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Lymphatic and
Immune System
Your Body’s Defense
The Lymphatic and
Immune Systems
Lesson 12.1: The Lymphatic System
Lesson 12.2: Nonspecific Defenses
Lesson 12.3: Specific Defenses
Lesson 12.4: Disorders and Diseases
of the Immune System
Chapter 12: The Lymphatic and Immune Systems
Lesson 12.1
The Lymphatic System
The Lymphatic System
• organization of the lymphatic system
– lymph formation and flow
– lymph drainage
• lymphatic cells, tissues, and organs
– lymphatic cells
– lymphatic tissues
– lymphatic organs
Lymphatic vs.
• Both systems extend throughout almost
all parts of the body
• Both have a network of vessels that
vary in size from microscopic capillaries
to large vessels
• Unlike the cardiovascular system, the
lymphatic system is not a closed loop
Organization of the
Lymphatic System
Lymph Formation and Flow
• fluid leaks out of blood
vessel capillaries
– about 4 liters per
day (becomes
interstitial fluid)
• enters lymphatic
• fluid is now called
• returns to circulatory
system through
lymphatic trunks
Lymph Formation and Flow
• No pump in the
lymphatic system
• Muscular contractions
and movement of
organs compress the
vessels, moving lymph
along its route
• Contains lymphatic
Lymph Drainage
• Lymphatic trunks are named for their location
and the part of the body they drain.
– Left and right jugular trunks
– Left and right subclavian trunks
– Left and right bronchomediastinal trunk
– Intestinal trunk
– Left and right lumbar trunk
Intestinal and lumbar trunks converge at the
cisterna chyli, at diaphragm level in front of
the vertebrae to forming an enlarged
Lymph Drainage
• thoracic duct
– drains legs,
abdominopelvic area,
left arm, and left side of
the head and thorax
• right lymphatic duct
– drains right arm, right
side of head, and right
side of the thorax
Lymph Drainage
Lymphatic Cells
• Lymphocytes – distinctive cells of the
system (20%-30% of WBC)
– T lymphocytes (T cells) mature in thymus
– B lymphocytes (natural killer {NK} cells)mature
in bone marrow
• Macrophages – phagocytize foreign cells
and substances, as well as activate T cells
– begin as monocytes
– leave lymphatic tissue to enter surrounding
Lymphatic Tissues
• Loose connective tissue that contains many
• mucosa-associated lymphatic tissue (MALT)
– tonsils
• Pharyngeal (adnoids) – back of the nasopharynx
• Palatine – back of the mouth both left and right
• Lingual – either side at the base of the tongue
• lymphatic nodules – clusters formed by
lymphocytes and macrophages
Lymphatic Tissues
• Peyer’s patches – clusters of MALT in
the small intestines
• MALT also protects the appendix
Lymphatic Organs
• lymph nodes
– cleanse lymph trapping bacteria, viruses, and
other harmful substances
– store and produce T and B cells
Lymphatic Organs
• Spleen
– Largest lymphatic organ in the body
– Scans and cleans blood
– Activates the Immune Response
– Functional tissue
• White pulp – rich in lymphocytes which monitor blood
flowing for infectious cells and viruses
• Red pulp – macrophages destroy old worn out red
blood cells, platelets and pathogens
• Because of the thin capsule and soft interior, the spleen
may tear easily during a tramatic blow to the abdomen.
Lymphatic Organs
• Thymus
– Lies behind the sternum and in front of
heart, trachea and esophagus
– nursery for T cells
– Also and endocrine organ
– Largest at childhood and steadily shrinks
after puberty
Review and Assessment
Match these words with 1–4 below: right
lymphatic duct, thoracic duct, tonsil, spleen.
1. drains left side of head
2. scan and clean blood
3. drains right side of head
4. palatine
Chapter 12: The Lymphatic and Immune Systems
Lesson 12.2
Nonspecific Defenses
Physical Barriers
• Skin – keratinized stratified squamous
epithelium makes the skin a strong, flexible
and impermeable barrier to infection
• Hair – provide protection from chafing,
sunburn, and insects
• acidic secretions from sebaceous glands
and sweat glands – contain toxic chemicals
that hinder bacterial growth
• mucous membranes – line the respiratory,
digestive, urinary, and reproductive tracts
Cellular and Chemical
• Phagocytosis
– engulf foreign cells and debris
– Neutrophils: most common WBC that moves out
of the capillaries and into the surrounding
– macrophages (formerly monocytes):also leave
the blood stream and enter tissues
– Lysosomes: fuse with phagocytes to secrete
digestive enzymes and acid to help destroy the
– Exocytosis
Cellular and Chemical
• natural killer cells: lymphocytes
– Attracted to virus infected cells and cancer
– release perforins (proteins that destroy
foreign cells) to perforate cells
Cellular and Chemical
• complement system – set of 11 proteins;
complements, or balances out the effect
of antibodies
– classical pathway: recognizes antibodies
bound to a target and activates the
– alternative pathway: recognizes foreign
• Opsonins – proteins that make cells more
attractive to phagocytes
• Opsonization – process of making cells more
The Complement System
Cellular and Chemical
• interferons
released by virus infected cells
Interfere with viral replication
Help neighboring cells to resist infection
Alpha: produced by virus infected leukocytes
Beta: Produced by virus infected fibroblasts
gamma interferons: Produced by NK cells and T
cells that have been activated by detection of
foreign materials; help macrophages to resist viral
infection and attack virus-infected cells
Inflammatory Response
• promotes repair of damaged tissue
• histamines and prostaglandins released
• symptoms
– heat
– redness
– swelling
– pain
The Development of
• tissue damage occurs
• intracellular contents are released from
damaged cells into interstitial fluid
• mast cells release histamine and other
inflammatory chemicals
• blood vessels dilate, blood flow increases,
capillary permeability increases
• clot formation occurs
• scar tissue forms, replacement cells grow
• maintenance of higher than normal body
• activation of leukocytes and macrophages
causes release of pyrogens
• hypothalamus raises body temperature,
causing a fever
Review and Assessment
True or False?
