Human Biology Exchange Essay

7/28/2019 Human Biology Exchange Essay

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HUMAN BIOLOGY MR MORGAN

SPECIAL SURFACES FOR EXCHANGE

WHY ORGANISMS NEED THEM

All LIVING cells need CERTAIN substances to keep ALIVE:

OXYGEN AEROBIC RESPIRATION GLUCOSE acts an ENERGY SOURCE OGPFWM PROTEINS needed for GROWTH & REPAIR FATS for making MEMBRANES + act as an ENERGY STORE WATER MINERALS for MAINTAINING WATER POTEN. And for ENZYME ACTION + METABOLISM

Organisms may take these in DIRECTLY FROM ENVIRONMENTOr into their CYTOPLASM FOR METABOLISM PROCESSES

Also need to REMOVE WASTE PRODUCTS from such activities in cytoplasm:

CARBON DIOXIDE OXYGEN (in PLANTS FROM PHOTOSYNTHESIS) Other wastes e.g. UREA AND AMMONIA

SINGLE CELLED/SMALL ORGANISMS can exchange such substances ACROSS THEIR SURFACES

They have LARGE SURFACE AREA-TO-VOLUME RATIOLARGE, MULTICELLUR ORGANISIMS these need EXCHANGE SURFACES

They have SMALL SURFACE-AREA-TO-VOLUME RATIO and cells need MORE SUPPLY: theouter surface is NOT LARGE ENOUGH to EFFICIENTLY supply cells with what they need.

Substances also have to TRAVEL FURTHER DISTANCES from the OUTER TO INNER CELLSAs do WASTE PRODUCTS

LARGER organisms need LARGE EXCHANGE SURFACES, + OFTEN A TRANSPORT SYSTEM to move

such substances around the body.

EXCHANGE SURFACE PROPERTIES

GOOD exchange surfaces have:

LARGE SURFACE AREA so there is MORE SPACE for molecules to pass through (often doneby FOLDING MEMBRANES/WALLS)

THIN BARRIER REDUCES diffusion DISTANCE FRESH SUPPLY of molecules to MAINTAIN CONCENTRATION GRADIENT (a HIGH CONC.) REMOVAL of REQUIRED molecules on the OTHER SIDE to keep CONCENTRATION LOW

LAST 3 needed for a STEEP DIFFSION GRADIENT

+ SOME exchange surfaces use ACTIVE TRANSPORT MECHANISMS.


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EXAMPLES OF SPECIALISED EXCHANGE SURFACES

Also found at IN ORGANS to REMOVE SUBSTANCES into the transport system

ALVEOLI the WALLS are exchange surfaces to permit GASEOUS EXCHANGE SMALL INTENSTINE NUTRIENTS are ABSORBED LIVER LEVELS of SUGAR are adjusted

ROOT HAIRS WATER AND MINERALS absorb

EXCHANGE SURFACEa SPECIALISED AREA that is ADAPTED to make it EASIER FOR MOLECULES

TO CROSS from ONE SIDE of the SURFACE to the OTHER

THE LUNG AS ORGAN OF EXCHANGETHE LUNGS

A PAIR of INFLATABLE STRUCTURES; in the CHEST CAVITY

Air passes via the NOSE, along the TRACHEA BRONCHI BRONCHIOLES

Each is ADAPTED to its function the PASSING OF AIRAir then reaches ALVEOLI these PERMIT GASEOUS EXCHANGE

The lungs PROTECTED BY RIBS their movement + MOVEMENT OF DIAPHRAGM produces

VENTILATION (breathing movements)

GASEOUS EXCHANGE IN LUNGS

Gases PASS THROUGH THIN WALLS of the alveoli

OXYGEN passes into the BLOOD in the CAPILLIARIES CARBON DIOXIDE passes FROM BLOOD into the AIR OF ALVEOLI

HOW ARE LUNGS ADAPTED FOR THIS EXCHANGE

LARGE SURFACE AREA

Provides MORE SPACE for passing molecules:ALVEOLI = 100-300um across but there are NUMEROUS AMOUNTS so TOTAL SURFACE

AREA is MUCH LARGER than surface of our skin

BARRIER PERMEABLE TO OXYGEN AND CARBON DIOXIDE

PLASMA MEMBRANES which surround THIN CYTOPLASM of the cells = THE EXCHANGEBARRIER

READILY ALLOWS the diffusion of OXYGEN + CO2

THIN BARRIER REDUCES DIFFUSION DISTANCE

NO. OF ADAPTATIONS:-ALVEOLUS = ONE CELL THICK

CAPILLARY WALL = ONE CELL THICK

BOTH consist of SQUAMOUS CELLS = very THIN/FLATTENED cells

CLOSE CONTACT of the CAPILLARIES & ALVEOLUS WALLSNARROW CAPILLARIES causes the red blood cells to be SQUEEZED AGAINST the WALLS

which makes them CLOSER TO AIR in the ALVEOLI + also REDUCES their RATE OF FLOW

TOTAL BARRIER = 2 (TWO) flattened cells, LESS THAN 1um thick


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THIN layer of MOISTURE lining ALVEOLI

Passes through CELL MEMBRANES to CYTOPLASM of ALVEOLUS CELLS When BREATHED OUT it EVAPORATES and is lost

Lungs MUST produce substance SURFACTANT to REDUCE COHESIVE FORCES BETWEEN WATER

MOLECULES

WITHOUT, alveolus would COLLAPSE due to cohesive forces of lining water moleculesMAINTAINING DIFFUSION GRADIENT

RAPID diffusion a STEEP DIFFUSION GRADIENT is needed

Meaning HIGH CONC. Of MOLECULES on SUPPLY SIDE/a LOW SUPPLY on DEMAND SIDETo MAINTAIN a FRESH SUPPLY of molecules ONE SIDE needed to keep CONC. HIGH THERE

+ a SYSTEM to REMOVE MOLECULES DEMAND SIDE to keep the conc. LOW

Achieved by VENTILATION MOVEMENTS and the BLOOD TRANSPORT SYSTEMBLOOD brings CARBON DIOXIDE from TISSUES to LUNGS

Ensures LARGER (HIGH) CONC. In the BLOOD than in air of alveoli+ also carries OXYGEN AWAY FROM LUNGS to ensure LOWER OXYGEN CONC. in the BLOOD

than in the air of alveoli (HIGH OXYGEN CONC. IN ALVEOLI AIR)

