Lymphatic System and Immunity

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Chapter 7

• Lymphatic System and Immunity

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Points to Ponder

• What is the connection between microbes and
  humans?
• What are the parts of the lymphatic system and
  what are their functions?
• What are the first and second line of defense in
  nonspecific immunity?
• What is cell-mediated and antibody- mediated
  immunity in the third line of defense?
• What are the different types of B cells in these
  processes?
• What is active and passive immunity? Be able to
  describe how they are different and give examples
  of each.
• Understand allergic reactions, tissue rejection,
  and immune system disorders as problems that the
  immune system faces.

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What about the interaction between microbes and
humans?
7.1 Microbes, pathogens and you

• Microbes are very abundant in the environment and
  as well as in and on our bodies
• We use microbes to make many foods and we even
  use them to make drugs
• Microbes are important as decomposers to recycle
  nutrients
• Some microbes cause disease in humans we call
  these pathogens

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What are microbes?
7.1 Microbes, pathogens and you

• Microbes are microscopic organisms and particles
  that include
• Bacteria
• Viruses
• Prions
• Others (fungi, multicellular parasites,
  single-celled protistans)

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How do the sizes of our cells, bacteria and
viruses compare?
7.1 Microbes, pathogens and you
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What are bacteria?
7.1 Microbes, pathogens and you

• Prokaryotic cells
• Single-celled
• Almost all have a cell wall
• Have DNA in a single chromosome
• Have ribosomes
• Some have accessory rings of DNA called plasmids

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What are specific structures and shapes of
bacteria?
7.1 Microbes, pathogens and you
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Bacterial Infections

• Chlamydia.
• Leading sexually transmitted disease in the US.
• Usually asymptomatic to mild burning sensation on
  urination.
• Risk of spreading from the cervix to the oviducts
  and into pelvic inflammatory disease.
• Usually treated with a single dose of antibiotics.

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Chlamydia Eye Infection
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Bacterial Infections

• Gonorrhea.
• Affected individuals often have a secondary
  infection with Chlamydia.
• Asymptomatic to pain on urination and milky
  urethral discharge within 3-5 days.
• Usually cured with antibiotics.
• If a pregnant woman has gonorrhea, she may give
  the infection to her baby as the baby passes
  through the birth canal during delivery. This can
  cause blindness, joint infection, or a
  life-threatening blood infection in the baby.

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Pelvic Inflammatory Disease

• In women, gonorrhea is a common cause of pelvic
  inflammatory disease (PID).
• When symptoms are present, they can be very
  severe and can include abdominal pain and fever.
• PID can lead to internal abscesses (pus-filled
  pockets that are hard to cure) and
  long-lasting, chronic pelvic pain.
• PID can damage the fallopian tubes enough to
  cause infertility or increase the risk of ectopic
  pregnancy.
• Ectopic pregnancy is a life-threatening condition
  in which a fertilized egg grows outside the
  uterus, usually in a fallopian tube.
• In men, gonorrhea can cause epididymitis, a
  painful condition of the testicles that can lead
  to infertility if left untreated.
• Gonorrhea can spread to the blood or joints. This
  condition can be life threatening.
• Some of these complications are also seen in
  Chlamydia

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Secondary Gonorrheal Infection
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Bacterial Infections

• Syphilis.
• Three stages.
• Primary stage - Hard chancre
• Secondary stage - Rash
• Tertiary stage - Weakened arterial walls
• Prompt and adequate treatment is critical for
  control
• Treatment is a form of penicillin

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Syphilis
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Bacterial Diseases

• Tuberculosis.
• Kills more people worldwide than any other
  infectious disease.
• Estimated one-third of worlds population is
  infected.
• Can be treated with antibiotics, but must be
  consistently taken for months or years.
• When the disease becomes active, 75 of the cases
  are pulmonary TB.
• Symptoms include chest pain, coughing up blood,
  and a productive, prolonged cough for more than
  three weeks.
• Systemic symptoms include fever, chills, night
  sweats, appetite loss, weight loss, pallor, and
  often a tendency to fatigue very easily

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Bacterial Diseases

• Food Poisoning.
• Can be caused by a variety of different bacteria
• Salmonella.
• Raw chicken
• Botulism
• Improperly canned food

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Tetanus

• Tetanus is a medical condition that is
  characterized by a prolonged contraction of
  skeletal muscle fibers.
• Spasms may occur frequently and last for several
  minutes. Spasms continue for 34 weeks and
  complete recovery may take months.

