Histology of blood

Question 1

What is histology?

Answer 1

• It is the study of normal tissue.

Question 2

Name at least five functions of blood.

Answer 2

1. Body heat; blood pumped around the body at a constant temperature.
2. Coagulation; seals cuts and grazes by clotting, blood contain platelets.
3. Defence; contains immune cells to fight against infections and diseases.
4. Export; helps to remove waste products.
5. Food; makes sure all the cells have the correct nutrients.
6. Gas exchange; supply of oxygen and removal of carbon dioxide.
7. Hormones; they are transported around the body so they can reach their target organs.

Question 3

What is the composition of blood?

Answer 3

1. Plasma
2. Red cells
3. White cells
4. Platelets

Question 4

Where is blood made in the body?

Answer 4

• Blood cells are made in the bone marrow.
• The bone marrow is an important stem cell.

Question 5

What is the process called when blood is produced?

Answer 5

Haematopoiesis

Question 6

What are the stem cells called that form blood?

Answer 6

Haematopoietic stem cells.

Question 7

What is haematopoieis?

Answer 7

-When blood cells are produced from immature cells that have differentiated into blood cells.

Question 8

Are HSC’s multipoint or multipoint?

Answer 8

• They are multipoint and this means they can differentiate into different type of blood cells.

Question 9

What are red, white blood cells and platelets known as?

Answer 9

Red blood cells: erythrocytes.
White blood cells: leukocytes.
Platelets: thrombocytes.

Question 10

How are blood cells released into the bloodstream?

Answer 10

• After the blood cells have matured they are related into the bloodstream by crossing the bone marrow barrier.
• They are released when they are ready.

Question 11

What is Erythropoietin?

Answer 11

• It is a hormone which is produced in the kidney and the liver.
• It is released due to hypoxic stress.
• Stimulates the survival of red blood cells precursor.

Question 12

Describe red blood cells.

Answer 12

-The main component of blood, they make 95% of all blood cells.
- Around 5,000,000,000 red cells in 1ml.
- Contains no nucleus so they have a larger surface area to carry more oxygen.
- Can easily deform so they can squeeze into tiny capillaries.

Question 13

Describe megakaryocytes.

Answer 13

• They are precursor cells and they release platelets into the blood stream.
• Have a lobated nucleus.

Question 14

What is a precursor cell?

Answer 14

• A stem cell with the capacity to differentiate into only one cell; unipotent stem cell.

Question 15

What are the roles of white blood cells?

Answer 15

• They help to defend and to protect us from viruses and bacteria .
• There are several leukocytes families and they all have their own specific functions.

Question 16

What is the innate immune system?

Answer 16

• It is the first line of defence when the body has recognised foreign material in the body.
• it can be known as the non-specific immune system and this is because it works quickly and efficiently by detecting and destroying the harmful substances in the body.
• Defence and protection can be via innate cells, proteins, skin and mucous membranes.

Question 17

What is an innate cell?

Answer 17

-A cell that acts non-selectively to destroy any material deemed harmful to the body.

Question 18

What is the adaptive immune system?

Answer 18

When the innate immune system is unable to destroy the harmful substances in the body, the adaptive immune system specifically targets the harmful substances.
- Slower to respond to foreign material compared to the innate system.
- Can be known as the specialised immune system.
- Accurate when destroying harmful microorganisms and this is because if the same microorganism invaded the body again, it will be recognised more quickly and the specialised cells will destroy it.

Question 19

What is the adaptive immune system made up of?

Answer 19

• T cells
• B cells (can differentiate into plasma cells).
• Antibodies

Question 20

What are adaptive immune cells?

Answer 20

• Cells that are target specific foreign bodies to minimise collateral damage to other cells in the body.

Question 21

Name at least five families that are white blood cells.

Answer 21

• Lymphoid
• Myeloid
• Agranulocytes
• Granulocytes
• Mononuclear cells
• Polymorphonuclear cells
• Monocyte
• Neutrophil

Question 22

What is a polymorphonuclear cell?

Answer 22

• A leukocyte that only contains one nucleus.
• They are phagocytes and they are formed in the bone marrow.
• They are guided to infected parts of the body by chemotactic substances.

Question 23

What are neutrophils?

Answer 23

• They are the first responders when there is an infection/ disease to the body.
• They are the most abundant type of white blood cells; make up 60%.
• They contain granules in their cytoplasm which also contain enzymes and biochemicals.
• The enzymes and biochemicals can break down and destroy harmful substances.
• Degranulation occurs.

Question 24

Name the three types of granulocytes.

Answer 24

• Basophils
• Eosinophils
• Basophils

Question 25

What is degranulation?

Answer 25

- It is a process where granules which are found in specific leukocytes and they release the enzymes/ cytotoxins they contain.

Question 26

Describe eosinophils

Answer 26

- A type of granulocyte (white blood cell). - They contain granules and they help the body by protecting it from large invading organisms such as worms.

Question 27

What are the four cytotoxic enzymes found in eosinophils?

Answer 27

1. Major basic protein, potent cytotoxic protein. 2. Eosinophilic peroxidase 3. Eosinophilic cationic protein 4. Eosinophilic derived neurotoxin.

Question 28

What dye does the granules in eosinophils react with?

Answer 28

- Eosin and a red colour defines the granules.

Question 29

What dye does the granules in basophils react with?

Answer 29

- Haemotoxylin and a blue/ purple colour defines the granules.

Question 30

What are basophils?

Answer 30

- Are a type of granulocyte. - They respond to expoarasites which are mites and ticks. - They have a receptor for a type of antibody called IgE.

Question 31

What does IgE stand for?

Answer 31

Immunoglobin E

Question 32

What are molecules found in basophils?

Answer 32

- Histamine - Herapin - Serotonin Enzymes such as protease, hydrolase cathepsin G. - Slow reacting substances of anaphylaxis.

Question 33

What does vasodilator mean?

Answer 33

- Medicines that open/ dilate the blood vessels and this increase blood flow around the body.

Question 34

What are monocytes?

Answer 34

- They are an antigen presenting leukocyte. - They posses a kidney/ horseshoe nucleus shape. - They are a unipotent progenitor cell.

Question 35

What is a unipotent progenitor cell?

Answer 35

-White blood cells that migrate into tissues and become a lineage committed leukocyte known as a macrophage.

Question 36

What are T-lymphocytes?

Answer 36

- They are produced in the bone marrow and they mature in the thymus/ - They have a T cell receptor complex on their cell surface and this allows them to recognise specific types of infections.

Question 37

What does MHC stand for?

Answer 37

- Major histocompatibility complex.

Question 38

What is the function of a T helper cell?

Answer 38

- Help to activate B cells and secret antibodies.

Question 39

What is the function of a cytotoxic cell?

Answer 39

- They directly kill the viruses.

Question 40

What is the function of a T regulatory cell?

Answer 40

- They help regulating the immune system.

Question 41

What are B- cells?

Answer 41

- They are produced by stem cells in the bone marrow. - They make antibodies and they are activated by T cells. - When they are activated they become plasma cells and this is when they migrate into soft tissue.

Question 42

What is a plasma cells?

Answer 42

- A type of B- cell that can secrete antibodies.

Question 43

What are memory cells?

Answer 43

- A type of B cell that members foreign antigens that have invaded the body.

Question 44

What are platelets?

Answer 44

- Known as thrombocytes. - They have a diameter of 1-3 micrometers. - No nucleus and they have a biconvex disk shape. - Formed in the bone marrow and from the cytoplasmic budding from megakaryocyte.