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Theme 2.1 Microbiology > Cells and organ invasion of the immune system > Flashcards

Cells and organ invasion of the immune system Flashcards

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Biology 101 flashcards
1
Q

Cells and organs of immune system

A

CELLS

White blood cells

ORGANS

Lymph nodes
Spleen
Bone marrow
Thymus

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2
Q

Discuss the origin of leucocytes

A

They all originate from a Pluripotent stem cell: Which divides into Myeloid and Lymphoid stem cells

From Myeloblast we get granulocytes:

  1. Eosinophils
  2. Neutrophils
  3. Basophils

From Lymphoblast:

  1. B-lymphocyte
  2. T-lymphocyte
  3. Natural killer cell
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3
Q

Lymphoid cells involved in specific immunity

A

Lymphoid Cells: Humoral and Cell-Mediated specific immunity
• B Lymphocytes
• T Lymphocytes (Helper and Cytolytic)

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4
Q

Lymphoid cells involved in non-specific immunity

A

Lymphoid Cells: non-specific immunity

• Natural Killer Cells

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5
Q

What do the myeloid cells do? and list them

A

Myeloid Cells: First line of defense, non-specific innate immunity (eg. when exposed to a microbe for the first time)

  • Neutrophils
  • Eosinophils
  • Basophils/Mast cells
  • Monocytes/Macrophages/Dendritic Cells
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6
Q

Myeloid cells pneumonic

A

BEN M

baso, eosi, neutro, mono(mac and den)

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7
Q

What are neutrophils?

A

Neutrophils are produced in the bone marrow from
myeloblast-type stem cells
often called polymorphonuclear cells (PMN’s).
Multilobed nucleus

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8
Q

What is the function of neutrophils in inflammation?

A

The neutrophil’s main role is in inflammation.
– First to arrive at the inflammation site
– Leave blood/endothelium into tissue (extravasation).

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9
Q

Neutrophils are attracted into the tissue by ** stimulated by tissue damage

A

chemotactic factors

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10
Q

What is the function of neutrophils in the tissue?

A

In the tissues, neutrophils are active phagocytes.
They destroy ingested microorganisms via oxygen-dependent or independent pathways.
Produce myeloperoxidases to assist with destroying microbes.

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11
Q

Eosinophils

A

Granulocytes stain intensely with ‘eosin’; bilobed nucleus.

Contain basic crystal granules in cytoplasm to mediate toxic reactions to large parasites

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12
Q

Eosinophils are motile, sometimes phagocytic, and are particularly active

A

in parasitic infection

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13
Q

What happens when Basophils cross-link with IgE?

A

Cross-linking of the IgE causes the basophils to release inflammatory mediators (histamine, prostaglandins, leukotrienes)

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14
Q

Basophils

A

Found in low numbers in the blood. Act like mast cells.
Involved in Type I hypersensitivity responses.
Have high-affinity receptors for IgE on their surface

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15
Q

Basophils act like which type of cell?

A

MAST CELLS

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16
Q

Basophils are involved in which responses?

A

Type 1 hypersensitivity responses

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17
Q

How are mast cells usually stimulated?

A
  1. by the anaphylatoxins
  2. complement or
  3. by cross-linking of surface immunoglobulin (IgE).
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18
Q

Mast cells

A

Formed in tissue from undifferentiated bone marrow precursors.

Similar importance in allergic reactions as basophils, but only found in tissues.

Contain granules with preformed mediators to be released after stimulation
– histamine, prostaglandins
– leukotrienes

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19
Q

What are the granules found in mast cells?

A

Contain granules with preformed mediators to be released after stimulation
– histamine, prostaglandins
– leukotrienes

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20
Q

What is the Reticuloendothelial system?

A

The “phagocytic system” of the body, including fixed macrophages of tissues

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21
Q

How do the cells of the RES provide natural immunity against microorganisms?

A
  1. phagocytosis and intracellular killing of microbes
  2. Immune cell Recruitment via molecular mediators
  3. Presentation of peptide antigens to lymphocytes
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22
Q

What are the cells that are part of the reticuloendothelial system?

A

Cells of the RES include:

* circulating monocytes
* resident macrophages in the liver, spleen, lymph nodes, thymus, submucosal tissues of the 	respiratory and alimentary tracts
    * macrophage-like cells including dendritic cells in lymph nodes, Langerhans cells in the skin, and glial cells in the central nervous system.
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23
Q

Monocytes/Macrophages

A

Monocytes circulate in the blood after leaving the bone marrow.
• Survive only a day or so before they enter the tissue to mature into macrophages.