1. Interferon is released by virus infected
2. Pyrogens cause fever.
3. Neutrophils are not phagocytes.
4. Mucous membranes are a physical barrier.
5. Perforins engulf cells.
Chapter 12: The Lymphatic and Immune Systems
Lesson 12.3
Specific Defenses
Specific Defenses – Immune
• called the specific immune system or
adaptive immune system
• Specific in its responses, recognizes new
challenges, adapts to those challenges, and
remembers what it has learned
– antigens
– immune system cells
– humoral immunity
– primary and secondary immune responses
– cellular immunity
• on the surface of cells
– proteins
– polysaccharides
– glycolipids
– nucleic acids
• determine “self” from “nonself” cells
Immune System Cells
• antigen-presenting cells (APCs)
– Macrophages, dendritic cells (immune cells in the skin
and lymphatic organs, and B cells
• lymphocytes
develop from stem cells in the red bone marrow
recognize only one antigen
circulate continuously or settle down in the lymph nodes
clonal selection: after a lymphocyte binds with its
antigen it begins to make exact copies of itself
– memory cells: clones that reside in lymphatic tissue,
ready to respond if the same antigen re-enters the body
Immune System Cells
• MHC proteins (major histocompatibility
complex glycoproteins) – presented on
surface of cells
– class I: found on all cells that contain nuclei
– class II: found only on the surfaces of APCs
Humoral Immunity
• called antibody-mediated immunity
B cell binds with an antigen
undergoes clonal selection
Presents the antigen to a helper T cell
T cell releases interleukins to stimulate an immune response
activates the B cell
• plasma cells
– Daughter cells from clonal selection
– make large quantities of antibodies in the rough endoplasmic
– antibodies recognize and bind to specific antigen
• antibodies
– also called immunoglobulins
– recognize, bind to, and mark antigens
– interfere with antigen function
Antibody Classes
Humoral Immunity
Primary and Secondary
Immune Responses
• primary immune response
– when first exposed
– neither fast nor widespread
• secondary immune response
– second or subsequent invasion
– memory cells respond to invader
Primary and Secondary
Immune Responses
Primary and Secondary
Immune Responses
• active immunity
– antibody-mediated immunity from invasion
• passive immunity
– antibody-mediated immunity from
antibodies received from an outside source
• vaccination
• breast feeding
Cellular Immunity
• facilitated or assisted by T cells
• directed at cells (bacterial infected, viral
infected, cancerous or precancerous cells)
• fully activated cytotoxic T cells divide
repeatedly, producing
– active cytotoxic T cells: seek and destroy
– memory cytotoxic T cells: prevents the
cellular response from being too strong or
too long
– suppressor T cells: same as memory cT
Cellular Immunity
• Ways in which the cytotoxic T cells kill
their targets
– stimulate intracellular pathways that lead to
apaptosis (programmed cell destruction)
– releasing perforins that insert themselves
into the target cell membrane and forming
a large opening, or perforation, in the cell
Cellular Immunity
Review and Assessment
Fill in the blanks with: antibodies, antigen,
memory cells, or vaccination.
1. A(n) _______________ is passive
2. _______________ are also called
3. Lymphocytes recognize only one
4. _______________ are part of the
secondary immune response.
Chapter 12: The Lymphatic and Immune Systems
Lesson 12.4
Disorders and Diseases
of the Immune System
Disorders and Diseases of
the Immune System
cancer and lymph nodes
autoimmune disorders
Cancer and Lymph Nodes
• rapid, unregulated cell growth
• metastasis
– cancerous cells move within body
• cancerous cells may lodge in lymph nodes
• biopsy and possible removal of lymph nodes
• risk to lymphatic system with the removal of
– disrupts lymphatic drainage and fluid build-up in
the interstitial fluid (lymphedema)
• 55% of Americans have an allergy to one
or more substances in the environment
• inappropriately strong response to a
harmless environmental antigen
• exposure to allergen causes mast cells to
release histamine
• histamine causes an inflammatory
response to the allergen
– runny nose, itchy eyes, anaphylaxis
• Anaphylaxis – pulmonary obstruction
due to inflammation and swelling of the
airways and low blood pressure due to
leakage of blood plasma into the
interstitial space
– Treated with an injection of epinepherine
and antihistamines
• Immunotherapy – allergy shots
Autoimmune Disorders
• immune system attacks own body
• cause unclear
• More than 80 different types have been
• examples
– rheumatoid arthritis: attacks the synovial membrane that
lines the joint cavity
– multiple sclerosis: attacks the myelin sheath that
surrounds the nerve cells
– type I diabetes: attacks the alpha and beta cells of the
• HIV (human immunodeficiency virus)
– infects and kills helper T cells
• AIDS (aquired immune deficiency
• Transmitted sexually, through sharing
needles, mother to child during pregnancy
or breastfeeding
– helper T cell count falls below 200/mm3
– immune system seriously weakened
– patient is susceptible to opportunistic infection
Review and Assessment
Match these words with 1–4 below:
metastasis, autoimmune disorder, HIV,
1. rapid, unregulated cell growth
2. cancerous cells move within the body
3. rheumatoid arthritis
4. infects and kills T cells