Histology 6 (Blood)

Question 1

What is blood?

Answer 1

Fluid connective tissue

Comprises cellular component making up 44% of the blood, and a fluid component (Plasma) making up remaining 56%.

Question 2

What is plasma?

Answer 2

Blood minus the cells

Comprises:
water
salts & minerals
plasma proteins (albumins, globulins, fibrinogen)
hormones, signal molecules
other clotting factors etc.

Question 3

What is serum?

Answer 3

Plasma minus clotting factors

Question 4

What are the most common cells within the blood?

Answer 4

Erythrocytes (Red blood cells)

Question 5

How many erythrocytes in the blood?

Answer 5

4 to 6 million per ml blood

Question 6

What is the lifespan of an erythrocyte?

Answer 6

Lifespan of 4 months/120 days

Question 7

What shape do erythrocytes have?

Answer 7

Enucleate bioconcave discs

Question 8

What is the size of erythrocytes?

Answer 8

Approximately 6.5 to 8.5 microns in diameter

Question 9

Where are erythrocytes produced?

Answer 9

Liver in the fetus
Haematopoietic bone marrow in adults

Question 10

Where are erythrocytes destroyed?

Answer 10

Liver and spleen

Question 11

What is the major protein in erythrocytes?

Answer 11

Haemoglobin

Question 12

How is the cell shape of erythrocytes maintained?

Answer 12

Endoskeleton attached via a major protein called spectrin

Question 13

What are the 3 categories of white blood cells?

Answer 13

Granulocytes (contain visible granules)

Agranulocytes (no visible granules)

Platelets (cell fragments)

Question 14

What are the most common white blood cells?

Answer 14

Neutrophils
40-75% of WBC

Question 15

What percentage of WBC are eosinophils?

Answer 15

5%

Question 16

What percentage of WBC are basophils?

Answer 16

0.5%

Question 17

What percentage of WBC are lymphocytes?

Answer 17

20-50%

Question 18

What percentage of WBC are monocytes?

Answer 18

1-5%

Question 19

What makes neutrophils easy to identify?

Answer 19

Multi lobed nucleus
Faintly granular cytoplasm

Question 20

How big are neutrophils?

Answer 20

12 to 14 microns in diameters

Question 21

Are neutrophils phagocytes?

Answer 21

Yes, they engulf and destroy bacteria and other foreign macromolecules using the respiratory burst

Question 22

What does the cytoplasm of neutrophils contain?

Answer 22

Enzyme myeloperoxidase needed in order to conduct the respiratory burst

Question 23

Are neutrophils mobile?

Answer 23

Yes they circulate in blood and invade through walls of blood vessels through the glycosaminoglycan matrix of the tissues

Question 24

What are the 3 types of granules?

Answer 24

Primary - lysosomes containing enzyme myeloperoxidase and acid hydrolases

Secondary - contain specific substances that are secreted to mobilise inflammatory mediators

Tertiary - contain gelatinases which break down proteins and adhesion molecules that aid neutrophils out of blood vessels and through tissue

Question 25

In which patients do eosinophils numbers increase?

Answer 25

Patients with parasitic infections or a number of other allergic conditions

Question 26

What is the size of eosinophils?

Answer 26

12-17 microns in diameter

Question 27

What characteristics doe eosinophils have?

Answer 27

Bi lobed nucleus Cytoplasm stuffed with distinctive large red granules containing crystalline inclusions

Question 28

What do eosinophils do?

Answer 28

Play a role in phagocytosis in our response to parasites and other allergens Antagonistic actions to basophils and mast cells

Question 29

What do eosinophils bear receptors for?

Answer 29

Immunoglobulin E

Question 30

What do eosinophils neutralise?

Answer 30

Histamine

Question 31

What size are basophils?

Answer 31

14-16 μm in diameter

Question 32

What characteristics do basophils have?

Answer 32

Bi-lobed nucleus and prominent dark blue-staining cytoplasmic granules

Question 33

What do basophils granules contain?

Answer 33

Histamine

Question 34

What do basophils do?

Answer 34

Involved in inflammatory reactions and act to prevent coagulation and agglutination

Question 35

What do basophils have receptors for?

Answer 35

Immunoglobulin E

Question 36

What are the two sub types of lymphocytes?

Answer 36

B Cells - become plasma cells and secrete antibodies T Cells - are involved in cell-mediated immunity

Question 37

Why do lymphocytes have a clear blue/grey cytoplasm?

Answer 37

Very few cytoplasmic inclusions

Question 38

What size are are lymphocytes?

Answer 38

Approx 10 microns in diameter

Question 39

What are the types of lymphocytes?

Answer 39

B Cells – produce antibodies T Helper (TH) Cells – help B cells and activate macrophages T Cytotoxic (TC) Cells – kill previously marked target cells T Suppressor (TS) Cells – suppress TH cells and hence suppress the immune response Natural Killer (NK) Cells – mainly kill virus infected cells

Question 40

What size are monocytes?

Answer 40

15-20 μm in diameter

Question 41

What are monocytes?

Answer 41

Immature cells, circulate briefly in blood

Question 42

What characteristic nucleus do they have?

Answer 42

Characteristic reniform nucleus Kidney bean shaped nucleus

Question 43

What can monocytes do?

Answer 43

Differentiate into one of several cell types within tissue

Question 44

What do monocytes do?

Answer 44

Major phagocytic and defensive role Some become antigen presenting cells, passing antigen fragments to lymphocytes

Question 45

What can monocytes differentiate into?

Answer 45

Tissue macrophages - everywhere Kupffer cells – liver Osteoclasts – bone Antigen presenting cells - everywhere Alveolar macrophages – lung

Question 46

What are platelets?

Answer 46

Fragments of cells derived from large multi-nucleated Megakaryocytes in the bone marrow

Question 47

What size are platelets?

Answer 47

1-3 microns in diameter

Question 48

What are platelets surrounded by?

Answer 48

Surrounded by cell membrane and containing vesicles with coagulation factors

Question 49

What do platelets do?

Answer 49

Responsible for clotting of blood, notably when the endothelium lining all blood vessels is breached

Question 50

What is the formation of blood cells called?

Answer 50

Haematopoeisis

Question 51

What do all blood cells derive from?

Answer 51

Multi-potential haematopoietic stem cell know as a haemocytoblast

Question 52

What is the bony trabeculum?

Answer 52

Hematopoietic bone marrow originated from an adult

Question 53

Where do all blood cells in adults form?

Answer 53

Haematopoietic bone marrow

Question 54

Where do all blood cells in children form?

Answer 54

Process begins in fetal life in liver

Question 55

What are the 3 broad cell series?

Answer 55

Myelon series lies next to bone and gives rise to white blood cells Erythron series lies in between bony trabeculae and gives rise to erythrocytes Megakaryocytes lie in between bony trabeculae and give rise to platelets

Question 56

What happens in Erythropoeisis?

Answer 56

•Reducing cell size •Haemoglobin production increases •Reduction and loss of organelles •Basophilia in early precursors changes to eosinophilia in late precursors •Loss of nucleus •Mediated by erythropoeitin (EPO)

Question 57

What happens in Granulopoeisis?

Answer 57

•Morphology similar for neutrophils, eosinophils and basophils •Increasing number of granules within cytoplasm •Increasingly complex shape of the nucleus •Large pool of stored mature neutrophils in marrow that can be release into the circulation during times of infection