organs of the immune system

Question 1

where are lymphoid cells first produced in the fetus

Answer 1

• yolk sac
• fetal omentum
• liver

Question 2

in older fetuses and adults lymphoid cells are produced

Answer 2

-in bone marrow

Question 3

what type of organ is bone marrow

Answer 3

• hematopoietic organ

- it gives rise to all blood cells

Question 4

what two types of lympoid organs are there

Answer 4

• primary lymphoid organs

- secondary lymphoid organs

Question 5

what makes up the primary lymphoid organs

Answer 5

• bone marrow
• thymus
• bursa of fabricius in birds

Question 6

what makes up the secondary lymphoid organs

Answer 6

• spleen
• lymph nodes
• non-encapsulated lymphoid tissue
• peter’s patches

Question 7

Primary lymphoid organs:

Answer 7

organs that regulate the development of lymphocytes

Question 8

Where do t lymphocytes develop and mature

Answer 8

t cells develop in bone marrow and mature in the thymus

Question 9

What is different about the t and b lymphocytes development and maturation differ

Answer 9

b cell development and maturation depends on the animal species

Question 10

where do B lymohocytes develop/mature in birds

Answer 10

-Bursa of Fabricius

Question 11

where do B lymohocytes develop/mature in primates and rodents

Answer 11

-bone marrow

Question 12

where do B lymohocytes develop/mature in rabbits, dogs, ruminants and pigs

Answer 12

intestinal lymphoid tissue

Question 13

where is the thymus located?

Answer 13

the thymus is located in the thoracic cavity in front and below the heart

Question 14

what does it mean when the thymus undergoes involution

Answer 14

-The thymus starts large in newborns but regresses to invisible in adult animals

Question 15

what is the structure of the thymus

Answer 15

-covered by connective tissue capsule and consists of lobules

Question 16

what is contained in the cortex of they thymus

Answer 16

thymocytes (lymphocytes)

Question 17

what is contained in the medulla of the thymus

Answer 17

• only a few lymphocytes

- no lymphatic vessels leave the thymus

Question 18

what is the primary function of the thymus

Answer 18

-the maturation of T lymphocytes

Question 19

where do T lymphocytes learn to recognize self antigens

Answer 19

thymus

Question 20

how myst t lymphocytes bond to self antigens

Answer 20

They must not respond/bond strongly to self antigens

Question 21

what happens to thymocytes with receptors that bind strongly to self antigens

Answer 21

they are destroyed through apoptosis

Question 22

apoptosis during the antigen selection is what kind of selection

Answer 22

negative selection

Question 23

what happens to thymocytes that cannot bind any MHC 2 molecules

Answer 23

they are also removed

Question 24

What happens to thymocytes that recognize MHC 2/Ag complexes with moderate affinity

Answer 24

-they are allowed to live and is known as positive selection

Question 25

What happens to the positively selected cells in the thymus

Answer 25

-the positively selected cells leave the thymus as mature T lymphocytes and populate the secondary lymphoid organs

Question 26

what regulates the maturation process in the thymus

Answer 26

- a mixture of cytokines and thymic hormones

Question 27

which cytokines and thymic hormones are used in the maturation of t cells in the thymus

Answer 27

- thymosin - thymopoietins - thymulin - thymostimulins

Question 28

where is the bursa of fabricius found

Answer 28

- only in birds | - round sac located just before the cloaca

Question 29

how is the bursa of fabricius and thymus similar in regards to the animals age

Answer 29

they both undergo involution

Question 30

what is the interior structure of the burs of fabricius

Answer 30

-epithelium embeds the lymphocytes and lines a hollow sac connected to the cloaca by a duct

Question 31

What are the follicles in the bursa fo fabricius

Answer 31

fold made of epithelium that extend into the sac

Question 32

each follicle in the bursa of fabricius has 2 zones called

Answer 32

the cortex and medulla

Question 33

the cortex of the bursa of fabricius containes

Answer 33

- lymphocytes - plasma cells - macrophages

Question 34

what is the function of the bursa of fabricius

Answer 34

-maturation of B lymphocytes

Question 35

what kind of selection takes place inside the bursa of fabricius

Answer 35

-negative and positive selection of B lymphocytes

Question 36

what differentiation takes place in the bursa of fabricius

Answer 36

differentiation of antibody-forming cells (b-Lymphocytes)

Question 37

what are the secondary lymphoid organs divided into

Answer 37

- encapsulated organs | - non-encapsulated tissue

Question 38

what are examples of encapsulated secondary lymphoid organs

Answer 38

- lymph nodes | - splee

Question 39

what are examples of non encapsulated secondary lymphoid tissue

Answer 39

-mucosal lymphoid aggregates

Question 40

when do secondary lymphoid organs develop and how long do the persist

Answer 40

- develop late in fetal life | - persist in adult life

Question 41

how do secondary lymphoid organs react to antigenic stimulation

Answer 41

Enlarge

Question 42

how is the immune system impaired when a secondary lymphoid organ is removed surgicaly

