Lymphatics & Immunity Flashcards Preview

A&P 300 > Lymphatics & Immunity > Flashcards

Flashcards in Lymphatics & Immunity Deck (138):
1

What does the lymphatic system consist of?

Lymph
Lymphatic vessels
Lymphatic tissue

2

Lymph

A liquid type of connective tissue that is clear and colourless.
Found in lymphatic vessels and tissues
In between cells = interstitial fluid
In blood = plasma

3

Lymphatic tissues

Lymph organs, RBM.
Specialized forms of reticular connective tissue that contain a large number of lymphocytes

4

Lymphocytes

Agranular white blood cells that participate in adaptive immune response (B and T cells)

(Plus granular nonspecific NK cells)

5

3 Major functions of the lymphatic system

1. Drains excess interstitial fluid
-- returns it to the blood via subclavian veins
-- approximately 3 litres/day
-- also returns lost plasma protein to blood stream
2. Transports dietary lipids
-- plus lipid soluble vitamins (A, D, E and K)
3. Carries out immune responses

6

Lymphatic vessel pathway

Blood capillaries --> interstitial space --> lymphatic capillaries --> lymph vessels --> lymph trunks --> lymph ducts --> veins

7

Lymphatic capillaries

- Located in the spaces between cells
- Have terminal (closed) ends on one end
- Cells overlap so interstitial fluid flows in by not out
- when pressure greater in interstitial fluid, cells separate; when greater in lymph, cells adhere
- Unite to form lymphatic vessels
- HIghly permeable

8

Anchoring filaments

Contain elastic fibres; attach lymphatic endothelial cells to surrounding tissues.
Also when excess interstitial fluid accumulates and tissues swell, filaments are pulled and openings between cells increase.

9

Lacteals

Specialized lymphatic capillaries in small intestines that carry dietary lipids into lymphatic vessels

10

Chyle

Lymph containing dietary lipids drained from small intestine, carried in lacteals. Appear creamy white.

11

Principle Lymph Trunks

1. Lumbar (lower limbs, wall and viscera of pelvis, kidneys, adrenals, abdominal walls)

2. Intestinal (stomach, intestines, pancreas, spleen, part of liver)

3. Bronchomediastinal (thoracic wall, lung, heart)

4. Subclavian (upper limbs)

5. Jugular (head and neck)

12

Lymph Ducts

1. Thoracic (Left Lymphatic) Duct
-- begins ate Cisterna Chyli
-- located anterior to L2
-- main duct for return of lymph to blood
-- receives from: R&L lumbar trunks; R&L intestinal trunks; Left jugular trunk; left subclavian trunk; left bronchomediastinal trunk

2. Right Lymphatic Duct
-- Receives lymph from the: Right jugular, Right subclavian, and Right bronchiomediastinal trunk

13

Where do the lymph ducts drain?

Thoracic (Left Lymphatic) duct drain into venous blood at the junction of the left internal jugular and left subclavian veins

Right Lymphatic duct drains into venous blood at the junction of the right internal jugular and right subclavian veins

14

Like veins, lymph flow is affected by

Valves
Skeletal muscle pump
Respiratory pump

15

Primary lymphatic organs

Where stem cells divide and become immunocompetent
Red bone marrow and thymus

16

Secondary lymphatic organs

Sites where most immune responses occur
Lymph nodES, spleen, lymph nodULES

17

Pluripotent cells in the RBM give rise to:

1. Mature immunocompetent B Cells
2. Pre-T cells

18

Thymus

Bilobed
In mediastinum, between sternum and aorta
Two lobes divided by CT capsule
Each lobule contains outer cortex and inner medulla

Mature T cells leave thymus via blood and travel to lymph nodes, spleen, and other lymphatic tissue.

Large in infants; after puberty not so much. Gets replaced by adipose and areolar CT

19

Trabeculae (thymus)

Extension of the CT capsule which penetrate inward and divide each lobe into lobules

20

Outer cortex (thymus)

Receive pre-T cells from RBM
Dendritic cells (derived from monocytes) assist T cell maturation
Epithelial cells: produce thymic hormones; educate pre-T cells through Positive Selection
Macrophages: clear out debris

Only 2% of developing T cells survive

21

Inner medulla (thymus)

Mature T cells
Epithelial cells: created clusters called thyme (Hassall's) corpuscles. (function unknown)
Dendritic cells
Macrophages.

