Lymphoid Tissue

Front 1

What is the purpose of the lymphoid system

Back 1

It responds immunologically to invading foreign substances

Front 2

What is the main function of the lymphoid system

Back 2

To protect organisms against invading pathogens or antigens or antigens ( bacteria, viruses, parasites)

Front 3

Wen does an immune response occur

Back 3

When organissm detects pathogens, able to enter organism at any point

Front 4

What is the minor function of lymphatic system

Back 4

1) Collects excess interstitial fluid into lymphatic capillaries

2) transports absorbed lipids from small intestine

Front 5

What percent of the blood does lyphocytes make up

Back 5

20 to 30%

Front 6

What percent of lymphocytes in the blood are small lymphocytes

Back 6

90%

Front 7

Where does mammalian stem cells differentiate

Back 7

in the bone marrow

Front 8

What cells that differentiate in the bone cells turn into

Back 8

several kinds of blood cells

Front 9

Where do lymphocytes originate from

Back 9

During the process from a common lymphoid progenitor before differentiating into their distinct lymphocyte types.

Front 10

What is the ormation of lymphocytes called

Back 10

lymphopoiesis

Front 11

B lymphocytes

Back 11

Mature from B cells in the bone Marrow

Front 12

T cells

Back 12

T cells migrate to and mature in a distinct organ, the thymus

Front 13

What occurs with the lymphoctes after maturation

Back 13

They enter the circulation and go to the peripheral lymphoid organs (e.g the spleen and lymph nodes )Where they survey for invading pathogens and/ or tumor cells

Front 14

What are the four types of T cells

Back 14

1) Hepler T cells

2) Cytoxic T cells

3) Memory T cells

4) Suppressor T cells

Front 15

Helper T ells

Back 15

Assist other lymphocytes by secreting immune chemicals called cytokines (interleukins). Plasma cells then produce antibodies
(immunoglobulins)

Front 16

Cytokines

Back 16

Protein hormones that stimulate proliferation, differentiation and maturation of B cells into plasma cells.

Front 17

Cytotoxic T cells

Back 17

Recognize antigenically different cells such as virus-infected cells, malignant cells or foreign cells, and estroy them.

Front 18

How are cytoxic T cells actiated

Back 18

When they combine with antigen that react with their receptors

Front 19

Memory T cells

Back 19

Long living progeny of T cells. Respond rapidly to same antigens if they reappear in the body and stimulate production of cytotoxic T Conterpart of memory B cells

Front 20

Suppresor T cells

Back 20

Decrease or inhibit the function of helper T cells and cytotoxic T cells. Modulate immune response

Front 21

What happens to the b cells in the bone marrow

Back 21

They mature and become immunocompetent

Front 22

What occurs after maturation to the B cells

Back 22

Blood carries B cells to the lymph nodes ,spleen and connective tissue

Front 23

How do B cells work

Back 23

They recognize antigen with with antigen receptors on their membrane surface

Front 24

What occurs after the B cells bind to specific antigen

Back 24

Immunocompetent B cells acrivate

Front 25

What is the response of B cells to an antigen

Back 25

Antigen-presenting cell ( eg. macrophage) presents the antigen to a B cell. A helper T cell secretes cytokine inducing proliferation and differentiation of antigen -activated B cell.

Front 26

What does activated B cells become

Back 26

Plasma cells

Front 27

Plasma cells

Back 27

Secrete large amounts of antibodies specific to the antigen that triggered plasma cell formation

Front 28

What is the job of antibodies

Back 28

To react with antigens and initiate a process that will destroy the foreign substance

Front 29

What happens to B cells that do not secrete antibodies

Back 29

They become memory B cells. These cells produe a more rapid immunologic response if the same antigen reappears

Front 30

What are the four stages of the Humoral immune response

Back 30

1) B cells are exposed to antigen

2) Proliferation and diferentiation of B cells into plasma cells

3) Plasma cells secrete specific antibodies into blood and lymph

4) Antibodies bind to, inactivate and destroy specific foreign substance of the antigen

Front 31

What does the activation and proliferation of B cells require to a specific antigen require

Back 31

Helper T cells taht respond to the same antigen and will secrete cytokines

Front 32

What is the basis of humoral response

Back 32

Presence of B cells, plasma cells and antibodies in blood and lymph are the basis of humoral immune response

Front 33

What encounters the innate immune system

Back 33

Microorganisms or toxins that successfully enter an organisms

Front 34

What usually innitiates the immune response

Back 34

It is usually triggered when microbes are identified by pattern recognition receptors ( PRR).