=Involved in phagocytosis and intracellular killing of
microorganisms.

Chew ingested proteins via degradative enzymes.
Generation of toxic metabolites through respiratory burst eg. nitric oxide, hydrogen peroxide, superoxide anion.

Monocytes/Macrophages are also antigen processing and presenting cells.
Present to adaptive cells (lymphocytes)

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24
Q

When monocytes enter the tissues they become?

A

become macrophages

25
Q

Monocytes/Macrophages are also antigen processing and presenting cells.
Present to

A

adaptive cells (lymphocytes)

26
Q

Macrophages

A

When monocytes enter the tissues and become macrophages:
– Enlarge and increase production of intracellular lysozymes
– Greater phagocytosis.
– Can live for years in tissue; highly motile.

• Activation of these cells occurs by phagocytosis of antigens, or in response to T cell-derived cytokines.

=Activated macrophages recognize and remove unwanted invading organisms

27
Q

How are macrophages activated?

A

Activation of these cells occurs by phagocytosis of antigens, or in response to T cell-derived cytokines.
Activated macrophages recognize and remove unwanted invading organisms

28
Q

What are dendritic cells?

A

Specialized phagocytic cells.
Found in most tissues.
Abundant at interfaces between the external and internal environments (skin, lining of the gastrointestinal tract), where they encounter invading pathogens

29
Q

Differentiate between innate and adaptive immunity.

A

The innate immune system responds to microbes quickly as it does not need prior exposure and is nonspecific.

Adaptive immunity responds more slowly as this is a more specific immune response directed against a specific antigen.

30
Q

Discuss Natural killer cells

A

Part of innate immunity.
Cells that kill viral infected or tumor target cells.
Killing is nonspecific - they do not need to recognize foreign antigens presented on the target cell.
NK cells do not have a specific cell receptor.
Target recognition occurs by a Killer Inhibitory Receptor, KIR, which is lacking on infected and tumor targets.
Kills targets by releasing perforin which damages target cell membranes

31
Q

How do natural killer cells kill infected cells?

A

Kills targets by releasing perforin which damages target cell membranes

32
Q

B lymphocytes

A

Develop from stem cells in the bone marrow.
Produce antibodies with specificity for antigens.
Plasma cells = Activated B cells
Plasma cells produce antibody

33
Q

How are B lymphocytes activated?

A

Activation into antibody-secreting cells is antigen-dependent.
Antigen binding to surface Ig molecules triggers differentiation into plasma cells.

34
Q

T-cells

A

A T cell is a type of lymphocyte, a white blood cell.
The “T” in the T cell stands for thymus.
The thymus is where T cells mature

35
Q

What are the types of t-cells?

A
  1. Cytotoxic T cells (Tc cells) CD8
  2. Helper T cells, (Th cells) CD4
  3. Regulatory T cells (Treg cells), used to be called suppressor T cells
  4. Natural Killer T cells (NKT cells)
36
Q

T Lymphocytes

A

T lymphocytes regulate immune responses.

T-lymphocytes Integral in cell-mediated immunity.

Mature T cells display either CD4 or CD8.
Develop in the thymus.

Cells with a CD4 marker are called helper T cells (Th cells).
CD8 marker positive cells are cytotoxic T cells (Tc cells).

Each T cell has a T cell receptor (TCR ) to recognize antigen

37
Q

Cluster of differentiation (CD)

A

Unique cell surface molecules.
Molecules are given number of designations.
The acronym CD describes the cluster of unique determinant
The number describes the order in which it was discovered.

38
Q

What are T-helper cells?

A

All express the CD4 molecule.
Aid effector T lymphocytes in cell-mediated immunity and
aid antigen-stimulated subsets of B cells to proliferate and differentiate toward antibody-producing cells.

39
Q

What are T-cytotoxic cells?

A

T cytotoxic cells (CTLs) are cytotoxic against tumor cells and host cells infected with intracellular pathogens.
These cells express CD8.

40
Q

What are T-suppressor/Regulatory cells?

A

Suppress T and B cell responses.

Serve as regulators of T cell responses.

41
Q

What are antigen-presenting cells?

A

An antigen-presenting cell (APC) is a cell that displays antigen complexed with major histocompatibility complexes (MHCs) on their surfaces.
This process is known as antigen presentation.
T cells may recognize these complexes using their T cell receptors (TCRs).
Antigen-presenting cells are vital for effective adaptive immune response, as the functioning of both cytotoxic and helper T cells is dependent on APCs.
Antigen presentation allows for specificity of adaptive immunity

42
Q

What do Antigen-presenting cells essentially do?