22

Lymph nodes

Secondary lymphatic organs
Usually occur in groups
Encapsulated

23

Important Lymph Nodes

Neck
1. supraclavicular
Arms
2. axillary
3. cubital
Legs
4. inguinal
5. popliteal
Thorax
6. paraspinal
7. parasternal

24

Trabeculae (lymph)

Capsular extension which:
- divide lymph node into compartments
- provide support
- provide a route for blood vessels

25

Stroma (lymph)

Structural supportive framework

Composed of :
1. capsule
2. trabeculae
3. reticular fibres
4. fibroblasts

26

Parenchyma (lymph)

Functional part of lymph node
Composed of:
1. Superficial cortex
a. outer cortex
b. inner cortex
2. Deep medulla

27

Lymphatic sinuses

In lymph nodes
Series of irregular channels that contain branching reticular fibres, lymphocytes and macrophages

28

Route through lymph node

Afferent lymphatic vessels
Subcapsular --> trabecular --> medullary sinuses
Efferent lymphatic vessels emerging from hilum

29

Hilum

Fissure of depression through which nerves or blood vessels enter an organ.

30

Lymphatic nodules (in lymph nodes)

Found in the outer cortex. Mostly secondary lymphatic nodules.

31

Primary Lymphatic Nodules

composed mostly of B cells

32

Secondary Lymphatic Nodules

Form in response to anagenetic challenge
Sites of plasma cell and memory B cell formation

33

Inner lymphatic cortex

In superficial cortex of lymphatic node.

Consists mainly of T cells and dendritic cells (APC/support cells) that enter lymph cell from other tissue

34

Spleen

Largest single mass of lymphatic tissue
Located in left hypochondriac region between stomach and diaphragm

Splenic artery, vein and efferent lymphatic vessel travel through hilum

Splenic arteries -- central arteries -- white pulp -- B and T cells carry out immune functions

35

Structure of spleen

Encapsulated by dense CT, covered by visceral peritoneum (serous membrane)

Trabeculae extend inwards from capsule

36

Splenic stroma

Capsule +
Trabeculae +
Reticular fibres +
Fibroblasts

37

Splenic parenchyma

White Pulp: lymphatic tissue; lymphocytes and macrophages arranged central arteries of spleen

Red Pulp: blood filled venous sinuses and cords of splenic tissue called splenic (Bilroth's) cords. Closely associated with veins.

38

3 Functions of Red Pulp

1. Removal by macrophages of ruptured, worn out or defective blood cells or platelets
2. Storage of platelets (up to 1/3 supply)
3. Fetal hemopoesis

39

Ruptured Spleen

Most often damaged in abdominal trauma
Can cause significant haemorrhage and shock
After splenectomy, RBM and liver can take over some of the functions

40

Lymphatic Nodules

Eggs shaped masses of lymphatic tissue
NOT encapsulated
Scattered through lamina propria of mucous membranes lining GI, urinary, reproductive and respiratory tracts = MALT (mucosa associated lymphatic tissue)

Often small and solitary, but can occur in aggregations.

41

Where lymphatic nodules aggregrate

Tonsils
Pharyngeal/adenoid x 1
Palentine x 2
Lingual x 2
Peyer's Patch (ileum of small intestine)

42

Innate Immunity

Non-specific immunity
Includes external and internal defences

43

First line of defence (innate immunity)


1. skin - epidermis
-- physical barrier, plus shedding removes microbes
2. mucous membranes

44

What elements of the muscosa combine to help first line of defence?

