Lymphatic System Overview

Immune ResponseSpring 2007

Functions

Draining interstitial fluids Return lymph fluid to veins

Transporting dietary lipids Protecting against invasion

Lymphatic Vessels Lymphatic capillaries

Slightly larger than blood capillaries Allow interstitial fluid to flow in but not out

Lymphatic Vessels Cap. unite to form lymphatic vessels

Resemble veins Thinner walls and more valves Lymph nodes-masses of B cells & T cells

Thoracic Duct Drains most of the body

Right Lymphatic Duct Drains upper right side of body

Organs

2 groups based on function Primary lymphatic organs

Sites where stem cells mature into B cells & T cells

Red bone marrow & thymus Secondary lymphatic organs &

tissues Lymph nodes, spleen, lymphatic nodules

Thymus Consists of T cells,

macrophages, and epithelial cells

Produce thymic hormones Promote the

proliferation & maturation of T cells

Lymph Nodes 600 bean shaped organs Usually occur in groups Contain B cells that develop into

plasma cells Secrete antibodies, T cells, &

macrophages Filter lymphatic fluid Method of metastasis of cancer

Lymph Node

Spleen Largest mass of lymphatic tissue in

body 2 tissue types

White pulp▪ Lymphatic tissue▪ Consists of lymphocytes and macrophages

Red pulp▪ Blood filled sinuses▪ Splenic tissues- RBC’s, macrophages,

lymphocytes, plasma cells, and granular leukocytes

Spleen

Enlarged Spleen

Lymphatic Nodules

Not enclosed with a capsule Includes tonsils

Nonspecific Resistance to Disease 1st line of defense-Skin and mucous

membranes Epidermis Mucous membranes▪ Hairs▪ Cilia

Lacrimal apparatus Saliva Sweat

Nonspecific Resistance to Disease 2nd line of defense-internal defenses

Antimicrobial proteins Phagocytes Natural killer cells Fever Inflammation

Antimicrobial Proteins

Found in blood & interstitial fluid Interferons

Interfere with viral replication Complement

Cytolysis, chemotaxis, oponization Transferrins

Bind iron = inhibit growth of some bacteria

Natural Killer & Phagocytosis Natural killer (NK)

Cytolysis Phagocytes

Phagocytosis-ingestion of microbes or other particles

During infection monocytes enlarge into macrophages

Phagocytosis

Inflammation

Can be caused by pathogens, abrasions, chemical irritations, distortion or disturbances of cells, extreme temps

4 symptons Redness Pain Heat swelling

Inflammation (con’t) 3 stages

1. Vasodilation and increased permeability of blood vessels▪ Increased blood flow to area

2. Phagocyte emigration▪ Neutrophils, then monocytes, then

wandering macrophages3. Repair▪ Pus-WBC’s & dead tissue debris

Inflamatory Response