lymphatic_immune.ppt

Essentials of Human Anatomy & Physiology
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Seventh Edition
Elaine N. Marieb
Chapter 12
The Lymphatic System
and Body Defenses

Lymph Nodes
Slide
Figure 12.3

The Lymphatic System
Slide 12.1
 Two parts
Lymphatic vessels
Lymphoid tissues and organs
 Lymphatic system functions
Transport fluids back to the blood
Play essential roles in body defense and
resistance to disease
 Absorb digested fat at the intestinal villi

Lymphatic Characteristics
Slide 12.2
 Lymph – excess tissue fluid carried by
lymphatic vessels
 Properties of lymphatic vessels
One way system toward the heart
No pump
Lymph moves toward the heart
Milking action of skeletal muscle
Rhythmic contraction of smooth muscle
in vessel walls

Lymphatic Vessels
Slide
Figure 12.1

Lymphatic Vessels
Slide
 Lymphatic
collecting vessels
Collects lymph
from lymph
capillaries
Carries lymph to
and away from
lymph nodes
Figure 12.2

Lymphatic Vessels
Slide
 Lymphatic
collecting vessels
(continued)
Returns fluid to
circulatory veins
near the heart
Right lymphatic
duct
Thoracic duct
Figure 12.2

Lymph
Slide
 Materials returned to the blood
Water
Blood cells
Proteins

Lymph
Slide
 Harmful materials that enter lymph
vessels
Bacteria
Viruses
Cancer cells
Cell debris

Lymph Nodes
Slide
 Filter lymph before it is returned to the
blood
 Defense cells within lymph nodes
Macrophages – engulf and destroy foreign
substances
Lymphocytes – provide immune response to
antigens

Lymph Node Structure
Slide
Figure 12.4

Other Lymphoid Organs
Slide 12.9
 Several other
organs contribute
to lymphatic
function
Spleen
Thymus
Tonsils
Peyer’s patches
Figure 12.5

The Spleen
Slide
 Located on the left side of the abdomen
 Filters blood
 Destroys worn out blood cells
 Forms blood cells in the fetus
 Acts as a blood reservoir

The Thymus
Slide
 Located low in the throat, overlying the
heart
 Functions at peak levels only during
childhood
 Produces hormones (like thymosin) to
program lymphocytes

Tonsils
Slide
 Small masses of lymphoid tissue
around the pharynx
 Trap and remove bacteria and other
foreign materials
 Tonsillitis is caused by congestion with
bacteria

Peyer’s Patches
Slide
 Found in the wall of the small intestine
 Resemble tonsils in structure
 Capture and destroy bacteria in the
intestine

Mucosa-Associated Lymphatic
Tissue (MALT)
Slide
 Includes:
Peyer’s patches
Tonsils
Other small accumulations of lymphoid
tissue
 Acts as a guard to protect respiratory
and digestive tracts

Body Defenses
Slide
 The body is constantly in contact with
bacteria, fungi, and viruses (pathogens)
 The body has two defense systems for
foreign materials
Nonspecific defense system
Mechanisms protect against a variety of
invaders
Responds immediately to protect body
from foreign materials

Body Defenses
Slide
Specific defense system
Specific defense is required for each type
of invader
Also known as the immune system

Nonspecific Body Defenses
Slide
 Body surface coverings
Intact skin
Mucous membranes
 Specialized human cells
 Chemicals produced by the body

Surface Membrane Barriers –
First Line of Defense
Slide
 The skin
Physical barrier to foreign materials
pH of the skin is acidic to inhibit bacterial
growth
Sebum is toxic to bacteria
Vaginal secretions are very acidic

Surface Membrane Barriers –
First Line of Defense
Slide
 Stomach mucosa
Secretes hydrochloric acid
Has protein-digesting enzymes
 Saliva and lacrimal fluid contain
lysozyme
 Mucus traps microogranisms in
digestive and respiratory pathways

Defensive Cells
Slide
 Phagocytes
(neutrophils and
macrophages)
Engulfs foreign
material into a
vacuole
Enzymes from
lysosomes digest
the material
Figure 12.6b

