Lymphoid Tissue

Question 1

Innate immune system

Answer 1

Monocytes/ macrophages, neutrophils
Lack immunological memory
Invertebrates

Question 2

Adaptive immune system

Answer 2

Added form of defense
High specificity and memory
Trillions of lymphocytes

Slow reaction
Major role = destruction

Lymphocytes must not react to self antigens - immune tolerance

When tolerance breaks down -immune system fails to distinguish self - ‘non- self’
= Autoimmune disease

Question 3

Autoimmune disease

Answer 3

When immune system fails to distinguish ‘self’ from ‘non self’ and attacks body

Question 4

Primary lymphoid organs

Answer 4

Site of lymphocytes production and maturation

Bone marrow and thymus

Question 5

Secondary lymphoid organs

Answer 5

Site to which lymphocytes migrate and aggregate

Spleen, lymph nodes and lymph nodules

Question 6

3 principal forms of lymphocytes

Answer 6

B lymphocytes (B cells)

T lymphocytes (T cells)

Natural killer cells

Question 7

B lymphocytes

Answer 7

Produce antibodies

Question 8

T lymphocytes (T cells)

Answer 8

Participate in cellular immunity

Found in 3 forms

• helper T cells
• cytotoxic T cells
• suppressor T cells

Question 9

Natural killer cells

Answer 9

Kill virus infected cells and some tumor cells

Question 10

How is identifying cells of the immune system done?

Answer 10

using immunohistochemistry for cell surface markers called cluster designation (CD) molecules

Question 11

thymus

Answer 11

Is located in the mediastinum
increases in size from birth to puberty, regresses and becomes more fatty
Two lobes subdivided by septa
The lobules have a higher cellular outer cortex and a less cellular inner medulla

Question 12

Cortex of thymus contains

Answer 12

large number of T cells - sometimes called thymocytes

as well as epithelioreticular cells and macrophages

Question 13

Medulla of thymus contains

Answer 13

mainly T cells- larger and less tightly packed

and also epithelioreticular cells

Question 14

Where do T cells enter first in thymus

Answer 14

cortex then if survive the medulla

Question 15

What happens to T cells that don’t survive the cortex

Answer 15

undergo apoptosis

Question 16

what are Hassall’s corpuscles

Answer 16

whorls of epithelial cells with keratin at the core , accumulate in medulla of thymus

Question 17

In the cortex the T cells must express the correct surface antigens and recognise self and foreign antigens to survive, this is called ?

Answer 17

Positive selection

Question 18

In the medulla maturing T cells that recognise self antigens are eliminated, this is called?

Answer 18

negative selection

Question 19

The system of lymphatic vessels and associated lymph nodes provide for:

Answer 19

Drainage of lymph into the vascular system

Surveillance of tissues for signs of antigens from foreign invaders such as bacteria

Delivery of absorbed fats from the small intestine into the vascular system via lymphatic vessels in the villi of small intestines.

Question 20

lymph vessels are

Answer 20

thin walled and lined by endothelium and anchored to tissue by filaments

Question 21

Lymphocytes enter the lymph node via

Answer 21

incoming lymph or from the blood stream

Question 22

lymph node structures

Answer 22

connective tissue capsule, subcapsular sinus, cortex, paracortex, medulla, follicles and connective tissue trabecular

Question 23

Follicles beneath capsule contain

Answer 23

mainly B cells

Question 24

Primary follicle in lymph node

Answer 24

uniformly and densely packed

unstimulated

Question 25

Active or secondary follicles of lymph node

Answer 25

less densely packed centres called germinal centres

consist of actively dividing B cells surrounded by a mantle zone containing resting B cells

Question 26

What cells do the germinal centres contain

Answer 26

actively dividing B cells

Question 27

What cells do mantle zone contain

Answer 27

resting B cells

Question 28

The paracortex region of the lymph node is populated by ?

Answer 28

T cells

Question 29

What is the lining of the high endothelial venules found in the paracortex region

Answer 29

cuboidal endothelium

Question 30

What does the medulla of the lymph node contain

Answer 30

medullary sinus and medullary cords which contain plasma cells and macrophages

Question 31

B cells progression in lymph node

Answer 31

from follicle, to paracortex and then medulla where they can mature into plasma cells

Question 32

Example of MALT

Answer 32

Waldeyer’s ring at the entrance to the pharynx

Question 33

Functions of the spleen

Answer 33

produce immune response against blood borne antigens
Removal of particulate matter and aged blood cells (RBC)
production of blood cells during fetal life

Question 34

two areas of the spleen

Answer 34

white pulp and red pulp

Question 35

what makes up the white pulp nodules

Answer 35

T cells or B cells

Question 36

what makes up the red pulp nodules

Answer 36

blood filled capillaries which are open

Question 37

Most red blood cells passing through the organ must leave the capillaries and pass through…

Answer 37

the parenchyma and find their way back through small spaces

Old red blood cells can not deform and will be phagocytosed by macrophages associated with the wall of the sinus