesmooth muscle tissue,more as ,more as you get further from the heart. These you get further from the heart. These muscles can muscles can contract,narrowing(constricting) the contract,narrowing(constricting) the arterioles and arterioles and control blood flow. control blood flow. When When they relax the arteriole dilates.they relax the arteriole dilates.

Vein Structure- Vein Structure- vessels vessels that return blood to the that return blood to the

heartheart

Veins – Structure & Veins – Structure & functionfunction

Walls Walls thinnerthinner – blood pressure much – blood pressure much lower so do not need to be so stronglower so do not need to be so strong

Thinner layers of collagen,elastic Thinner layers of collagen,elastic fibres and smooth muscle.They do fibres and smooth muscle.They do not need to constrict to control flow.not need to constrict to control flow.

Larger lumenLarger lumen to ease blood flow. to ease blood flow. Valves to prevent backflowValves to prevent backflow

Movement of blood Movement of blood through veinsthrough veins

The The low blood low blood pressurepressure means it is means it is harder to return the harder to return the blood to the blood to the heart(less push)heart(less push)

Valves ensure there is Valves ensure there is no back flowno back flow

The valves are semi-The valves are semi-lunar or pocket valveslunar or pocket valves

Movement of blood Movement of blood through veinsthrough veins

Many veins run Many veins run close to skeletal close to skeletal muscles.muscles.

Contraction of Contraction of these muscles these muscles squeezes the squeezes the veins and helps veins and helps move blood move blood through themthrough them

Blood PressureBlood Pressure The pressure of blood pushing The pressure of blood pushing

against the walls of the blood vessel.against the walls of the blood vessel. Mammals have a high blood pressureMammals have a high blood pressure This is useful as it maintains a This is useful as it maintains a fast fast

flowflow of blood through the circulatory of blood through the circulatory system.system.

Measuring Measuring blood blood

pressurepressure

•A cuff that inflates is wrapped around your upper arm and kept in place with Velcro. A tube leads out of the cuff to a rubber bulb.

•Air is then blown into the cuff and increasing pressure and tightening is felt on the upper arm.

•The doctor puts a stethoscope to your arm and listens to the pulse while the air is slowly let out again.

•The systolic pressure(Heart contracting) is measured when the doctor first hears the pulse.

•This sound will slowly become more distant and finally disappear.

•The diastolic pressure(heart relaxing)is measured from the moment the doctor is unable to hear the sound of the pulse.

•The blood pressure is measured in terms of millimetres of mercury (mmHg).

Blood pressure changes in the Blood pressure changes in the circulatory system.circulatory system.

Blood Pressure Changes Blood Pressure Changes during circulationduring circulation

1.1. Pressure is highest in the aorta having just Pressure is highest in the aorta having just been pumped out of the left side of the heartbeen pumped out of the left side of the heart

2.2. Pressure varies during a heart beat(systolic) Pressure varies during a heart beat(systolic) when it is higher and during heart when it is higher and during heart relaxation(diastolic) when it is lower. This relaxation(diastolic) when it is lower. This change in pressure can be felt as a change in pressure can be felt as a pulsepulse

3.3. As blood moves further from the heart the As blood moves further from the heart the pressure drops- due to friction (peripheral pressure drops- due to friction (peripheral resistance) with the walls of the vessels. resistance) with the walls of the vessels. Pulse also disappears due to evening of flowPulse also disappears due to evening of flow

4.4. Largest drop occurs in the arterioles due to Largest drop occurs in the arterioles due to increase in area of wall touching the blood.increase in area of wall touching the blood.

Changes in blood Changes in blood pressurepressure

5. 5. Passing through the narrow capillaries sees a Passing through the narrow capillaries sees a further drop in pressure. Also caused by loss of further drop in pressure. Also caused by loss of tissue fluid from the capillariestissue fluid from the capillaries

6. Venous blood is low in pressure normally about 6. Venous blood is low in pressure normally about 5 mm Hg5 mm Hg

7. Blood returns to the right side of the heart and 7. Blood returns to the right side of the heart and is pumped to the lungs by the right is pumped to the lungs by the right ventricle.Thinner walls than left side so lower ventricle.Thinner walls than left side so lower pressure(again surges in the pressure are seen)pressure(again surges in the pressure are seen)

8. Again pressure drops while passing through the 8. Again pressure drops while passing through the lung arterioles & capillaries and stays low until lung arterioles & capillaries and stays low until returning to the left side of the heart.returning to the left side of the heart.