Macrophage attacking e-coli.
•
Macrophage attacking e-coli.
•

Defensive Cells
Slide
 Natural killer cells
Can lyse and kill
cancer cells
Can destroy virus-
infected cells
Figure 12.6b

Inflammatory Response -
Second Line of Defense
Slide
 Triggered when body tissues are injured
 Produces four cardinal signs
Redness
Heat
Swelling
Pain
 Results in a chain of events leading to
protection and healing

Functions of the Inflammatory
Response
Slide
 Prevents spread of damaging agents
 Disposes of cell debris and pathogens
 Sets the stage for repair

Steps in the Inflammatory Response
Slide
Figure 12.7

Antimicrobial Chemicals
Slide
 Complement
A group of at
least 20
plasma
proteins
Activated when
they encounter
and attach to
cells
(complement
fixation) Figure 12.8

Slide
 Complement
(continued)
Damage
foreign cell
surfaces
Will rupture or
lyse the foreign
cell membrane
Figure 12.8

Slide
 Interferon
Secreted proteins of virus-infected cells
Bind to healthy cell surfaces to inhibit viruses
binding

Interferons are a family species-specific proteins synthesized by
eukaryotic cells in response to viruses and a variety of natural and
synthetic stimuli. There are several different interferons commonly used
as therapeutics, termed alpha, beta, and gamma. These peptides are
used to treat hairy cell leukemia, AIDS-related Kaposi's sarcoma,
laryngeal papillomatosis, genital warts, and chronic granulomatous
disease. Side effects include black tarry stools, blood in the urine,
confusion, and loss of balance.

Fever
Slide
 Abnormally high body temperature
 Hypothalmus heat regulation can be
reset by pyrogens (secreted by white
blood cells)
 High temperatures inhibit the release of
iron and zinc from liver and spleen
needed by bacteria
 Fever also increases the speed of
tissue repair

Specific Defense: The Immune
System – Third Line of Defense
Slide
 Antigen specific – recognizes and acts
against particular foreign substances
 Systemic – not restricted to the initial
infection site
 Has memory – recognizes and mounts
a stronger attack on previously
encountered pathogens

Types of Immunity
Slide
 Humoral immunity
Antibody-mediated immunity
Cells produce chemicals for defense
 Cellular immunity
Cell-mediated immunity
Cells target virus infected cells

Antigens (Nonself)
Slide
 Any substance capable of exciting the
immune system and provoking an immune
response
 Examples of common antigens
 Foreign proteins
 Nucleic acids
 Large carbohydrates
 Some lipids
 Pollen grains
 Microorganisms

Self-Antigens
Slide
 Human cells have many surface
proteins
 Our immune cells do not attack our own
proteins
 Our cells in another person’s body can
trigger an immune response because
they are foreign
Restricts donors for transplants

Allergies
Slide
 Many small molecules (called haptens
or incomplete antigens) are not
antigenic, but link up with our own
proteins
 The immune system may recognize and
respond to a protein-hapten
combination
 The immune response is harmful rather
than protective because it attacks our
own cells

Cells of the Immune System
Slide
 Lymphocytes
 Originate from hemocytoblasts in the red bone
marrow
 B lymphocytes become immunocompetent in
the bone marrow
 T lymphocytes become immunocompetent in
the thymus
 Macrophages
 Arise from monocytes
 Become widely distributed in lymphoid organs

Activation of Lymphocytes
Slide
Figure 12.9

Humoral (Antibody-Mediated)
Immune Response
Slide
 B lymphocytes with specific receptors
bind to a specific antigen
 The binding event activates the
lymphocyte to undergo clonal selection
 A large number of clones are produced
(primary humoral response)

Humoral (Antibody Mediated)
Immune Response
Slide
 Most B cells become plasma cells
Produce antibodies to destroy antigens
Activity lasts for four or five days
 Some B cells become long-lived memory
cells (secondary humoral response)

Humoral Immune Response
Slide
Figure 12.10

Active Immunity
Slide
 Your B cells
encounter
antigens and
produce
antibodies
 Active immunity
can be naturally
or artificially
acquired
Figure 12.12

