The Lymphatic System - North Seattle College
Download
Report
Transcript The Lymphatic System - North Seattle College
The Lymphatic System
Introduction
The ability to ward off pathogens
that produce disease is called
resistance
Introduction
Lack of resistance is called
susceptibility
Lymphatic System
Consist of;
lymph (fluid)
lymphatic vessels
lymphatic organs and tissues
bone marrow
Lymphatic System
1.
Functions;
Drain interstitial fluid
Lymphatic System
2. Return leaked plasma proteins to
the blood
Lymphatic System
3. Protects against invasion by
nonspecific defenses and specific
immune responses
Lymphatic Circulation
Interstitial fluid drains into lymphatic
capillaries thus forming lymph
Lymphatic Circulation
Lymph capillaries merge to form
larger vessels, called lymphatic
vessels
Lymphatic Circulation
Convey lymph into and out of
structures called lymph nodes
Lymphatic Capillaries
Lymphatic capillaries are found
everywhere except;
1. Avascular tissue
Lymphatic Capillaries
2. CNS
Lymphatic Capillaries
3. Portions of the spleen
Lymphatic Capillaries
4. Red bone marrow
Lymphatic Capillaries
Lacteal – lymphatic capillary in the
villus of the small intestine which
transport fats
Lymph Trunk and Ducts
1.
2.
Thoracic Duct
Right Lymphatic Duct
Thoracic Duct
Main collecting duct of the lymphatic
system
Thoracic Duct
Receives lymph from the left side of
the head, neck, and chest, the left
upper extremity and the entire body
below the ribs
Thoracic Duct
It drains lymph into venous blood via
the left subclavian vein
Right Lymphatic Duct
Drains lymph from the upper right
side of the body
Right Lymphatic Duct
It drains lymph into venous blood via
the right subclavian vein
Flow of Lymph
1. Fluid flows from arteries and blood
capillaries to interstitial spaces
(interstitial fluid)
Flow of Lymph
2. To lymph capillaries (lymph)
Flow of Lymph
3. To lymphatic vessels
Flow of Lymph
4. To lymph trunks
Flow of Lymph
5.To the thoracic duct or right
lymphatic duct
Flow of Lymph
6. To the subclavian veins (blood)
Lymphatic Organs and Tissues
Lymphatic organs are classified as
primary or secondary
Primary Lymphatic Organs
Red bone marrow
Thymus gland
Secondary Lymphatic Organs
Lymph nodes
Spleen
Lymphatic nodules
Thymus Gland
Lies between the sternum and the
heart
Thymus Gland
Functions in immunity as the site of
T cell maturation
Thymus Gland
Large in the infant and after puberty
it is replaced by adipose and areolar
connective tissue
Lymph Nodes
Are encapsulated oval structures
located along lymphatic vessels
Lymph Nodes
Contain T cells, macrophages,
follicular dendritic cells, B cells, and
plasma cells
Lymph Nodes
Lymph enters nodes through afferent
lymphatic vessels and is filtered to
remove damage cells and
microorganisms
Lymph Nodes
Exits through efferent lymphatic
vessel
Lymph Nodes
Foreign substances filtered by the
lymph nodes are trapped by nodal
reticular fibers
Lymph Nodes
Macrophages destroys foreign
substances by phagocytosis
Lymph Nodes
Lymphocytes bring about the
destruction of others by immune
response
Lymph Nodes
Site of proliferation of plasma cells
(from B cells) and T cells
Plasma cells make antibodies
Spleen
Largest mass of lymphatic tissue in
the body
Spleen
Located between the stomach and
diaphragm
Spleen
Made up of white and red pulp
White Pulp
Lymphatic Tissue
White Pulp
Its T lymphocytes directly attack and
destroy antigens in blood
White Pulp
Its B lymphocytes develop into
antibody producing plasma cells, and
the antibodies inactivate antigens in
blood
White Pulp
Macrophages destroy antigens in
blood by phagocytosis
Red Pulp
1.
2.
Consists of;
Venous sinuses
Splenic cords
Red Pulp
Venous sinuses are filled with blood
Red Pulp
1.
2.
3.
4.
5.
