Structure and Function of Blood

Question 1

What is blood?

Answer 1

Blood is a specialised fluid composed of cells suspended in plasma

Question 2

What are the types of blood cells?

Answer 2

Red blood cells, white blood cells, platelets

Question 3

What is haematopoiesis?

Answer 3

Production of blood cells from pluripotent stem cells

Question 4

Where does blood production occur in the embryo?

Answer 4

Yolk sac then liver then marrow

Spleen from 3rd-7th month

Question 5

Where is blood produced at birth?

Answer 5

Mostly bone marrow

Liver and spleen when needed

Question 6

How does blood production change from birth to maturity?

Answer 6

Number of active sites in bone marrow decreases but retain ability to produce

Question 7

Where is blood produced in adults?

Answer 7

Not all bones contain marrow = restricted to skull, ribs, sternum, pelvis and proximal ends of femur

Question 8

What state do most stem cells sit in?

Answer 8

Quiescent state = need to proliferate and differentiate to produce blood cells

Question 9

How does maturation of stem cells progress in bone marrow?

Answer 9

Orderly progression from stem cell to mature forms

Question 10

What is the maturation of neutrophils?

Answer 10

Myeloblast - promyelocyte - myelocyte - metamyelocyte - neutrophil

Question 11

What are the functions of blood cells?

Answer 11

Red blood cells = carry oxygen, buffer CO2
Platelets = stop bleeding
White blood cells = fight infection, cancer prevention

Question 12

What are the types of white blood cells?

Answer 12

Granulocytes = neutrophils, eosinophils, basophils

Monocytes and lymphocytes

Question 13

How did granulocytes get their name?

Answer 13

Contain granules that are easily visible on light microscopy

Question 14

What is the structure of neutrophils?

Answer 14

Segmented nucleus and neutral staining granules

Question 15

What is the function of neutrophils?

Answer 15

Phagocytose invaders = kill with granule contents and die in the process
Attract other cells

Question 16

What are some features of neutrophils?

Answer 16

Short life in circulation

Increased by body stress (e.g infection)

Question 17

What is the structure of eosinophils?

Answer 17

Usually bi-lobed and have bright red granules

Question 18

In what patients can eosinophil levels be raised in?

Answer 18

Those with allergic conditions

Question 19

What is the function of eosinophils?

Answer 19

Fight parasitic infections

Involved in hypersensitivity

Question 20

What are basophils?

Answer 20

Circulating version of tissue mast cell = infrequent in circulation

Question 21

What is the structure of basophils?

Answer 21

Large deep purple granules obscuring nucleus = contain histamine

Question 22

What is the function of basophils?

Answer 22

Mediates hypersensitivity reaction = Fc receptors bind IgE

Question 23

What is the structure of monocytes?

Answer 23

Large simple nucleus and faintly staining granules that are often vacuolated

Question 24

What is the life cycle of monocytes?

Answer 24

More long lived than neutrophils

Circulate for one week and enter tissues to become macrophages

Question 25

What is the function of monocytes?

Answer 25

Phagocytose invaders = kill them and present antigens to lymphocytes Attract other cells

Question 26

What is the appearance of mature lymphocytes?

Answer 26

Small with condensed nucleus and rim of cytoplasm

Question 27

What is the appearance of activated lymphocytes?

Answer 27

Often called atypical = large with plentiful blue cytoplasm extending round neighbouring red cells, nucleus more open structure

Question 28

What is the function of lymphocytes?

Answer 28

Numerous types and functions but main role is as the brain of the immune system = cognates response to infection

Question 29

Why is testing needed to tell different early precursors and stem cells apart?

Answer 29

Stem cells and early precursors are infrequent with unremarkable morphology

Question 30

What are some methods used to recognise stem cells and early precursors?

Answer 30

Immunophenotyping and bio-assay

Question 31

What is immunophenotyping?

Answer 31

Expression profile of antigens present on surface of cell

Question 32

How is a bio-assay carried out?

Answer 32

Culture in vitro and show lineage of progeny in different growth conditions

Question 33

How is the haematopoietic system examined?

Answer 33

Look at peripheral blood and bone marrow Specialised bone marrow tests Look at other sites relevant to blood production (e.g hepatomegaly)

Question 34

What is a common site for bone marrow aspiration and biospy?

Answer 34

The posterior iliac crests