Blood and Anemia

Question 1

Explain why blood is important to living things.

Answer 1

Blood is important as a transport system. No blood flow means no life for a large multicultural organism. It is more important than any other individual organ as nothing else works without blood flow.

Question 2

What is anemia?

Answer 2

Not enough RBCs; haemoglobin (Hb) is measured rather than RBC count as Anaemia is defined as a Hb level below that which is normal for age and gender.

Question 3

What is the formula for tissue oxygen delivery and what is the clinical significance of it?

Answer 3

Red blood cells deliver oxygen:

Tissue oxygen delivery = C.O x Hb x %Satn x 1.34
l/min x g/l x % x mls/g = mls/min

C.O = HR x SV

This is a very important physiological principle and is the basis for resuscitation of sick patients. It determines when to use blood, iontropes, oxygen etc.

Question 4

What is the impact of anaemia?

Answer 4

• Reduced oxygen to the tissue unless the CO can be increased to compensate.
• Ability to maintain increased CO varies
• Ability to compensate depends on time
• The number (Hb) alone is never the only factor.

Question 5

What are the clinical signs of Anaemia?

Answer 5

• pale
• lethargic
• failure to thrive
• hypoxic
• ischaemia
• tachycardia

Question 6

What are the causes of anaemia?

Answer 6

• failure of production of Hb
• Increased loss or destruction of Hb
• Inappropriate production of Hb

Question 7

How would you investigate clinically for anaemia?

Answer 7

• Full blood examination - FBE, FBC, CBC (looking at Hb, RCC, Hct, MCV, MCH, MCHC, Plts, WCC differential, blood film)

Blood Film:

• morphology of red cells, white cells and platelets
• Red cells examination includes size (normocytic, microcytic, macrocytic), shape (many variations, each with different meaning), colour (normochromic, hypochromic, polychromasia)

Question 8

How can anaemia be classified?

Answer 8

• Regenerative/aregerative

- Microcytic, normocytic, macrocytic

Question 9

How much blood is enough blood?

Answer 9

Red cells: 3-5 x 1012/ litre (Replace every 120 days)

White cells: 2-6 x 109/ litre (Replace every 3-5 days)

Platelets: 150- 400 x 109/ litre (Replace every 10 days)

Question 10

Where is blood made?

Answer 10

The site of Haemopoiesis:

• Yolk Sac - first few weeks
• Liver and spleen - 6weeks-7 months
• Bone marrow - 7 months- throughout life
• Progressive fatty replacement of marrow throughout life
• 50% marrow consists of fat spaces, even in active haemopoietic areas

Question 11

Define a pluripotent stem cell.

Answer 11

– capable of self renewal
– differentiates into all haemopoietic cell lines
– also give rise to lymphocytes, and osteoclasts
– exist in small numbers in the marrow (mice studies 1 in 100,000 nucleated cell)
– as yet not definitively identified

Question 12

What is the purpose of bone marrow stroma?

Answer 12

– provides a specific microenvironment for bone marrow to grow
– many elements required
– Changes in adhesion molecules mark the progression of cells through the stroma
– Bone marrow in continuity with blood circulation

Question 13

Give examples and purposes of Haemopoeitic Growth Factors?

Answer 13

– glycoprotein hormones
– local and circulating action
– effects mediated through specific receptors

Question 14

What are the three Haematinics?

Answer 14

Iron, B12, Folate

Question 15

Give a rundown of the sources, puposes and characteristics of haematinics.

Answer 15

Iron:

• critical to maintain red cell production
• adequate diet
• blood loss
• important for more than just blood

Vitamin B12

• animal products (meat, fish, dairy)
• Not in fruits, cereals, vegetables
• Important for all blood cell production
• Important to all cells, especially rapidly producing
• Dietary deficiency
• Poor absorption
• Metabolic pathways

Folate

• Green leafy vegetables
• Important for all blood cell production
• Important for all cells
• Dietary deficiency
• drugs