Capillary structureCapillary structure

Capillary – Structure & FunctionCapillary – Structure & Function

Connect arterioles to Connect arterioles to venulesvenules

Take blood as Take blood as close as close as possiblepossible to all cells in the to all cells in the body – red blood cell may body – red blood cell may be as little as 1be as little as 1μm from a μm from a cellcell

Allowing Allowing rapid transferrapid transfer of of materials between cells & materials between cells & bloodblood

Tiny size allows this- 7Tiny size allows this- 7μm μm diameterdiameter

Similar size to red blood Similar size to red blood cells which must squeeze cells which must squeeze through-slows flow so through-slows flow so oxygen can be exchanged oxygen can be exchanged presses them close to the presses them close to the capillary wallcapillary wall

Capillary – Structure & FunctionCapillary – Structure & Function

Walls of capillaries are only made up of a Walls of capillaries are only made up of a single layer of endothelial cells – very thin single layer of endothelial cells – very thin for fast and easy diffusionfor fast and easy diffusion

Cells have gaps between them making them Cells have gaps between them making them leakyleaky- tissue fluid seeps out into the cells- tissue fluid seeps out into the cells

Comparison of blood vesselsComparison of blood vesselsFeature Artery Vein Capillary

Function

Wall thickness

Wall compositionInner lining

Shape

Lumen

Valves

Blood pressure

Plasma & Tissue Plasma & Tissue FluidFluid

The liquid part of the blood is The liquid part of the blood is plasma plasma it carries it carries the blood cells and many dissolved materialsthe blood cells and many dissolved materials

Tissue FluidTissue Fluid As blood flows through the capillaries As blood flows through the capillaries

fluid leaks out into the spaces around fluid leaks out into the spaces around your cells(one sixth of your body!!)your cells(one sixth of your body!!)

This is TISSUE FLUID-it surrounds our This is TISSUE FLUID-it surrounds our cells and allows exchange of materials-cells and allows exchange of materials-will contain Owill contain O22,nutrients etc,nutrients etc

Identical to plasma Identical to plasma except except does not does not contain red blood cells,though some contain red blood cells,though some white cells can squeeze outwhite cells can squeeze out

Contains Contains less proteinsless proteins as these are as these are too too largelarge to pass out to pass out

Factors controlling Factors controlling movement of tissue fluidmovement of tissue fluid

Blood pressureBlood pressure: (hydrostatic : (hydrostatic pressure) forces fluid out at the pressure) forces fluid out at the arteriole end of the capillary bedarteriole end of the capillary bed

Osmotic pressure (solute Osmotic pressure (solute pressure)pressure) : returns fluid to the blood : returns fluid to the blood at the venule end at the venule end

Overall net flow Overall net flow OUTOUT into the tissues into the tissues

Arteriole end Venule end

4.3

1.1

Hydrostatic pressure

solute pressure(water potential)

-1.3

-3.3

Net outflow 1.2kPa

1.6

1.1

-3.3

-1.3

Net inflow -1.5kPa

Arterial endArterial end Effective HP = 4.3-1.1 = 3.2kPa(out)Effective HP = 4.3-1.1 = 3.2kPa(out) Effective SP = -3.3-(-1.3) = -2kPa(in)Effective SP = -3.3-(-1.3) = -2kPa(in) Overall effective blood P = 3.2-2=1.2 kPa Overall effective blood P = 3.2-2=1.2 kPa Fluid pushed outFluid pushed out

Venule endVenule end Effective HP = 1.6-1.1=0.5 kPa(out)Effective HP = 1.6-1.1=0.5 kPa(out) Effective SP =-3.3-(-1.3)=-2kPa(in)Effective SP =-3.3-(-1.3)=-2kPa(in) Overall effective blood P= 0.5 -2 = -1.5 kPaOverall effective blood P= 0.5 -2 = -1.5 kPa Fluid pushed back into capillaryFluid pushed back into capillary

