Blood and Tissue Fluidexplain the differences between blood, tissue fluid and lymphdescribe how tissue fluid is formed from plasma;

BloodBlood is liquid held in our blood vesselsIt consists of:Plasma: watery fluid containing dissolved oxygen, carbon dioxide, salt, glucose, fatty acids, amino acids, hormones and plasma proteins (proteins made in the liver)Cells including red blood cells (erythrocytes) white blood cells (leucocytes) and platelets

Tissue FluidSimilar to blood but does not contain most of the cells found in blood or any plasma proteinsRole is to transport oxygen and nutrients from the blood to the cells and to carry carbon dioxide and other wastes back to the blood

TaskUsing Biology 1 p77-78, explain what tissue fluid is and how it is formedComplete SAQ 9 & 10 on p78

How Tissue Fluid is Formed?When blood is under high pressure in the artery before it enters the capillary, some blood fluid is pushed out of the capillaries though tiny gaps in the capillary wall, this is called tissue fluid.The pressure that the blood is under due to the contraction of the heart is called hydrostatic pressure (a bit like fluid pushing up against the walls of a container)

What is in Tissue Fluid?Plasma with dissolved nutrients and oxygenThe red blood cells, platelets and most of the white blood cells remain in the blood, with the plasma proteins. These are too large to fit through the gaps in the capillary wall

What does tissue fluid do?It surrounds the body cells, so exchange of gases and nutrients can occur across the cell membranes (plasma membranes)This exchange occurs by diffusion and facilitated diffusionOxygen and nutrients (e.g. glucose) enter the cells, carbon dioxide and other wastes (e.g. urea) leave the cells

How does the fluid get back into the blood?The tissue fluid itself has some hydrostatic pressure and is pushed up against the capillaries allowing it to re-enterThe blood and the tissue fluid both contain solutes (dissolved substances) making their water potential more negativeThe bloods water potential is usually more negative so water tends to move from the tissue fluid back into the blood by osmosis, down the water potential gradient

Water potential: the analogyImagine 3 people, all of whom have a bank account with an overdraft (which means they can borrow money from the bank and make their account negative)Bill (Student)-$800Shelly (Office Worker)-$475 Jim (Computer Designer)$0

Whom should give money to whom?

Water potential: the analogyImagine 3 people, all of whom have a bank account with an overdraft (which means they can borrow money from the bank and make their account negative)Bill (Student)-$425Shelly (Office Worker)-$425Jim (Computer Designer)-$425Total = -$1275 /3

High hydrostatic pressure in capillaryLower hydrostatic pressure in capillaryTissue fluid has lower hydrostatic pressureTissue fluid has higher hydrostatic pressureHydrostatic pressure = 1.1Hydrostatic pressure = 4.3Water potential = -1.3Water potential = -3.3Total Hydrostatic pressure = 4.3-1.1 = 3.2kPaTotal water potential = -3.3 (-1.3) = -2kPaEffective blood pressure = 3.2 - 2 = 1.2kPaInside capillary (arterial end) fluid moves out of capillary as tissue fluidHydrostatic pressure = 1.1Hydrostatic pressure = 1.6Water potential = -1.3Water potential = -3.3Total Hydrostatic pressure = 1.6 -1.1 = 0.5kPaTotal water potential = -3.3 (-1.3) = -2kPaEffective blood pressure = 0.5 - 2 = -1.5kPaInside capillary (venous end) fluid moves into capillary from tissue fluidArterial endVenous end

Movement back into the blood streamAt the venous (vein) end of the capillary, the blood has lost its hydrostatic pressure. The combined effect of the hydrostatic pressure in the tissue fluid and the osmotic force of the plasma proteins is sufficient to move fluid back into the capillary.It carries with it any dissolved waste substances, such as carbon dioxide, that have left the cells

LymphComplete the following questions using Biology 1 p78

What determines the amount of fluid leaving the capillaries?Explain why fluid flows out at the arterial end and in the venous endWhat is tissue fluid?What is lymph?How does tissue fluid get into the lymphatic system?What is oedema?

FeatureBloodTissue FluidLymphCellsSome phagocytic white blood cellsProteinsSome proteinsFatsSome transported as lipoproteinsSome/noneMore than in blood (absorbed from lacteals in intestine-villi)Glucose80-120mg per 100mlMore/lessMore/lessAmino AcidsMore/lessMore/lessMore/lessOxygenMore/lessMore/lessMore/lessCarbon dioxideLot/littleMore/lessMore/less

FeatureBloodTissue FluidLymphCellsErythrocytes, leucocytes and plateletsSome phagocytic white blood cellsLymphocytesProteinsHormones and plasma proteinsSome hormones, proteins secreted by body cellsSome proteinsFatsSome transported as lipoproteinsNoneMore than in blood (absorbed from lacteals in intestine-villi)Glucose80-120mg per 100mlLess (absorbed by body cells)LessAmino AcidsMoreLess (absorbed by body cells)LessOxygenMoreLess (absorbed by body cells)LessCarbon dioxideLittleMore (released by body cellsMore

Carriage of Oxygendescribe the role of haemoglobin in carrying oxygen and carbon dioxide;describe and explain the significance of the dissociation curves of adult oxyhaemoglobin at different carbon dioxide levels (the Bohr effect);explain the significance of the different affinities of fetal haemoglobin and adult haemoglobin for oxygen.

TaskUsing Biology 1 p80-84, produce a revision box for each of the following:Haemoglobin dissociation curveCarbon dioxide transport in the bloodThe Bohr shiftFetal HaemoglobinYou are limited to one piece of A3 paper- you will need to read the information, decide what is important, and include it in the box, highlighting key terms

Haemoglobin Dissociation CurveCarbon Dioxide TransportThe Bohr ShiftFetal Haemoglobin

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