Transport of Substances in Blood & Blood Transfusions Flashcards
Transport of Oxygen in Blood
Oxygen is not very soluble in water – so only 3% is dissolved in the plasma
The other 97% is carried inside the RBCs where it is combined with haemoglobin
Haemoglobin + oxygen = oxyhaemoglobin
This combination is called “loose” as it can break down easily so the oxygen can be released quickly
Presence of haemoglobin in the RBC increases the oxygen carrying ability by about 60-70 times
Oxygen combines with haemoglobin in places where oxygen concentrations are high (i.e. capillaries in lungs)
Oxyhaemoglobin breaks down to haemoglobin and oxygen in places where oxygen concentrations are low (i.e. tissue fluid around cells)
Oxygenated blood
high proportion of oxyhaemoglobin, this gives it the bright red colour.
Deoxygenated blood
low proportion of oxyhaemoglobin, which gives it a dark red colour
Erythrocytes (RBCs) & Transport of Oxygen
RBCs are suited to their function of oxygen transport because they:
Contain haemoglobin
Don’t have a nucleus leaves more room for haemoglobin molecules
Shaped like biconcave discs increases surface area for oxygen exchange, thicker edges give large volume that allows more room for haemoglobin
Transport of Carbon Dioxide
7-8% is dissolved in plasma
22% combines with the globin part of haemoglobin (thus forming carbaminohaemoglobin)
70% is carried in plasma as bicarbonate ions (HCO3-)
Carbon dioxide reacts with water to form carbonic acid (H2CO3)
Carbonic acid then dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3-
Nutrients & Waste
Nutrients and wastes are transported dissolved in the plasma
Inorganic nutrients are transported as ions dissolved in plasma. Examples include: sodium ions (Na+), calcium ions (Ca2+), potassium ions (K+), chloride (Cl-), iodide (I-)
Organic nutrients are dissolved in blood plasma. Examples include: glucose, vitamins, amino acids, fatty acids and glycerol
Metabolic wastes (which are harmful if allowed to accumulate) include: urea, creatinine and uric acid.
Blood Transfusions
A blood transfusion is given to someone suffering blood loss, anaemia, leukaemia, haemophilia etc.
Blood or blood product from donor is injected directly into the bloodstream of patient.
Important to match the blood groups of donor and receiver (except for some blood products)
What happens if the wrong blood type is given?
Mixing of blood types can cause the RBC’s to clump together (agglutinate)
If receiver’s blood contains, or is able to produce, antibodies against the donor’s antigens, the foreign cells will clump together & break apart.
Universal Donor blood type
Blood type O
Because they have neither A or B antigens to react with the donor blood, they can be given to any other blood type.
Universal receiver blood type
Blood type AB
Because they don’t make any antibodies due to having both antigens so they can receive blood from all other blood types
Whole blood
taken “as is” from the donor. Chemicals are added to prevent clotting. Used for cases of severe blood loss.
Red cell concentrates
most widely used. Blood is spun at a high speed. Heavy cells sink to the bottom, leaving plasma on top. Might have the platelets and leucocytes removed. Used for heart disease or anaemia sufferers
Plasma
May be given to patients requiring extra blood clotting factors & patients with liver disease
Platelet concentrates
given to patients with abnormal or limited platelets
Cryoprecipitate
Obtained by freezing the plasma & thawing it slowly. Contains many substances required for clotting. Used for haemophilia and severe bleeding
Immunoglobins
Group of proteins that act as antibodies extracted from the blood. Used to treat patients who are deficient in antibodies or have no immunity to particular diseases
Autologous transfusion
Patients own blood is used. Blood collected about 4 weeks prior to a procedure where blood might be required
