2. Concept of Immunity
Immunity (or resistance): host defenses (what you have)
to ward off disease.
Susceptibility: lack of resistance (what you don’t have) to
a disease.
2
3. Synopsis of Immune System
The immune system is a complex system composed
of several types of mobile and fixed cells that
interact in lymphoid tissue dispersed throughout
the body
The system is stimulated by the introduction of
foreign material into the host; its function is the
elimination of this material
3
4. 4
The Invaders . . .
Bacteria
Viruses
Parasites
such as fungi,
protista, & worms
Other – e.g.,
allergins, toxins
worm trichura.jpg
http://www.hhs.gov/asphep/presentation/images/bacteria.jpg
http://www.skidmore.edu/academics/biology/plant_bio/lab13.FUNGI.html
5. Overview of Lymphatic System
1. Lymphatic system consists of lymph,
lymph vessels, lymph nodes, and lymph
tissue
2. Works with the circulatory system
3. Removes waste and excess fluid from the
tissues
5
6. Lymph – the fluid in the tissues
an extracellular fluid (ECF) similar to
plasma
ECF is found in several places in the body:
body tissues (interstitial fluid)
blood (plasma)
lymphatic vessels (lymph)
6
8. 8
Small, open-ended lymph vessels
Act like drainpipes
Pick up lymph at tissues throughout
the body
Capillaries join together to form larger
lymphatic vessels
Lymphatic Capillaries
9. 9
Lymphatic vessels carry lymph
Contractions of skeletal muscles against
lymph vessels cause lymph to flow through
vessels
Vessels pass through lymph nodes
Contain valves that keep the lymph flowing
one way – towards the heart
Lymphatic Vessels con’t.:
10. 10
Specialized lymphatic capillaries, called
lacteals, located in area of small intestine
a. Pick up digested fats or lipids
b. When lymph is mixed with the lipids it
is called chyle
c. Lacteals transport the chyle to the
blood stream through the thoracic duct
Lacteals
11. 11
Popularly called “glands”
Located all over the body
usually in groups or clusters
– principal groupings are
located in the neck, armpits,
chest, abdomen, pelvis, and
groin
Small, oval masses ranging
in size from a pinhead to an
almond nut
Killing field for
phagocytosed bacteria
Lymph Nodes
13. 13
As lymphatic vessels leave the lymph
nodes, they continue to join together to
form larger lymph vessels
Eventually they drain into one of two
lymphatic ducts: the right lymphatic
duct or the thoracic duct
Lymphatic Ducts
14. 14
Short tube
Receives all the
purified lymph
from the right side
of the head and
neck, the right
chest, and the right
arm
Empties into the
right subclavian
vein, returning the
purified lymph to
the blood
Right Lymphatic Duct
15. 15
Much larger tube
Drains the lymph from
the rest of the body
Empties into the left
subclavian vein
Enlarged pouchlike
structure called the
cisterna chyli is located
at the start of the
thoracic duct
Thoracic Duct
16. 16
Serves as a
storage area
for purified
lymph
Receives chyle
from the
intestinal
lacteals
Cisterna Chyli
17. 17
Located
throughout the
body in addition to
being in the lymph
nodes
Tonsils, spleen, and
thymus are
examples of
lymphatic tissue
Lymph Tissue
18. 18
Masses of lymph tissue
Filter interstitial fluid
Three pairs of tonsils
Palatine tonsils on each side
of the soft palate
Pharyngeal tonsils (also
called adenoids) located in
the nasopharynx (upper part
of the throat)
Lingual tonsils on the back
of the tongue
Tonsils
19. 19
Stores erythrocytes to release into blood
stream if excessive bleeding occurs
Destroys thrombocytes or platelets
Filters some metabolites and wastes from
tissues
http://www.youtube.com/watch?v=0CqWul
ccLMo
Spleen
20. 20
Mass of lymph tissue
located in the center of
the upper chest
Atrophies or wastes away
after puberty and is
replaced by fat and
connective tissue
Thymus
21. 21
Functions during early life
Produces antibodies
Manufactures T lymphocytes to fight
infection
Function is taken over by lymph nodes
after it atrophies
http://www.youtube.com/watch?v=fFXQV-
XJf3M
Thymus
22. Lymphoid Cells, Tissues, and Organs
Types of Lymphocytes:
T CELLS (T lymphocytes) - attack foreign cells or body cells infected by
viruses; T cells mature and divide in the thymus; T cells are responsible for
cell-mediated immunity (meaning that the protection is directly from
living cells)
B CELLS (B lymphocytes) - responsible for antibody-mediated
immunity (=humoral immunity); a percentage of circulating B
lymphocytes mature into PLASMA CELLS; plasma cells produce and
secrete antibodies which destroy antigens
NK CELLS (natural killer cells) - attack foreign cells and cells infected
with viruses and cancer cells
22
24. 24
Origin of Immune Cells
Lymphoid tissue:
Thymus, bone marrow, lymph nodes, tonsils
T cells, B cells, NK cells
Gut-associated lymphoid tissue (GALT)
40% of T cells are processed
Myeloid Tissue:
Red bone marrow, liver, spleen
Macrophages
25. 25
Some Important Cells of the Immune System
Innate Bridging Adaptive
Neutrophil -
primarily phagocytoses
bacteria and other pathogens
NK cells –
destroy cells nonspecifically
that are non-self (including
virus-infected and cancer
cells)
Macrophage -
phagocytoses bacteria,
dead cells, etc., and secretes
cytokines that affect many
cell types. It plays an
important role in bridging
innate and adaptive
immunity by activating T
cells
B cell -
bears many membrane-
bound immunoglubulins
that act as B cell receptors. It
secretes immunoglubulins as
antibodies
Dendritic cell -
takes in foreign material,
secretes cytokines, and
activates T cells
T cells –
bears many identical
membrane-bound T cell
receptors. Some T cell
secrete cytokines that
regulate immune responses
while others (CTL) kill
tumor cells and virus-
infected cells
26. 26
How coordination of immune system
works: Cell Signaling
Cytokines (Greek cyto-, cell; and -kinos, movement) are small cell-
signaling protein molecules that are secreted by numerous cells used
extensively in intercellular communication.
- can be classified as proteins, peptides, or glycoproteins; the term
"cytokine" encompasses a large and diverse family of regulators
produced throughout the body by cells of diverse embryological origin.
e.g., interleukins and TNF
Chemokines (Greek -kinos, movement) are a family of small cytokines
- derived from their ability to induce directed chemotaxis in nearby
responsive cells; they are chemotactic cytokines
27. 27
Cytokines that regulate lymphocyte
growth and activation
Interleukin-2
Macrophage colony-stimulating factor (M-CSF)
28. 28
Cytokines that regulate lymphocyte
growth and activation
Interleukin-2
Macrophage colony-stimulating factor (M-CSF)
29. 29
Toll-like Receptors
Toll-like receptors are protein receptors found in the plasma
membrane of defensive cells that activate the innate immune
system
Toll-like receptors attach to Pathogen-Associated Molecular Patterns
(PAMPs) of microbes:
LPS
Flagellin
Lipoteichoic acid
DNA of bacteria
DNA and RNA to viruses
Components of fungi and parasites
32. 32
Features of Innate
and Adaptive Immunity
Feature Innate Immunity (1st
and 2nd)
Adaptive Immunity (3rd)
Specificity for microbes Relatively low (not
antigen specific)
High (antigen specific)
Specialization Low High
Immunological Memory No Yes