Mucus
Hairs
Cilia
Lacrimal apparatus
Saliva
Lysosomes
Effluents (urine, vaginal secretions, barfing)
Chemicals -- all acidic to discourage bacterial growth

45

Second line of defense

1. Antimicrobial substances
-- Interferon
-- Complement
-- Iron binding proteins
-- Antimicrobial Proteins
2. Natural killer cells and phagocytes

46

Interferon

IFN
Released by virus-infected cells
Interfere with viral replication in neighbouring cells

47

Complement

Normally inactive proteins in blood plasma and plasma membranes
When infected enhance immune reactions:
--> cytolysis
--> phagocytosis (opsinization)
--> inflammation (histamine release, chemotaxis)

48

Iron binding proteins

inhibit bacterial growth by reducing amount of available iron (transferrin, lactoferrin, ferreting, hemoglobin)

49

Antimicrobial proteins

Short peptides that have a broad spectrum of antimicrobial activity
ex. dermicidin, defensin, catherlicidins, thrombocidin

50

Natural Killer Cells

5-10% lymphocytes in blood. Also in spleen, lymph nodes and RBM
Attack any cell with unusual plasma membrane proteins
Release perforins and granzymes

51

Perforins

Cytokine released by NK cells that act like spears, poking holes in the membrane of the target cells

52

Granzymes

Cytokine that causes target cell to undergo apoptosis. Released by NK cells

53

Phagocytes

Neutrophils and macrophages

54

5 steps of phagocytosis

1. Chemotaxis
2. Adherence
3. Ingestion
4. Digestion
5. Killing

55

Inflammation

Nonspecific response of the body to tissue damage.
Characterized by swelling, heat, altered function, redness and pain.

56

3 stages of inflammatory response

1. vasodilation and increased vasopermeability
2. emigration of phagocytes from blood to interstitial fluid
3. tissue repair

57

Histamine

Released by mast cells, blast cells, and platelets.
Release stimulated by neutrophils and macrophages
Cause vasodilation and increased permeability

58

Kinins

Polypeptides formed in blood, induce vasodilation and permeability.
Chemotactic.
Ex. bradykinin

59

Prostaglandins

Lipids released by damaged cells; intensify effects of histamine and kinins
May also stimulate emigration of phagocytes

60

Leukotrienes (LTs)

Produced by basophils and mast cells
Cause increased permeability
Adherence of phagocytes to pathogens
Chemotactic agents

61

Complement (inflammatory response)

Stimulates histamine release, attracts neutrophils by chemotaxis, promote phagocytosis

62

Leukocytosis

Increase in total local WBCs
A result of emigration

63

Fever

intensifies the effects of interferons, inhibits the growth of some microbes, and speeds up reactions that aid repair

64

Adaptive specific immunity

The ability of the body to defend itself agains specific invading agents

65

Antigens

substances that are recognized as foreign and provoke immune response

66

Two properties of specific immunity

1. specificity
2. memory

67

Immunocompetence

The ability to carry out adaptive immune response.
In T cells before they leave the thymus; B cells before they leave RBM

68

Two types of mature T cells leave thymus

Helper T (CD 4)
Cytotoxic T (CD 8)

69

Two types of adaptive immunity

1. Cell mediated
2. Antibody meditated

70

Cell mediated immunity

Cytotoxic T cells directly attack invading antigens (endogenous)

Intracellular pathogens: viruses, bacteria, fungi, some CA cells, foreign tissue transplants

71

Antibody mediated immunity

B cells transform into plasma cells, secrete antibodies/immunoglobulins

Effective against exogenous/extracellular pathogens (viruses, bacteria, fungi in fluids outside cell)

72

Clonal selection

The process by which lymphocytes 1) proliferate and 2) differentiate in response to a specific antigen
(antigenic challenge)

Results in population of clones that can recognize the original lymphocyte

Occur secondary lymphatic organs

73

Clonal selection gives rise to two types of cell:

1. Effector cells
2. memory cells

74

Effector cells

Result of clonal selection
Carry out immune response to destroy or deactivates antigen.
Gets shit done. Then dies.

Active helper and cytotoxic T cells, plasma cells

75

Memory Cells

Result of clonal selection
Do not actively participate in initial immune response
Response quicker in subsequent invasion

Memory helper T, memory cytotoxic T, memory B cells

76

Antigen

Proteins (or protein aggregates) located on or associated with a pathogen (can also be nucleic acids, lipoproteins, glycoproteins, large polysaccharides)

May be entire microbe, or just a part of it.