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What are viruses?
7.1 Microbes, pathogens and you

• Small, non-living obligate parasites
• Must reproduce inside of a host cell
• Acellular (not composed of cells)
• All viruses have an outer protein coat called a
  capsid and nucleic acid (RNA or DNA) inside
• Some viruses have an envelope
• Viruses are specific to which cell they will
  attach to and enter

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Viral Diseases

• Herpes.
• Herpes Simplex Virus Type 1
• Cold sores and fever blisters around the mouth
• Herpes Simplex Virus Type 2
• Herpes infection of the genitals
• Asymptomatic to tingling and itching prior to
  blistering
• May be reccurring due to stressors. Both type I
  and type II viruses hide in nerves until
  stimulated
• Presently no cure
• Varicella-zoster Virus. Also hides in nervous
  system
• Causes chicken pox vaccine is avaliable
• can later remerge as shingles

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Genital Herpes
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Chicken pox
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Viral Diseases

• Measles
• One of most contagious of all human diseases
• Spread through respiratory route as airborne
  particles
• Common Cold
• More than 200 different cold viruses
• Half are caused by rhinoviruses

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Smallpox

• Pus-filled bumps (pustules)
• Transmitted by respiratory route
• Easily transmitted and very deadly
• Infect many organs
• Eradicated

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Genital Warts

• Human papillomaviruses cause many forms of warts,
  including genital warts
• Commonly seen on the penis and near vaginal
  opening
• Associated with cervical cancer
• Presently no cure
• Effective treatment relies on various forms of
  wart removal
• Vaccine is now avaliable

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Prevalence of AIDS

• Pandemic disease.
• Transmitted by sexual contact with an infected
  person, needle-sharing, and transfusions of
  infected blood.
• Incidence in more-developed countries is modest,
  while incidence in less-developed countries is
  much higher.
• In sub-Saharan Africa, AIDS affects 9 of adult
  population between 15 and 49 years of age.

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Phases of an HIV Infection

• Category C AIDS.
• CD4 T-cell count is below 200 per mm3.
• Lymph nodes have degenerated and patient is
  extremely weak and thin.
• Develop opportunistic infection.
• Pneumonia.
• Tuberculosis.
• Encephalitis.
• Kaposis sarcoma.
• Invasive cervical cancer.

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Other Infectious Agents

• Fungi.
• Molds and yeasts.
• Tineas
• Ringworm
• Athletes foot
• Jock itch
• Candidiasis
• Yeast infections
• Histoplasmosis
• Primarily affects the lungs
• Respiratory disease-chest pains and cough
• Gets worse over years

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Protozoans

• Protozoans are generally single eukaryotic cells
  with a nucleus and organelles
• Malaria
• Most widespread and dangerous of protozoan
  diseases
• Caused by Plasmodium spp
• Toxoplasmosis
• Cat feces, soil, and contaminated meat
• Only serious problem in pregnant women and people
  with compromised immune systems.

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What are prions?
7.1 Microbes, pathogens and you

• Infectious protein particles
• Cause degenerative disease of the nervous system
• Normal proteins change their shape
• Mad Cow disease
• Creutzfeldt-Jakob Disease

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4 functions of the lymphatic system
7.2 The lymphatic system

• Lymphatic capillaries absorb excess tissue fluid
  and return it to the bloodstream
• Lymphatic capillaries (lacteals) in the small
  intestine absorb fats associated with proteins
• Works in the production, maintenance, and
  distribution of lymphocytes in the body
• Helps in defense against pathogens

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What are the components of the lymphatic system?
7.2 The lymphatic system
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Lymphatic vessels
7.2 The lymphatic system

• One-way valve system that carries fluid called
  lymph
• Made of capillaries, vessels, and ducts
• Function to return tissue fluid (includes water,
  solutes, and cell products) to the bloodstream
• The larger vessels are similar in structure to
  veins and even have valves

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Classifying lymphatic organs
7.2 The lymphatic system

• Primary
• Red bone marrow
• Thymus gland
• Secondary
• Lymph nodes and spleen

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Primary lymphatic organs
7.2 The lymphatic system

