Immune System, diseases, pathogens

1. Chapter 17 The
Immune System
And Diseases
Anatomy and
Physiology

2. Lymphatic System
• Drain excess fluid.
• Transport dietary lipids.
• Carry out immune response.
• Consist of veins and capillaries similiar to
blood vessels.
• Contain lymph nodes to filter interstitial
fluid.

7. Lymphatic organs and tissues
• Thymus- two-lobed organ, located medial
to the lungs and superior to the heart,
contains T cells and macrophages, clear
dead and dying cells
• Lymph nodes- 600 bean shaped nodes, B
cells, T cells, macrophages, filter lymph
and circulate lymph through valves and
vessels

8. Lymphatic Organs and Tissues
• Spleen- between stomach and diaphragm,
lymphocytes and macrophages,
macrophages destroy pathogens, storage
of platelets, production of fetal blood cells,
B and T cells carry out immune responses

9. Lymphatic Organs and Tissues
• Lymphatic nodules are egg shaped,
tonsils
• 5 tonsils
• Pharyngeal, adenoid, two palatine tonsils
(obvious ones) 2 lingual tonsils at the base
of the tongue.

11. Barrier Defenses-non-specific
• External barriers
prevent pathogens
from entering the
body:
• Skin
• Mucous membranes
• Saliva
• Tears
• Cilia
• Hair
• Sweat
• oil

12. Internal Defenses
• Interferon- protein
that interferes with
virus replication
• Complement system-
proteins that enhance
other immune
responses, normally
inactive
• Natural killer cells-
kills microbes and
tumors
• Phagocytes- ingest
microbes
• Macrophages-
developed from
monocytes, eat
microbes

14. Inflammation and Fever Responses
• Helps prevent the spread of microbes.
• Allows more blood to flow to the injury site.
• Helps remove toxins.
• Carries immune cells to the site faster
• Fever is caused by interleukins.
• Elevated body temperature increases the
effects of interferon, and speeds up bodily
reactions and repair.

15. Vocabulary
Cards
Inflammation
Interferon
Macrophage
Natural killer cells
Phagocyte
Non-specific immune response

16. Lymphocytes-Specific response
• B and T cells.
• Contain antigen receptors.
• Cell-mediated response- directly attack
invaders
• Antibody mediated response- release
antibodies against the microbe.

17. Antigens and Antibodies
• An antigen causes the body to produce
antibodies.
• Specific T cells will react to certain
proteins and toxins.
• MHC molecules (major histocompatibility
complex)-unique proteins that identify you
to help T cells recognize foreign invaders.
• Major roadblock to organ transplantation.

18. Antigens and Antibodies
• Antigens induce plasma cells to secrete
proteins called antibodies against them.
• The antibody fits against the antigen on
the surface of the microbe.
• Antibodies belong to a group of proteins
called immunoglobulins.
• Each has a distinct function and chemical
structure.

21. T Cells
• The presence of antigens inform
the T cells to begin attack but it
only becomes active once the
foreign antigen binds with it.
• APC or antigen presenting cell
must ingest a foreign antigen,
process it and present it to a T cell
for recognition. Dendritic cells,
helper T cells and macrophages
can do this.

23. T Cells
• T cells also need a second stimulator
to prevent false alarms. Interleukin
does this.
• Once activated, the T cell clones
itself into an army.
• Causes swollen lymph nodes.

24. 3 types of T Cells
• Helper T cells release interleukins and
also offer antigens.
• Cytotoxic T cells kill cells that are infected
with precision using enzymes.
• Memory T cells remain in the body to
prevent reinfection.

