Blood and Tissue Fluid explain the differences between blood, tissue fluid and lymph describe how...
Transcript of Blood and Tissue Fluid explain the differences between blood, tissue fluid and lymph describe how...
Blood and Tissue Fluid
• explain the differences between blood, tissue fluid and lymph
• describe how tissue fluid is formed from plasma;
Blood• Blood is liquid held in our blood vessels• It 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 Fluid• Similar to blood but does not contain most of the cells found
in blood or any plasma proteins• Role is to transport oxygen and nutrients from the blood to
the cells and to carry carbon dioxide and other wastes back to the blood
Task
• Using Biology 1 p77-78, explain what tissue fluid is and how it is formed
• Complete 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 oxygen• The 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 diffusion
• Oxygen 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-enter
• The blood and the tissue fluid both contain solutes (dissolved substances) making their water potential more negative
• The blood’s 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 analogy• Imagine 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)-$800
Shelly (Office Worker)-$475
Jim (Computer Designer)$0
Whom should give money to whom?
Water potential: the analogy• Imagine 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)-$425
Shelly (Office Worker)-$425
Jim (Computer Designer)-$425
Total = -$1275 /3
High hydrostatic pressure in capillary
Lower hydrostatic pressure in capillary
Tissue fluid has lower hydrostatic pressure
Tissue fluid has higher hydrostatic pressure
Hydrostatic pressure = 1.1
Hydrostatic pressure = 4.3
Water potential = -1.3
Water potential = -3.3
Total Hydrostatic pressure = 4.3-1.1 = 3.2kPa
Total water potential = -3.3 – (-1.3) = -2kPa
Effective blood pressure = 3.2 - 2 = 1.2kPa
Inside capillary (arterial end) fluid moves out of capillary as tissue fluid
Hydrostatic pressure = 1.1
Hydrostatic pressure = 1.6 Water potential = -1.3
Water potential = -3.3
Total Hydrostatic pressure = 1.6 -1.1 = 0.5kPa
Total water potential = -3.3 – (-1.3) = -2kPa
Effective blood pressure = 0.5 - 2 = -1.5kPa
Inside capillary (venous end) fluid moves into capillary from tissue fluid
Arterial end
Venous end
Movement back into the blood stream
• At 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
1. What determines the amount of fluid leaving the capillaries?2. Explain why fluid flows out at the arterial end and in the venous end3. What is tissue fluid?4. What is lymph?5. How does tissue fluid get into the lymphatic system?6. What is oedema?
Feature Blood Tissue Fluid Lymph
Cells Some phagocytic white blood cells
Proteins Some proteins
Fats Some transported as lipoproteins
Some/none More than in blood (absorbed from lacteals in intestine-villi)
Glucose 80-120mg per 100ml
More/less More/less
Amino Acids More/less More/less More/less
Oxygen More/less More/less More/less
Carbon dioxide Lot/little More/less More/less
Feature Blood Tissue Fluid Lymph
Cells Erythrocytes, leucocytes and platelets
Some phagocytic white blood cells
Lymphocytes
Proteins Hormones and plasma proteins
Some hormones, proteins secreted by body cells
Some proteins
Fats Some transported as lipoproteins
None More than in blood (absorbed from lacteals in intestine-villi)
Glucose 80-120mg per 100ml
Less (absorbed by body cells)
Less
Amino Acids More Less (absorbed by body cells)
Less
Oxygen More Less (absorbed by body cells)
Less
Carbon dioxide Little More (released by body cells
More
Carriage of Oxygen
• describe 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.
Task• Using Biology 1 p80-84, produce a revision
box for each of the following:• Haemoglobin dissociation curve• Carbon dioxide transport in the blood• The Bohr shift• Fetal 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 Curve Carbon Dioxide Transport
The Bohr Shift Fetal Haemoglobin