The Lymphatic systemThe Lymphatic system About 90% of fluid About 90% of fluid

that leaks from the that leaks from the capillaries returns to capillaries returns to themthem

10% does not - and 10% does not - and must be drained away must be drained away by lymph vesselsby lymph vessels

These vessels form These vessels form the lymphatic systemthe lymphatic system

The Lymphatic systemThe Lymphatic system

Lymph VesselsLymph Vessels Tiny,dead end vessels Tiny,dead end vessels

which are found in which are found in almost all tissuesalmost all tissues

Fluid enters them Fluid enters them through through tiny valvestiny valves

This fluid is called This fluid is called lymphlymph and is virtually and is virtually identical to tissue fluididentical to tissue fluid

Lymph vesselsLymph vessels The tiny valves allow The tiny valves allow large large

proteinsproteins to enter the to enter the lymph(cannot enter the lymph(cannot enter the blood capillary)blood capillary)

With outWith out them protein them protein would build up in your tissue would build up in your tissue fluid causing fluid causing oedemaoedema

(Water(Water leaving your blood leaving your blood causing swelling of tissues)causing swelling of tissues)

And death within 24 hoursAnd death within 24 hours

LymphLymph In some parts of the In some parts of the

body the lymph has body the lymph has differences:differences:

Small intestine Small intestine lymphlymph will contain will contain high amounts of high amounts of lipidslipids after a meal after a meal

The The villivilli contain a contain a lymph vessel(a lymph vessel(a lacteallacteal),which ),which absorbs digested fatsabsorbs digested fats

LymphLymph Tissue fluid and lymph in the Tissue fluid and lymph in the

liver has high concentrations liver has high concentrations of proteins.of proteins.

Lymph is moved through the Lymph is moved through the vessels very slowly(100cmvessels very slowly(100cm³/h ³/h – blood 80cm³/sec!)– blood 80cm³/sec!)

Contraction of skeletal Contraction of skeletal muscles help this andmuscles help this and

also the vessels have smooth also the vessels have smooth muscle in their walls which muscle in their walls which contracts to squeeze lymph contracts to squeeze lymph alongalong

Lymph eventually drains back Lymph eventually drains back into the blood in the into the blood in the subclavian veinssubclavian veins

Lymph Lymph NodesNodes

Found at intervals in the lymphatic Found at intervals in the lymphatic system system

Involved in protection from diseaseInvolved in protection from disease Microbes are filtered from the lymph as it Microbes are filtered from the lymph as it

passes through the lymph nodes by white passes through the lymph nodes by white blood cells - blood cells - lymphocyteslymphocytes

Comparison of blood,tissue fluid and Comparison of blood,tissue fluid and lymphlymph

Feature Blood plasma Tissue fluid lymph

Proteins

Fats

Glucose

Amino acids

Oxygen

Carbon dioxide

Cells

The cardiac cycleThe cardiac cycle The heart beats on average 70bpmThe heart beats on average 70bpm The The cardiac cyclecardiac cycle is the events that is the events that

take place in one heart beat.take place in one heart beat.

The cardiac cycleThe cardiac cycle1.1. Atrial systole(0.1s)Atrial systole(0.1s) Heart full of blood . Heart full of blood .

Atria walls contract, Atria walls contract, blood pushed through blood pushed through the AV valves into the the AV valves into the ventricles.Valves in ventricles.Valves in the vena cava and the vena cava and pulmonary vein pulmonary vein prevent backflow.prevent backflow.

2. Ventricular systole(0.3s)2. Ventricular systole(0.3s) Thick ventricle muscle walls Thick ventricle muscle walls

contract.This produces a contract.This produces a higher pressure.Blood is higher pressure.Blood is forced into the PA and forced into the PA and aorta, through the aorta, through the semilunar valves which are semilunar valves which are forced open. forced open.

Papillary muscles also Papillary muscles also contract to pull on the contract to pull on the tendons, stopping the tendons, stopping the closed AV valve flaps closed AV valve flaps turning inside out.turning inside out.