PULMONARY ARTERY pumps BLOOD TO LUNGS

In LUNGS, this DIVIDES SMALLER into CAPILLARIES which COVER SURFACE OF ALVEOLICAPILLARIES are VERY NARROW = SQUEEZES red blood cells through ONE AT A TIME

BREATHING MOVEMENTS VENTILATE the lungs

Replace USED AIR with FRESH air brings more OXYGEN INTO lungs to maintain a HIGHOXYGEN CONC. in the ALVEOLI

Means it is HIGHER THAN IN BLOOD

VENTILATION also REMOVES CARBON DIOXIDE from the ALVEOLI

Maintains a LOW CARBON DIOXIDE CONC. in them, LOWER THAN IN BLOODCONSTANT SUPPLY of such gases on ONE SIDE & its REMOVAL OTHER SIDE, maintains a STEEP

DIFFUSION GRADIENT so gaseous exchange continues


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INHALING = INSPIRATION

DIAPHRAGM CONTRACTS to become FLATTER/pushes DIGESTIVE ORGANS DOWN EXTERNAL INTERCOSTAL MUSCLES these CONTRACT/RAISE RIBS Chest cavity VOLUME INCREASES AIR INTO the lungs

EXHALING = EXPIRATION

DIAPHRAGM RELAXES and PUSHED UP by displaced organs EXTERNAL INTERCOSTAL MUSCLES these RELAX/RIBS FALL Chest cavity VOLUME DECREASES AIR OUT of the lungsTISSUES IN THE LUNGS

THE LUNGS

There is the TRACHEA, BRONCHI AND BRONCHIOLES which ALLOW AIR INTO and OUT LUNGS

ADAPTED for EFFECTIVE passage of air through these airways:- LARGER airways = large ENOUGH to allow SUFFICIENT AIR FLOW with NO OBSTRUCTIONS Must DIVIDE SMALLER to deliver air TO ALL ALVEOLI Air ways must be STRONG ENOUGH to PREVENT COLLAPSING when air PRESSURE in the

lungs is LOW (during INHALATION)

Be FLEXIBLE Able to STRETCH + RECOIL

TRACHEA & BRONCHI

Have SIMILIAR STRUCTURES; DIFFER only in SIZE:TRACHEA WIDER/BRONCHI NARROWER

BOTH have relatively THICK WALLS/have SEVERAL LAYERS of TISSUEConsists mainly of CARTILAGE:-

C-SHAPED RINGS in the TRACHEA LESS REGULAR in the BRONCHI

INSIDE SURFACE there is layer of GLANDULAR TISSUE, CONNECTIVE TISSUE, ELASTICFIBRES, SMOOTH MUSCLE (and BLOOD VESSELS)

INNER LINING = an EPITHELIUM LAYER consists of TWO TYPES of cell CILIATED EPITHELIUM GOBLET CELLS

BRONCHIOLES

NARROWER than the bronchi

LARGER ones some CARTILAGE SMALLER NO CARTILAGE WALLS made mainly of SMOOTH MUSCLE and ELASTIC FIBRES SMALLEST bronchioles have attached ALVEOLI at their ends


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ROLE OF EACH TISSUE

CARTILAGE

A type of ELASTIC CONNECTIVE TISSUE found in the TRACHEA & BRONCHI which acts as SUPPORT

C-SHAPED RINGS which keep AIRWAY OPEN when PRESSURE LOW in the lungs(INHALATION)

NOT COMPLETE RINGS = FLEXIBILITY (neck can be MOVED WITHOUT CONSTRICTINGairway) + allows OESOPHAGUS to EXPAND during swallowing

SMOOTH MUSCLE

Type of INVOLUNTARY MUSCLE; allows for INVOLUNTARY MOVEMENTS e.g. BREATHING and

usually found in SOME INTERNAL ORGANS.

CONTRACTS to CONSTRICT AIRWAY; this NARROWS LUMEN of the airwayNamely in the BRONCHIOLES

Narrowing RESTRICTS AIR FLOW which can PREVENT HARMFUL SUBSTANCESENTERING the lungs which could cause infection

ASTHMA people who are ALLERGIC to SUBSTANCES IN AIR causes thisINVOLUNTARY MOVEMENT, making breathing difficult

ELASTIC FIBRES

LONG fibres, DEFORMED BY SMOOTH MUSCLE and are a type of PROTEIN ELASTIN

smooth muscle CANT UNDO NARROWING OF LUMEN Elastic fibres RECOIL TO ORIGINAL SIZE/SHAPE when SMOOTH MUSCLE

RELAXES

This WIDENS/DILATES the LUMENGOBLET CELLS/GLANDULAR TISSUE

Found BENEATH EPITHELIUM (particularly in the trachea) and SECRETE MUCUS The MUCUS = GLYCOPROTEIN Mucus TRAPS TINY PARTICLES from the air which could be HARMFUL

SUBSTANCES/BACTERIA

Trapping such things REDUCES CHANCE OF INFECTIONCILIATED EPITHELIUM

The EPITHELIUM consists of CILIATED CELLS

CILIATED CELLS have numerous TINY, HAIR-LIKE EXTENSIONS projecting from CELLMEMBRANE

These extensions = CILIA CILIA move in a SYNCHRONISED PATTERN, so that MUCUS can be WAFTED

UP the AIRWAY, to back of throat so it can be SWALLOWED

ACID IN STOMACH = will KILL ANY BACTERIA


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MEASURING LUNG CAPACITYBREATHING

To breathe, DIAPHRAGM and INTERCOSTAL MUSCLES CONTRACT and RELAX

EXERCISING/FRIGHTENED = breathing is MORE RAPID/DEEPER Means MORE OXYGENATED AIR INTO lungs/CARBON DIOXIDERICH AIR

OUTELEMENTS OF LUNG VOLUME

TIDAL VOLUME:-

The vol. of air MOVED IN & OUT of the lungs with EACH BREATH AT REST

(approx. 0.5dm3)VITAL CAPACITY:-

LARGEST (max.) vol. of air MOVED IN & OUT of the lungs in ONE BREATH

(approx. 5.0dm3 but VARIES BETWEEN MEN/WOMEN/AGE/SIZE + regular exercise)RESIDUAL VOLUME:-

Vol. of air that ALWAYS REMAINS IN LUNGS, even AFTER BIGGEST POSSIBLE EXHALATION

(approx. 1.5dm3)DEAD SPACE:-

AIR found in the TRACHEA, BRONCHI & BRONCHIOLES

NO gas exchange in these areasINSPIRATORY RESERVE VOLUME:-

HOW MUCH MORE AIR can be breathed IN, OVER and ABOVE TIDAL VOLUME when a BIG breath is

taken

This reserve CALLED ON DURING EXERCISEEXPIRATORY RESERVE VOLUME:-

HOW MUCH MORE AIR can be breathed OUT, OVER and ABOVE amount breathed in a TIDAL VOL.

