Download The Function of the Immune System

UNIT
9
The Immune System
11 - 1
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The Function of the Immune System

The function of the
immune system is to
create effective
immune responses to
continually defend the
body against antigens.
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Lymphatic System Function

Network of vessels that transport fluids

Lymphatic vessels carry away excess
fluid from interstitial spaces and return it
to blood stream

Attacks foreign particles, cancer cells
and toxins
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Overview

https://study.com/academy/lesson/functio
ns-of-the-lymphatic-system.html
11 - 4
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Lymphatic Pathways

Lymphatic Capillaries





Microscopic tubes
Extend into interstitial
spaces
Parallel to blood capillaries
Simple Squamous
epithelium
Fluid is called lymph (limf)
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Lymphatic Pathways

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Lymphatic Vessels

Similar to veins, but
thinner

Have flap like valves to
prevent backflow of lymph
(like veins)

Larger vessels lead to
specialized organs called
lymph nodes

After leaving lymph
nodes, vessels merge to
form even larger lymph
trunks
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11 - 7
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Lymphatic Pathways

Lymphatic Trunks &
Collecting Drains


Lymphatic trunks,
which drain lymph, are
named for the region
they serve
Join one or two
collecting ducts


Thoracic duct
Right lymphatic duct
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Lymphatic Pathways

Lymphatic Trunks & Collecting Ducts

Thoracic Duct – Longer and larger collecting
duct


Received lymph from: lower limbs, abdominal
region, left upper limb and left side of the thorax,
head and neck
Empties into left subclavian vein near the junction
of the left jugular vein
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11 - 10
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Lymphatic Pathways

Lymphatic Trunks & Collecting Ducts

Right Lymphatic Duct



Receives lymph from: right side of head and neck,
right upper limb, and right thorax
Empties into right subclavian vein near junction
of right jugular vein
After leaving collecting ducts, lymph enters
venous system and becomes part of plasma
11 - 11
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Lymphatic Pathway

Lymphatic capillary  lymphatic vessel
 lymph node  lymphatic vessel 
lymphatic trunk  collecting duct 
subclavian vein
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Tissue Fluid & Lymph


Lymph is tissue fluid that has entered a
lymphatic capillary
Lymph formation depends on tissue fluid
formation
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Tissue Fluid Formation

Tissue fluid originates from blood plasma

Composed of water & dissolved
substances that leave blood capillaries

Capillary blood pressure causes filtration
of water and other molecules from the
plasma
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Lymph Movement


Lymph is under low hydrostatic pressure
and may not flow readily without outside
help
These forces include:



Skeletal muscle
Smooth muscle
Breathing
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Lymph Movement

Skeletal Muscle

Contracting skeletal muscle compresses lymphatic
vessels and moves lymph in these vessels

Vessels have valves  lymph can only travel
towards collecting duct

Smooth Muscle

Smooth muscle in walls of lymphatic trunks can
contract & compress lymph inside, moving it forward
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Lymph Movement

Breathing



Creates relatively low pressure in thoracic
cavity during inhalation
At the same time, diaphragm increases
pressure in abdominal cavity
This forces lymph from abdominal vessels to
thoracic vessels
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The Organs of the Immune System




Bone marrow
Thymus
Lymph nodes
Spleen




Tonsils
Adenoids
Appendix
Peyer’s patches:
clumps of lymph tissue
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11 - 19
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Lymph Nodes


Located along lymphatic pathways
Contain many lymphocytes and
macrophages – fight invading organisms
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Lymph Nodes

Structure

Vary in size & shape, but usually less than 2.5cm
long, bean shaped

Hilum – indented region where blood vessels and
nerves join
 Lymphatic vessels exit from here

Capsule of connective tissue enclose nodes

Peyer’s Patches – aggregations of nodules
scattered throughout ileum region of small intestine
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11 - 22
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Locations
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Functions of Lymph Nodes


Filtering potentially
harmful particles from
lymph before returning
it to blood stream
Immune Surveillance –
lymphocytes &
macrophages
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Thymus


Large during infancy/childhood – shrinks
during puberty
Connective tissues extend inward from
surface, subdividing the gland into
lobules


Abundant lymphocytes
Most cells (thymocytes) are inactive, but
some mature into Tcells that leave thymus &
provide immunity
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Thymus
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Spleen





Largest lymphatic organ
Resemble lymph node, but the spaces of the
spleen contain blood instead of lymph
White Pulp – islands throughout spleen.
Contains many lymphocytes
Red Pulp – RBC, lymphocytes, macrophages
Filters blood, like lymph nodes filter lymph
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Spleen
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Body Defenses Against Infection

Innate (nonspecific) defense


General, protect against many pathogens
Adaptive (specific) defense

Precise, targets certain pathogens

https://study.com/academy/lesson/what-isthe-immune-system-our-bodys-defenseagainst-pathogens.html
11 - 29
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Innate Defenses

Species Resistance – each species has
a specific set of diseases that is unique
to it


Mechanical Barriers – 1st line of defense


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Ex: Pathogens that cause measles and
mumps affect humans, but not other species
Skin & mucus membranes (hair, mucus,
sweat)
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Innate Defenses

Chemical Barriers – Enzymes in body fluid

Ex: Gastric juice & tears contain enzymes and
antibacterial agents that kill many pathogens

Lymphocytes and fibroblasts produce interferons in
response to viruses or tumor cells

Once released from virus-infected cell, interferon binds
to receptors on uninfected cells, causing them to
produce proteins that block replication of a variety of
viruses
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Innate Defenses

Fever – higher body temperature causes
liver and spleen to hold on to iron.