3.Ventricular diastole3.Ventricular diastole Ventricle and atrial Ventricle and atrial

muscles are relaxed. muscles are relaxed. heart begins to fill heart begins to fill with blood starting in with blood starting in the atria . Blood the atria . Blood pressure in the aorta pressure in the aorta and pulmonary artery and pulmonary artery shuts the semi lunar shuts the semi lunar valves valves

Heart valvesHeart valves Semilunar valveSemilunar valve Consists of 3 Consists of 3

pockets in half pockets in half moon shapemoon shape

Blood flowing Blood flowing through pushes through pushes past the pocketspast the pockets

When it tries to When it tries to return it will fill return it will fill the pockets the pockets closing the valve.closing the valve.

Pressure changes in the heart during the Pressure changes in the heart during the cardiac cyclecardiac cycle

1.1. Atria contract (atrial systole)Atria contract (atrial systole)2.2. ventricular systole begins. ventricular systole begins.

When pressure in the ventricle When pressure in the ventricle exceeds pressure in the atria exceeds pressure in the atria AV valves shut.AV valves shut.

3.3. Ventricular systole,rapid Ventricular systole,rapid increase in pressure as increase in pressure as ventricles contractventricles contract

4.4. Pressure in ventricle exceeds Pressure in ventricle exceeds that in aorta, semilunar valves that in aorta, semilunar valves open.open.

5.5. Maximum systolic Maximum systolic pressure,ventricles now start to pressure,ventricles now start to relaxrelax

6.6. Pressure in ventricles drops Pressure in ventricles drops below aorta.SL valves shutbelow aorta.SL valves shut

7.7. Wave of contraction running Wave of contraction running down aorta raises pressuredown aorta raises pressure

8.8. Ventricular diastole startsVentricular diastole starts9.9. Blood starts to refill the atria Blood starts to refill the atria

increasing pressureincreasing pressure10.10. When pressure exceeds When pressure exceeds

ventricle, AV valves open and ventricle, AV valves open and blood flows into the ventriclesblood flows into the ventricles

(a) Atrial systole (b) ventricular systole

Control of Heart beatControl of Heart beat Cardiac(heart)muscle contracts by Cardiac(heart)muscle contracts by

itselfitself. It does not need a nerve supply(only . It does not need a nerve supply(only muscle in the body that does this)muscle in the body that does this)

It is said to be It is said to be MYOGENICMYOGENIC- if cardiac - if cardiac muscle cells are cultured-they will beat muscle cells are cultured-they will beat with their own rhythm with their own rhythm

Muscles that need a nerve impulse sent to Muscles that need a nerve impulse sent to them to cause contraction are called them to cause contraction are called NEUROGENICNEUROGENIC

Control of heart beatControl of heart beat

The PacemakerThe Pacemaker The heart beat is initiated by a patch of The heart beat is initiated by a patch of

tissue in the wall of the right atriumtissue in the wall of the right atrium Called the Called the SINOATRIAL NODESINOATRIAL NODE(SAN)- (SAN)-

naturally beats at 70 bpmnaturally beats at 70 bpm This sets the This sets the rhythmrhythm for the heart so is for the heart so is

called the called the pacemakerpacemaker It starts a It starts a wave of electrical activitywave of electrical activity- -

which spreads across the atria-causing which spreads across the atria-causing them to contract them to contract

The ATRIOVENTRICULAR The ATRIOVENTRICULAR NODE(AVN)NODE(AVN)

The electrical wave The electrical wave cannotcannot spread straight to spread straight to the ventriclesthe ventricles

There is a band of There is a band of non conducting fibresnon conducting fibres between the atria and ventriclesbetween the atria and ventricles

Electrical wave has to first go to the Electrical wave has to first go to the AVNAVN and and then down the then down the SEPTUMSEPTUM in the in the BUNDLE OF HISBUNDLE OF HIS and then in and then in PURKYNE TISSUEPURKYNE TISSUE.to the ventricles.to the ventricles

It then spreads It then spreads UPUP the ventricle walls from the the ventricle walls from the base,causing them to contractbase,causing them to contract

Why does this happen?Why does this happen?