BREATH

These volumes can be shown on a TRACE DIAGRAM:

SHOWS A

LUNG

VOLUMEGRAPH:

ON A

SPIROMETER

VOLUME

GRAPH:

INSPIRATORY AND

EXPIRATORY

RESERVES SWAP


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SPIROMETERS AND LUNG VOLUME

SPIROMETERS can MEASURE VITAL CAPACITY, TIDAL VOLUME, BREATHING RATE and OXYGEN

UPTAKE

Spirometers CONSIST OF:

CHAMBER filled with OXYGEN it FLOATS on a TANK OF WATER Person BREATHES IN from a DISPOSABLE MOUTHPIECE ATTACHED (FOR

SAFETY) TO A TUBE CONNECTED TO OXYGEN CHAMBER

OXYGEN used in MEDICAL GRADE (FOR SAFETY) BREATHING IN oxygen from chamber, causes CHAMBER TO SINK DOWN BREATHING OUT (into the chamber), causes CHAMBER TO FLOAT UP MOVEMENT OF CHAMBER is RECORDED using a DATALOGGER

This produces a SPIROMETER TRACEPerson breathing can be asked to do so at REST, AFTER EXERCISE or to take DEEP BREATHS

So DIFFERENT BREATHING PATTERNS can be recorded.MEASURING OXYGEN UPTAKE

Breathing IN & OUT causes a DANGEROUS BUILD UP OF CARBON DIOXIDE in the chamber

To AVOID THIS, SODA LIME is used to ABSORB EXHALED CO2 (FOR SAFETY) Which causes TOTAL VOL. of gas in spirometer to DECREASE

VOL. OF CO2 = VOL. OF OXYGEN BREATHED IN...

...TOTAL REDUCTION = VOL. OF OXYGEN USED TO BREATHE IN & OUT

So CALCULATIONS can be made of USE OF OXYGEN under DIFFERENT BREATHING CONDITIONS

INTERPRETING SPIROMETER TRACES:

TO CALCULATEOXYGEN UPTAKE:

1. Find the REDUCTION inchamber using Y-AXIS

2. Find TIME TAKEN for reduction3. DIVIDE REDUCTION BY TIME

TAKEN

EXAMPLE:

0.3 dm3 = (REDUCTION)

55 seconds = (TIME TAKEN (s))

0.3/55 = uptake in SECONDS

0.3X60/55 = uptake in MINUTES

Unit: dm3 min-1


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TRANSPORT IN ANIMALSTRANSPORT - the MOVEMENT of OXYGEN, NUTRIENTS, HORMOMES, WASTE & HEAT around the

body

LARGE ANIMAL TRANSPORT

ALL LIVING CELLS require OXYGEN SUPPLY + NUTRIENTS so that they SURVIVE Must also REMOVE WASTES to AVOID TOXIC BUILD UP

SMALL animals DONT need a SEPARATE TRANSPORT SYSTEM as ALL theircells are NEAR/SURROUNDED by the EXTERNAL ENVIRONMENT

SMALL ANIMALS = DIFFUSION alone, ENOUGH for their supply of oxygen/nutrientsAnimals with 2+ LAYERS OF CELLS, diffusion ALONE = TOO SLOW

3 (THREE) factors AFFECT NEED FOR TRANSPORT SYSTEM: SIZE SURFACE- AREA-TO-VOLUME RATIO LEVEL OF ACTIVITY

SIZE

Animals with SEVERAL LAYERS OF CELLS = OUTER CELLS will USE UP diffusing nutrients/oxygen

So WILL NOT REACH INNER MOST CELLSSURFACE-AREA-TO-VOLUME RATIO

SMALL animals = LARGE SURFACE-AREA-TO-VOLUME ratio

This is AFFECTED by SHAPE e.g. FLATWORMS: have THIN/FLAT bodies giving large S-A-T-V R

but this LIMITS THEIR SIZE To GROW LARGE, animals will need RANGE OF TISSUES & STRUCTUAL

support for BODY STRENGTH:

VOLUME INCREASES/BODY GETS THICKER but SURFACE AREA DOESNT increase as much

Hence LARGE ANIMALS = RELATIVELY SMALL S-A-T-V R So is NOT LARGE to SUPPLY ALL required oxygen/nutrients needed by cells

LEVEL OF ACTIVITY

Animals need ENERGY FROM FOOD so they can MOVE

RELEASING ENERGY from food requires RESPIRATION RESPIRATION needs OXYGEN

VERY ACTIVE animals their CELLS NEED MORE ENERGY, so NEED GOOD SUPPLY OF OXYGEN and

NUTRIENTS so that SUFFICIENT RESPIRATION takes place to provide the necessary energy

WARM-BLOODED animals = EVEN MORE ENERGYFEATURES OF EFFECTIVE TRANSPORT SYSTEM

Will need to include:

1. A FLUID/MEDIUM to CARRY nutrients/oxygen around body this is BLOOD2. A PUMP to create PRESSURE to PUSH FLUID around the body the HEART3. EXCHANGE SURFACES so that oxygen/nutrients can ENTER BLOOD and LEAVE IT AGAIN

where NEEDED

4. TUBES/VESSELS TO CARRY the blood5. TWO CIRCUITS one to PICK UP OXYGEN/another to DELIVER OXYGEN to the TISSUES


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SINGLE AND DOUBLE CIRCULATORY SYSTEMS

Example of a SINGLE CIRCULATORY SYSTEM = the FISH

Blood flows FROM HEART TO GILLS, then to the GILLS TO BODY then BACK TO HEARTHEARTGILLS BODYHEART

