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Histology Unit 4 > Lymphatic System > Flashcards

Lymphatic System Flashcards

1
Q

What are the two parts of the immune system?

A

Innate Immunity

Adaptive Immunity

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2
Q

Does the innate system respond first or second? What types of cells are a part of innate immunity? What does it do?

A

1st responder
Basophiles, esosinophiles, neutrophiles, macrophages
Phagocytosis, complement, inflammation

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3
Q

Does the adaptive system respond first or second? What types of cells are a part of adaptive immunity? What does it do?

A

2nd Response
B cells, T cells, NK cells
Target the specific pathogen

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4
Q

What is a humoral response? Which cells are acting? Is the response concentrated? Is it part of innate or adaptive immunity?

A

B cells secrete antibodies
Antibodies can travel to distant locations
Part of the adaptive immunity

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5
Q

What is a cell-mediated response? Which cells are acting? Is the response concentrated? Is it part of innate or adaptive immunity?

A

T cells, specifically CD4+ and CD8+
Requires direct contact
Part of the adaptive immunity

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6
Q

What is an antigen?

A

something that induces an immune response

any ligand recognized by B and T cells

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7
Q

What are the two fates of a B cell after activation?

A
  1. Plasma Cell - pump antibodies

2. Memory Cell

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8
Q

What are the 5 isotypes of antibodies? What are their functions?

A
  1. IgM - Primary response
  2. IgG - Secondary response
  3. IgA - Body Secretions
  4. IgE - Parasitic infections, allergies, hypersensitivities
  5. IgD - unknown
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9
Q

What is class switching?

A

Antibodies start as IgM and can then class switch to IgG, IgA, IgE by changing the heavy chain of the BCR

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10
Q

What are the five functions humoral immunity does to help defeat the pathogen?

A
  1. Neutralization
  2. Opsonization
  3. Oxidation
  4. Agglutination
  5. Antibody-dependent cellular cytotoxicity (ADCC)
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11
Q

What is neutralization? How does it work?

A

Antibodies bind to the pathogen and neutralize it
Two methods:
1. Prevents toxins ability to act
2. Block attachment site = can’t enter into host cells

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12
Q

What is opsonization?

A

The antibodies coat the pathogen making it easier for the pathogen to by phagocytosed

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13
Q

What is oxidation? (In regards to humoral immunity)

A

Antibodies activate ROS production, the build-up of ROS kills the pathogen

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14
Q

What is agglutination? When does it occur?

A

Antibodies and the foreign cells clump together to form an immune complex
Occurs during miss-match blood transfusions

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15
Q

What is the process of Cell-Mediated immunity?

A

Antigen-presenting cell (usually a dendritic cell) presents the antigen to the T-cell > T cell become activated > differentiation > proliferation

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16
Q

What are the two fates of an activated T cell?

A
  1. Memory

2. Join the effector pool (Th, Tfh, Tc, etc)

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17
Q

What is an epitope?

A

Part of the pathogen that can be bound to

It can be processed and presented by antigen-presenting cells

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18
Q

What causes swollen lymph nodes during times of infection?

A

T cells recognize antigen in secondary lymphatic leading to massive proliferation and differentiation

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19
Q

What is a lymph node? What shape does it have? What is its function?

A

Kidney shaped thing part of the immune system

Filter lymph, cite of development for T and B cells

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20
Q

What about the vasculature of the lymph nodes aids it in filtering the lymph?

A

There are multiple afferent tubules, but only one efferent tubule
This creates a bottleneck, cause the lymph to move through more slowly

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21
Q

What does the CD8+ T cell do once it is activated?

A

CD8+ T cell checks cells > recognized antigen and MHC > releases porfin > creates a pore in the cell > releases granzymes into the pore > death of the infected cell

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22
Q

What is lymph (2)?

A
  1. Excess interstitial fluid

2. large, foreign debris

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23
Q

What is the thymus? Where is it located? Does B or T cell maturation happen here?

A

Primary Lymphatic organ
Above the heart
T cell maturation (T - Thymus)

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24
Q

Where does hematopoiesis occur?