Splenic cords consist of;
RBCs
Macrophages
Lymphocytes
Plasma cells
granulocytes
Red Pulp
Macrophages remove deffective
RBCs, WBCs, and platelets
Red Pulp
Stores blood platelets
Lymphatic Nodules
Oval-shaped concentrations of
lymphatic tissue
Lymphatic Nodules
Scattered throughout the mucous
membranes lining the GI tract,
respiratory airways, urinary tract,
and reproductive tract
Peyer’s patches
Lymphatic nodules in the ileum of
the small intestine
Tonsils
Multiple aggregations of large
lymphatic nodules at the junction of
the oral cavity and the pharynx
Tonsils
1.
2.
3.
Include;
Pharyngeal
Palatine
Lingual tonsils
Tonsils
Participate in immune responses by
producing lymphocytes and
antibodies
Nonspecific Resistance to Disease
Involves a
1. First line of Defense
2. Second line of Defense
First Line of Defense
Involves
1. Mechanical Protection
2. Chemical Protection
Mechanical Protection
Include
1. Epidermis layer of the skin
Mechanical Protection
2. Mucous membranes in the nose
and trachea
Mechanical Protection
3. Lacrimal apparatus
Mechanical Protection
4. Saliva
Mechanical Protection
5. Mucus
Mechanical Protection
6. Cilia
Mechanical Protection
7. Epiglottis
Mechanical Protection
8. Flow of urine
Mechanical Protection
9. Defecation
Mechanical Protection
10. Vomiting
Chemical Protection
1. The skin produces sebum, which
has a low pH
Chemical Protection
2. Lysozyme in sweat has
antimicrobial properties
Chemical Protection
3. Gastric juice in the stomach has
a low pH
Chemical Protection
4. Vaginal
acidic
secretions are also
Second Line of Defense
Involves
1. Antimicrobial proteins
2. Phagocytic and natural killer cells
3. Inflammation
4. Fever
Antimicrobial Proteins
1.
2.
Interferons
Complement System
Interferons
Body cells infected with viruses
produce proteins called interferons
(IFNs)
Interferons
IFN diffuses to uninfected cells and
binds to surface receptors
Interferons
This induces uninfected cells to
synthesize antiviral proteins that
inhibit viral replication
Complement System
A group of 20 proteins present in
blood plasma and on cell membranes
Complement System
When activated, these proteins
enhance immune, allergic, and
inflammatory reactions
Natural Killer Cells
Lymphocytes that lack the
membrane molecules that identify T
and B cells
Natural Killer Cells
Can kill a variety of infectious
microbes and some tumor cells
Natural Killer Cells
Sometime release perforins that
insert into the plasma membrane of
a microbe and make the membrane
leaky so that cytolysis occurs
Natural Killer Cells
Sometimes they bind to a target cell
and inflict damage by direct contact
Phagocytes
Neutrophils and macrophages
Inflammation
Four symptoms
1. Redness
2. Pain
3. Heat
4. Swelling
Inflammation
Three stages
1. Vasodilation and increased
permeability
Inflammation
2. Emigration of phagocytes from the
blood into interstitial fluid
Inflammation
3. Tissue Repair
Inflammation
Vasodilation and increased
permeability are responsible for heat,
redness, and swelling
Inflammation
Pain results from injury to neurons
and from toxic chemicals released by
microbes
Fever
When macrophages respond to an
infection, they release interleukin
-1
Fever
Interleukin-1 stimulates the
hypothalamus to initiate a fever
Fever
Inhibits some microbial growth and
speeds up body reactions that aid
repair
Major Histocompatibility Complex
Antigens
Unique to each person’s body cells
Major Histocompatibility Complex
Antigens
All cells except rbc display MHC class
I antigens
Major Histocompatibility Complex
Antigens
Antigen presenting cells
(macrophages) also display MHC
class II antigens
Pathways of Antigen Processing
For an immune response to occur, B
and T cells must recognize that a
foreign antigen is present
Pathways of Antigen Processing
Antigens are chemical substances
that are recognized as foreign by
antigen receptors when introduced
into the body
Pathways of Antigen Processing
The body contains millions of
different T and B cells each capable
of responding to a specific antigen
Cell-Mediated Immunity
Refers to destruction of antigens by
T cells
Cell-Mediated Immunity
Three main steps
Cell-Mediated Immunity
1. T cells recognize antigen fragments
associated with MHC II class
molecules on the surface of an
antigen presenting cell
(macrophage).
