ToB - Blood Cells Flashcards
What do the membranes of RBCs contain and what is the function of some of these?
Antigens
Glycoproteins
Spectrin and actin - aids with shape change = flexibility through capillaries
What is the function of RBCs?
Maintain osmotic equilibrium
Generate ATP via anaerobic glycolysis
Maintain Hb in its reduced state
Deliver O2 by carrying Hb
What is the function of Hb?
Confers solubility
Protects haem from oxidation
Permits variation in O2 affinity by changing shape
What is the reason that RBCs are a biconcave disc?
To allow flexibility so an 8um RBC can pass through a 3.5um capillary
What are the 2 ways in that metabolism can occur in RBCs?
1) . Embeds Meyerhof pathway
- Glucose is converted into lactate
- Uses ATP
- Anaerobic
2) . Hexose monophosphate pathway
- G6P is metabolised
- Uses NADPH
- Anaerobic
How are RBCs catabolised?
1) . RBCs are broken down to give Hb.
2) . Hb is broken down to give haem.
3) . Haem is converted into bilirubin which can be:
- -> conjugated by liver and stored in gall bladder
- -> taken up by the kidney as urobilinogen and excreted.
- -> released into the small intestine via the bile duct.
How does a RBC spend its life and how long is its lifespan?
Lifespan ~ 120days
1) . Produced in bone marrow via erythropoeisis.
2) . Lives in circulation.
3) . Removed via spleen once damaged/old.
What hormone controls RBC production?
Erythropoietin
How is RBC production controlled?
1). Interstitial peritubular cells of the kidney detects low pO2 = stimulate secretion of erythropoietin.
2). Erythropoietin stimulates bone marrow to produce RBCs
= pO2 increases as number of RBCs does
= interstitial peritubular cells of the kidney detects this and stop the production of erythropoietin.
Where is the bone marrow found?
It is extensive in childhood but retracts as an adult, and is found in the pelvis, skull, sternum, ribs and top of long bones.
How are platelets formed?
Megakaryocytes grow in size and replicate their DNA
Platelets bud off from the cytoplasm
–>2-3um
–> cell fragments so have no nucleus
Where are platelets stored?
The spleen
What hormone controls platelet production?
Thrombopoietin
What is the function of platelets?
Aggregate to each other
Phospholipid membrane facilitates the clotting cascade
Adhere to connective tissue exposed in tissue damage
What is the structure of platelets and their function?
1) . Phospholipid membrane - contains glycoprotein receptors which aid in the aggregation of platelets to each other and to clotting factors.
2) . Alpha granules - produce the glycoprotein that form the receptors that aid aggregations (e.g. Von Willebrand Factor)
3) . Dense bodies - contain Ca2+, ADP and serotonin, all which aid aggregation.
How do platelets work?
1) . Damage to the endothelial lining of the capillaries exposes collagen.
2) . Platelets bind to the collagen via vwf.
3) . ADP is released from dense bodies, which makes the glycoprotein receptors on the platelet membrane exposed = primary and secondary aggregation.
4) . This provides a surface for clotting factors to bind and interact = held together by a mesh.
What cells stem from lymphocytes?
T cells
B cells
Natural killer cells
Where do T cells migrate?
To the thymus, where they differentiate
What can T cells differentiate into and what is the function of these?
CD4+ (helper)
- induces proliferation and differentiation of T/B cells
- activates macrophages
CD8+ (suppressor)
- cytotoxic activity= instant cell destruction
How do T cells work?
1) . An infected macrophage displays foreign antigens
2) . Suppressor cells (CD8+) interact and make a hole in the cell membrane = it lyses
3) . T helper cells produce cytokines to activate B and memory cells
What do B cells express and what do they have once they mature?
They express antigen specific immunoglobulins.
When mature, they have different antigen receptors in their plasma membrane. They then recirculate
How do B cells work?
They interact with T cells via cytokine response. They can then:
- Transform into plasmablasts = produce antibodies
- Transform into memory cells
What do natural killer cells do?
Recognise and kill non self antigens via lysis (making a hole in the cell).
What organs does the reticuloendothelial system consist of?
Spleen
Liver
Lymph nodes
What cells are included in the reticuloendothelial system and what is their job?
Kupffer cell - locked in tissues
Microglia - in CNS
Macrophages
Monocytes
These identify and amount a response to antigens.
How many lobes does each type of white blood cell have?
Neutrophil - many
Basophil - 2/3
Eosinophil - 2
Monocyte - 1(kidney shaped)
What is the function of basophils?
Active in allergic reactions by containing granules of heparin, histamine, serotonin etc
What is the function of eosinophils?
Mediate allergic reactions by performing phagocytosis, and releasing cytotoxic particles to kill larger foreign particles onto epithelial surfaces such as the gut and lung.
Why do eosinophils stain well?
They contain granules of phospholipid and arginine.
How long are eoisionophils in circulation and what is their lifespan?
3-8h in circulation with 8-12h lifespan.
What is the function of monocytes?
They respond to inflammation and antigenic stimuli by moving out of capillaries via diapedesis and forming macrophages.
What do monocytes contain?
Lysosomes containing CSF, lysozyme and complement.
How is maturation of neutrophils controlled and what does this achieve?
By the hormone G-CSF in the bone marrow. This: Enhances phagocytosis Enhances chemotaxis Increases neutrophil production Reduces time it takes for bone marrow to release neutrophils
What is the function of neutrophils?
It moves out of the circulation to the site of infection.