77

Epitope

Fragment of microbe which acts as an antigen

78

Two important characteristics of antigens

1. Immunogenicity (provokes response)
2. Reactivity (reacts to responding cells)

79

Three routes of antigens past innate defences

1. blood stream to spleen
2. skin through lymphatic vessels to lymph nodes
3. mucous membranes to MALT

80

Haptens

Like antigens, have reactivity but lack immunogenicity
Can stimulate an immune response but only if attached to a carrier protein

ie Poison Ivy

81

Major Histocompatibility Complex (MHC)

Self-antigens
AKA human leukocyte antigens (HLA)
Help T cells recognize cell as self/foreign

82

Two types of MHC

MHC 1: Built into the PM of all body cells except RBC's

MHC 2: Appear on the surface of Antigen Presenting Cells (macrophages, dendritic cells, and B cells)

83

Pathway of Antigen Processing.

Antigenic proteins broken down into peptide fragments -- associates with MHC

Antigen-MHC complex is inserted into the PM of a body cell [Antigen presentation]

84

Processing Exogenous Antigens

Bacteria, worms, pollen and dust, viruses that are still outside the cell

APCs ingest AG
Digestion of antigen into peptide fragments
Synthesis of MCH-2
Packaging of MCH-2
Fusion of vesicles
Binding of peptide fragment + MHC-2
Insertion of AG-MHC2 complex into PM

Located in areas where AGs are likely to penetrate innate defences

After processing and presenting, migrate tissues --> lymph vessels --> lymph nodes

85

Processing Endogenous Antigens

Bacterial toxins, abnormal proteins synthesized by CA cells, viruses inside cells

Digestion of AG
Synthesis of MHC-1 molecules
Binding of peptide fragments to MHC-1
Packaging of AG-MHC1 complexes
Insertion of AG-MHC1 complex into PM

86

Cytokines

Small protein hormones that stimulate or inhibit many normal cell functions, such as cell growth and differentiation

Ex: interleukins, TNF, granzymes, perforin, interferons

87

What secretes cytokines?

Secreted by lymphocytes, APCs, fibroblasts, endothelial cells, monocytes, heptocytes and kidney cells

88

Interleukin 1

Cytokine
Produced by macrophages
Promotes proliferation helper T cells
Acts on hypothalamus to cause fever

89

Interleukin 2

Cytokine
Secreted by helper T cells
Costimulates proliferation of helper T cells, cytotoxic T cells, and B cells
Activates NK cells

90

Interleukin 4

Cytokine
B stimulating factor
Produced by helper T cells
Costimulator for B cells.
Causes plasma cells to secrete IgE
Promotes growth of T cells

91

Interleukin 5

Cytokine
Produced by some helper T and mast cells
Costimulator by B cells
Causes plasma cells to secrete IgA

92

Interleukin 6

Produced by helper T cells
Enhances B cell proliferation, B cell differentiation into plasma cells, and secretion of Abs

93

Tumour Necrosis Factor

Cytokine
Produced mainly by macrophages
Stimulates accumulation of neutrophils and macrophages at sites of inflammation and stimulates their killing of microbes

94

Interferons

Cytokine
Produced by virus-infected cells to inhibit viral replication in uninfected cells
Activate cytotoxic T cells and natural killer cells
Inhibits cell division and suppresses tumour formation

95

Macrophage migration inhibiting factor

Cytokine
Produced by cytotoxic T cells
Prevents macrophages from leaving site of infection

96

Cell Mediated Immunity

Activation of T cells by a specific antigen

97

T Cell Receptors

Antigen receptors on the surface of T cells that recognize and bind to specific foreign Ags that are presented in Ag-MHC complexes

98

Coreceptors

Surface proteins on T cells that help maintain TCR-MHC coupling

CD-4 (Helper) or CD-8 (Cytotoxic)

Antigen recognition by a TCR with CD4 or CD8 protein is the first signal in T cell activation

99

Costimulation

A second (chemical) signal required for a T Cell to activate after binding to an antigen

Prevents accidental immune response

Ex. IL-2, twinned plasma membrane molecules

100

What does a T cell need in order to activate?

Bind to an antigen, with coreceptor
Costimulation

101

Anergy

Immune recognition with no costimulation
State of prolonged inactivity

102

CD4 Cells

Helper T cells

103

What sort of Ags are recognized by Helper T cells?

exogenous

104

What type of MHC molecules are associated with Helper T cells?

