The blood and bone marrow

Question 1

Describe hemopoiesis

Answer 1

The process by which mature blood cells are generated by stem cells in bone marrow
Most mature blood cell types relatively short lived so is a constant process
Tightly regulated, narrow range for circulating blood cell numbers but can be altered rapidly if needed

Question 2

When is additional hemopoiesis required?

Answer 2

stress e.g. blood loss or infection

Question 3

The eight main lineages for mature cells in the peripheral blood

Answer 3

erythroid, neutrophil, monocyte/macrophage, eosinophil, basophil, megakaryocyte, T lymphoid and B lymphoid.

Question 4

Where are haematopoietic tissues restricted to?

Answer 4

bone marrow 95% - sternum, ribs, sacrum, vertebrae, long bones, and spleen 5%

Question 5

Blood tests useful in what aspect of treating patients

Answer 5

diagnosis

monitioring

Question 6

understanding the function of blood cells assists in?

Answer 6

interpretation of investigations

diagnosis and management of disorders e.g. anaemia and leukaemia

Question 7

relationship between proliferative potential and frequency turnover rate

Answer 7

inversely proportional

Question 8

Draw the hemopoiesis diagram

Answer 8

check course guide

Question 9

embryonic origin or haematopoietic tissue

Answer 9

mesoderm in blood islands of yolk sac, and then definitive cells from endothelium in the aorta, gonad, mesonephros region, then to the fatal liver then the bone marrow

Question 10

The change in bone marrow during adolescence

Answer 10

in infancy all bone marrow haematopoietic, but during childhood there is progressive fatty replacement of marrow throughout long bone so that even in adult life haematopoietic marrow confined to central skeleton (here 50% of the marrow still consists of fat)

Question 11

fatty marrow capable of?

Answer 11

reversion to haematopoiesis, in some blood disorders there is also expansion of haematopoiesis into long bones

Question 12

Extra medullary haematopoiesis

Answer 12

When the liver and spleen resume their fatal haematopoietic roles

Question 13

Bone marrow constituents

Answer 13

adult = trabecular bone, containing fat and haemopoietic tissue
Cellularity from 30-70% and decreases with age,
major cellular elements = haematopoietic cells + bone marrow stromal cells (fibroblasts, macrophages, fat cells and endothelial cells) provide physical support and a microenvironment suitable for blood cell production (ECM, adhesion molecules, blood cell growth factors)

Question 14

What is a measure of haematopoietic stem cell number?

Answer 14

all HSC’s express the antigen CD34

Measured when preparing cells for transplantation

Question 15

neutrophilic granulocyte development - example of a recognisable haematopoietic lineage

Answer 15

promyleocytes, myelocytes, metamyleocytes, band neutrophils, segmented neutrophils

Question 16

what types of cells circulate in the blood

Answer 16

mainly the most mature cells in each lineage enter circulation in significant numbers although small numbers of stem cells and progenitors present

Question 17

What are the two key factors in achieving precise regulation of hematopoiesis

Answer 17

transcription factors, cytokines

Question 18

the names of two key transcription factors essential for haematopoiesis

Answer 18

Runx1

GATA-2

Question 19

Clinical assessment of blood + bone marrow - peripheral blood cells

Answer 19

full/ complete good count, usually automated giving absolute numbers of different cell types, examination of film for morphology if abnormal parameters noted

Question 20

Clin assessment - bone marrow aspiration

Answer 20

cytological examination of haematopoietic cells, trephine produces a core biopsy, good for histological examination and cellularity

Question 21

Lin assessment - stem cells

Answer 21

assessed indirectly by colony assays and measurement of CD34 positive cells