Blood, Tissue Fluid Blood, Tissue Fluid and Lymphand Lymph

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Blood plasmaBlood plasma

Pale yellow liquid consisting of a variety of Pale yellow liquid consisting of a variety of substances (10%) dissolved in water (90%)substances (10%) dissolved in water (90%)

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Tissue fluidTissue fluid Almost identical in Almost identical in

composition to blood composition to blood plasma except fewer plasma except fewer protein molecules, no protein molecules, no red blood cells and red blood cells and some white blood cellsome white blood cell

The amount depends The amount depends on 2 opposing on 2 opposing pressurespressures– Blood pressure at arterial Blood pressure at arterial

end of capillary end of capillary – osmosisosmosis

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Tissue fluid (cont)Tissue fluid (cont)

Importance:Importance:– Exchanges of materials between cells and the Exchanges of materials between cells and the

bloodblood

– Provides optimum environment in which cells Provides optimum environment in which cells can workcan work

– HomeostasisHomeostasis – maintenance of a constant – maintenance of a constant internal environment (regulation of glucose internal environment (regulation of glucose concentration, water, pH, metabolic wastes concentration, water, pH, metabolic wastes and temperature)/takes place to maintain the and temperature)/takes place to maintain the composition of tissue fluid at a constant levelcomposition of tissue fluid at a constant level

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LymphLymph 10% of tissue fluid are collected and returned to 10% of tissue fluid are collected and returned to

blood system through blood system through lymph vesselslymph vessels and and lymphaticslymphatics

Lymphatics – tiny, blind-ending vessels with valves Lymphatics – tiny, blind-ending vessels with valves (wide enough to allow large protein molecules to (wide enough to allow large protein molecules to pass through), found in almost all tissuespass through), found in almost all tissues

OedemaOedema – build up of tissue fluid due to imbalance – build up of tissue fluid due to imbalance of protein and rate of loss from plasma with of protein and rate of loss from plasma with concentration and rate of loss from tissue fluidconcentration and rate of loss from tissue fluid

LymphLymph – fluid inside lymphatics identical to tissue – fluid inside lymphatics identical to tissue fluidfluid

Lymph nodesLymph nodes – intervals along lymph vessels which – intervals along lymph vessels which is involved in protection against disease is involved in protection against disease

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OedemaOedema

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Lymph (cont)Lymph (cont)

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Largest lymph vessel

Red colour caused by the pigment Red colour caused by the pigment haemoglobin (globular protein)haemoglobin (globular protein)

Haemoglobin – transports oxygen from Haemoglobin – transports oxygen from lungs to respiring tissueslungs to respiring tissues

Formed in bone marrow (liver; humerus, Formed in bone marrow (liver; humerus, femur; skull, ribs, pelvis, vertebrae)femur; skull, ribs, pelvis, vertebrae)

Eventually rupture within some ‘tight spot’ Eventually rupture within some ‘tight spot’ in the circulatory system, often inside the in the circulatory system, often inside the spleenspleen

Red blood cells Red blood cells (erythrocytes)(erythrocytes)

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Red blood cells (cont)Red blood cells (cont)

The structure is unusual in 3 ways:The structure is unusual in 3 ways:i) Red blood cells are very small i) Red blood cells are very small (diameter=7(diameter=7μμm) – haemoglobin/capillariesm) – haemoglobin/capillaries

ii) Red blood cells are shaped like a ii) Red blood cells are shaped like a biconcave disc – surface area to volume biconcave disc – surface area to volume ratioratio

iii) Red blood cells have no nucleus, no iii) Red blood cells have no nucleus, no mitochondria and no endoplasmic mitochondria and no endoplasmic reticulum – more haemoglobinreticulum – more haemoglobin

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White blood cells White blood cells (leucocytes)(leucocytes)

Made in bone marrowMade in bone marrow

Distinguished from red blood cells:Distinguished from red blood cells:– White blood cells all have nucleusWhite blood cells all have nucleus– White blood cells are mostly larger (except White blood cells are mostly larger (except

lymphocytes)lymphocytes)– White blood cells are either spherical or White blood cells are either spherical or

irregular in shapeirregular in shape

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White blood cellsWhite blood cells

PhagocytesPhagocytes – cells that destroy invading – cells that destroy invading microorganisms by phagocytosis (lobed microorganisms by phagocytosis (lobed nuclei and granular cytoplasm)nuclei and granular cytoplasm)

LymphocytesLymphocytes – destroy microorganisms – destroy microorganisms by secreting chemicals called antibodies by secreting chemicals called antibodies which attach to and destroy the invading which attach to and destroy the invading cells (smaller, large round nucleus and cells (smaller, large round nucleus and small amount of cytoplasm)small amount of cytoplasm)

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White blood cellsWhite blood cells

