Immunology

Organs of the Immune System 22/10/2014

Presented By:

Mohammad Nouman (7202) Hamza mehmood (7247) Shafia Shahid (7253) Naveed Akber (7254) Narjis Khatoon (7257) Asiya Ejaz (7266) Ayesha Nasir (7270)

Scheme of presentation:

Organ: Student:

Introduction to organs & LT: Narjis Khatoon

Thymus: Ayesha Nasir

Bone Marrow: Shafia Shahid

Lymph Nodes: Naveed Akbar

Spleen: Asiya Ejaz

Tonsils: Hamza Mehmood

Appendix & peyer’s Patches: M. Noumaan

Lymphoid System

Primary lymphoid organs Bone marrow

Thymus

Secondary lymphoid organs Organized Lymph nodes

Spleen

Tonsils

Less organized

Lymphatic System

Network of vessels

Collects fluid from tissues

Major cell is lymphocyte

Unidirectional

Often first place where antigens are detected

Fig: Lymphatic system

.

Thymus

Structure

Gross

Bi-lobed

Lies above heart

Microscopic

Capsular

Lobules with outer cortex and inner medulla

Fig : Internal structure of Thymus

Thymus

Function

Takes in immature T cells and puts out mature (immunocompetent) T cells

Increased diversity of T cells

T cell selection

Thymus

T cell selection

Based on MHC/Ag complex recognition

Recognize MHC/Non self AG complexes

Recognize MHC/Self Ag complexes

Do not recognize MHC/Ag complexes

Athymic condition

Natural

Other

Bone marrow

Structure

Microscopic

Less well defined than thymus

Role of stromal cells

Function

Hematopoiesis

B cell maturation

B cell selection

Puts out mature, naive B cells

Fig: Structure of Bone Marrow

.

Lymph Nodes

Structure

Gross

Bean-shaped structures

Drains major segments of lymphatic system

Lymph Nodes

Structure

Microscopic

Major cell types

Lymphocytes

Macrophages

Dendritic cells

Cortex/paracortex/medulla

Follicles

Primary

Secondary

Fig: Microscopic structure of Lymph node

Lymph Nodes

Function

1st line of response to antigens

Secondary follicle (Germinal center) is site of B cell proliferation, mutation, differentiation

Specificity is high

Lympadenopathy

Lymphodoema

Spleen

Structure

Gross Ovoid organ in upper left quadrant of abdomen

Microscopic Compartmentalized

Red pulp

White pulp

Periarticualr lymphoid sheath Site of Ag presentation

Major cell types Lymphocytes

Macrophages

Dendritic cells

RBCs

Spleen

Function

Filters out older blood cells

Responds to Ag in circulatory system

Produces activated B cells

Production of blood cells

Reservior function

Splenagamy

Splenotomy

Tonsils

Collection of lymphoid tissue facing into

the aerodigestive track

1st line of defence against indested or inhaled foreign pathogens

Germinal centers appear in response to Ag

Produce T lymphocyte in a different way from spleen’s

Protective role in URI (Tonsillitis)

Fig: Tonsil’s Location

Appendix and Peyer’s Patches

Associated with large intestines and illium

Responds to Ag

Role in GI immune response

MALT (Mucosal associated lymphoid

tissue)

GALT (gut associated lymphoid tissue)

BALT (bronchial assiciated lymphoid

tissue)

NALT (nose associated lymphoid tissue)

VALT (vulvoveginal lymphoid tissue)

Fig: Lymph Tissues

References:

www.innerbody.com

www.sciencenetlink.com

www.livestrong.com

http://www.nature.com/cmi/journal/v9/n1/pdf/cmi201147a.pdf

http://www.bio.tamu.edu/courses/microbio/notes/Organs%20of%20the%20Immune%20System.pdf

And many more….