2. Immune cells and organs Flashcards Preview

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Flashcards in 2. Immune cells and organs Deck (32)
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1
Q

Primary lymphoid organs

A

Where lymphocytes are produced and mature
Bone marrow
Thymus

2
Q

Secondary lymphoid organs

A

Where lymphocytes can interact with antigen and with other lymphocytes
• Spleen
• Lymph nodes
• Mucosal associated lymphoid tissues (MALT)

3
Q

What does Thymic output decline with?

A

Age
Total number doesn’t decrease
Production of new specificities decreases with age

4
Q

What does the bone marrow do during infection?

A

Increases WBC production

5
Q

What are swollen lymph nodes a sign of?

A

Infection

6
Q

Why do all lymphoid tissues (except spleen) have HEVs?

A

For cells to leave circulation and enter lymphoid tissue

7
Q

What is the Spleen composed of?

A

Red pulp-RBCs

White pulp- WBCs

8
Q

What can the Spleen act as?

A

a filter for antigens in the blood

9
Q

1st line of defence

A
Epithelium	
Mucosae and skin form a physical barrier
Very large surface area
HEAVILY DEFENDED BY THE IMMUNE SYSTEM
MALT cutaneous immune system
10
Q

Gut Associated Lymphoid Tissue

A

Villi with draining lymphatic vessels
Intraepithelial lymphocytes
Peyer’s patches- large aggregates of lymphocytes and follicles

11
Q

Peyer’s patches

A

only found in gut
predominantly B lymphocytes
contain germinal centres during immune responses

12
Q

Cutaneous Immune system

A

Dense network of immune system cells in skin
Many draining lymphatic vessels from skin
Lymphocytes in layers of skin itself
Langerhan cells- type of dendritic cell able to present antigens

13
Q

How does the body ensure that the antigen meets lymphocyte with specific receptor?

A

Anatomical structure of immune system: lymphatic structure drains whole body and filters fluid through lymph nodes
Lymphocyte recirculation- lymphocytes recirculate to find their antigens

14
Q

Recirculation

A

Naïve lymphocytes produced in 1° lymphoid organs.
Enter blood and peripheral 2° lymphoid tissues.
If encounter their antigen they become activated
If they don’t, they keep recirculating till they die.

15
Q

Dendritic cell action

A
  1. Pathogen enters through mucosal surface
  2. Dendritic cell circulating captures pathogen
  3. Migrates in lymphatics to draining lymph node and tries to present antigen
  4. Appropriate cells need to get into lymph node to respond to it
16
Q

Extravasation of naïve T cells into lymph nodes

A
  1. Naïve T cells roll along surface of endothelium with low affinity binding. Mainly Selectin binding to carbohydrates on proteins.
  2. When they reach HEV, receive chemical signals from chemokines. T cell changes conformation of integrin molecules on its surface -> high affinity binding form.
  3. Stop rolling, become ‘arrested’
  4. Can migrate through endothelium
17
Q

Lymphocytes

A

Small cells with agranular cytoplasm and a large nucleus

18
Q

Cluster of Differentiation (CD) markers

A

nomenclature for cell surface molecules

used to discriminate between cells of the haematopoietic system (and other cells)

19
Q

All T cells express

A

CD3

20
Q

60% T cells express

A

CD4

21
Q

30% T cells express

A

CD8

22
Q

CD4 T cells

A

T helper cells, regulatory T cells

Secrete cytokines

23
Q

CD8 T cells

A

cytotoxic T cells

Lyse infected cells, secrete cytokines

24
Q

T cells only recognise processed antigen presented at surface of another cell using TCR

A

Antigen is presented by an MHC molecule

25
Q

Where are B Lymphocytes produced and developed?

A

Bone marrow

26
Q

B cell receptor

A

Surface antigen receptor: immunoglobulin like molecule

27
Q

B cell CD markers

A

CD19 and CD20

28
Q

B cells express MHC Class II

A

Can present antigen to helper T cells

29
Q

B cell effector function

A

Produce antibodies

30
Q

B Cell antigen recognition

A

B cells recognise intact antigen free in body fluids (not presented by another molecule) or on cell surfaces
Use B cell receptor, a membrane anchored form of antibody linked to signalling subunits

31
Q

Antigen Presenting Cells (APCs) function

A

present processed antigen (peptides) to T lymphocytes to initiate an adaptive immune response

32
Q

APC examples

A

Dendritic cells (DC)
B lymphocytes
Macrophages (activated)