Answer 42

-this does not impair immune capabiltiy

Question 43

how do DC interact with the secondary lymphoid organs

Answer 43

-The secondary lymphoid organs contain DC which trap and process antigens, and later present these antigens to lymphocytes to initiate an immune response

Question 44

Lymph nodes act as

Answer 44

filters of lymph to trap antigens

Question 45

what is the shape of the lymph nodes

Answer 45

- round/bean shaped | - encapsulated organ

Question 46

how is the interior of the lymph nodes divided

Answer 46

- outer:cortex - between the cortex and medulla: paracortex - Inner: medulla

Question 47

where are B lymphocytes found in the lymph nodes

Answer 47

- in the cortex | - in germinal centers surrounded by capsules

Question 48

where are T cells and DC found in lymph nodes

Answer 48

-mainly in the paracortex

Question 49

what is contained in the medulla of the lymph node

Answer 49

-the medullar contains many different types of cells

Question 50

what is the dirrection of the afferent lymph flow.

Answer 50

flow of lymph from local tissue into the lymph node

Question 51

Lymphocytes, DCs and Antigens are carried in the ______ lymph flow (to/from) the lymph node

Answer 51

- Afferent | - to the lymph node

Question 52

Lymph enter the lymph node through

Answer 52

the subscapsular sinus

Question 53

what happens to the lymph oafter it enters the lymph node via the subscapular sinus

Answer 53

-it percolates through the lymph node to the medullary sinus

Question 54

Where does lymph exit the lymph node

Answer 54

-through the efferent lymphatic vessels

Question 55

do lymph nodes have blood supply?

Answer 55

yes lymph nodes have arterial and venous blood supply

Question 56

what is the principle function of Lymph nodes

Answer 56

-is to facilitate the interaction between dendritic cells and antigen sensitive T and B lymphocytes

Question 57

what is the spleen

Answer 57

- a large encapsulated organ found in almost all vertebrate animals - structured by a network of connective tissue trabeculae

Question 58

what two types of tissue makes up the spleen

Answer 58

- Red pulp | - White pulp

Question 59

What is Red pulp tissue in the spleen

Answer 59

it is tissue that does blood filtering and RBC storage

Question 60

what is the white tissue in the spleen

Answer 60

- where immune induction occurs | - rich in lymphocytes

Question 61

what does the spleen filter the blood for

Answer 61

the spleen filters blood for - blood-borne antigens - cellular debris - aged blood cells

Question 62

what does the spleen store

Answer 62

- RBC - Platelets - recycles iron

Question 63

what type of lymphoid organ is the peyers patch and where is it located?

Answer 63

- it is a non encapsulated lymphoid tissue | - located in the wall of the small intestines

Question 64

where is the peyers patch found in ruminants pigs dogs and rabbits

Answer 64

in the ileum

Question 65

what type of lymphoid organ is the peyers patch found in ruminants pigs dogs and rabbits

Answer 65

it is a primary lymphoid organ for B cell development

Question 66

what is in the peyers patch

Answer 66

-it contains densely packed lymphoid follicles containing only B lymphocytes

Question 67

Peyers patches are covered by an _________ layer containing specialized cells called ________ which have characteristic membrane ruffles

Answer 67

- epithelial layer | - M cells

Question 68

does the peyers patch undergo involution

Answer 68

yes

Question 69

what other lymphoid organ has a similar function to the peyers patch

Answer 69

-Bursa of Fabricius

Question 70

where is the peyers patch located in rabbits and rodents

Answer 70

-located in the ileum and jejunum at random intervals

Question 71

what is different about the peyers patch in the rodents and rabbits

Answer 71

-in these species the PP develops 2-4 weeks after birth and do not undergo involution

Question 72

T/F non-encapsulated lymphoid aggregates do not make up a large portion of the total lymphoid tissue

Answer 72

false

Question 73

where is most of the non-encapsulated lymphoid tissue found

Answer 73

in the intestinal mucosal

Question 74

MALT

Answer 74

Mucosal-associated lymphoid tissue

Question 75

what 4 groups of tissues make up MALT

Answer 75

- GALT - BALT - NALT - CALT

Question 76

GALT:

Answer 76

Gastrointestinal associated lymphoid tissue

Question 77

BALT:

Answer 77

Bronchial associated lymphoid tissue

Question 78

NALT:

Answer 78

Nasal associated lymphoid tissue

Question 79

CALT:

Answer 79

conjunctiva associated lymphoid tissue

Question 80

which of the 4 tissues that makes up the MALT is the best know

Answer 80

GALT

Question 81

Why is the GALT important

Answer 81

-it is the induction site and effector site of the intestinal immune response