Lymphatic System I & II

Question 1

How are the functions of the lymphatic system carried out by?

Answer 1

Cells
effector molecules
tissues
organs

Question 2

what cells arise from lymphoid stem cells?

Answer 2

T lymphocytes
NK cells
B lymphocytes – plasma cells

Question 3

what are the two types of T cells?

Answer 3

Helper CD 4+

Cytotoxic CD 8+

Question 4

what do helper CD 4 activate?

Answer 4

B lymphocytes

CD 8+ with IL-2 production

Question 5

what types of lymphocytes are capable of recirculation?

Answer 5

T cells - 60-70% of circulating lymphocytes

Question 6

Where are B cells produced?

Answer 6

bone marrow

Question 7

what do NK cells attack?

Answer 7

virally infected cells

cancer/tumor cells

Question 8

what types of cells carryout innate responses?

Answer 8

neutrophils
macrophages
mast cells
NK cells

Question 9

what are the characteristics of innate responses?

Answer 9

fast and non specific

does not produce memory cells

Question 10

What cells are involved in adaptive response?

Answer 10

B and T cells - depends on the initial recognition of antigens

Question 11

what are the characteristics of adaptive responses?

Answer 11

slower and specific

produces memory cells

Question 12

when is antibody mediate immunity (humoral immune response) important?

Answer 12

bacterial infections

Question 13

what cells are involved in humoral immune responses? what are the effectors?

Answer 13

helper T cells
B cells
plasma cells

Immunoglobin molecules

Question 14

When is cell mediated immunity important?

Answer 14

viral and fungal infections - involved in the rejection of transplanted organs and tissue grafts

Question 15

what are the cells involved in cell mediated immunity? what are the effectors?

Answer 15

Cytotoxic T cells

T cells (effector)

Question 16

what is the characteristic of diffuse, loose lymphoid tissue?

Answer 16

few lymphocytes present

initial immune response
found in lamina propria
intercepts antigen
no capsule

Question 17

what is the characteristic of diffuse, dense lymphoid tissue?

Answer 17

many lymphocytes are present

contained in meshwork of reticular fibers
No capsule

Question 18

what does the GC indicate?

Answer 18

lymphatic tissue response to antigen

Question 19

what does a primary nodule consist of?

Answer 19

small lymphocytes
not ever exposed to antigen
found in newborns only

Question 20

what does a secondary nodule consist of?

Answer 20

germinal cortex (GC)

Question 21

what is the germinal cortex?

Answer 21

where lymphocytes undergo proliferation

Question 22

what is a follicular dendritic cell?

Answer 22

Not an antigen presenting cell

help keep the antigen-antibody complex in place

Question 23

what is the major cell found in lymphoid nodules?

Answer 23

B lymphocytes

Question 24

what cells are found around the periphery of the lymphoid nodules?

Answer 24

T cells

Question 25

where does the thymus originate from?

Answer 25

3rd pharyngeal pouch | epithelium?

Question 26

what is important to note about the thymus?

Answer 26

no afferent lymphatics - just efferent why? - because there is no filter, just production and migration through efferent

Question 27

what type of cells make up the epithelial component of the thymus?

Answer 27

ERC - epithelial reticular cells

Question 28

what are thymocytes?

Answer 28

immature T lymphocytes

Question 29

what are the parenchyma of the thymus?

Answer 29

Cortex and medulla

Question 30

what is in the cortex?

Answer 30

immature T lymphocytes = thymocytes | ERCs

Question 31

whats in the medulla?

Answer 31

mature T lymphocytes ERCs thymic corpuscle (Hassall) - consist of rings of degenerating epithelial reticular cells

Question 32

what type of tissue make up the thymus capsule?

Answer 32

dense irregular CT - throw in septa to divide tissue into lobule = trebeculae

Question 33

what are the primary support cells in the cortex?

Answer 33

ERCs | they form a cytoreticulum which is held together by desmosomes (keratin)

Question 34

what happens to the thymus after puberty?

Answer 34

involution - replaced with fat (accumulation)

Question 35

What condition is the thymus gland absent?

Answer 35

DiGeorge Syndrome 22q11

Question 36

where is the defect in DiGeorge's Syndrome?

Answer 36

Defect in the development of the 3rd & 4th branchial pouche s& arches.

Question 37

what does the mneumonic "Catch 22" stand for?

