Lecture 18 - Immune and Lymphatic System Flashcards Preview

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Flashcards in Lecture 18 - Immune and Lymphatic System Deck (18)
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1
Q

What are innate immunity and acquired immunity?

L18 S4

A

Innate:

  • lacks specificity
  • results in inflammation
  • primarily neutrophils

Acquired immunity:

  • specific to antigens
  • takes time to develop
  • has specificity and memory
2
Q

What are passive and active immunity?

L18 S4

A

Passive:
-temporary immunity due to donated antibodies (ie. transplacental antibodies)

Active:
-long-lasting immunity due to memory T cells and B cells specific to certain antigens

3
Q

What are the different types of lymphoid tissue/organs?
What are the different types and what differentiates them?

L18 S6

A

Primary lymphoid tissue:

  • thymus
  • bone marrow

Secondary lymphoid tissue:

  • lymph nodes
  • spleen
  • tonsils

Lymphocytes mature in primary lymphoid tissue and later reside in secondary lymphoid tissue

4
Q

What are lymphoid follicles?
What are the different types and what differentiates them?

L18 S7

A

-transients sites of B cell localization and proliferation

Primary follicles:

  • tightly packed accumulations of virgin B cells
  • not yet exposed to antigens

Secondary follicles:
-derived from primary follicles that have been exposed to non-self antigens

5
Q

Differentiate between diffuse and aggregated lymphoid tissue.

L18 S9

A

Diffuse:

  • clusters of plasma cells, macrophages, and lymphocytes
  • located in connective tissue

Aggregated:
-located beneath epithelium and is in direct contact with it

6
Q

All immune cells originate in __________. T cells mature in __________ and B cells mature in __________.

L18 S11

A

Bone marrow; the thymus; bone marrow

7
Q

What are MHCs?
What are the two types and how are they differentiated?

L18 S16

A

-present antigenic peptide to T cells

MHC I:
-expressed on all cells except trophoblasts and RBCs

MHC II:
-expressed on the surface of B cells and antigen presenting cells

8
Q

What are the main types of T cells discussed and what differentiates them?

L18 S18-19

A

CD4+ T cells:

  • helper cells
  • assist in differentiation of CD8+ T cells and B cells
  • recognize MHC class II molecules

CD8+ T cells:

  • cytolytic T cells
  • bind to antigen presenting cells and
  • recognize MHC class I molecules

CD16+ T cells:

  • natural killer (NK) cells
  • activated by tumor cell antigens by releasing cytokines
9
Q

Describe the process of T cell-mediated immunity.

L18 S22-23

A
  • macrophage phagocytizes foreign material
  • foreign proteins are broken down and present on cell surface my MHC II complex
  • complex is bound by helper T cell
  • helper T cell undergoes mitosis producing interleukin secreting cells and memory cells
  • helper T cells attract B cells
  • B cells undergo mitosis producing plasma cells which secrete antibodies or memory cells
10
Q

Describe the classic pathway of the compliment cascade.

L18 S29-34

A
  • C1q subunit binds to Fc portion of antigen bound antibody
  • C1q activates C1r which then activates C1s
  • C1s activates both C4 and C2 splitting them both into #a and #b
  • 4b binds pathogen and 2b binds 4b (this is C3 convertase)
  • C3 is activated splitting into 3a and 3b
  • 3b binds 4b2b (this is C5 convertase)
  • C5 is activated splitting into 5a and 5b
  • 5b binds 4b2b3b resulting in opsonization of the pathogen
11
Q

What role do 3a and 5a play once release by the compliment cascade?

L18 S34

A

-recruit leukocytes to site of infection

12
Q

Differentiate parenchyma and stroma.

L18 S37

A

Parenchyma:
-cells that pack areas of lymphoid organs (typically leukocytes)

Stroma:

  • reticular fibers and cells
  • undifferentiated cells and free/mixed macrophages
13
Q

Describe the histological features of a lymph node.

L18 S38-41

A

Hilus:
-entry and exit point for vessels

Capsule:
-dense collagen fibers with some elastic fiber and smooth muscle

Trabeculae:
-extensions of the capsule into the lymph node

Follicles:

  • outer cortex
  • contain B cells, follicular dendritic cells, and migrating dendritic cells
  • secondary follicles contain mantle and germinal centers; primary do no

Medulla:

  • loose medullary sinuses and dense medullary cords
  • site of lymphocyte reentry
14
Q

The thymus has __________ lymph vessels but not __________ vessels. This means lymph does not flow through the thymus.

L18 S51

A

Efferent; afferent

15
Q

Describe the process through which a T cell differentiates.

L18 S54-55

A

Double negative T cells:

  • lack surface molecules (CD4, CD8 and TCR)
  • enter cortex from blood vessels

Double positive T cells:
-Express CD4, CD8 and TCR in response to epithelial cells present in the outer cortex

Single positive cell:

  • lose expression of either CD4 or CD8 by binding to self-MHC molecule
  • occurs in the medulla
16
Q

What is the role of the blood-thymic barrier?

L18 S59

A

-prevents antigens from ente

17
Q

What are the functions of the spleen?

L18 S64

A

Blood filtering:

  • removes worn out red blood cells
  • recycles iron
  • converts hemoglobin to bilirubin

Immunologic:

  • screens blood for foreign material
  • produces lymphocytes and plasma cells
18
Q

Differentiate between white pulp and red pulp in the spleen.

L18 S65-67

A

White pulp:

  • branched strand associated with arteries
  • site of cloanal expansion
  • T cells surrounding central artery (forms periarterial lymphatic sheath (PALS))
  • B cell area

Red pulp:

  • surrounds white pulp
  • filters blood
  • stores RBCs