kkkkk

1. Immune System Overview
JL Torres, Ph.D.
1

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

7. 7
Located
throughout
the body in
almost all
tissues that
have blood
vessels
Lymphatic Vessels/”Lymphatics”

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

12. 12
https://www.youtube.com/watch?v=MfALH
zheD-g
https://www.youtube.com/watch?v=QU6X
MOo5UOE
“What are Lymphatic Malformations?
(Lymphatic System Part 2)”
“What is the Lymphatic System? (Part 1:
Anatomy and Physiology)”
https://www.youtube.com/watch?v=o0-
1OknbO3M
The lymphatic system | Health | Biology |
FuseSchool

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

23. 23
Blood Cells

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

30. 30

31. 31
Acquired, specific
(Adaptive)
Third line of
defense
B cells, T cells
and their effects
Fever
Antimicrobial
proteins

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