Bacteria & fungi need iron to produce in high
temperatures
Phagocytosis – neutrophils & monocytes
are blood’s most active phagocytes

Removes foreign particles from lymph as it
moves from interstitial spaces to blood
stream
Innate Defenses

Inflammation – tissue response to injury or
infection, causing localized redness, heat, and
pain


Results in walling off of the site so infection cannot
spread
Brings more blood to area with phagocytes to
remove microorganisms


Heat speeds up phagocytes
Infected cells stimulate WBC to area. In bacterial
infections, this may create pus
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Adaptive Defenses

Antigens


Things the immune system sees as non-self,
such as bacteria, viruses, fungi, and
parasites
The body responds by destroying them or
rendering them ineffective.
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Adaptive Defenses

Lymphocyte Origins

Before birth, red bone marrow releases
undifferentiated lymphocytes into circulation

About half reach the thymus where they develop
into T Cells
» Other T Cells reside in lymphatic organs, lymph
nodes, thoracic duct and spleen

Other non-T lymphocytes remain in red
bone marrow until they differentiate into B
cells
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Adaptive Defenses

Lymphocyte functions

T cells attach to foreign, antigen bearing
cells and interact directly (cell to cell contact)


Cellular immune response
B cells, when stimulated by antigen, grow
and divide into plasma cells that produce
antibodies or immunoglobulins

Humoral immune response
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T Cells

Act directly on target cells and provide
cell-mediated immunity
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The 4 Types of T Cells
1.
Helper T cells


2.
Suppressor T cells

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Produce proteins that help other
lymphocytes and phagocytes perform their
functions
Also help B lymphocytes make antibodies
Stop or turn off T cell actions when the
“battle” is under control
(continued)
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The 4 Types of T Cells
3.
Memory T cells

4.
Have a memory from previous experiences
with specific antigens and are prepared to
act immediately upon recontact
Killer T cells


Can directly kill infected or malignant cells
and those cells carrying a target antigen
Can attach to the target and insert toxic
chemicals that make holes in the membrane
and destroy the cell before it can reproduce
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How NK Cell Action Differs from
Phagocytic Action


Natural killer (NK) cells can kill cancer
cells and cells infected with viruses
without using antibodies or having prior
exposure to the antigen.
This is done by injecting a toxin into the
membrane to destroy the cell, instead of
eating it as phagocytes would.
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Major Histocompatibility Complex (MHC)


Molecules that function as biochemical
“fingerprints”
This serves as the “ID” for cells so they
are marked and recognized as self.
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The Purpose of MHC



MHC markers enable the immune
system to achieve its primary function of
communication.
The body can recognize cells as self and
non-self.
This promotes homeostasis through the
destruction of damaged or dead cells.
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The Role of the B Cell


B lymphocytes produce antibodies in a
process called humoral immunity
B cells have 2 stages of development:
1.
2.
Cells insert molecules of one specific
antibody into the cell membrane.
The antibody contacts antigens and they
change into an antigen-antibody complex.
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The Body’s 3 Main Lines of Defense
1.
First line of defense: barriers



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Anatomic barrier: the skin, mucous
membranes, and intestinal tract
Biochemical barrier: sebaceous glands,
tears, and sweat
Mechanical: coughing, urination, and skin
cells slough off
(continued)
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The Body’s 3 Main Lines of Defense
2.
Second line of defense: the inflammation
process


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Begins within seconds of an injury or
invasion
Area becomes red, swollen, and warm to the
touch
(continued)
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The Body’s 3 Main Lines of Defense
3.
Third line of defense: antibody defense


This is our immunity.
Results from a dual-system response and
involves the actions of specific cells and
other immune system components to attack
the antigen.
11 - 46
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3 Basic Services of the Immune System
1.
2.
3.
Identifies self and destroys non-self
substances
Maintains a normal internal environment
(homeostasis)
Conducts continual surveillance
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Allergens


The result of an inappropriate response
to a harmless substance such as grass,
cat hair, etc.
This results in the condition known as an
allergy.
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Allergic Reactions



Immune attack against a non-harmful
substance
Similar to immune response – synthesize
lymphocytes, antibodies may bind
antigens, but allergic reactions may
damage tissues
Allergy testing

https://www.youtube.com/watch?v=atOI5c_u
NIs
11 - 49
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Tissue Rejection Reaction



