Lymphoid Structures III

Question 1

Where are macrophages found in the spleen?

Answer 1

Nearby to the sinusoids (p.193)

Question 2

What are the 5 layers of a splenic sinusoid from outside to inside?

Answer 2

Red pulp; Marginal zone; Germinal Centres; PALS; Central arteriole (p.193)

Question 3

In what layer of the splenic sinusoid does venous drainage occur?

Answer 3

In the red pulp (p.193)

Question 4

What is housed in the red pulp of the spleen?

Answer 4

RBCs (p.193)

Question 5

What is housed in PALS of the spleen?

Answer 5

T cells (p.193)

Question 6

What is housed in the marginal zone of the spleen?

Answer 6

APCs (p.193)

Question 7

What are housed in germinal centres of the spleen?

Answer 7

B cells (p.193)

Question 8

In what general area of the spleen are both T cells and B cells found?

Answer 8

In the white pulp (p.193)

Question 9

Where are T cells found in the spleen?

Answer 9

In the periarterial lymphatic sheath (PALS) (p.193)

Question 10

Where are B cells found in the spleen?

Answer 10

In follicles (p.193)

Question 11

What is the function of splenic macrophages?

Answer 11

To remove encapsulated bacteria (p.193)

Question 12

Describe the mechanism by which splenic dysfunction leads to increased susceptibility to encapsulated organisms.

Answer 12

Splenic dysfunction –> Decreased IgM –> Decreased compliment activation –> Decreased C3b opsonization –> Increased susceptability to encapsulated organisms (p.193)

Question 13

Name the six encapsulated organisms.

Answer 13

Streptococcus pneumoniae, Haemophilus influenzae type B, Neisseria meningitidis, Salmonella, Klebsiella pneumoniae, Group B Streptococci (pneumonic: SHiN SKiS) (p.193)

Question 14

Name three pathological findings associated with splenectomy.

Answer 14

Howell-Jolly bodies (nuclear remnants), target cells, thrombocytosis (p.193)

Question 15

What is the primary function of the thymus?

Answer 15

Site of T cell differentiation and maturation (p.193)

Question 16

Describe the structure of the thymus.

Answer 16

Encapsulated organ with a dense cortex filled with immature T cells. Contains a medulla and epithelial retirular cells (p.193)

Question 17

What is the embryological origin of the thymus?

Answer 17

From the epithelium of the 3rd branchial pouch (p.193)

Question 18

What is the origin of thymus lymphocytes?

Answer 18

Mesenchymal origin (p.193)

Question 19

What is contained in the cortex of the thymus?

Answer 19

Densely packed with immature T cells (p.193)

Question 20

What is contained in the medulla of the thymus?

Answer 20

Medulla is pale with mature T cells and epithelial reticular cells containing Hassall’s corpuscles (p.193)

Question 21

Where do positive and negative selection of T cells occur in the thymus?

Answer 21

Positive selection (MHC restriction) occurs in the cortex; negative selection (nonreactive to self) occurs in the medulla (p.193)