A

Present foreign antigens to helper T cells, and/or cytotoxic T cells.

43
Q

Where are Antigen-presenting cells found?

A

APCs are found primarily in the skin, lymph nodes, spleen, and thymus.
These cells process antigens and present them to T-cells.
Professional antigen-presenting cells, including macrophages, B cells and dendritic cells.

44
Q

Antigen presentation discuss

A

After dendritic cells( in various parts of body) have phagocytosed pathogens, they usually migrate to the vast network of lymph vessels and are carried by lymph flow to the draining lymph nodes.
Each lymph node is a collection point where APCs can interact with T cells.
The antigen is digested into smaller peptides containing epitopes, which are then presented to T cells by the MHC.( major histocompatibility complex)
Antigen presentation activates the immune system via cytokines and can lead to antibody production or activation of other cells.
Antibodies formed are specific to a particular antigen.

45
Q

Antigen presentation activates the immune system via (A) and can lead to (B)

A

A) cytokines

B) antibody production or activation of other cells.

46
Q

Antibodies formed are specific to?

A

to a particular antigen.

47
Q

Primary/Secondary Lymphoid Tissues

A 
Primary: 
	- Adult Bone Marrow
	- Thymus Gland
Secondary:
	- Spleen
	- Lymph Nodes
	- Tonsils
	- Appendix
	- Peyer’s patches
	- Aggregates of cells in
	lamina propria (GALT,
	BALT, MALT)
48
Q

Secondary lymphoid tissues

A
  • Spleen
    • Lymph Nodes
    • Tonsils
    • Appendix
    • Peyer’s patches
    • Aggregates of cells in
      lamina propria (GALT,
      BALT, MALT)
49
Q

Primary lymphoid cells

A
  • Adult Bone Marrow

- Thymus Gland

50
Q

Thymus discuss

A

The encapsulated organ where T cells mature and are selected based in part on their ability to not recognize the host

What happens here:
•Thymocytes are educated to become T lymphocytes here.
• Expression of specific receptors.
•T cells learn to recognize self as self so that immune cells don’t kill bodies own cells.

51
Q

Bone Marrow discuss

A

site of remaining hematopoiesis, B cells mature here, mostly in the skull, ribs, sternum, and pelvis

52
Q

Lymphatic vessels - What do they do?

A

Drain the entire body to regional lymph nodes – is a secondary circulatory system moving antigen to lymph nodes where B and T cells can respond

53
Q

Lymph nodes define

A
  1. Enscapsulated organ found throughout the body.
  2. Antigen from the periphery is moved here through lymphatics by antigen-presenting cells.
  3. Lymphoid follicles (collection of T cells and B cells) in the node on encountering their specific antigen will proliferate generating a germinal center that leads to the formation of fully mature, effector T and B cells.
54
Q

What is lymphoid tissue?

A

Specialized connective tissue and organs where lymphocytes form the major cellular component.

• Physical location for interaction between leukocytes
– Myeloid (innate)
– Lymphoid (specific)
• Contains high numbers of lymphocytes that mediate responses.

Cellular immunity (protection from pathogens)
Humoral immunity (immunoglobulin production)
55
Q

Lymph nodes discuss the structure

A

The substance of the lymph node is divided into the outer cortex and the inner medulla.

B cells are mainly found in the outer (superficial cortex) where they are clustered together as follicular B cells in lymphoid follicles and the T cells are mainly in the paracortex.

The number and composition of follicles can change especially when challenged by an antigen, when they develop a germinal center.

Lymph enters the lymph node through multiple afferent lymphatic vessels, and flows through spaces called sinuses.

Sinuses drain the filtered lymphatic fluid into the medullary sinuses, from where the lymph flows into the efferent lymph vessels to exit the node.

56
Q

Spleen define

A
  1. FOUND IN THE LIVER
  2. Highly vascular and filters blood
  3. Eliminates blood-borne pathogens
  4. RBCs carrying immune complexes are processed here to remove antigen.
  5. Also has follicles that will proliferate generating a germinal center that leads to the formation of fully mature T and B cells.
57
Q

Spleen function

A

Defense against microorganisms in blood, filters blood.
•Site of removal of aged or abnormal RBCs/platelets
•Capsule with trabeculae
•Comprised of splenic pulp – Red pulp and White pulp with follicles
•Supported by a network of reticular fibers
•Largest lymphoid organ

58
Q

What i should know from these flashcards

A
  • Identify cell types involved in the innate and adaptive immune response.
  • Understand structure and function of primary and secondary lymphoid organs.

Theme 2.1 Microbiology (10 decks)

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