Introduction to Blood and Blood Groups

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Questions and Answers

What is the primary route of administration for Anti-D immunoglobulin?

Intravenous administration

Subcutaneous injection

Oral administration

Deep intramuscular injection (correct)

Which of the following is NOT classified as a sensitising event?

Routine ultrasound (correct)

Ectopic pregnancy

Termination of pregnancy

External cephalic version

When should Anti-D immunoglobulin be administered to an Rh- female undergoing a procedure?

After the procedure

Only if indicated by symptoms

It is not necessary for any procedure

Prior to the procedure or as soon as possible (correct)

What is the primary purpose of understanding the composition and function of blood during this session?

To support safe transfusion practices Signup and view all the answers

What special care is provided for an Rh- woman who has developed anti-D antibodies?

Supervision by an obstetrician with assessments on antibody concentration Signup and view all the answers

Which of the following is NOT a recommended action for women with a history of premature births?

Delay Anti-D immunoglobulin until labour Signup and view all the answers

What does the term 'haematopoiesis' refer to in the context of blood?

The formation of blood cellular components Signup and view all the answers

What is one potential outcome that may happen if sensitisation has occurred in an Rh- mother?

Foetal transfusion may be required Signup and view all the answers

Which of the following best describes haemostasis?

The process of blood clot formation and cessation of bleeding Signup and view all the answers

What is the expected time frame for reticulocytes to mature in the bloodstream?

1-2 days Signup and view all the answers

In which situation is intravenous administration of Anti-D immunoglobulin specifically warranted?

If there are special clinical indications Signup and view all the answers

Which procedure does NOT typically require Anti-D immunoglobulin to be administered beforehand?

Routine blood test Signup and view all the answers

How can knowledge of blood groups contribute to medical procedures?

It is essential for safe blood transfusions Signup and view all the answers

Which aspect of blood is most likely to be covered in the upcoming blood workshop?

Erythrocyte production and blood groups Signup and view all the answers

What is a major challenge faced in providing anti-D immunoglobulin healthcare in certain regions?

Insufficient supplies from donors Signup and view all the answers

What modification does the A allele perform on the cell surface glycoprotein?

Adds N-acetyl galactosamine Signup and view all the answers

Which of the following statements is true regarding the Rhesus (Rh) factor?

Anti-D antibodies are produced after exposure to Rh+ blood Signup and view all the answers

What is the primary focus of the clotting cascade in the process of haemostasis?

To create fibrin strands that form a blood clot Signup and view all the answers

Which component of blood plasma is primarily responsible for transporting nutrients?

Albumin Signup and view all the answers

What blood type has the highest prevalence in Australia?

O+ Signup and view all the answers

What is one key characteristic of the blood workshop mentioned in the session guidelines?

It includes practical applications of blood group knowledge Signup and view all the answers

Which condition relates to the production of anti-Rh antibodies in Rh- mothers?

Haemolytic disease of the newborn Signup and view all the answers

At what gestation weeks do Rh- mothers typically receive Anti-D prophylaxis?

28 and 34 weeks Signup and view all the answers

What enzyme does the ABO gene encode for in relation to blood group antigens?

Glycosyltransferase Signup and view all the answers

What is the consequence if a Rh- person is transfused with Rh+ blood?

The body produces anti-D antibodies Signup and view all the answers

Which blood type is least common in Australia?

AB+ Signup and view all the answers

Which antigen is critical for determining the Rh blood group status?

D antigen Signup and view all the answers

What is a common treatment during pregnancy for Rh- mothers?

Anti-D immunoglobulin Signup and view all the answers

Study Notes

Blood

Blood is thicker than water, flowing more slowly.
Blood viscosity depends on the number of blood cells, primarily red blood cells (RBCs).
Aspirin does not affect blood thickness, reducing clotting ability.
Human blood temperature is 38°C.
Blood pH is around 7.4 (range 7.35-7.45).
Blood makes up 8% of total body weight.
Average blood volume is 5-6 liters in males and 4-5 liters in females.

Blood Composition

Blood is composed of 55% plasma and 45% formed elements.
Formed elements are primarily 99% red blood cells (RBCs) and less than 1% white blood cells (WBCs) and platelets.
Haematocrit is the percentage of total blood volume occupied by RBCs.
- Values are 47% ± 5% for males and 42% ± 5% for females.

