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Lymphatic and
Immune System
Your Body’s Defense
Mechanism
12
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.
Cardiovascular
• 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
capillaries
• fluid is now called
lymph
• 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
valves
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
chamber
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
tissue
Lymphatic Tissues
• Loose connective tissue that contains many
lymphocytes
• 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
Defenses
• Phagocytosis
https://www.youtube.com/watch?v=rPLfnZHcICA
– engulf foreign cells and debris
– Neutrophils: most common WBC that moves out
of the capillaries and into the surrounding
tissues
– 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
target
– Exocytosis
Cellular and Chemical
Defenses
• natural killer cells: lymphocytes
– Attracted to virus infected cells and cancer
cells
– release perforins (proteins that destroy
foreign cells) to perforate cells
– https://www.youtube.com/watch?v=HNP1E
AYLhOs
Cellular and Chemical
Defenses
• 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
compliment-protein
– alternative pathway: recognizes foreign
materials
• Opsonins – proteins that make cells more
attractive to phagocytes
• Opsonization – process of making cells more
attractive
The Complement System
Cellular and Chemical
Defenses
• 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
Inflammation
• 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
Fever
• maintenance of higher than normal body
temperature
• 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
cells.
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
System
• 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
Antigens
• 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
reticulum
– 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
• https://www.youtube.com/watch?v=dTb
0iEUS1oA
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
cells
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
immunity.
2. _______________ are also called
immunoglobulins.
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
allergies
autoimmune disorders
HIV and AIDS
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
nodes
– disrupts lymphatic drainage and fluid build-up in
the interstitial fluid (lymphedema)
Allergies
• 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
Allergies
• 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
Allergies
Autoimmune Disorders
• immune system attacks own body
• cause unclear
• More than 80 different types have been
identified
• 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
pancreas
HIV and AIDS
• HIV (human immunodeficiency virus)
– infects and kills helper T cells
• AIDS (aquired immune deficiency
syndrome)
• 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,
cancer.
1. rapid, unregulated cell growth
2. cancerous cells move within the body
3. rheumatoid arthritis
4. infects and kills T cells