Cell-Mediated Immunity
Although CD8 cell receptors bind to
the antigen associated with MHC
class I molecules on the virus
infected cell
Cell-Mediated Immunity
2. A small number of T cells
proliferate and differentiate into a
clone of effector cells
Cell-Mediated Immunity
2 continued …
Clone of effector cells – a pop. of
identical cells that can recognize the
same antigen
Cell-Mediated Immunity
3. Antigen (intruder) is eliminated
Types of T Cells
1.
2.
3.
Helper T (TH) cells
Cytotoxic T (TC) cells
Memory T cells
Helper T cells
T4 cells
Helper T cells
Display CD4 proteins
Helper T cells
Recognize antigen fragments
associated with MHC-II molecules
Helper T cells
Secrete interleukin-2 which as a
costimulator
Helper T cells
Proliferation of T cells requires
costimulation
Cytotoxic T cells
Fight foreign invaders by killing the
target cell
Cytotoxic T cells
Target cell – the cell that bears the
same antigen that stimulated
proliferation
Cytotoxic T cells
One killing mechanism uses perforin
to cause cytolysis of the target cell.
Cytotoxic T cells
The second mechanism uses
lymphotoxin to activate damaging
enzymes within the target cells
Cytotoxic T cells
Main targets are virus infected cells
Memory T cells
Programmed to recognize the
original invading antigen
Antibody-Mediated Immunity
Refers to destruction of antigens by
antibodies
Antibody-Mediated Immunity
There are 4 steps
Antibody-Mediated Immunity
1. An antigen binds to the surface of
B cells
Antibody-Mediated Immunity
2. Some antigen is taken into the B
cell, broken down into peptide
fragments and combined with the
MHC-II self antigen, and moved to
the B cell surface
Antibody-Mediated Immunity
3. Hepler T cells recognize the
antigen-MHC-II combination and
secrete interleukins
Antibody-Mediated Immunity
The interleukins deliver the
costimulation needed for B cell
proliferation
Antibody-Mediated Immunity
4. Some activated B cells become
antibody-secretion plasma cells.
Others become B cells
Antibodies
A protein that can combine
specifically with the antigenic
determinant on the antigen that
triggered its production
Antibodies
1.
2.
3.
4.
5.
Five classes
IgG
IgA
IgM
IgD
IgE
IgG
It binds to bacteria and viruses
IgG
It crosses the placenta until it can
begin secreting its own.
IgA
It is in blood, breast milk, tears,
saliva, and intestinal secretions.
IgA
Levels decrease during stress
IgA
Protects our mucous membranes
against infections with bacteria and
viruses
IgM
First antibody to be secreted by
plasma cells after exposure to
antigens
IgM
Antibodies to A and B red cell
antigens are IgM
IgM
Cannot cross the placenta
IgD
Activate B cells
IgE
On the surface of mast cells and
basophils
IgE
Involved in allergic reactions
IgE
When a person with pollen allergies
inhales pollen, it combines with the
IgE on their mast cells
IgE
Causes mast cells to release
histamine
AIDS
A condition in which a person
experiences infections as a result of
the progressive destruction of cells
by the humon immunodeficiency
virus
HIV
The only documented transmissions
are by way of blood, semen, vaginal
secretions, and breast milk
HIV
A recent study in San Fran showed
that 8% of their HIV-infected
patients acquired it via oral sex
HIV
Form of a retrovirus with a protein
coat
HIV
HIV enters CD4 positive T
lymphocytes and macrophages
where it sheds its protein coat
HIV
New HIV DNA is produced in the T
cell along with new protein coats and
then released
HIV
The T cells are ultimately destroyed
HIV
Progression to AIDS occurs because
of reduced numbers of T cells and
resulting immunodeficiency
AIDS
Person now susceptible to
opportunistic infections
HIV
Treatment of HIV infection with
reverse transcriptase inhibitors has
shown to delay the progression of
HIV infection to AIDS