A

In the bone marrow

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25
What three regions of the body do lymph nodes concentrate around?
1. Groin 2. Axillary 3. Cervical Region
26
What is the main function of the spleen?
Removes aged and dying RBC
27
What is the main function of tonsils?
Form ring of protection around the oral pharynx
28
What does the diffuse lymphatic tissue consist of?
1. MALT (GALT and BALT) | 2. Lymphatic nodules
29
What is MALT?
Mucosa-associated lymphoid tissue | Immune cells in the lamina propria
30
What are lymphatic nodules?
Unencapsulated aggregates of immune cells
31
``` Which of the following lymphoid organs are primary? Secondary? Lymph nodes Spleen Tonsils Thymus Bone Marrow ```
Primary: thymus, bone marrow Secondary: lymph nodes, spleen, tonsils
32
Where does B cell development take place?
In the bone marrow
33
What are the characteristics of diffuse lymphatic tissue? What is its function?
Not enclosed by a capsule Enriched in alimentary canal, respiratory passages, and genitourinary tract Site of initial immune response
34
What types of cells are enriched in MALT?
Lymphocytes, Eosinophils, Mast cells, Macrophages
35
What are the two major features of lymphatic nodules?
1. Germinal Center | 2. Corona
36
What occurs in the germinal centers of lymphatic nodules? How does it stain? Why?
Site of lymphocyte activation and clonal expansion | Stains lighter due to cells increasing in size and thus having more cytoplasm
37
What occurs in the corona of lymphatic nodules? How does it stain? Why?
Site of small lymphocytes (storage) | Stains more densely due to packed lymphocytes
38
What are the three tonsils? Where are they located?
1. Lingual tonsils: posterior 1/3 of the tongue 2. Pharyngeal tonsils: nasal cavity 3. Palatine tonsils: sides of the throat
39
What cell type composed the palatine tonsils?
Stratified Squamous | LCT directly below epithelium - not always clearly visible
40
What are tonsillar crypts? What is their function?
Crevices in tonsils | Important for catching food/particles/debris in order to bring them into proximity with immune cells
41
What is the hilum region of lymph nodes?
Place where efferent lymph vessels leave and entry/exit for arteries and veins
42
The sinuses create a meshwork of ________ which is very important for filtration through the lymph nodes
Reticular Fibers
43
What is the order that lymph flows through the lymph node? (include the 3 different sinus types)
1. Subcapsular Sinus 2. Trabecular Sinuses 3. Cortex 4. Paracortex 5. Medullary Sinuses 6. Efferent exit
44
What type of tissue is the capsule of the lymph node made of? What does it surround?
DCT | Surrounds node
45
What type of tissue are the trabeculae of the lymph node made of? What does it form? What does it deliver?
DCT Forms framework Delivers blood vessels and nerves
46
What does reticular tissue form in the lymph node? What are its two functions?
Reticular tissue = reticular cells, reticular fibers (Type III collagen) 1. filters lymph 2. Attracts T cells, B cells, and dendritic cells AND acts as an attachment point
47
What is the primary site of B cell germination?
the cortex of the lymph nodes
48
What is the primary site of T cells?
paracortex (deep cortex) of the lymph nodes
49
What are HEVs? Where are they located?
HEV = High Endothelial Venuels - entrance point for 90% of lymphocytes Located in the para/deep cortex
50
What can be found in the medulla of the lymph nodes?
Irregular lymphatic/medullary chords separated by medullary sinuses
51
What are medullary chords? Medullary sinuses?
Medullary chords = reticular fibers with macrophages, dendritic cells, and B cells attached Medullary sinuses = in between the medullary chords, where the lymph drains
52
What tissue type do you find around the HEV?
Simple cuboidal / simple columnar | Absorb large amounts of fluid
53
What do AQ1 do for HEVs?
Facilitate absorption of fluid from lymph
54
What two processes do T cells undergo in the thymus?
1. Positive selection - is it functional? | 2. Negative selection - does it respond to self?
55
When is the thymus most active? How does it change in size throughout your life?
Most active shortly after birth | Involutes (gets smaller?) once you hit puberty and is replaced with adipose tissue