25. B cells
• Usually stay in the lymph nodes.
• Secrete antibodies once activated
by T cells and interleukins.
• Can receive unprocessed
antigens but respond faster to
processed ones
• Can become memory cells to
respond to the same antigen in
the future

26. Immunity
• Naturally Acquired Active- get sick,
memory cells remember and prevent
future attacks
• Naturally Acquired Passive- Antibody
transfer from mother to fetus across
placenta, or breastfeeding

27. Immunity
• Artificially Acquired Active- vaccinations
cause an immune response without
causing sickness, usually involves
injecting antigens or weakened viruses
• Artificially Acquired Passive- injection of
immunoglobulins (antibodies)

29. Vocabulary
Cards
B cell
T cell
Antigen
Antibody
Memory cell
Vaccine
MHC
APC (antigen
processing cell)
40
total
cards
B cell
T cell
Antigen
Antibody
Memory cell
MHC
APC
Specific immune response

30. Pathogenic Diseases of
the Human Body

31. Virus structure
• The structure of a virus is well suited to its
function; entering a host cell and
reproducing.
• A virus is composed of a relatively short
piece of nucleic acid DNA or RNA surround
by a protein coat.
• Since a virus doesn’t have its own cellular
machinery, it must use the host cell’s
machinery to make copies of itself.

34. T-4 bacteriophage

35. Virus replication
• Viruses that infect bacteria called
bacteriophages reproduce in 2 ways.
This will be used as our example.
• In the lytic cycle, the phage attaches
to the host cell and injects its DNA.
• The host cell’s enzymes and
synthesis machinery make copies of
the viral DNA and the viral proteins.

36. • The viral proteins and nucleic acids
then assemble themselves inside the
host cell making copies of the original
infecting virus.
• The host cell then bursts open and
these offspring infect new host cells
and repeat the cycle.

37. Virus replication
• In the lysogenic cycle, a virus injects it genes into
the host.
• The viral DNA then adds itself directly to the host
cell’s DNA.
• Each time the host cell reproduces, the viral DNA
is copied along with the host’s DNA.
• Occasionally, the viral DNA separates from the
host DNA and starts a lytic cycle.
• New phages are made and released.

38. Lytic and lysogenic cycles

40. Using Phages to Help
• Although bacteriophages are viruses, since
they don’t attack humans they are useful to
help humans combat bacterial infections.
• Many antibiotics are no longer useful
because bacterial develop resistance to
them.
• Developing new antibiotics to deal with
these “superbugs” is costly and doesn’t
always work.

41. • Attack good and
bad bacteria
• Affect the whole
body and “wear off”
• Multiple side effects
• Bacteria develop
resistance
• Time consuming to
create new
antibiotics
Bacteriophages Antibiotics
• Very specific and only
attack intended
bacteria
• Site specific, where
they are needed
• No side effects
reported
• Not many resistant
bacteria
• Easy to find new
phages

42. Viruses and disease
• Some viruses use RNA as their genetic material.
• Some viruses that use RNA are flu, the common
cold, measles, mumps, HIV, and polio.
• DNA viruses are herpes and hepatitis.
• The way viruses cause disease is radically different
from bacterial infections.
• A virus uses the equipment of a host cell to
reproduce therefore approaches to control and
cure infection are different from bacterial infection
controls.

43. Viral Diseases/illnesses
• Common cold
(rhinovirus)
• AIDS (HIV)
• Measles
• Mumps
• Herpes (Many forms
including chicken pox)
• HPV (Human
Papilloma Virus)
• Hepatitis (A,B,C)
• Mono
• Norovirus
• Bird flu
• Ebola and Marburg
• Smallpox
• Dengue Fever
• Yellow Fever
• Polio
• Lassa Fever
• Meningitis (some
forms)
• West Nile
• Rotavirus

44. HIV: A retrovirus
• HIV is a virus that causes AIDS.
• It is particularly dangerous because it attacks our
own immune system, the very thing meant to
protect us.
• HIV is different because it is called a retrovirus.
• A retrovirus synthesizes DNA from RNA which is
the opposite of what normally happens.
• An HIV virus carries 2 copies of RNA instead of
DNA.
• The RNA then uses an enzyme called reverse
transcriptase to form DNA from the RNA.