MAMMALS have a circulation WITH TWO SEPARATE CIRCUITS DOUBLE CIRCULATORY SYSTEM

ONE CIRCUIT: carries BLOOD FROM HEARTLUNGS the PULMONARY CIRCULATION SECOND CIRCUIT: carries the OXYGEN & NUTRIENTSAROUND THE BODY the SYSTEMIC

CIRCULATION

MAMMALIAN HEART adapted to have TWO (2) PUMPS one for EACH CIRCULATION

BLOOD goes through HEART TWICE FOR EACH COMPLETECIRCULATION of the bodyHEARTBODYHEARTLUNGS HEART

PULMONARY CIRCULATION pumps DEOXYGENATED BLOOD to the LUNGS to pick up oxygen

SYSTEMATIC CIRCULATION carries NEWLY OXYGENATED BLOOD to the BODY (TISSUES)

RIGHT SIDE of the heart pumps blood to LUNGS (picks up oxygen - DEOXYGENATED)FROM LUNGS, travels to LEFT SIDE OF HEART, to pump the blood to THE BODY (OXYGENATED)

When BLOOD RETURNS to the heart, ENTERS RIGHT SIDE (DEOXYGENATED)

DOUBLE CIRCULATION ADVANTAGES

EFFICIENT circulatory system = QUICK DELIVERY of oxygen and nutrients to PARTS OF BODY (where

they are needed)

SINGLE system:

BLOOD PRESSURE is REDUCED so it will NOT flow as QUICK to rest of body This LIMITS RATE in which oxygen/nutrients gets DELIVERED to respiring tissues

FISH = NOT AS ACTIVE AS MAMMALS + they DONT need to MAITAIN BODYTEMP.

So they need LESS ENERGY; their single system is SUFFICIENT FOR THEIR NEEDS

DOUBLE system:

The HEART can INCREASE PRESSURE OF BLOOD AFTER passing through the LUNGS so that itFLOWS FASTER TO BODY TISSUES

SYSTEMATIC circulation can CARRY BLOOD AT HIGHER PRESSURE THAN PULMONARYcirculation

Must NOT be TOO HIGH in PULMONARY as it could damage DELICATECAPILLARIES IN LUNGS

MAMMALS are ACTIVE + need to MAINTAIN BODY TEMP.

BOTH require ENERGY FROM FOOD via respiration To release LOTS ENERGY = GOOD SUPPLY of oxygen and nutrients


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STRUCTURE OF MAMMALIAN HEARTTHE HEART

Is a MUSCULAR DOUBLE PUMP

DIVIDED into TWO SIDES RIGHT SIDE pumps DEOXYGENATED blood to LUNGS to be oxygenated LEFT-SIDE pumps blood to the BODY (TISSUES)

BOTH sides apply PRESSURE to the BLOOD by SQUEEZING, forcing the blood INTO theARTERIES

EXTERNAL FEATURES OF HEART

It sits SLIGHTLY OFF CENTRE to LEFT of the chest cavity with MAIN PART of the heart being FIRM,

RED MUSCLE

2 main PUMPING CHAMBERS are the VENTRICLES ABOVE ventricles, are the ATRIA chambers

These have THIN WALLSCORONARY ARTERIES lie OVER HEART SURFACE

Carry OXYGENATED BLOOD to the HEART ITSELF As the heart is a MUSCLE so needs to RESPIRE also to gain energy

If these arteries become CONSTRICTED, will have SEVERE HEALTH IMPLICATIONS for theanimal

RESTRICTED BLOOD FLOW = will cause a LACK OF OXYGEN/NUTRIENTS toBODY (delivery REDUCES) so could cause heart conditions such asANGINA

ora HEART ATTACK (myocardial infarcation) At TOP of the heart, there are tubes these are VEINS

Veins are responsible for CARRYING BLOOD INTO HEART and ARTERIES(which carry BLOOD OUT OF HEART)

LookingATdiagram of

heart;

RIGHT side REPRESENTS the

LEFT SIDE


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INTERAL FEATURES OF HEART

Heart DIVIDED into 4 CHAMBERS

2 upper ATRIA These RECEIVE blood from MAJOR VEINS DEOXYGENATED blood from BODY flows fromVENA CAVA into RIGHT

ATRIUM

OXYGENATED blood from LUNGS flows from PULMONARY VEIN into theLEFT ATRIUM

From the ATRIA, blood flows through ATRIOVENTRICULAR VALVES into the VENTRICLES

ATRIOVENTRICULAR valves are thin FLAPS of TISSUE in a CUP SHAPE VENTRICLES CONTRACT = VALVES FILL with blood/REMAIN CLOSED to

ensure BLOOD FLOWS UPWARDS into major arteries and NOT INTO ATRIA

TENDINOUS CORDS ATTACH VALVES to the WALLS to prevent thenTURNING INSIDE OUT (which would cause BLOOD to FLOW UP TO ATRIA)

LOCATED in the ventricles

SEPTUM is a WALL of MUSCLE, with SEPARATES the VENTRICLES from each other

Ensures DEOXYGENATED BLOOD (in the LEFT SIDE) does not mix with OXYGENATED BLOODin the RIGHT SIDE

SEPARATES the two types of bloodDEOXYGENATED blood LEAVING RIGHT VENTRICLE flows into the PULMONARY ARTERY

Pulmonary artery LEADS TO LUNGSOXYGENATED blood LEAVING LEFT SIDE, goes into the AORTA

Which pumps to ARTERIES SUPPLYING BODYAt the BASE of MAJOR ARTERIES, are SEMILUNAR VALVES which

prevent blood RETURNING TO HEART when the VENTRICLES RELAXPERICARDIUM

SACK which the heart is in.