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Types of WBCs:Types of WBCs:

i) i) granulargranular white blood cells include: white blood cells include: – neutrophilsneutrophils (50 - 70% of WBCs) - (50 - 70% of WBCs) - phagocytosis (bacteria & (bacteria &

cellular debris); very important in inflammation cellular debris); very important in inflammation – eosinophilseosinophils (1 - 4%) - (1 - 4%) - help break down blood clots & kill help break down blood clots & kill

parasites parasites – basophilsbasophils (less than 1%) - (less than 1%) - synthesize & store histamine (a synthesize & store histamine (a

substance released during inflammation) & heparin (an substance released during inflammation) & heparin (an anticoagulant); functions(s) remain unclear anticoagulant); functions(s) remain unclear

ii) ii) agranularagranular (or non-granular) white blood cells (or non-granular) white blood cells include: include: – lymphocyteslymphocytes (25 - 40%) - (25 - 40%) - immune response (including immune response (including

production of antibodies) production of antibodies) – monocytes monocytes (2 - 8%) - (2 - 8%) - phagocytosis (typically as phagocytosis (typically as

macrophages in tissues of the liver, spleen, lungs, & lymph macrophages in tissues of the liver, spleen, lungs, & lymph nodes) nodes)

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Thrombocytes (platelets) Thrombocytes (platelets) - bits of - bits of broken up blood cells that help clot the broken up blood cells that help clot the blood when we cut ourselves and bleed. blood when we cut ourselves and bleed. When we bleed, platelets, chemicals and When we bleed, platelets, chemicals and substances called clotting proteins substances called clotting proteins (prothrombin) help to form an insoluble (prothrombin) help to form an insoluble 'plug' to seal off the bleeding point. 'plug' to seal off the bleeding point.

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Some related diseasesSome related diseases AnemiaAnemia Lymphatic filariasisLymphatic filariasis HemophiliaHemophilia AIDSAIDS LeukemiaLeukemia Thalassemia Thalassemia

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Oxygen is transported around the body Oxygen is transported around the body inside red blood cells in combination inside red blood cells in combination with the protein haemoglobinwith the protein haemoglobin

Hb + 4OHb + 4O22 HbO HbO88

haemoglobin oxygen oxyhaemoglobinhaemoglobin oxygen oxyhaemoglobin

HaemoglobinHaemoglobin

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85% CO85% CO22 is transported by the blood is transported by the blood through hydrogencarbonate ions, HCOthrough hydrogencarbonate ions, HCO33

--, , after dissociation of dissolved COafter dissociation of dissolved CO22

5% CO5% CO22 dissolve in blood plasma without dissolve in blood plasma without dissociationdissociation

10% CO10% CO22 diffuse into red blood cells, diffuse into red blood cells, combining directly with the terminal combining directly with the terminal amine groups (-NHamine groups (-NH22) of some of the ) of some of the haemoglobin molecules (haemoglobin molecules (carbamino-carbamino-haemoglobinhaemoglobin))

When blood reaches lungs, the reactions When blood reaches lungs, the reactions go into reversego into reverse

The haemoglobin dissociation The haemoglobin dissociation curvecurve

Haemoglobin performs the task of Haemoglobin performs the task of picking picking upup and and releasingreleasing oxygen very well oxygen very well

Investigate how haemoglobin behaves:Investigate how haemoglobin behaves:– Samples extracted from blood and exposed to Samples extracted from blood and exposed to

different concentrations (different concentrations (partial pressurespartial pressures) of ) of oxygenoxygen

– Amount of oxygen that combines with each Amount of oxygen that combines with each sample of haemoglobin is measuredsample of haemoglobin is measured

– Maximum amount of oxygen given a value of Maximum amount of oxygen given a value of 100% (100% (saturatedsaturated))

– Amounts at lower oxygen partial pressures are Amounts at lower oxygen partial pressures are expressed as a percentage of the maximum expressed as a percentage of the maximum value value

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The percentage saturation of each The percentage saturation of each sample can be plotted against the sample can be plotted against the

partial pressure of oxygen to obtain partial pressure of oxygen to obtain the curve the curve

The shape of the haemoglobin dissociation curve can be The shape of the haemoglobin dissociation curve can be explained by the behaviour of a haemoglobin molecule explained by the behaviour of a haemoglobin molecule as it combines with or loses oxygen moleculesas it combines with or loses oxygen molecules

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Amount of oxygen that haemoglobin carries is Amount of oxygen that haemoglobin carries is affected not only by the partial pressure of affected not only by the partial pressure of oxygenoxygen, , but also by the partial pressure of but also by the partial pressure of carbon dioxidecarbon dioxide

carbonic anhydrasecarbonic anhydrase COCO22 + H + H22O HO H22COCO33

carbon dioxide water carbonic acidcarbon dioxide water carbonic acid

The carbonic acid dissociates:The carbonic acid dissociates: HH22COCO33 H H++ + HCO + HCO33