45. • The DNA integrates into the host DNA and
takes over.
• The viral DNA can be dormant for years but
occasionally it is transcribed into RNA again
and new viruses are made.
• While the virus is inactive, the disease
symptoms are not evidence.
• Only when the virus reproduces and
destroys host cells does an individual get
AIDS.

46. HIV Life cycle

47. HIV

48. Where in the world?

49. History of HIV
• The first known case of HIV was from a blood
sample taken from a man in 1959 from the
Democratic Republic of the Congo.
• The most common form of the virus is called HIV-
1.
• This variety appears to have originated in late
1940’s and early 1950’s.
• We know the virus existed in the United States
from the mid 1970’s based on reports of strange
and rare illnesses that normally don’t affect people
with healthy immune systems.

50. History of HIV
• Public health officials first used the
term AIDS in 1982 but it wasn’t until a
year later in 1983 that it was
discovered that HIV caused AIDS.
• It was first noticed in groups of
homosexual men which led to the
myth that it was a “gay man’s
disease.”

51. Where did HIV come from?
• In 1999, a team of researchers discovered the
original strain of HIV-1, the most common type
affecting the developed world.
• It was found in a subspecies of chimpanzee native
to west equatorial Africa.
• It was common practice for people the hunt these
animals for food and contamination of the people
with chimpanzee blood is the mostly likely
transmission.

52. Where did HIV come from?
• HIV-2 is a less prevalent strain of the virus more
common in west Africa.
• This strain originates from a population of primates
called sooty mangabeys.
• These primates are found only in west Africa.
• The two strains HIV-1 and HIV-2 have multiple
types of each kind that have mutated over the
years.
• All types and strains of HIV descended from SIV
which is a similar virus found in several primate
species.

54. Defense against viral
diseases
• The immune system is critical to fighting infections
and provides the basis for a major medical weapon
for preventing certain viral and bacterial infections
from occurring.
• This weapon is called the vaccine.
• Vaccines are deactivated varieties or small pieces
of pathogens that stimulate the immune system to
defend against the actual pathogen.

55. The first vaccine
• The first vaccine was made against the virus that causes
smallpox, an often fatal disease.
• Edward Jenner, a physician, discovered that milk maids who
had been exposed to cowpox, a mild disease, were resistant
to smallpox.
• The two diseases were so similar that the immune system
couldn’t tell them apart.
• Jenner injected people with cowpox which then causes
resistance to smallpox.
• Currently, smallpox has been eradicated.
• NOTE: Smallpox the disease is gone but not the virus. It’s
“on ice” in a lab somewhere.

56. Vocabulary
Cards
Lytic cycle
Lysogenic
cycle
Retrovirus
vaccine

57. Bacteria have three shapes.
• Cocci- spherical shapes that are sometimes
formed in chains, clumps or clusters, Strep throat
and pneumonia are this type
• Bacilli- rod shaped such as E. coli that live in your
intestines.
• Spirochete- curved or spiral shape, this type
causes Lyme disease

58. Purple or pink?
• Bacteria are stained with two dyes, purple and pink
to determine which antibiotics will work for each
kind.
• Gram positive retain the purple dye in their cell
walls.
• Gram negative do not retain the purple dye but
retain the pink dye instead.
• Some antibiotics will only work for one kind.
Gram
positive
Gram
negative

59. Bacterial Motility
• Flagella- a long thin filament anchored
to the plasma membrane , may be one
or many anchored all over the bacteria
• Pili- shorter and thinner filaments that
help bacteria stick together in clumps
• NOTE: The flagella and pili are
different than the kinds you will
observe in eukaryotes.

60. Most bacteria can copy
themselves every 20 minutes!
• Binary fission-DNA duplicates and moves to
opposite ends of the cell, then the cell divides
• This method allows quick reproduction and is much
simple than mitosis.
• Allows for quick passing of mutant genes. (More on
this later!)

61. Genetic Variation
• Since bacteria do not undergo meiosis, they do not
exchange genetic information, however, they can
do other things.
• Transformation occurs when some bacteria take up
pieces of DNA from the environment and
incorporate it into its genetic material.
• In conjugation, two bacterial cells temporarily join
and directly transfer genetic material between
them.