Recipient’s immune system may
recognize the donor’s cell surfaces as
foreign
Resembles cellular immune response
Immunosuppressive drugs are used to
prevent this

Suppresses formation of antibodies and T
cells
11 - 50
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Autoimmunity


Attack against self
Immune system fails to distinguish self
from non-self
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Vaccines

https://study.com/academy/lesson/immu
nization-and-vaccination.html

https://study.com/academy/lesson/antibio
tics-and-vaccines.html
11 - 52
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Diseases and Disorders
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https://study.com/academy/lesson/immunedeficiency-diseases-definitions-types.html
11 - 54
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
https://study.com/academy/lesson/autoi
mmune-diseases-andhypersensitivity.html
11 - 55
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AIDS



Acquired immunodeficiency syndrome
The most advanced stage of the human
immunodeficiency virus (HIV)
This syndrome renders the body’s
immune system ineffective.
11 - 56
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How AIDS Destroys the Immune System


The virus invades the T cells and
macrophages.
With the helper T cells disabled, the
macrophages do no act, the B cell
antibodies are diverted, and there is no
NK cell formation.
11 - 57
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5 Ways to Acquire the AIDS Virus
1.
2.
3.
4.
5.
Unprotected sex with an infected partner
Sharing drug needles or syringes
HIV-positive mother passes it on to her
child
Blood transfusions
Accidental needlesticks and contact with
infected blood
11 - 58
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4 High-Risk Behaviors to Avoid
1.
2.
3.
4.
High-risk sexual activities
Using intravenous drugs and sharing
needles
Having multiple sex partners
Untreated sexually transmitted diseases
11 - 59
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The 3 Most Common
Opportunistic Diseases

Pneumocystis carinii pneumonia


Kaposi’s sarcoma


Lung infection with fever, cough, and
dyspnea
Form of cancer that appears as purplish skin
blotches
Candidiasis

Yeast infection that can attack the mouth,
esophagus, and vagina
11 - 60
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Cancer



A group of diseases characterized by the
growth of abnormal cells
These cells accumulate and form tumors
that may compress, invade, or destroy
normal tissue.
The spread of a tumor to a new site is
called metastasis.
11 - 61
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The Classifications of Cancer

Cancer is classified according to its
cellular origin



Carcinomas arise from epithelial tissue.
Sarcomas arise from connective tissue.
Leukemias arise from blood and bloodforming organs.
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Describing Grading and
Staging of Cancer


Grading describes the degree of cell
differentiation from grade I to grade IV
Grade I


Cells are well differentiated.
Grade IV

Cells are undifferentiated.
11 - 63
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Staging




Staging identifies the extent of the
spread of the disease
T: size of the primary tumor
N: presence or absence of regional
metastasis
M: presence or absence of distant
metastasis
11 - 64
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4 Types or Categories of Carcinogens
1.
2.
3.
4.
Chemical: arsenic, tobacco, benzene,
etc.
Viral: Epstein-Barr, hepatitis B, leukemia,
etc.
Physical: asbestos, radiation, etc.
Familial: melanoma, leukemia, etc.
11 - 65
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Chronic Fatigue Syndrome

A debilitating disorder that causes
overwhelming fatigue that lasts at least 6
months and does not go away with rest
11 - 66
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Lymphedema

Swelling of body tissues caused by an
accumulation of lymphatic fluid
11 - 67
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Lymphedema Wrapping

https://www.youtube.com/watch?v=jC6LzOlI1w
11 - 68
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Lupus



Chronic disease that causes changes in
the immune system
This disorder causes inflammation.
Lupus can involve only a few body
organs or can cause serious, lifethreatening problems.
11 - 69
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How Lupus Affects the Immune System
and Major Body Organs

Usually protective antibodies are
produced in large quantities, but they
react against the person’s own normal
tissues
11 - 70
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Rheumatoid Arthritis

A chronic systemic inflammatory
autoimmune disease that affects the
joints and surrounding muscles, tendons,
ligaments, and blood vessels
11 - 71
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Diagnostic Tests and Treatments
11 - 72
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3 Categories of Diagnostic Testing
1.
2.
3.
Biopsies: visual examination of cells
removed by needle aspiration, excision,
or bone marrow aspiration
Lab tests: Blood, semen, and urine are
evaluated for abnormal cancer cells and
tumor markers.
Tumor imaging: x-rays, CT scans, and
MRIs
11 - 73
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Major Cancer Treatment Methods




Surgery
Chemotherapy
Radiation:
external beam
therapy
Radiation:
brachytherapy





Radiation:
biosurgery
Biological response
modifiers
Gene therapy
Complementary
therapy
Alternative therapy
11 - 74
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Immunization and Vaccinations


The deliberate introduction of an antigen
into the body, which causes a minor
reaction in the patient
After injection, the body produces an
antigen-antibody complex and eventually
memory cells against the disease are
produced.
11 - 75
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Boy in a Bubble

https://www.youtube.com/watch?v=4CFP
dUAj41Y
11 - 76
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