Blood Plasma

Blood plasma is over 90% water.
Plasma proteins make up 7% of plasma, mostly produced in the liver.
Albumin maintains blood osmotic pressure.
Globulins (alpha, beta, gamma) have transport and immune functions (gamma globulins are antibodies).
Fibrinogen is crucial for blood clotting.
Plasma contains electrolytes, nutrients, hormones, gases, waste products, etc.

Blood Cells

Red blood cells (erythrocytes):
- Biconcave discs, anucleate, salmon-colored, diameter 7-8 µm.
- Transport oxygen and carbon dioxide.
White blood cells (leukocytes):
- Granular (eosinophils, basophils, neutrophils) and agranular (lymphocytes, monocytes) types.
- Crucial in immune responses and other bodily functions.
Platelets (thrombocytes):
- Cell fragments, crucial for blood clotting.

Blood Functions

Transportation: O2, CO2, metabolic wastes, nutrients, heat, hormones, and medications.
Regulation: Blood regulates pH, temperature, and intracellular fluid composition.
Protection: Blood plays a role in immunity and inflammation.

Platelet Physiology

Platelets are disc-shaped cell fragments without a nucleus.
Normal count is 150-400 x 10⁹/L.
They are essential for haemostasis, stopping blood loss from damaged blood vessels through
1. Vascular spasm (constriction of damaged blood vessel).
2. Platelet plug formation (adhesion to damaged tissue and aggregation).
3. Blood clotting (coagulation—formation of fibrin threads and meshwork).

Blood Clotting

Clotting requires calcium, clotting proteins, and substances released by damaged tissues or platelets
The clotting cascade is a series of reactions with each factor activating the next (intrinsic and extrinsic pathways)
It results in the formation of a fibrin meshwork, trapping blood cells to form a clot.
Both pathways result in producing thrombin and ultimately fibrin for blood clotting.

Haematopoiesis

Blood cell formation (RBCs) occurs in red bone marrow of flat bones, ribs, skull, pelvis, ends of long bone, and lymphoid organs.
- Stem cells are responsible for all cell types of blood.
- It's an ongoing process, with cells dying and being continually replaced (approximately 100 billion RBCs produced per day)
- EPO (Erythropoietin) is a crucial hormone in erythropoiesis released by the kidneys as a response to low oxygen levels.

Control of RBC Production

Factors influencing RBC production include iron, vitamin B12, folic acid, tissue hypoxia, and anaemia.
The production of RBCs is controlled by the hormone erythropoietin which is produced in the kidneys.

RBC Oxygen Carrying Capacity

Haemoglobin (Hb) is the protein in RBCs that carries oxygen (binds with oxygen).
Each Haemoglobin can carry 4 oxygen molecules.
Blood containing haemoglobin and oxygen becomes oxyhaemoglobin.

Destruction of RBCs

RBCs lack nuclei and have limited repair abilities.
They are engulfed by macrophages in the spleen, liver, and bone marrow when they age/or are damaged.
- The haemoglobin degrades into heme and globin.
- Iron is recycled, heme is converted to biliverdin and bilirubin.
- Bilirubin is processed by the liver and excreted in bile as stercobilin.

Blood Groups

ABO blood types are determined by the presence or absence of A and/or B antigens on the surface of RBCs.
- O blood type lacks both A and B antigens.
Rh factor is another critical antigen.
A person either has it(Rh+) ore doesn't (Rh-).
Blood typing is essential to avoid incompatibility issues when transfusions are needed.

Haemolytic Disease of the Newborn

HDN occurs due to Rh factor incompatibility between mother and fetus, where antibodies from the mother attack the baby's RBCs.
Early detection and treatment (e.g., administration of anti-Rh antibodies) can drastically reduce issues.
Several sensitising events can make a mother develop anti-D antibodies, including -Ectopic pregnancy, termination of pregnancy, miscarriage, trauma, abdominal pain and antepartum haemorrhage.

Physical characteristics of Blood

Thicker (viscous) than water
Blood flows more slowly than water.
pH is in the range 7.35 to 7.45
Blood constitutes 8% of a person's total body weight
Blood volume: approximately 5-6 liters in males and 4-5 liters in females.

Learning Outcomes

Understanding the basis of Blood groups and applying this knowledge towards safe transfusions
Describe the process of haemostasis and the clotting cascade.
Outline erythrocyte production (haematopoiesis).

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