Front 35

How do pattern recognition receptors recognize

Back 35

PRRs recognize

1) components that are conserved among broad groups of microorganisms

2) or when damaged ,injured or stressed cells send out alarm signals, many of which are recognized by the same receptors as those that recognize pathogens

Front 36

Describe Innate immune defenses

Back 36

1) They are non-specific: these systems respond to pathogens in a generic way

2) This system does not confer long-lasting immunit against a pathogen

3) Innate immune system is the dominate system of host defense in most organisms

Front 37

What are lymph nodes

Back 37

Small, flattened oval or bean shaped organs, located in the course of the collecting lymph vessel

Front 38

What is the size of a lymph node

Back 38

From a few mm to more than 2 cm

Front 39

How are the capsule and trabeculae of lymph nodes formed

Back 39

By connective tissue

Front 40

Describe capsule in reference to trabeculae

Back 40

The connective tissue capsule surrounds lymph node and sends trabeculae into its interior

Front 41

What are the 2 major parts of the lymph node

Back 41

1) Outer cortex

2) Inner medulla

Front 42

What forms the cortex

Back 42

The reticular fibers and aggregations of lymphocytes

Front 43

What are the lighter staining central areas of the lymphoid nodules

Back 43

germinal centers

Front 44

What is the germinal center

Back 44

the area of lymphocyte poliferation

Front 45

What makes up the medulla

Back 45

medulalry cords and medullary sinuses

Front 46

medularry cors

Back 46

network of reticular fibers filled with plasma cells, macrophages and lymphocytes

Front 47

What separates the medullary cords

Back 47

Medullary sinuses

Front 48

What are medullary sinuses

Back 48

capillary like channels

Front 49

What is lymph entering the lymph node vi

Back 49

afferent lymphatic vessels

Front 50

Where do afferent lymphatic vessels penetrate the capsule surface

Back 50

These penetrate the capsule on the convex surface

Front 51

What does the afferent lympgatic vessels composed of

Back 51

Valves

Front 52

Where do the valves empty

Back 52

that empty into the subscapular ( marginal) sinus

Front 53

Where is lymph carried once reaching the node and entering via the afferent lymphatic vessels that penetrate the capsule on the cortex surface

Back 53

The lymph flows through trabecular ( cortical) sinuses then medullary sinuses

Front 54

What is the concavity of the lymph node called

Back 54

a hilus

Front 55

What is in the hilus of the lymph node

Back 55

Nerve, blood vessels and veins

Front 56

Where does lymph exist

Back 56

Opposite side via efferent lymphatic vessels in the hilus

Front 57

Describe the circulation of lymph

Back 57

1) enters through the lymph node via the afferent lymphatic vessels which peentrate the capsule on the convex surface

2) Afferent lymphatic vessels have valves that empty in to the subscapula sinuses

3) lymph flows through the trabecualr (cortical sinuses) then medullary sinuses

4) Lymph exits lymph node on the opposite side via efferent lymphatic vessels in the hilus

Front 58

What are the functions of lymph nodes

Back 58

Lymph filtration and phagocytosis of bacteria or foreign substances from the lymph

Front 59

Where are lymph nodes located

Back 59

along the path of lymphatic vessels

Front 60

Where are lymph nodes more prominent

Back 60

In inguinal and axillary regions

Front 61

What is the job of macrophages

Back 61

1) To destroy bacteria trapped in retinacular net

2) To producte, recirculate B cells and T cells

- T cells proliferate - B cells turn into plasma cells

Front 62

What is located in lymph leaving the lymph node

Back 62

Antibodies or the whole body

Front 63

Where are B cells located

Back 63

In lymphatic nodules

Front 64

Where are T clls located

Back 64

Deep cortical/paracortical regions

Front 65

Lymph nodes:

Back 65

sites of antigen recognition and antigen activation of B cells

Front 66

By what do lymphocytes leave the node and where is the lymph going

Back 66

By efferent lymph vessels to return to the blood stream

Front 67

What is the thymus

Back 67

A soft lobulated organ

Front 68

Where is the thymus located

Back 68

In the upper anterior mediastinum

Front 69

When is the thymus most active

Back 69

During childhood

Front 70

What happens to the thymus in adults

Back 70

Involuation ( it becomes filled with adipose tissue

Front 71

What is the thymus surrounded by

Back 71

Connective tissue capsules

Front 72

What is the thymus made up of

Back 72

A dark stained cortex with a network of interconnecting spaces

Front 73

What is located in the spaces

Back 73

They are colonized by immature lymphocytes migrating from bone marrow

Front 74

What occurs in the thymus

Back 74

The maturation and differentiation of T lymphocytes in the thymus

Front 75

What occurs in the lighter- stained medulla of the thymus,

Back 75

the epithelial cells form a network containing fewer lymphocytes and whorls of epithelial cells from thymic (Hassall's) corpuscles