BLOOD PRESSURE

VENA CAVACarries

DEOXYGENATED blood

back to

RIGHT ATRIUM OF

HEART

PULMONARY

ARTERYONLY ARTERY

which carries

DEOXYGENATED

blood (to the LUNGS)

AORTACarries OXYGENATED

BLOOD from

LEFT VENTRICLE to

NUMEROUS ARTERIES

which SUPPLY BODY

PULMONARY

VEINCarries

OXYGENATED blood

AWAY FROM LUNGS

to LEFT ATRIUM

R L

ATRIOVENTRICULAR VALVESLocated IN ATRIA; these are VALVES which PREVENT

blood FLOWING BACK INTO ATRIAVENTRICULAR SYSTOLEcauses VENTRICLES to

CONTRACT/pressure CHANGE causes valves to CLOSE

and make blood flow into ARTERIES

SEMILUNAR VALVESLocated BASE OF MAJOR ARTERIES;

are valves which PREVENT blood RETURNING TOHEART after the VENTRICLES RELAX


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EACH chamber CONTRACTS to create INCREASED PRESSURE IN BLOOD

HIGHER the PRESSURE, the FURTHER BLOOD WILL FLOWATRIA

The atria have THIN MUSCLE because they DONT PUMP BLOOD AT SUCH HIGH PRESSURES

RIGHT VENTRICLE

The WALLS are THICKER THAN ATRIA to allow for blood to be PUMPED OUT OF HEART

However, RIGHT VENTRICLE walls are much THINNER THAN the LEFT RIGHT VENTRICLE pumps DEOXYGENATED blood to LUNGS FROM HEART, so

DOESNT TRAVEL AS FAR

PRESSURE MUST NOT be TOO HIGH, as it could cause DAMAGE to theDELICATE CAPILLARIES in the lungs which are IN CLOSE CONTACT WITH

ALVEOLI WALLS (which have minimal/no tissue fluid) so they are NOT well

SUPPORTED so COULD BURST

LEFT VENTRICLE

The WALLS are up to x2/3 THICKER THAN RIGHT VENTRICLE walls Blood from LEFT VENTRICLE is pumped at HIGHER PRESSURE THROUGH AORTA to the

BODY

Pressure needs to BE SUFFICIENT so as to EFFICIENTLY PUMP blood to bodyand to OVERCOME RESISTANCE of the systematic circulation

THE CARDIAC CYCLESEQUENCE OF CONTRACTION

The hearts chambers contract in a COORDINATED FASHION

OUT OF SEQUENCE contraction = INEFFICIENT PUMPING THIS sequence in ONE HEARTBEAT = THE CARDIAC CYCLE

FILLING PHASE = DIASTOLE

BOTH atria and ventricles RELAXING

Internal VOL. INCREASES and BLOOD FLOWS INTO the heart FROM MAJOR VEINSBlood INTO ATRIA THROUGH OPEN ATRIOVENTRICULAR VALVES to VENTRICLES

ATRIAL CONTRACTION =ATRIAL SYSTOLE

The HEARTBEAT STARTS when the ATRIA CONTRACT; both LEFT & RIGHT at the same time

SMALL PRESSURE created by contraction HELPS PUSH blood INTO VENTRICLES This STRETCHES VENTRICLE WALLS, to ensure VENTRICLES ARE FULL

Once VENTRICLES are FULL, they begin to CONTRACT Causes blood to FLOW INTO ATRIOVENTRICULAR VALVES, causing them to

SNAP SHUT and prevent blood FLOWING BACK INTO ATRIIA

VENTRICULAR CONTRACT = VENTRICULAR SYSTOLESHORT PERIOD in which ALL 4 HEART VALVES are CLOSED

VENTRICLE walls then CONTRACT which RAISES PRESSURE in ventricles VERY QUICKLY STARTS at the APEX (base) of the heart; causes blood to be PUSHED

UPWARDS to arteries


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SEMILUNAR VALVES OPEN and blood is pushed OUT OF HEART Contraction is for SHORT TIME so ventricles RELAX to allow heart to FILL

AGAIN (DIASTOLE)

HOW VALVES WORK

ENSURE that blood flows IN RIGHT DIRECTION

OPEN and CLOSED by the changing PRESSURE in the various chambersATRIOVENTICULAR VALVES

AFTER VENTRICLE WALLS RELAX/RECOIL after contracting, pressure IN VENTRICLES DROPS BELOW

the pressure in ATRIA

VENTRICLE PRESSURE ATRIA PRESSURE = blood moves UPWARDSand FILLS ATRIOVENTRICULAR VALVES, which keeps them CLOSED to

prevent BACKFLOW OF BLOOD, back into the ATRIA.

SEMILUNAR VALVES

When the VENTRICLES CONTRACT (ventricular systole), pressure in MAJOR ARTERIES is HIGHERTHAN the pressure in the ventricles, causing SEMILUNAR VALVES to be CLOSED

As VENTRICLES FILL with blood, pressure RISES QUICKLY because the blood CANNOTESCAPE

When VENTRICLE PRESSURE > major arteries (AORTA/PULMONARYARTERIES) the semilunar valves are PUSHED OPEN

The blood is under GREAT PRESSURE, so is FORCED OUT QUICKLY AFTER ventricles STOP CONTRACTING, the heart starts to RELAX

ELASTIC TISSUE in the WALLS OF VENTRICLES, start to RECOIL & STRETCHthe MUSCLE OUT to return ventricles to ORIGINAL SIZE

Causes ventricle pressure to DROP QUICKLY, becoming LOWER thanpressure in major arteries and PUSHES CLOSED the semilunar valves when

blood flows backwards TOWARDS VENTRICLES; prevents blood RETURNING

TO VENTRICLES.

SOUND OF HEART

Makes a LUB-DUB sound, caused bythe hearts VALVES CLOSING

FIRST SOUND (LUB) is the ATRIOVENTRICULAR valves CLOSING as the VENTRICLESCONTRACT

SECOND SOUND (DUB) is caused by SEMILUNAR valves CLOSING as VENTRICLES RELAXThe LUB sound is LOUDER because the atrioventricular valves SNAP SHUT

The DUB is not as loud, as semilunar valves CLOSE DUE TO the ACCUMULATION of blood intheir pockets.


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CONTROL OF CARDIAC CYCLENEED FOR COORDINATION

CARDIAC muscle can INITIATE OWN CONTRACTION

BECAUSE of this, it is known as a MYOGENIC the heart would continue relaxing andcontracting even if not attached to the body!

ATRIA andVENTRICLES have their OWN NATURAL FREQUENCY of contraction ATRIA muscle = contracts at HIGHER FREQUENCY

INEFFICIENT pumping is a result of UNSYNCHRONISED CONTRACTIONS so A condition known as FIBRILLATION A MECHANISM is required to COORDINATE contractions of each chamber

HOW HEARTBEAT STARTS

At TOP OF RIGHT ATRIUM, (near where the vena cava empties blood into right atrium) is the

SINOATRIAL NODE (SAN).