--

carbonic acid hydrogen ion hydrogencarbonate ioncarbonic acid hydrogen ion hydrogencarbonate ion

Haemoglobin readily combines with these hydrogen Haemoglobin readily combines with these hydrogen ions, forming haemoglobinic acid, HHb (releasing ions, forming haemoglobinic acid, HHb (releasing oxygen)oxygen)

The Bohr shiftThe Bohr shift

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By removing the hydrogen ions from By removing the hydrogen ions from solution, haemoglobin helps to maintain the solution, haemoglobin helps to maintain the pH of the blood close to neutral (pH of the blood close to neutral (bufferbuffer))

Bohr effectBohr effect – the presence of high partial – the presence of high partial pressure of carbon dioxide causes pressure of carbon dioxide causes haemoglobin to release oxygenhaemoglobin to release oxygen

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The partial pressure of oxygen in the The partial pressure of oxygen in the fetus’ blood is only a little lower than fetus’ blood is only a little lower than that in its mother’s bloodthat in its mother’s blood

Fetal haemoglobin combines more Fetal haemoglobin combines more readily with oxygen than adult readily with oxygen than adult haemoglobin (haemoglobin (higher affinityhigher affinity for for oxygen)oxygen)

Dissociation curve lies Dissociation curve lies aboveabove the the curve for adult haemoglobincurve for adult haemoglobin

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Fetal haemoglobinFetal haemoglobin

Red pigment which combines reversibly with Red pigment which combines reversibly with oxygenoxygen

Found inside cells in some tissues of the body Found inside cells in some tissues of the body (muscle cells)(muscle cells)

Made up of only 1 polypeptide, 1 haem group and Made up of only 1 polypeptide, 1 haem group and can combine with 1 oxygen moleculecan combine with 1 oxygen molecule

The oxymyoglobin molecule is very stable and will The oxymyoglobin molecule is very stable and will not release its oxygen unless partial pressure of not release its oxygen unless partial pressure of oxygen around it is very lowoxygen around it is very low

Myoglobin has a higher percentage of saturation Myoglobin has a higher percentage of saturation with oxygen than haemoglobinwith oxygen than haemoglobin

Acts as an Acts as an oxygen storageoxygen storage The oxygen held by the myoglobin is a reserve, to The oxygen held by the myoglobin is a reserve, to

be used up only in conditions of particularly great be used up only in conditions of particularly great oxygen demandoxygen demand

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Myoglobin Myoglobin

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At sea level: At sea level: – Partial pressure of OPartial pressure of O22 in atmosphere = 20kPa in atmosphere = 20kPa– Partial pressure of OPartial pressure of O22 in an alveolus = 13kPa in an alveolus = 13kPa– Haemoglobin almost completely saturated with Haemoglobin almost completely saturated with

oxygenoxygen At 6500m:At 6500m:

– Partial pressure of OPartial pressure of O22 in atmosphere = 10kPa in atmosphere = 10kPa– Partial pressure of OPartial pressure of O22 in an alveolus = 5.3kPa in an alveolus = 5.3kPa– Haemoglobin only about 70% saturated in lungsHaemoglobin only about 70% saturated in lungs

Altitude sickness:Altitude sickness:– Increase in the rate and depth of breathingIncrease in the rate and depth of breathing– General feeling of dizziness and weakness General feeling of dizziness and weakness

(nausea)(nausea)– Arterioles in the brains dilate (fluids begins to leak Arterioles in the brains dilate (fluids begins to leak

into brain tissues causing disorientation and into into brain tissues causing disorientation and into lungs)lungs)

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High altitudeHigh altitude

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High altitudeHigh altitude

Changes that take place as Changes that take place as body acclimatises:body acclimatises:– Number of red blood cells Number of red blood cells

increases (40-50% to 50-increases (40-50% to 50-70%)70%)

Adaptations to low-oxygen Adaptations to low-oxygen environments:environments:– Broad chests (larger lung Broad chests (larger lung

capacities)capacities)– Larger hearts (especially Larger hearts (especially

right side that pumps blood right side that pumps blood to the lungs)to the lungs)

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CO combines with the haem groups in the CO combines with the haem groups in the haemoglobin molecules forming haemoglobin molecules forming carboxyhaemoglobincarboxyhaemoglobin

Haemoglobin combines with CO 250 times Haemoglobin combines with CO 250 times more readily than it does with Omore readily than it does with O22

Carboxyhaemoglobin is a very stable Carboxyhaemoglobin is a very stable compoundcompound

Low concentrations of CO (0.1%) in the air Low concentrations of CO (0.1%) in the air can cause death by asphyxiationcan cause death by asphyxiation

Treatment: administration of a mixture of Treatment: administration of a mixture of pure oxygen and carbon dioxidepure oxygen and carbon dioxide

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Carbon monoxideCarbon monoxide

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