Changing the heart rateChanging the heart rate Left alone the heart rate would be 70 bpmLeft alone the heart rate would be 70 bpm Why would this be a problem?Why would this be a problem? Heart rate can be Heart rate can be slowedslowed or or increasedincreased 1.1. By By nervesnerves from the from the cardiovascular centrecardiovascular centre of the of the

brain to the SANbrain to the SAN Stimulating the Stimulating the sympathetic nervesympathetic nerve speeds upspeeds up the the

heart rate(neurotransmitter – noradrenaline)heart rate(neurotransmitter – noradrenaline) Stimulating the Stimulating the parasympathetic(vagus) nerveparasympathetic(vagus) nerve

slows the heart rateslows the heart rate(neurotransmitter - acetyl (neurotransmitter - acetyl choline)choline)

2. By the 2. By the hormone hormone ADRENALINEADRENALINE secreted by the secreted by the adrenal glands,to heart in the blood -this adrenal glands,to heart in the blood -this speeds upspeeds up heart rateheart rate

Cardiac muscleCardiac muscle

Cardiac Muscle StructureCardiac Muscle Structure Consists of cylindrical branching fibresConsists of cylindrical branching fibres Form a 3D structureForm a 3D structure Very well supplied with Very well supplied with mitochondriamitochondria and and

blood capillariesblood capillaries(from coronary artery) (from coronary artery) Cells joined by special Cells joined by special intercalated discsintercalated discs,pass ,pass

the electrical wave rapidly between cells,helped the electrical wave rapidly between cells,helped by the by the branchingbranching-so they all contract almost at -so they all contract almost at onceonce

Long refractory periodLong refractory period(time when muscle will (time when muscle will not contract),means it has a recovery time so it not contract),means it has a recovery time so it can continue beating without tiringcan continue beating without tiring

ElectrocardiogramElectrocardiogram Electrodes are placed Electrodes are placed

over the opposite sides over the opposite sides of the heartof the heart

The electrical potentials The electrical potentials generated are generated are measuredmeasured

Shows the wave of Shows the wave of electrical activity electrical activity passing through the passing through the heartheart

ECG graphECG graph The ECG graph shows The ECG graph shows

a plot of voltage a plot of voltage against timeagainst time

P wave atria P wave atria contractingcontracting

QRS wave ventricles QRS wave ventricles contractingcontracting

T wave recovery of the T wave recovery of the ventriclesventricles

Diagnosis using ECGDiagnosis using ECG Abnormal ECG trace can identify:Abnormal ECG trace can identify: Myocardial infarction Myocardial infarction (heart attack)(heart attack) FibrillationFibrillation (atrial or ventricular) (atrial or ventricular) Ventricular hypertrophy Ventricular hypertrophy (increase in (increase in

muscle thickness)muscle thickness) Heart block Heart block (problems with the (problems with the

movement of the electrical signals movement of the electrical signals between parts of the heart)between parts of the heart)

ArrhythmiaArrhythmia(irregular heart beat) (irregular heart beat) bradycardia and tachycardia bradycardia and tachycardia

Heart muscle Heart muscle respires fatty respires fatty acidsacids

This can only be This can only be aerobicaerobic

Any lack of Any lack of oxygen will oxygen will cause cells to cause cells to die leading to a die leading to a heart attackheart attack

http://www.cableguy.net/ECG/2nddegreeavblockvariation2.gif

FibrillationFibrillation

No regular heart rhythm No regular heart rhythm So no cardiac outputSo no cardiac output Patient will lose consciousness and life threatenedPatient will lose consciousness and life threatened Defibrillation passes a large voltage through the Defibrillation passes a large voltage through the

heart,stopping it and allowing pacemaker to heart,stopping it and allowing pacemaker to restart in natural rhythmrestart in natural rhythm

Heart SoundsHeart Sounds

Heart murmursHeart murmurs Abnormal heart Abnormal heart

soundssounds Can be due to Can be due to

leaking valves, leaking valves, thickened or thickened or abnormal valvesabnormal valves

Often “innocent Often “innocent murmurs” common murmurs” common in childhood with no in childhood with no danger to healthdanger to health