SAN = small PATCH of TISSUE which GENERATES ELECTRICAL ACTIVITY It INITIATES a WAVE OF EXCITATION at regular intervals Approx. 55-80 times PER MIN aka. The PACEMAKER

CONTRACTION OF ATRIA

WAVE OF EXCITATION passes OVER WALLS of BOTH atria

Wave travels ALONG MEMBRANES of the muscle tissue As it PASSES, causes the ATRIA TO CONTRACT (ATRIAL SYSTOLE)

At the BASE OF ATRIA, is a DISC which CANNOT CONDUCT the wave of excitation So wave of excitation CANT PASS TO VENTRICLE WALLS DIRECTLY

At the TOP OF INTER-VENTRICULAR SEPTUM (septum separating the ventricles) is theATRIOVENTRICULAR NODE (AVN)

AVN = ONLY ROUTE which excitation wave THROUGH NON-CONDUCTINGtissue

Wave of excitation DELAYED AT AVN allows TIME FOR ATRIA TO FINISHCONTRACTING + for the blood to flow to ventricles beforethey contract

CONTRACTION OF VENTRICLES

AFTER the delay, the excitation wave CARRIED AWAY FROM AVN and DOWN specialised

CONDUCTING TISSUES

Conducting tissue = PURKYNE TISSUE which runs DOWN INTER-VENTRICULAR SEPTUM At septum BASE, wave of excitation SPREADS OVER ventricle WALLS

Then spreads UPWARDS from the base (apex) of ventricles Causes VENTRICLES TO CONTRACT from apex UPWARDS, pushing the blood

upwards to the major arteries at top of heart

ELECTROCARDIOGRAMS (ECGs)

These MONITOR ELECTRICAL ACTIVITY of the heart

Involves ATTACHING SENSORS TO SKIN


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Some of the electrical activity generated by heart SPREADS TONEIGHBOURING TISSUES next to heart and ONWARDS TO SKIN

The SENSORS pick up the electrical excitation by the heart and CONVERTthem to TRACES

A NORMAL/HEALTHY person:

P = EXCITATON ofatria

QRS = EXCITATION ofventricles

T = DIASTOLE (heart relaxing)

CHANGES in the normal ECG can indicate parts of heart not WORKING CORRECTLY

IRREGULAR heartbeat UNCOORDINATED heartbeat (fibrillation) If a person has SUFFERED A HEART ATTACK An ENLARGED heart PURKYNE TISSUE not conducting electrical activity correctly

HEART MUSCLE (myogenic) RESPIRES FATTY ACIDS

A CONTINUOUS SUPPLY OF oxygen neededas fat RESPIRED ONLY AEROBICALLY A BLOOD CLOT in coronary artery STARVES part of heart muscle of oxygen,

causing THOSE CELLS TO DIE a HEART ATTACK (myocardial infarction)

HEARTARTERIES GILLS VEINS BODY TISSUES VEINS - HEART

BLOOD VESSELSOPEN AND CLOSED CIRCULATORY SYSTEMS

OPEN

MANY animals e.g. insects have OPEN CIRCULATORY SYSTEMS

BLOOD is NOT CONFINED to within BLOOD VESSELS Instead the blood fluid CIRCULATES THROUGH BODY CAVITY Cells and tissues are DIRECTLY BATHED in the blood Animals with open circulatory systems, SOME will have ACTION OF

MUSCLES during movement to CIRCULATE the blood

OTHERS e.g. insects have a MUSCULAR PUMPING ORGAN (like a heart)

Is a LONG, MUSCULAR TUBE, found underneath dorsal surface of the insect Blood FROM BODY enters the heart via OSTIA (likes pores) HEART then pumps blood via PERISTALSIS TOWARDS the HEAD Blood at head POURS INTO BODY CAVITY

WHY DONT ALL ANIMALS HAVE OPEN SYSTEMS?

ONLY works for SMALL ANIMALS like insects because the blood DOESNT NEED TO TRAVEL FAR

Also DONT RELY on blood to transport oxygen and carbon dioxide as they have aSEPARATE TRANSPORT SYSTEM

LARGER organisms RELY ON BLOOD for transportation of oxygen/carbon dioxide


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Open systems = blood at LOW PRESSURE/flow is VERY SLOW so thisWOULDNT BE SUFFICIENT for large, active animals

Also mean parts of the body would NOT SUFFICIENT RECEIVEOXYGEN/NUTRIENTS

CLOSED

Blood is CONFINED TO BLOOD VESSELS (TISSUE FLUID is a separate fluid which BATHES

TISSUES/CELLS)

CONFINEMENT TO BLOOD VESSELS = heart can pump blood AT HIGHER PRESSURE so it willFLOW QUICKER

Means DELIVERY of blood carrying OXYGEN/NUTRIENTS to the body isQUICKER

Mean REMOVAL of CARBON DIOXIDE/WASTES from the body is QUICKER FISH have CLOSED systems so require EXCHANGE SURFACES AT GILLS so that

material can be exchanged BETWEEN BLOOD & TISSUE FLUID

BLOOD VESSELS

ARTERIES

Carry OXYGENATED blood AWAY FROM the heart

(pulmonary artery is an exception:it carries DEOXYGENATED) Blood is at HIGH PRESSURE so the artery wall MUST be able to WITHSTAND the pressure

LUMEN = relatively SMALL to MAINTAIN pressure THICK WALL = contains COLLAGEN (fibrous protein) which PROVIDES

STRENGTH

ELASTIC TISSUE in wall = ALLOWS it to STRETCH + RECOIL when heartpumps (felt as a PULSE where arteries close to skin)

SMOOTH MUSCLE in wall = CONTRACTS + CONSTRICTS the arterys LUMEN1. (in arterioles, lumen narrowsto LIMIT BLOOD FLOW to certain

organs/DIRECTS FLOW to other organs where NEEDED)

ENDOTHELIUM = is FOLDED and can UNFOLD when artery stretchesVEINS

Carry DEOXYGENATED blood BACK TO the heart

Blood is at LOWER PRESSURE so the walls DONT NEED TO BE ASK THICK as artery LUMEN = relatively LARGE to EASE FLOW of blood WALLS = THINNER layers of COLLAGEN, SMOOTH MUSCLE + ELASTIC TISSUE

as veins dont need to STRETCH + RECOIL and dont need to ACTIVELY

CONSTRICT

VALVES = MAIN FEATURE as these prevent BACK FLOW of blood to theheart and blood FLOWING IN OPPOSITE DIRECTION

