L12 - Blood as transport system

Question 1

What are the main components of blood?

Answer 1

• Plasma:
• Plasma proteins: albumins, globulins + fibrinogen
• Serum
• Blood cells:
• Erythrocytes (RBC)
• Leucocytes (WBC)
• Platelets

Question 2

What is Haematopoiesis?

Answer 2

The formation of blood cellular components

Question 3

What is plasma?

Answer 3

• Makes up 55% of normal blood by volume
• Water is 90% of plasma by volume
• Many different solutes in plasma - dissolved organic + inorganic substances
• It is the intravascular part of extracellular fluid.

Question 4

What are the components of plasma?

Answer 4

• Albumin => pH buffer + osmotic pressure
• Globulins => binding proteins + antibodies
• Fibrinogen + prothrombin => clotting proteins
• Other proteins => enzymes, hormones, etc.
• Nutrients => glucose, fatty acids, amino acids, cholesterol, vitamins
• Electrolytes - Na+, K+, Ca2+, Mg2+, Cl-, phosphate, sulphate, bicarbonate, etc.

Question 5

What are erythrocytes?

Answer 5

• AKA red blood cells (RBC)
• Function => O2 + CO2 transport
• Shape => biconcave disk with flexible membrane – large surface area for diffusion of gases
• No: nucleus, DNA, RNA, mitochondria, other organelles — no cell division of mature RBCs, hence short life span of 120 days
• Contains enzymes => Haemoglobin , Glycolytic enzymes + carbonic anhydrase (CO2 conversion)
• Produced in red bone marrow - process called Erythropoiesis - then filtered by spleen + liver
• Hormone erythropoietin (from kidneys) triggers differentiation of stem cells to erythrocytes.

Question 6

What is haemoglobin (Hb)?

Answer 6

• Iron-containing oxygen-transport protein present in erythrocytes
• Oxyhaemoglobin = O2 bound to iron
• Deoxyhaemoglobin = no O2 bound to iron
• Carbaminohaemoglobin = CO bound to polypeptide chain (not iron)

Question 7

What is the oxygen-haemoglobin Bohr Effect?

Answer 7

The Bohr effect describes haemoglobin’s lower affinity for oxygen secondary to increases in the partial pressure of carbon dioxide and/or decreased blood pH.

This lower affinity, in turn, enhances the unloading of oxygen into tissues to meet the oxygen demand of the tissue.

• CO2/H+ are affecting the affinity of Hb for O2
• Dissociation curve = effects of pH described

Question 8

What is the oxygen-haemoglobin Haldane Effect?

Answer 8

Oxygenation of blood in the lungs displaces carbon dioxide from haemoglobin, increasing the removal of carbon dioxide. Consequently, oxygenated blood has a reduced affinity for carbon dioxide.

• O2 is affecting the affinity for Hb for CO2/H+

Question 9

What are the requirements for erythrocyte production?

Answer 9

• Iron
• Folic acid
• Vitamin B12
• Deficiencies of any = a type of anaemia

Question 10

What are the 3 of the main erythrocyte disorders?

Answer 10

• Haemorrhagic anaemia => loss of blood from bleeding (wound, ulcers, etc)
• Haemolytic anaemia => erythrocytes rupture (haemoglobin/transfusion problems, infection)
• Aplastic anaemia => red marrow problems (cancer treatment, marrow disease, etc)

Question 11

What are the anaemias that is caused by decrease in haemoglobin?

Answer 11

• Iron-deficiency anaemia => low iron levels (diet; absorption, bleeding, etc)
• Pernicious anaemia => low Vitamin B12 (diet; low in intrinsic factor for vitamin B12 absorption)
• Megaloblastic anaemia => low folic acid levels or low vitamin B12

Question 12

Morphological classification of anaemia

Answer 12

• Microcytic (Hypochromic) anaemia:
• low MCV + MCH (chronic)
• cause – low iron levels

*Macrocytic (Hyperchromic) anaemia:
- aka Megablastic anaemia
- high MCV + MCH
- cause – low B12 or low folic acid

MCV = mean cell volume
MCH = mean cell height

Question 13

How are the erythrocytes filtered and destroyed?

Answer 13

• Spleen - filters + removes old erythrocytes
• Liver - metabolises by-products from the breakdown of erythrocytes
• Iron - recycled for new Hb
  - transported in blood bound to transferrin to red bone marrow (site of Hb production)
  - stored bound to ferritin in liver, spleen + small intestines (until needed for new Hb)

Question 14

How does the spleen filter + destroy old erythrocytes?

Answer 14

• Macrophages - filter blood by phagocytosis of old fragile RBCs — mechanisms or recognition (T-antigen exposure)
• Hb is catabolised — iron removed + haeme converted to bilirubin
• Bilirubin - in blood, travels to liver for further metabolism — products secreted in bile (part of GI)

Question 15

What are leukocytes (white blood cells)?

Answer 15

• Classified as granulocytes and agranulocytes based on the presence and absence of microscopic granules in their cytoplasm when stained with Giemsa or Leishman stains

Question 16

What are neutrophils?

Answer 16

• Type of granulocytes
• Destroy/ingest (causes lysis) – bacteria + fungi
• How? - antibiotic-like proteins (granules)
• Polymorphonuclear - many-lobed nuclei
• Most numerous WBC

Question 17

What are eosinophils?

Answer 17

• Type of granulocytes
• Phagocytosis — antigens + antigen/antibody complex
• Contains granules of digestive enzymes
• Two-lobed, purplish nucleus
• Only 1-4% of all WBC

Question 18

What are basophils?

Answer 18

• Type of granulocytes
• Defend your body against:
  Allergens.
  Bacterial, fungal and viral infections (pathogens).
  Blood clotting.
  Parasites.
• Contains basophilic (blue) granules with histamine
• Deep purple U or S shaped nucleus
• Rarest of all WBC (0.5%)

Question 19

What are the different types of Agranulocytes?

Answer 19

• T lymphocytes => (in thymus) respond against virus infected cells + tumour cells
• B lymphocytes => (in bone) differentiate into different “plasma cells” which each produce antibodies against different antigens
• Monocytes => differentiate to become macrophages (largest of all WBC - 18 microns)