56
What are the four structures that make up the thymus?
1. Capsule - thin CT 2. Trabeculae - CT 3. Cortex 4. Medulla
57
What does each lobule of the thymus have? (2)
1. Cortex | 2. Medulla
58
What cell types are in the cortex of the thymus? How does it stain?
Outer region Small thymocytes Stains dark because of small amount of cytoplasm
59
What cell type is in the medulla of the thymus? what other structure can you find there? how does it stain?
Inner region Large thymocytes Thymic (Hassall's) Corpuscle Stains lighter because larger cytoplasm
60
What do Hassall's / thymic corpuscles look like? Where are they located? What is their function?
Large pink structures Located in the medulla of the thymus Produce cytokines
61
What is the function of the blood-thymus barrier?
Protects developing lymphocytes from exposure to antigens | Don't want premature exposure
62
What are the three layers to the blood-thymus barrier?
1. Capillary epithelium - continuous with tight junctions reinforced by pericytes 2. Perivascular CT with macrophages (engulf anything that might get through) 3. Epithelioreticular Cells - create a wall that surrounds CT
63
What is thymic education?
T cells come from the BM > enter the thymus through post-capillary venules in medulla > traffic upwards to cortex > positive selection (presented by type II epithelial cells = dendritic cells) > pass positive selection = pass-through type III and IV epithelial cells > medulla > negative selection (presented self-antigen by V epithelial cells) > pass neg selection = exit and traffic to the site of infection
64
What happens if the T cell fails positive selection?
Apoptosis
65
What happens if the T cell fails negative selection?
Apoptosis
66
What do type VI epithelial cells form in the thymus?
Form a lamellar structure that gives an eosinophil stain
67
What would be the outcome if negative selection fails?
Autoimmune disease
68
What are the two functions of the spleen?
1. Filters Blood | 2. Performs Immune Functions
69
What are the two things the spleen removes from the blood? Where does the blood enter from?
Senescent (dying) RBC Microbes Splenic artery
70
What two immune functions does the spleen serve?
1. Antigen presentation by APCs | 2. Production of antibodies
71
The spleen in enclosed by a __________ and trabeculaie containing ________
Dense CT capsule | Myofibroblasts
72
What is the function of myofibroblasts in the spleen?
Have the potential to contract to cause the spleen to act like a sponge and expel all the blood out
73
What are the two regions of the spleen?
Red Pulp Region | White Pulp Region
74
What is the in red pulp region of the spleen (3)? Does it take up the majority of space? How does it stain?
Red Pulp region has: RBC, sinusoidal capillaries = splenic sinuses, splenic chords The vast majority of spleen Stains eosinophilic
75
What are splenic sinuses?
Discontinuous sinusoidal capillaries in the red pulp region of the spleen
76
What are splenic chords?
Reticular fibers which serve for an attachment point for macrophages, dendritic cells, B cells in the red pulp region of the spleen
77
Why are B cells attached to the splenic chords in the spleen?
They are positioned close to the splenic sinuses so they can pump antibodies into the capillary
78
Why are macrophages attached to the splenic chords in the spleen?
Positioned close to the splenic sinuses so they can engulf RBC and microbes
79
What is in the white pulp region of the spleen? How much space does it take up? How does it stain?
B cells, T cells, central artery, PALS, germinal center Minority of space Basophilic Stain
80
What is PALS?
Periarterial lymphatic sheath | When B and T cells exit from the arteriole they form a sheath
81
What is the central artery in the white pulp region really?
Arteriole of the splenic artery
82
What is the matrix region in the spleen? What kinds of cells do you find here?
Creates a border between white and red pulp regions | T cells, dendritic cells, macrophages
83
If lymphocytes become activated in the spleen they move off to the side to form a _________
Lymphatic nodule with a germinal center

Histology Unit 4 (5 decks)

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