Answer 37

``` Cardiac defects Abnormal facies Thymic hypoplasia Cleft palate Hypocalcaemia resulting from 22q11 deletions. ```

Question 38

what types of cells are found in the paracortex (inner cortex)?

Answer 38

T cells

Question 39

what do lymph nodes have?

Answer 39

afferent lymphatic vessel - drains lymph through convex margin

Question 40

what does the outer cortex of lymph nodes contain?

Answer 40

lymphatic nodules - composed of mainly B cells | few T cells, reticular cells, macrophages, antigen presenting cells

Question 41

what do HEVs allow?

Answer 41

transition of lymphocytes from the blood stream to lymph tissue found in deep cortex

Question 42

what are the two parts of the medulla in the lymph nodes?

Answer 42

medullary cords | medullary sinuses

Question 43

whats in the medullary cords?

Answer 43

its dense lymphoid tissue | contains B cells, plasma cells, reticular cells, macrophages

Question 44

what do medullary sinus contain?

Answer 44

separates medullary cords contains lymph, few macrophages granulocytes maybe present

Question 45

what makes up the stroma of lymph nodes?

Answer 45

reticular cells (modified fibroblasts)

Question 46

what is the stroma of lymph nodes a framework for?

Answer 46

myeloid (bone marrow) and lymphoid (lymph nodes, spleen) organs

Question 47

where does lymph tissue/organs come from?

Answer 47

mesoderm

Question 48

what is the parenchyma of the spleen?

Answer 48

red pulp | white pulp

Question 49

what is in the red pulp?

Answer 49

cords of cells (cords of Billroth) Sinusoidal capillaries dense network of reticular fibers - numerous erythrocytes, lymphocytes, plasma cells, macrophages and other graulocytes

Question 50

what is in the white pulp?

Answer 50

thick accumulation of lymphocytes | lymphatic nodules - GC decrease with age

Question 51

what is PALS?

Answer 51

T lymphocytes surround the central artery | "peri arteriolar lymphatic sheath"

Question 52

what surrounds PALS?

Answer 52

B cells - sheathed artery

Question 53

what is the marginal zone?

Answer 53

the rim of lymphocytes (T cells and B cells) along with APCs and macrophages

Question 54

where do lymphocytes first come in contact with antigens?

Answer 54

marginal zone

Question 55

in the red pulp, the central a. gives ride to what?

Answer 55

penicillar arteries which ultimately become sinusoidal capillaries

Question 56

what is closed circulation?

Answer 56

sinusoidal capillaries may continue into venues to pulp veins

Question 57

what is open circulation?

Answer 57

sinusoidal capillaries can open into the cords, drain blood cells and eventually the pulp veins are formed

Question 58

what are splenic sinusoids lined by?

Answer 58

elongated endothelial cells (Littoral Cells) - supported by an incomplete basal lamina of reticular fibers

Question 59

what is the function of macrophages in circulation?

Answer 59

to remove damaged or effete erythrocytes from circulation

Question 60

what secondary lymphoid organ is GALT?

Answer 60

"gut associated lymphoid tissue" | Tonsils

Question 61

what is the function of the tonsils?

Answer 61

process antigens that enter the body through oral cavity and nasal passage

Question 62

what are lymphatic tissue lined by epithelium?

Answer 62

tonsils

Question 63

how many palatine tonsils do we have?

Answer 63

2

Question 64

what are crypts and what do they do?

Answer 64

invagination of epithelium | contain desquamated epithelial cells, live and dead lymphocytes and bacteria

Question 65

what is found in the region where crypts are found?

Answer 65

mainly secondary nodules (with GC)

Question 66

what is the purpose of the posterior separation from the superior constrictors by a thick capsule?

Answer 66

prevents the spread of infection

Question 67

what is pharyngeal tonsils lined with?

Answer 67

pseudostratified columnar epithelium = respiratory epithelium

Question 68

what do you call inflammed pharyngeal tonsils?

Answer 68

adenoids

Question 69

what is Waldeyer's Ring?

Answer 69

1 pharyngeal tonsil 2 palatine tonsils 1 lingual tonsil

Question 70

what do thymic corpuscles have?

Answer 70

keratin filaments which can be keratinized and calcify - which is why in elderly people you can see calcified spots in thymus in the superior mediastinum

Question 71

if you see a central artery, what organ are we looking at?

Answer 71

spleen!