Lecture 24: Lymphatic Tissue And Organs

Question 1

Identify and describe the structures and function of the spleen.

Answer 1

Location:
-Left posterior ab wall

Structure:
-Covered by DCT capsule –> line outside
-Myofibroblasts
-Trabequlae
-white pulp (Spenic nodules) and red pulp–> areas between nodules
Function:
-One site where immune responds to antigens
-Filtration of the blood –> Old erythrocytes and platelets

Question 2

Describe the general circulation through the spleen.

Answer 2

Splenic artery/Capsular arteries –> Branches run through trabeculae = trabecular artery –> runs through interior of parenchyma –> central artery (Surround lymphocytes) –> penicillar arterioles –> venous sinuses (Splenic sinuses)

Question 3

Identify & describe the structures and function of white pulp

Answer 3

White pulp = Lymphatic nodules
(Looks pale/purple–> Full of lymphoblasts)
-Thick accumulation of lymphocytes
-Lymphatic nodules - Germinal centers that decrease w age

Question 4

Identify & describe the structures and function of red pulp.

Answer 4

Red pulp

• Region between the nodules
• Contains chords of cells (Billroth)
• Contains Venous sinuses/capillaries
• Surrounds white pulp
• RBC accumulate here (Reddish color)
• Reticular fibers

Function:
-Filtration of antigens and senile and abnormal erythrocytes and platelets from the blood

Circulation:

1) Closed
- Cells go into the sinuses and come out of the pulp veins

2) Open
- Blood opens up to the chords and drain the blood cells, and eventually the pulp veins are formed

Question 5

Describe the importance of marginal zone and periarteriolar lymphatic sheath (PALS)

Answer 5

Peri artierl lymphatic sheath

-Marginal zones allow antigens in the blood to open and go into sinuses, allows antigens to come out of blood and be recognized by macrophages and activates immune response

• First area the lymphocytes comes in contact w the antigens
• Trap antigens from thee circulation and present the antigen to the lymphocytes of the spleen

Question 6

Identify & describe the structure and function of the different types of tonsils

Answer 6

-Lymphatic tissue lined by epithelial
-Tonsils apart of gut associated
lymphoid tissue (GALT)

Function:
-Process antigens that enter the body through oral cavity and nasal passage

Types:

1) Pharngeal tonsil –>
- Causes Mouth breathing
- patches ofstratified squamous non keratinized epithelium

2) Lingual tonsil –> Tongue
- Posterior aspect of tongue
- Shallow crypts
- B

3) Palatine tonsil –>
- Towards the oral cavity
- Secondary nodules (Germinal centers)
- Stratified squamous non keratinized

Question 7

Define the term “lymphadenopathy”

Answer 7

1) Follicular hyperplasia –> Increases in number and size of cortical lymphoid follicles
- Happens during Humoral response –> Producing antibodies

2) Paracortical hyperplasia –> Expansion of paracortical zone
- Happens in viral infection

3) Sinus hyperplasia –> Medullary sinuses are extremely prominent
- draining necrotic tumor

Question 8

Explain the concept of metastasis of cancer through lymph nodes

Answer 8

-Lymph draining from an organ or area
with malignancy

-malignant cells enter the
subcapsular sinus (SS) of the lymph
node and may settle at this site where
they could proliferate to form a
secondary tumor mass.

Question 9

Explain the consequence of thymic aplasia in Di George syndrome

Answer 9

• Chrom 22 at q11.2
• Defect in 3rd and 4th brachial pouches and arches
• Absent thymus gland is the main clinical finding

Question 10

Correlate the histologic changes that take place in the spleen secondary to its enlargement inpathological states.

Answer 10

x

Question 11

Correlate the histologic changes that take place in the spleen secondary to its enlargement inpathological states.

Answer 11

x