THIN WALLS = veins can be FLATTENED by surrounding skeletal muscle sothat PRESSURE IS APPLIED to force blood in direction dictated by valves

CAPILLARIES

Have VERY THIN WALLS to allow for the EXCHANGE of materials between blood and cells of

tissues via tissue fluid

1. WALLS = consist of SINGLE LAYER of FLATTENED ENDOTHELIAL CELLS REDUCES diffusion distance for exchanging materials


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2. LUMEN = VERY NARROW Same diameter as RED BLOOD CELL (7um) so that such cells are SQUEEZED

as they PASS through the capillary so that again, the diffusion distance

DECREASES and the OXYGEN MOLECULES are PRESSED CLOSE to capillary

walls

BLOOD, TISSUE FLUID AND LYMPHBLOOD AND TISSUE FLUID

BLOOD is CONFINED to our blood vessels

Consists of BLOOD CELLS in PLASMA, which contains many substances: CARBON DIOXIDE (small amount in blood) SALTS

GLUCOSE FATTY ACIDS AMINO ACIDS HORMONES PLASMA PROTEIN

Cells include ERYTHROCYTES (red blood cells), LMPHOCYTES (white blood cells) andPLATELETS

TISSUE FLUID

Is SIMILAR TO BLOOD but it DOESNT CONTAIN most substances found in blood + NO PLASMA

PROTEINS Its ROLE = to TRANSPORT OXYGEN/NUTRIENTS from blood to cells

And REMOVE CARBON DIOXIDE/OTHER WASTES back to the blood


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FORMATION OF TISSUE FLUID

Arteries REACHING TISSUES branch into SMALLER ARTERIOLES

Then INTO CAPILLARIES which eventuallyLINK BACK TO VENULES, to pass blood BACKTO VEINS. So Blood INTO ORGAN/TISSUE = contained in CAPILLARIES

At ATERIAL END = pressure of blood is VERY HIGH (due to contraction ofheartHYDROSTATIC PRESSURE

Tends to FORCE OUT blood fluid, OUT OF CAPILLARIES through the TINYGAPS in capillary wall

Fluid that LEAVES becomes TISSUE FLUID and consists of platelets, oxygen andnutrients

ALL RED BLOOD CELLS, PLATELETS + most WHITE BLOOD CELLS are TOOLARGE to leave as gaps in capillary wall are TOO SMALL

It BATHES tissues and cells to permit exchange of oxygen/nutrients ACROSS CELLSURFACE MEMBRANES via (facilitated)diffusion

Oxygen + nutrients ENTER CELLS

Carbon dioxide + other wastes LEAVE CELLSHOW FLUID RETURNS TO BLOOD

The HYDROSTATIC PRESSURE is not only force acting on the fluid

The tissue fluid ITSELF has SOME HYDROSTATIC PRESSURE which causes it to be forcedback into the capillaries

Blood + tissue fluid have SOLUTES which DECREASES THEIR WATER POTENTIAL (morenegative)

Tissue fluid water potential LESS NEGATIVE than blood; causes TISSUEFLUID to move BACK INTO the BLOOD, via osmosis, down water potential

gradient

At the VENOUS END (of capillary) = blood LOSES HYDROSTATIC PRESSUREHydrostatic pressure in TISSUE FLUID + OSMOTIC FORCES of plasma proteins

= sufficient to move FLUID BACK INTO CAPILLARIES (carrying any waste products e.g. carbon

dioxide, leaving the cells)

FORMATION OF LYMPH

NOT ALL tissue fluid returns to capillaries SOME DRAINED AWAY INTO LYMPHATIC SYSTEM

Lymphatic system consists of numerous vessels (similar to capillaries) whichSTART IN TISSUES to drain excess fluid into LARGER VESSELS (that

eventually rejoin blood system in chest cavity)

Lymph is SIMILAR TO TISSUE FLUID as has same solutes But has FEWER OXYGEN/NUTRIENTS (as been absorbed by body cells) Will be MORE CARBON DIOXIDE + WASTES (released from body cells) Also MORE FATTY MATERIAL (absorbed from the intestines)

MAIN DIFFERENCE between tissue fluid and lymph

Lymph = LOTS OF LYMPHOCYTES, produced in LYMPH NODES LYMPH NODES = SWELLINGS found at INTERVALS along lymphatic system SWELLINGS = can FILTER bacteria/foreign material from lymph fluid so that

the LYMPHOCYTES can DESTROY thempart of IMMUNE SYSTEM


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FEATURE BLOOD TISSUE FLUID LYMPHCELLS ERYTHROCYTES,

LEUCOCYTES &

PLATELETS

SOME (PHAGOCYTIC)

WHITE BLOOD CELLS -

leucocytes

LYMPHOCYTES

PROTEINS PLASMA PROTEINS

and HORMONES

SOME HORMONES &

SECRETED PROTEINS

from cells

SOME proteins

FATS SOME LIPOPROTEINS NONE ABSORBED from

INTENSTINES

GLUCOSE 80-120mg per 100cm3 LESS AMOUNT

(absorbed by body

cells)

EVEN LESS

AMINO ACIDS MORE LESS (absorbed by

body cells)

EVEN LESS

CARBON DIOXDE LITTLE MORE (released from

body cells)

MORE

CARRIAGE OF OXYGENHAEMOGLOBIN

Oxygen is TRANSPORTED IN red blood cells (erythrocytes)

Erythrocytes CONTAIN the protein HAEMOGLOBIN; when it TAKES UP OXYGEN, itbecomes OXYHAEMOGLOBIN

HAEMOGLOBIN + OXYGEN = OXYHAEMOGLOBIN

Haemoglobin = COMPLEX PROTEIN with FOUR SUBUNITS EACH subunit consists of a HAEM GROUP + POLYPEPTIDE CHAIN HAEM GROUP contains a SINGLE Fe2+(iron ion) that can ATTRACT AND HOLD

an OXYGEN MOLECULE an AFFINITY FOR OXYGEN (attraction)