Front 76

What is the job of trabeculae in the thymus

Back 76

-Trabeculae extend into thymus and divide it intonumerous incomplete lobules

Front 77

What does eaxh lobule consists of

Back 77

-dark-stained outer cortex and light-staining inner medulla

Front 78

How do blood vessels get into the thymus

Back 78

1) capsule

2) trabeculae

Front 79

Describe the histology changes of the thymus with age

Back 79

-greatest development shortly after birth. Thymus begins to regress and degenerate attime of puberty. Consequently, lymphocyte productiondecreases and the number of Hassall’s corpuscles increases with time -Progressively, parenchyma replaced by loose connectivetissue and adipose tissue

Front 80

What is the spleen

Back 80

A large lymphoid organ with rich blood supply. Like the lymph nod it is a discriminatory filter

Front 81

What is the difference between spleen and lymph nodes

Back 81

The slpleen is inserted into the blood stream

Front 82

What does the spleen do to the blood

Back 82

It clears the blood of aged blood cells and foreign particles and is the site of immune reaction to blood-borne antigens

Front 83

What is the spleen not essential for

Back 83

life in adult individuals

Front 84

What role does trabeculae play in the spleen

Back 84

Connective tissue capsule surrounds the spleen, giving trabeculae that divide interior into compartments.

Front 85

What is in the trabeculae

Back 85

arteries and veins

Front 86

What does the spleen exhibit

Back 86

Not distinct cortex and medulla but it has white and red pulp

Front 87

White pulp

Back 87

dark staining lymphoid aggregation or lymphatic nodules surroundinga central artery, branch of trabecular arteries, located atthe peripheryg

Front 88

What does the lymphatic nodules containe

Back 88

germinal centers

Front 89

Red pulp

Back 89

-pulp (rich in blood vessels) consists of spleniccords and splenic sinusoidsor venoussinuses

Front 90

What does red pupl contain

Back 90

pulparteries, venous sinuses and splenic cordsj*4e

Front 91

splenic cord

Back 91

-network of reticular fibers containing macrophages, lymphocytes, plasma cells, located betweenvenous sinuses`

Front 92

Splenic sinusoids

Back 92

-interconnected blood channels draining splenic blood into larger sinuses that will leavespleen via splenic veinfx

Front 93

What is the function of the spleen

Back 93

-Filters blood and site of immune response to bloodborne pathogensg

Front 94

Red pulp

Back 94

-dense network of reticular fibers containingerythrocytes, macrophages, lymphocytes, plasma cells

Front 95

Main function of red pulp

Back 95

-filter the blood; removes microorganisms, antigens and aged or abnormal erythrocytesfrom the blood fD

Front 96

What does macrophages do in the spleen

Back 96

-Macrophages break down hemoglobin of aged erythrocytesFD03C20}

Front 97

White pulp

Back 97

immunecomponent of the spleen- Lymphatic tissuej*4e

Front 98

What lymphatic cells surround the arteries

Back 98

-Lymphatic cells surrounding central arteries are Tcells3C20}

Front 99

What are the lymphatic nodules containing

Back 99

Mainly B cells

Front 100

What is located in the white pulp

Back 100

Antigen-presenting cells and macrophages

Front 101

What is th purpose of white pulp

Back 101

-Detect trapped bacteria and antigens and initiateimmune response against them

Front 102

Importance of white pulp during fetal life

Back 102

-During fetal life, spleen is haematopoietic organ, producing erythrocytes and granulocytestml>fD

Front 103

What does the spleen contain an important resevoir for

Back 103

Blood

Front 104

What is the palatine tonsil

Back 104

-Aggregates of lymphatic nodules located in the oralcavityD03C20}

Front 105

What is the relationship between tonsils and connective tissue

Back 105

-Not surrounded by aconnective tissue capsule

Front 106

What covers the surface of the tonsil

Back 106

-Surface protected by stratified squamous nonkeratinized epithelium

Front 107

What invaginates each tonsil

Back 107

-deep grooves called tonsillarcrypts (also lined by stratified squamous nonkeratinized epithelium

Front 108

What is below the epithelium

Back 108

1) numerouslymphatic nodules that Can merge with each other

2) Present lighter germinal center

Front 109

What is underlying the palatine tonsil

Back 109

-connective tissue capsule with trabeculae-