lymphatics and the immune system. lymphatic system the lymphatic system actually consists of two...
TRANSCRIPT
Lymphatics and the Immune System
Lymphatic System
The lymphatic system actually consists of two semi-independent systems
Lymphatic Capillaries and Vessels
Lymphoid Tissues and Organs
2
3
Lymphatic System
One way system: to the heart
Return of collected excess tissue fluid
Return of leaked protein
“Lymph” is this fluid Edema results if
system blocked or surgically removed
4
Lymph capillaries Have one way minivalves allowing
excess fluid to enter but not leave Picks up bacteria and viruses as well
as proteins, electrolytes and fluid
(lymph nodes destroy most pathogens)
5
Lymph flows from the lymphatic capillaries through successively larger and thicker vessels. Capillaries – Collecting Vessels – trunks – lymph ducts. With in this net work of tubing are Lymph Nodes.
Lymph is transported by the same mechanism that moves blood back to the heart.
- squeezing of skeletal muscles
- pressure changes in the bodies cavities
- capillary action and valves to prevent back flow
6
Superficial groups
-Cervical
-Axillary
-Inguinal
Deep groups
-Tracheobronchial
-Aortic
-Iliac
Lymph Nodes
*
*
7
Lymph nodes: bean shaped organs along lymphatic collecting vessels.
Two basic functions: Filters: Macrophages remove and destroy
microorganisms and debris. Immune activation: Lymphocytes monitor the
lymph for invaders.
8
Surrounded by a fibrous capsule Connective tissue strands called trabeculae divide up the node into
compartments.
There are three distinct regions histologically Cortex Medullary Cords Lymph Sinuses
Lymph node anatomy
The cortex contains densely packed follicles that produce B-cells (a type of lymphocyte).
T-cells (another type of Lymphocyte) can also be stored in the cortex.
9
Lymph Node
The Medullary Cords are thin projections from the cortex deeper into the node.
The cords can hold the lymphocytes, but also plasma cells.
10
Lymph Nodes
The lymph sinuses are large reticular fibers that span the node.
They contain the macrophages that consume debris and invaders.
11
12
Lymphoid Organs
Lymphoid organs Lymph nodes Spleen Thymus Tonsils Small intestine & appendix aggregated lymphoid
nodules
Spleen
The spleen provides a site for lymphocyte proliferation.
It also extracts damaged and aged blood cells.
Produces erythrocytes in a fetus. Stores blood platelets
13
Thymus
The thymus releases the hormones thymosin and thymopoietin.
These hormones cause T-cells to full develop their their ability to kill certain pathogens.
14
Tonsils
Tonsils have a variety of locations in and near the pharynx.
The oral tonsils are the most likely to get infected.
All tonsils house lymph follicles that produce lymphocytes and filter lymph.
15
Intestines and Appendix
Peyer’s Patches are large clusters of lymph tissue on the intestines.
There are also similar patches in the appendix.
They destroy bacteria and generate “memory lymphocytes” for immunity.
16
17
18
Components of the immune system
Innate immune system Response is non-specific
Exposure leads to immediate maximal response
Cell-mediated and humoral components
No immunological memory
Found in nearly all forms of life (plants & animals)
Adaptive immune system
Pathogen and antigen specific response
Lag time between exposure and maximal response
Cell-mediated and humoral components
Exposure leads to immunologic memory
Found only in jawed vertebrates
External Innate Defenses
The skin secretions we produce are acidic helping to fight fungus and bacteria.
Mucus comes from a variety of membranes and is meant to trap and filter incoming particles.
Salivia cleans and prtotects our oral cavity. Eyes produce lacrimnal fluid that contains
lysozyme a natural bacteria killer.
19
Internal Innate Defenses
When we get hurt or infected with a virus, bacteria or fungi the body activates the inflammatory response.
The symptoms of the response are: Swelling Redness Heat Pain
20
Internal Innate Defenses
Steps of Infalmmatory Rsponse
Step 1: A flood of inflammatory chemical are released into the tissue.
Step 2: Epithelial cells and Macro phages release cytokines that promote inflammation and attract WBC’s
21
Internal Innate Defenses
Step 2 continued: At the same time other cells (phagocytes, lymphocytes, etc.) release other chemicals (histamine, kinins, prostagladins and complement).
All of these chemical have different roles in inflammation, but they all cause more blood flow to the area and capillaries release clotting factors and antibodies.
22
Internal Innate Defenses
Step 3: The major players (lymphocytes, antibodies, etc) of the adaptive immune system are activated.
23
Internal Innate Defenses
Phagocytes: The main phagocyte is the macrophage (big eater).
They wonder through tissue looking for debris and invaders to phagocytize (eat).
24
Internal Innate Defenses
Neutrophils: WBC that phagocitize infectious material
Eosinophils: WBC that phagocitize parasites.
Mast Cells: WBC that phagoitize bacteria.
25
Internal Innate Defenses
Natural Killer cells: a unique group of defensive cells that patrol the blood and lymph killing cancer cells and viruses.
Not phagocytic. They release chemicals called perforins that break down the cells membranes and disintegrate the nucleus.