Each haemoglobin molecule = hold max. of4 oxygen moleculesTAKING UP OXYGEN

Oxygen absorbed by blood in the lungs

Oxygen molecules diffuse into blood plasma and ENTER RED BLOOD CELLS

Here, TAKEN UP by the haemoglobin so MAINTAINS STEEP DIFFUSIONGRADIENT of oxygen, which allows more oxygen to enter cells

RELEASING OXYGEN

Body tissues and cells NEED OXYGEN FOR AEROBIC RESPIRATION

So oxyhaemoglobin MUST BE ABLE to RELEASE its oxygen This is DISSOCIATION

HAEMOGLOBIN AND OXYGEN TRANSPORT

ABILITY of haemoglobin to TAKE UP and RELEASE OXYGEN depends on amount in the surrounding

tissues AMOUNT OF OXYGENmeasured by RELATIVE PRESSURE it CONTRIBUTES TO

MIXTURE OF GASES called PARTIAL PRESSURE (pO) or OXYGEN (unit = kPa)

In a NORMAL FLUID:-


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AMOUNT of oxygen is directly proportional to SURROUNDING AIRSOXYGEN TENSION

Graph showing %saturation against oxygen tension = STRAIGHT LINE BLOOD CONTAINING FLUID:-

Haemoglobin takes up oxygen to CREATE S-SHAPED CURVE called theOXYHAEMOGLOBIC DISSOCIATION CURVE

LOW OXYGEN TENSION = haemoglobin doesnt uptake oxygen READILYbecause the heam groups which attract oxygen are in CENTRE OF

HAEMOGLOBIN MOLECULE so makes it difficult for oxygen to REACH and

associate with them

This difficulty ACCOUNTS FOR LOW SATURATION of haemoglobin at lowoxygen tensions

RISING oxygen tension = INCREASED DIFFUSION of oxygen molecules into haemoglobin Eventually, an oxygen molecule WILL DIFFUSE and ASSOCIATE INTO

haemoglobin molecule Creates SLIGHT CHANGE in SHAPE of haemoglobin (conformational change) SHAPE CHANGE = MORE oxygen molecules can diffuse and associate MORE

EASILY (accounts for STEEP CHANGE in oxyhaemoglobin dissociation curve

as OXYGEN TENSION RISES

Once contains 3 OXYGEN MOLECULES = HARDER for fourth oxygen molecule toassociate with final haem group

Means DIFFICULT for 100% SATURATION of ALL haemoglobin moleculesDESPITE increased oxygen tension

The graph curve will LEVEL OFFFETAL HAEMOGLOBIN

Haemoglobin of MAMMALIAN FETUS = HIGHER AFFINITY for oxygen than an adults haemoglobin

Fetal haemoglobin must be able to PICK UP OXYGEN from an ENVIRONMENT whichmakes ADULT HAEMOGLOBIN RELEASE OXYGEN

This is the PLACENTA; fetal haemoglobin must absorb oxygen from fluid inmothers blood

This REDUCES OXYGEN TENSION in blood fluid, causing maternalhaemoglobin to RELEASE ITS OXYGEN

Oxyhaemoglobin disassociation curve FOR FETAL HAEMOGLOBIN is to theleft of curve for adult haemoglobin.

CARRIAGE OF CARBON DIOXIDEHOW IS CARBON DIOXIDE TRANSPORTED?

Carbon dioxide RELEASED from RESPRING TISSUES

NEEDS to be REMOVED from tissues and TRANSPORTED TO THE LUNGS Is transported in 3 WAYS:-

1. 5% DISSOLVED directly in PLASMA2. 10% COMBINED directly WITH HAEMOGLOBIN3. 85% TRANSPORTED in form of HYDROGENCARBONATE IONS (HCO)

FORMATION OF HYDROGENCARBONATE IONS

As carbon dioxide diffuses into blood, some ENTERS RED BLOOD CELLS


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It COMBINES WITH WATER, creating a weak CARBONIC ACID The acid is CATALYSED by ENZYME CARBONIC ANHYDRASE

CO + HO HCO

Carbonic acid then DISSOCIATES RELEASES HYDROGEN IONS (H+) and HYDROGENCARBONATE IONS (HCO -)

HCO + HCO- + H+

The hydrogencarbonate ions DIFFUSE OUT of the red blood cell INTO PLASMA The CHARGE INSIDE the red blood cell is maintained by movement of

CHLORIDE IONS (CL-) FROM PLASMA INTO red blood cell

= THE CHLORIDE SHIFT

The hydrogen ions could cause CONTENTS OF RED BLOOD CELL to BECOME ACIDIC To prevent this, HYDROGEN IONS are TAKEN UP BY HAEMOGLOBIN This produces HAEMOGLOBNIC ACID which ACTS AS A BUFFER= maintains CONSTANT pH

RELEASING OXYGEN

As blood ENTERS RESPIRING tissues, haemoglobin CARRIES OXYGEN in form of OXYHAEMOGLOBIN

The OXYGEN TENSION of respiring tissues IS LOWER THAN LUNGS (because oxygen isused in respiration)

Causes OXYHAEMOGLOBIN to DISASSOCIATE & RELEASE oxygen to tissuesRELEASING MORE OXYGEN the BOHR EFFECT

Hydrogen ions released from dissociation of carbonic acid COMPETE FOR SPACE TAKEN UP BY

OXYGEN on the haemoglobin molecule

When CARBON DIOXIDE IS PRESENT, the hydrogen ions DISPLACE the oxygen onhaemoglobin molecule

Causes OXYHAEMOGLOBIN to RELEASE MORE OXYGEN to tissuesTissues which RESPIRE MORE (e.g contracting muscles) there will be MORE CARBON DIOXIDE

as a result, will be MORE HYDROGEN IONS PRODUCED in the red blood cells causes OXYHAEMOGLOBIN to release MORE OXYGEN

= the BOHR EFFECT

At any particular oxygen tension, oxyhaemoglobin RELEASES MORE OXYGEN when MORECARBON DIOXIDE is present

MORE carbon dioxide = LESS SATURATED haemoglobin, causing the dissociationcurve SHIFT DOWNWARDS, to THE RIGHT (the BOHR SHIFT)

Bohr shift results in MORE OXYGEN, READILY RELEASED when there is MORECARBON DIOXIDE produced via respiration, which is NECESSARY for muscles to

continue aerobic respiration

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