• Red bone marrow
• Site of blood cell production
• More bones in children have red marrow, and it
  decreases as we age
• Some white blood cells mature here
• Thymus gland
• Bilobed gland found in the thoracic cavity
  superior to the heart
• Largest in children and shrinks as we age
• Immature T lymphocytes move from the marrow to
  the thymus where they mature and 95 will stay

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Secondary lymphatic organs
7.2 The lymphatic system

• Lymph nodes
• Small, oval-shaped structures found along the
  lymphatic vessels filled B cells, T cells, and
  macrophages
• Common in the neck, armpit, and groin regions
• Spleen
• In the upper left region of the abdominal cavity
• Filled with white pulp containing lymphocytes,
  and red pulp is involved with filtering the blood

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What do the nonspecific defenses include?
7.3 Nonspecific Defenses

• First line of defense
• Barriers to entry physical and chemical
• Second line of defense
• Phagocytic white blood cells
• Inflammatory response
• Protective proteins complement and interferons

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The first line of defense
7.3 Nonspecific Defenses

• Physical barriers
• Skin
• Tears, saliva, and urine physically flush out
  microbes
• Mucous membranes line the respiratory, digestive,
  reproductive, and urinary tracts
• Resident bacteria/normal flora that inhabit the
  body use available nutrients and space thus
  preventing pathogens from taking up residence
• Chemical barriers
• Secretions of the oil glands
• Lysozyme found in saliva, tears, and sweat
• Acidic pH of the stomach and vagina

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The second line of defense Phagocytic white
blood cells
7.3 Nonspecific Defenses

• Includes neutrophils and macrophages
• Both leave circulation and move into tissue
• Cells that are important in the inflammatory
  response

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The second line of defense Inflammatory response
7.3 Nonspecific Defenses

• Four hallmark symptoms are redness, heat,
  swelling, and pain
• Histamine is released by mast cells causes the
  capillaries to dilate and become more permeable
  to phagocytic white blood cells
• Increased blood flow to an area increases the
  warmth that inhibits some pathogens
• Increased blood flow also brings more white blood
  cells to an injured area, with neutrophils being
  the first scouts to kill pathogens
• This response can be short-lived, but if the
  neutrophils cannot control the damage, cytokines
  (chemicals) will call in more white blood cells
  including macrophages

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Summary of the inflammatory response
7.3 Nonspecific Defenses
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What do the specific defenses include?
7.4 Specific Defenses

• Third line of defense
• Helps protect us against specific pathogens when
  nonspecific defenses fail
• Helps protect us against cancer
• Depends on the action of B and T cells (remember
  that these are lymphocytes)

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T- cells

• T cells begin the immune response
• Come in contact with foreign substance
• Become active
• Some T cells produce chemicals that stimulate
  more T cells and B cells
• Others become memory cells
• HIV infects T cells
• B cells once stimulated by T cells, they
• Become plasma cells that secrete antibodies
• Others become memory cells

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Summary of the types of B and T cells
7.4 Specific Defenses
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Immunity
7.5 Acquired immunity

• Is the ability to combat diseases and cancer
• Can be brought about naturally through an
  infection or artificially through medical
  intervention
• There are two types of immunity active and
  passive

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Active immunity
7.5 Acquired immunity

• The individuals body makes antibodies against a
  particular antigen
• This can happen through natural infection or
  through immunization involving vaccines
• Primary exposure is shorter-lived and slower to
  respond while a secondary exposure is a rapid,
  strong response
• This type of immunity is usually long-lasting
• It depends on memory B and T cells

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Examples of immunizations a type of active
immunity
7.5 Acquired immunity
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Passive immunity
7.5 Acquired immunity

• An individual is given prepared antibodies
  against a particular antigen
• This type of immunity is short-lived
• This can happen naturally as antibodies are
  passed from mother to fetus or artificially via
  an injection of antibodies

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How can the immune system react that maybe
harmful to the body?
7.6 Hypersensitivity reactions

• Allergies
• Tissue rejection
• Immune system disorders

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Disorders of the immune system
7.6 Hypersensitivity reactions

• Autoimmune diseases
• A disease in which cytotoxic T cells or
  antibodies attack the bodys own cells as if they
  were foreign
• Examples multiple sclerosis, lupus, myasthenia
  gravis, and rheumatoid arthritis
• Immunodeficiency disease
• A disease in which the immune system is
  compromised and thus unable to defend the body
  against disease
• Examples AIDS and SCID