Immune and Hematological Tissues

Question 1

(hematopoiesis)

Answer 1

formation of blood cells

Question 2

where does hematopeisis happen in the fetus

Answer 2

yolk sac from week 4 of development

• liver until shortly before birth
• spleen until cartilagenous bones vascularised

Question 3

where does hematopeisis happen in adult to infant/adult

Answer 3

marrow of most bones in children
- mainly marrow of pelvis, sternum,
vertebrae and cranial bones in adults (due to
fat deposition in marrow of long bones)

Question 4

what are primary lymphoid tissue? and give examples

Answer 4

sites where
lymphocytes differentiate to express antigen receptors
– Thymus (T lymphocytes)
– Bone Marrow (B lymphocytes)

Question 5

what are secondary lymphoid tissue and give examples

Answer 5

specialised sites for
turning on the acquired immune response
– Lymph nodes
– Spleen
– Mucosal Associated Lymphoid Tissue (MALT)
• Gut associated lymphoid tissue (GALT)
• Nasal asociated lymphoid tissue (NALT)
• etc

Question 6

what is the lymphatic system

Answer 6

A drainage system involved in fluid balance, returning to the blood
– excess interstitial fluid (approx. 3 litres/24h)
– plasma proteins

Question 7

where do lymph capillaries orginiate as

Answer 7

“closed tubes” in almost all tissues (except CNS,

epidermis and cartilage)

Question 8

what are the walls of the lymph capillaries made of?

Answer 8

• Capillary wall constructed of overlapping endothelial cells that
respond to fluid pressure

Question 9

how are lymphatics made?

Answer 9

Form from joining lymph capillaries

Question 10

what do the superficial mylphatics follow and where do they drain

Answer 10

follow superficial veins
– flow into lymph nodes in axillary (armpit), inguinal (groin) or cervical
(neck) areas where they drain into deep lymphatics

Question 11

what do the deep lymphatics follow and where do they drain

Answer 11

follow main vessels
– lymph nodes either side of the aorta (para-aortic) drain the paired
organs, nodes lying anterior (pre-aortic) the gut etc

Question 12

how is the the trunk devideded in Superficial lymphatic

drainage

Answer 12

The trunk can be
divided into 4
quadrants with
different drainage by
vertical and
horizontal lines
through the
umbilicu

Question 13

where, in the Deep lymphatic

drainage does lymph from 3 quarters of the body drain into

Answer 13

the left
brachiocephalic vein via
the thoracic duct

Question 14

where, in the Deep lymphatic

drainage does lymph from the upper right quadrant of the body drain into

Answer 14

right brachiocephalic

vein

Question 15

what are lymph nodes

Answer 15

– An important component of host defense
– Filter lymphatics
– LN represent the anatomical meeting p

Question 16

desrcibe lymph nodes of the MALT

Answer 16

Aggregates of lymphocytes in a reticular mesh
– No incoming lymphatic vessels
– May be isolated or form clusters (Peyer’s Patches in ileum; tonsil)

Question 17

what is the largest lymphoid organ

Answer 17

the spleen

Question 18

role of the spleen

Answer 18

Directs immune responses to antigens in the blood

– Important for clearance of effete red blood cells

Question 19

what is wrong with hypospleenia/asplenia

Answer 19

not fatal, but predisposes to infection

especially of capsulated bacteria

Question 20

how do we diagnose hypospleia/aspleenia

Answer 20

Presence of Howell-Jolly bodies (erythrocytes with nuclear
fragments) in peripheral blood is often diagnostic of
hyposplenism / asplenia

Question 21

what disease is splenomegaly common in?

Answer 21

Splenomegaly common in chronic disease (malaria,

leishmaniasis, Hodgkin’s disease)

Question 22

where is the spleen found

Answer 22

Left hypochondriac region of abdominal cavity

Question 23

in what percentage of the population is an accesoory spleen resernt

Answer 23

10%

Question 24

what directs the the nderlying structure of lymphoid tissue and the behaviour of hematopieotc
cells in lymphoid tissue

Answer 24

non-hematopoietic ‘stromal’ cells