7a. Human Transport System: Blood Flashcards
Blood Plasma
Composition & Function
Composistion:
- Plasma is a yellowish fluid made of 91.5% water and 8.5% solutes.
- Solutes include dissovled food substances (glucose, amino acids, lipids), mineral salts, O2, CO2, metabolic waste, plasma proteins, hormones and antibodies.
Function:
- Transports dissolved substances (mentioned above) throughout the body.
- Maintains homeostasis of body (optimum pH through the use of buffers, water potential & temperature of blood: water plays a part in heat distribution).
Red Blood Cells (Erythrocytes)
Function & 4 Structural Adaptations
Function:
- Transports oxygen to body cells and carbon dioxide away from body cells.
Structural adaptations:
- Presence of haemoglobin: which combines with oxygen reversibly to form oxyhaemogoblin, to enable red blood cells to transport oxygen from the lungs to all cells in the body.
- Circular, flattened biconcave disc: increases surface area to volume ratio to increase rate of diffusion of oxygen and carbon dioxide.
- Absence of nucleus: allows more haemoglobin to be packed in the cell.
- Elastic, flexible and can turn bell-shaped: to be able to squeeze through blood vessels smaller than itself in diameter without breaking.
White Blood Cells (Leucocytes)
Function & Types
Function:
- Protect the body against disease-causing organisms.
Types of leucocytes:
- Phagocytes
- Lymphocytes
Phagocytes
Structure & Function
Structure:
- Irregular in shape
- Lobed nucleus to be able to squeeze between epithelial cells of the capillaries
Function:
- Engulfs and ingests foregin particles such as bacteria by phagocytosis
Phagocytosis is the process of engulfing and ingesting foreign particles.
In the process, some phagocytes are killed with the bacteria, forming pus.
Monocytes transform into macrophages to carry out phagocytosis
Lymphocytes
Structure & Function
Structure:
- Round in shape
- Large nucleus
Function:
- Lymphocytes are stimulated when pathogens or disease-causing organisms enter the bloodstream, to produce antibodies to protect the body against bacteria by:
- Agglutination: causing pathogens to clump together and attract phagocytes to engulf the clumped bacteria by phagocytosis
- Neutralise harmful toxins produced by pathogens
Immunisation or vaccination directly induces lymphocytes to produce antibodies by exposing a person to dead or weakened forms of the pathogen
Platelets (Thrombocytes)
Structure & Function
Structure:
- Membrane-bound bodies without nucleus (not considered cells)
Function:
- Prevent excessive blood loss
- Prevent the entry of pathogens
Mechanism of Blood Clotting
Process + What do undamaged blood vessels contain?
- When blood vessels are damaged, damaged tissue and platelets produce thrombokinase (enzyme).
- Thrombokinase converts prothrombin into thrombin (enzyme).
- Thrombin converts soluble fibrinogen into insoluble fibrin threads that trap blood cells and the whole mass forms a clot or a scab.
Undamaged blood vessels contain an anti-clotting substance called heparin.
When thrombokinase is relased in damaged tissues, it neutralises heparin so clotting can take place.
Blood Groups A, B, O, AB
Antigens present on RBC & Antibodies present in blood
Blood Group A:
- Antigen A
- Anti-B antibody
Blood Group B:
- Antigen B
- Anti-A antibody
Blood Group O (Universal Donor):
- No antigen
- Anti-A & anti-B antibodies
Blood Group AB (Universal Acceptor):
- Antigens A & B
- No antibodies
Incompatible Transfusions
What happens to blood + Why it dangerous
Incompatible transfusions can result in agglutination of red blood cells, when antibodies in the recepient’s blood bind onto antigens on donated red blood cells.
The clumps may block up small blood vessels and prevent the flow of blood.
The immune system is triggered to rupture the red blood cells.
Released haemoglobin may cause kidney damage.
The reaction between the donor’s antibodies in plasma and the recepient’s antigens on red blood cells is not significant as the donor’s antibodies are diluted in the recepient’s plasma.
Universal Donor & Universal Acceptor
Universal Donor: Blood Group O
- No antigens on the donor’s red blood cells, thus the recipient’s antibodies would not cause agglutination of the donor’s blood.
Universal Acceptor: Blood Group AB
- No antibodies in the plasma of the recipient, which could cause agglutination of the donor’s blood.
Blood Typing
Anti-A serum & Anti-B serum
Anti-A serum (contains Anti-A antibody): if blood agglutinates when serum used, red blood cells contain antigen A.
Anti-B serum (contains Anti-B antibody): if blood agglutinates when serum used, red blood cells contain antigen B.
Both serums will be used to determine which blood group the person belongs to.