Passive Immunity
Slide
 Antibodies are obtained from someone
else
Conferred naturally from a mother to her
fetus
Conferred artificially from immune serum or
gamma globulin
 Immunological memory does not occur
 Protection provided by “borrowed
antibodies”

Antibodies (Immunoglobulins) (Igs)
Slide
 Soluble proteins secreted by B cells
(plasma cells)
 Carried in blood plasma
 Capable of binding specifically to an
antigen

Antibody Classes
Slide
 Antibodies of each class have slightly
different roles
 Five major immunoglobulin classes –
(Do Not Need to know!)
IgM – can fix complement
IgA – found mainly in mucus
IgD – important in activation of B cell
IgG – can cross the placental barrier
IgE – involved in allergies

Cellular (Cell-Mediated) Immune
Response
Slide
 Antigens must be presented by
macrophages to an immunocompetent
T cell (antigen presentation)
 T cells must recognize nonself and self
(double recognition)
 After antigen binding, clones form as
with B cells, but different classes of cells
are produced

Cellular (Cell-Mediated) Immune
Response
Slide
Figure 12.15

T Cell Clones
Slide
 Cytotoxic T cells
Specialize in killing infected cells
Insert a toxic chemical (perforin)
 Helper T cells
Recruit other cells to fight the invaders
Interact directly with B cells

T Cell Clones
Slide
 Suppressor T cells
Release chemicals to suppress the activity
of T and B cells
Stop the immune response to prevent
uncontrolled activity
 A few members of each clone are
memory cells

Summary of the Immune Response
Slide
Figure 12.16

Organ Transplants and Rejection
Slide
 Major types of grafts
Autografts – tissue transplanted from one
site to another on the same person
Isografts – tissue grafts from an identical
person (identical twin)
Allografts – tissue taken from an unrelated
person
Xenografts – tissue taken from a different
animal species

Organ Transplants and Rejection
Slide
 Autografts and isografts are ideal
donors
 Xenografts are never successful
 Allografts are more successful with a
closer tissue match

Disorders of Immunity:
Immunodeficiencies
Slide
 Production or function of immune cells
or complement is abnormal
 May be congenital or acquired
 Includes AIDS – Acquired Immune
Deficiency Syndrome

Autoimmune Diseases
Slide
 The immune system does not
distinguish between self and nonself
 The body produces antibodies and
sensitized T lymphocytes that attack its
own tissues

Autoimmune Diseases
Slide
 Examples of autoimmune diseases
Multiple sclerosis – white matter of brain
and spinal cord are destroyed
Myasthenia gravis – impairs
communication between nerves and
skeletal muscles
Juvenile diabetes – destroys pancreatic
beta cells that produce insulin
Rheumatoid arthritis – destroys joints

Autoimmune Diseases
Slide
 Examples of autoimmune diseases
(continued)
Systemic lupus erythematosus (SLE) –
affects kidney, heart, lung and skin
Glomerulonephritis – impairment of renal
function

• HIV targets cells
• Retrovirus attaches to CD4 receptors of
T helper cells
– Transmission: Body fluids, i.e., blood, semen,
breast milk, vaginal secretions
Immune Deficiency: AIDS

The Structure of HIV
Figure 9.19

Time Course of the Progression of
AIDS after HIV Infection
Figure 9.21

•AIDS progression:
–Phase I: few weeks to a few years; flu like symptoms, swollen
lymph nodes, chills, fever, fatigue, body aches. Virus is
multiplying, antibodies are made but ineffective for complete
virus removal
–Phase II: within six months to 10 years; opportunistic
infections present, Helper T cells affected, 5% may not
progress to next phase
–Phase III: Helper T cells fall below 200 per cubic millimeter
of blood AND the person has an opportunistic infection or type
of cancer. Person is now termed as having “AIDS” May
include pneumonia, meningitis, tuberculosis, encephalitis,
Kaposi’s sarcoma, and non-Hodgkin’s lumphoma….

• More than 36 million infected with HIV
worldwide
• Most infections in sub-Sahara of Africa
• Increasing spread in Asia and India
• Most often spread by heterosexual contact
outside U.S.
AIDS Pandemic

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