Lymphoid Structures

Question 1

What is a Lymph node?

Answer 1

A 2° lymphoid organ that has many afferents, 1 or more efferents. Encapsulated w/ trabeculae

Question 2

What are the functions of a lymph node?

Answer 2

Nonspecific filtration by macrophages, storage & activation of B & T cells, Ab production

Question 3

What is a Follicle?

Answer 3

Site of B-cell localization & proliferation in the outer cortex of a LN

Question 4

What are 1° follicles?

Answer 4

Dense & dormant

Question 5

What are 2° follicles?

Answer 5

Pale central germincal centers (GC) & are active

Question 6

What does the LN medulla consist of?

Answer 6

Medullary cords (closely packed lymphocytes & plasma cells) & medullary sinuses

Question 7

What do the Medullary sinuses communicate w/?

Answer 7

Efferent lymphatics & contain reticular cells & macrophages

Question 8

What does the Paracortex of LN do?

Answer 8

Houses T cells

Question 9

Where is the Paracortex?

Answer 9

Region of cortex b/w follicles & medulla

Question 10

What does the Paracortex contain?

Answer 10

High endothelial venules through which T & B cells enter from blood

Question 11

What happens in an extreme cellular immune response?

Answer 11

Paracortex becomes greatly enlarged

Question 12

When is the paracortex NOT well dev?

Answer 12

Pts w/ DiGeorge synd

Question 13

What is the LN drainage for the upper limb & lateral breast?

Answer 13

Axillary

Question 14

What is the LN drainage for the Stomach?

Answer 14

Celiac

Question 15

What is the LN drainage for the duodenum & jejunum?

Answer 15

Superior mesenteric

Question 16

What is the LN drainage for the sigmoid colon?

Answer 16

Colic→ inferior mesenteric

Question 17

What is the LN drainage for the rectum (lower portion) & anal canal (above the pectinate line)?

Answer 17

Internal iliac

Question 18

What is the LN drainage for the anal canal (below pectinate line)?

Answer 18

Superficial inguinal

Question 19

What the the LN drainage for the testes?

Answer 19

Superficial & deep plexus→ para-arotic

Question 20

What is the LN drainage for the scrotum?

Answer 20

Superficial inguinal

Question 21

What is the LN drainage for the thigh (superficial)?

Answer 21

Superficial inguinal

Question 22

What is the LN drainage for the lateral side of the dorsum of foot?

Answer 22

Popliteal

Question 23

What does the Right lymphatic duct drain?

Answer 23

Righ arm, right chest & right half of the head

Question 24

What does the Thoracic duct drain?

Answer 24

Everything else

Question 25

What are the sinusoids of the spleen?

Answer 25

Long, vascular channels in red pupl w/ fenestrated "barrel hoop" basement membrane (BM) Macrophages found nearby

Question 26

Where are T cells found in the spleen?

Answer 26

Periarterial lymphatic sheath (PALS) w/in the white pulp of the spleen

Question 27

Where are the B cells found in the spleen?

Answer 27

Found in follicles w/in the white pulp of the spleen

Question 28

What do macrophages do in the spleen?

Answer 28

Remove encapsulated bacteria

Question 29

What causes splenic dysfucntion?

Answer 29

Dec IgM→ dec complement activation→ Dec C3b opsonization→ Inc suspectibility to encapsulated organisms

Question 30

What are the encapsulated organisms splenic dysfunction pts are susceptible to?

Answer 30

* *Streptococcus pneumoniae* * *Haemophilus influenzae* type B * *Neisseria meningitidis* * *Salmonella* * *Klebsiella pneumoniae* * Group B Streptococci

Question 31

What are the signs of Postsplenectomy?

Answer 31

* Howell-Jolly bodies (nuclear remnants) * Target cells * Thrombocytosis

Question 32

What is the Thymus?

Answer 32

Encapsulated site of T-cell differentiation & maturation

Question 33

Where does the Thymus develop from?

Answer 33

Epithelium of 3rd brachial pouches

Question 34

What is in the cortex of the Thymus?

Answer 34

Dense w/ immature T cells

Question 35

What is in the medulla of the Thymus?

Answer 35

Pale w/ mature T cells & epithelial reticular cells containing Hassall's corpuscles

Question 36

What is Positive selection?

Answer 36

MHC restriction occurs in the cortex

Question 37

What is Negative selection?

Answer 37

Nonreactive to self occurs in the medulla