MHC-2

105

What do Active Helper T Cells secrete

Cytokines, especially IL-2
Needed for virtually all immune responses and prime trigger of T cell proliferation

106

Memory Helper T Cells

Not active
Upon second exposure to same Ag, quickly proliferate and differentiate into more Active Helper T cells and Memory Helper T Cells

107

CD8 Cells

Cytotoxic T cells

108

What type of MHC molecules are associated with Cytotoxic T Cells?

endogenous

109

In order to become active, Cytotoxic T cells need costimulation by

IL 2 or other cytokines produced by Active HTC

110

How do cytotoxic T cells kill?

Granzymes: trigger apoptosis
Perforin & Granulysin: pierce membrane --> cytolysis
Lymphotoxin: activates enzymes in the target cell that causes its DNA to fragment

111

Antibody mediated immunity

B cells activate into plasma cells and release Ab/Ig

B cells remain in lymphatic tissue
B cells can react to unprocessed Ag

112

In B cells, clonal selection results in

Plasma cells and Memory B cells

113

Plasma cells

Activated B cells that secrete Ab that travel in lymph and/or blood

114

What cytokines help B cell proliferation?

IL4 and IL6
Produced by HTCs

115

Antibodies

aka Immunoglobulins (because they belong to the Globulin glycoprotein group)

Combine specially with the epitope on the Ag that triggered its production

Contain 4 polypeptide chains (2 heavy, 2 light)

116

What antibodies can be passed between mother and child?

IgG
IgA

117

IgG

Smallest, most numerous
Found in blood, lymph and intestines
Only Ab that can cross placenta

118

IgA

Second most common
Found in exocrine glands (sweat, tears, saliva, mucous, breast milk)

119

IgM

Largest, third most numerous
makes up ABO antibodies
Short lived, first to be secreted by plasma cells
Presence indicates recent invasion

120

IgD

Found in B-cells as antigen receptors.
Remain in plasma membrane.

121

IgE

Least common.
Located on mast cells and basophils
Allergic, parasitic and hypersensitivity reactions

122

5 Ways Igs disable and Ag

1. neutralize
2. immobilize
3. compliment activation
4. enhances phagocytosis
5. agglutination/precipitating

123

Complement System

Defensive system made up over 30 proteins produced by liver
Destroys microbes by:
1) phagocytosis
2) cytolysis (MAC)
3) inflammation

124

Primary Response

Slower, weaker, generates initial population of immune cells

125

Secondary Response

Faster, stronger, generates second population of immune cells
Where memory happens

126

Attenuated

In vaccine, a weakened microbe

127

4 types on invoked immunity

Naturally Acquired Active (normal)
Naturally Acquired Passive (mother-child)
Artificially Acquired Active (typical vaccine)
Artificially Acquired Passive (direct injection of Abs -- antivenom)

128

HIV

Retrovirus that cause AIDS

129

Infectious Mononucleosis

Epstein-Barr Virus
Herpes Type 4 virus
Results in fatigue, headache, dizziness, sore throat, enlarged lymph nodes and fever

130

Type 1 Allergic Reaction

Anaphylactic, mostly due to reexposure
Mostly IgE

131

Type 2 Allergic Reaction

Cytotoxic
Antibodies directed again person's own cells
IgG or IgM

132

Type 3 Allergic Reaction

Immune Complex
Ag/Ab complexes that escape phagocytosis lead to inflammation
IgA or IgM

133

Type 4 Allergic Reaction

Cell Mediated
AKA Delayed hypersensitivity
12-72 hours after exposure, immunocompetent T cells return to site and stimulate inflammation

134

SLE

Lupis
Chronic autoimmune inflammatory disease that affects multiple body systems
Most common symptom: butterfly rash

135

Rheumatoid arthritis

Body's Ab's recognize joints as foreign and attract them
Pain, inflammation, joint deterioration

136

Myasthenia Gravis

Body produces Abs that block ACh receptors at neuromuscular junction
Progressive muscle weakness and atrophy

137

Hodgkins Disease

Lymphoma
mostly affects men 15-35
Painless, nontender enlargement of one or more lymph nodes in the neck, chest and axilla
Can metastasize

138

Non-hodgkin lymphoma

All age groups
Like hodgekins but also enlarged spleen, anemia and general malaise.