26
Internal Innate Defenses
Antimicrobial Proteins attack microorganisms directly or keep them from reproducing:
Two most important antimicrobials Interferon Complement
27
Internal Innate Defenses
Infected cells produce small proteins called Interferons.
The interferons diffuse to healthy cells and synthesize a protein that interferes with the viruses ability to replicate.
28
Internal Innate Defenses
Complement is actually short for Complement System.
It is a group of over 20 plasma proteins that circulate in the blood.
Normally inactive, when inflammation response is stimulated these chemicals enhance every aspect of the response.
29
Internal Innate Defenses
Fevers are another form of natural defense.
A mild fever causes the body stores zinc and iron instead of producing them. Bacteria require large amounts of both.
It also speeds up the metabolic rate, which speeds up tissue repair.
30
31
Components of the immune system
Innate immune system Response is non-specific
Exposure leads to immediate maximal response
Cell-mediated and humoral components
No immunological memory
Found in nearly all forms of life (plants & animals)
Adaptive immune system
Pathogen and antigen specific response
Lag time between exposure and maximal response
Cell-mediated and humoral components
Exposure leads to immunologic memory
Found only in jawed vertebrates
Adaptive Immunity
The adaptive immune response is more complex than the innate.
The antigen first must be recognized. The three crucial cell types include:
Antigen – presenting cells B Cells T Cells
32
Antigens
Antigens are anything that can provoke an immune response.
There are two types of antigens Complete: ability to stimulate proliferation of
and react with specific lymphocytes and antibodies.
Incomplete: small molecules that have hooked up with the bodies own proteins and the immune system does not recognize them.
33
34
“Humoral” vs “Cell mediated”
Antibody-mediated (humoral) immunity – attack by circulating antibodies released by the plasma cells derived from activated B cells. This response is only good for non complicated “obvious” bacteria
or invaders.
Cell-mediated immunity - direct attack by activated T cells (react with foreign antigens on the surface of other host cells). This response deals with more complicated or unknown invaders.
These two systems interact with each other
Antigen-Presenting Cells
APC’s engulf anitgens and display fragments of the antigen on their cell membrane for identification by T-cells or B-cells.
35
36
B Cells (humoral response)
The B-cell with the correct receptor complex is duplicated many times. Called Colonial Selection.
Differentiate into plasmocytes (plasma cells) when stimulated by exposure to an antigen.
Most of the clones produce antibodies that kill the antigen .
B -Cells
Memory B cells: produced by activated B cells that do not turn into plasma cells.
Upon re-exposure the memory B cells go into immediate action and your body is able to handle the invader faster, more efficiently and actually produces way more of the correct B-cells.
37
Passive and Active Humoral Immunity
Active Immunity: The proliferation of B-cells and their production of antibodies by your own body.
Passive Immunity: When those antibodies and B-cells are acquired from an outside source. A fetus has the same immunity as his/her
mother for the first few days after birth.38
Cell mediated response
What the B-cells miss or are not programmed to deal with T-cells are able to handle.
Usually
39
40
T Cells 80% of circulating lymphocytes. Much more complex structure. All T cells get “primed” to fight a certain
antigen in the Thymus gland.
Some of the types: Regulatory T cells Cytotoxic T cells Memory Cells Suppressor T cells
T Cell response
How T-cells respond is similar to B-cells. They identify the antigen The correct T-cell goes through colonial
selection and proliferation. Then the correct T-cell performs it’s specific
function (phaocytosis, chemical secretion, or signaling other cells)
41
Regulator T-Cells
Once regulatory (helper) T-cells have bound with an antigen they stimulate proliferation of B cells and other Tcells.
Without helper T-cells your body would not know to send out the killer Tcells nor what antigen to fight.
42
Cytotoxic T cells
Cytotoxic (killer) T cells: attack foreign cells or body cells infected by viruses (“cell-mediated immunity”).
They roam freely around the body looking for infected cells to chemically Kill.
They can be called to action in a certain area by helper T-cells.
43
Memory Cell
Memory T cells: produced by the division of activated T cells following exposure to a particular antigen (remain on reserve, to be reactivated following
Basically they remember the shape of a certain antigen and upon coming in contact know exactly which immune cell to call.
44
Suppressor T Cells
Also a type of regulator cell, but this one releases the chemical signal that stops the production of B and T cells.
45
46
Development of lymphocytesOriginate in bone marrow from lymphoid stem cellsB cells stay in bone marrow, hence “B” cellsT cells mature in thymus, hence “T” cells
These divide rapidly into familiesEach has surface receptors able to recognize one unique type of antigen=immunocompetence
47
48
The immune system protects organisms with layered defenses of increasing specificity
Most simply, 1. physical barriers prevent pathogens such as bacteria and viruses from entering the body
If a pathogen breaches these barriers, the 2. innate immune system provides an immediate, but non-specific response Innate immune systems are found in all plants and animals
If pathogens successfully evade the innate response, vertebrates possess a third layer of protection, the 3. adaptive immune system Here, the immune system adapts its response during an infection to
improve its recognition of the pathogen This improved response is then retained after the pathogen has
been eliminated, in the form of an immunological memory, and allows the adaptive immune system to mount faster and stronger attacks each time this pathogen is encountered