62. • Plasmids are separate rings of DNA apart from the
cell’s main chromosomes.
• Transduction is when viruses that infect bacteria
carry their genes to another.
• They are called bacteriophages.
• Some bacteria can survive extended periods of
very hostile conditions by forming specialized
resting cells called endospores.

63. Bacterial Reproduction

64. How Bacteria Cause Illness
• Bacteria and other microorganisms that cause disease
are called pathogens.
• Most pathogenic bacteria cause disease by producing
poisons.
• Some bacteria produce proteins that cause illness while
others produce cell wall secretion that lead to fever,
aches and shock.

65. Defense Against Bacterial
Diseases
• Since the discovery of bacteria, many
diseases have declined.
• This is due to better health and sanitation
procedures.
• Much of the decline is due to antibiotics.

66. The first Antibiotic
• In 1928, professor Alexander Fleming was
returning from a holiday vacation and noticed he
forgot to clean some of his petri dishes in the sink.
• He noticed all the dishes were growing bacteria
except one dish that had mold on it was clear.
• The mold inhibited the bacterial growth.
• It took many years and other scientists before the
mold Penicillin was purified and available for use.
• It became widely used in the 1940’s just in time for
war.

67. Antibiotic Resistance
• Antibiotics have been widely used for 70 years.
• Since their introduction, antibiotics are being used
everywhere including our food.
• Antibiotics are also overprescribed even when they cannot
help.
• Because of this overuse, bacteria are becoming increasingly
resistant to some antibiotics.
• These “superbugs” are extremely dangerous because they
can kill the patient but also because they can pass on their
resistance to other types of bacteria.

70. Diseases/Illnesses Caused
By Bacteria• MRSA
• TSS (Toxic Shock
Syndrome)
• Pneumonia
• Gonorrhea
• Meningitis
• Salmonella
• E. Coli
• Cholera
• Bubonic plague
• Botulism
• Peptic ulcer
• Anthrax
• Typhoid
• Staph
• Strep throat
• Sepsis
• Chlamyadia
• Tuberculosis
• Syphilis
• Leprosy
• Diphtheria
• Tetanus
• Rocky mountain spotted
fever
• Lyme disease

71. Vocabular
y Cards
Cocci
Bacilli
Spirochete
Gram negative
Gram positive
Flagella
Pili
Binary fission
Plasmid
Antibiotic resistance
conjugation

72. Diseases caused
by Fungi, Prions
and protozoans

73. When it’s not a virus or a bacteria
• Prions are proteins that are similar to viruses in
that they aren’t alive and can replicate themselves.
• Prions are misfolded proteins that pass on their
mutated folding to other proteins in the body.

74. Prion Diseases
• Human:
• Creutzfeldt-Jakob
Disease (CJD)
• Variant Creutzfeldt-
Jakob Disease (vCJD)
• Gerstmann-Straussler-
Scheinker Syndrome
• Fatal Familial
Insomnia
• Kuru
• Other Animal:
• Bovine Spongiform
Encephalopathy (BSE)
• Chronic Wasting Disease
(CWD)
• Scrapie
• Transmissible mink
encephalopathy
• Feline spongiform
encephalopathy
• Ungulate spongiform
encephalopathy

77. Fungal Infections
• Fungal spores are always present in the air so
fungal infections commonly start on the skin or the
lungs.
• Fungus like mushrooms make spores and have
roots.
• Many are toxic and release poisons, like toxic black
mold.
• Common infections: ringworm, athlete’s foot, and
other general skin infections that look like rashes

78. Parasitic Infections
• There are three categories of parasitic infections
that cause disease in humans.
• Protozoa, helminthes, and ectoparasites.
• Some are unicellular and some are multicellular.
• They often have complicated life cycles involving
more than one host.

79. Protozoa
Protozoa are microscopic, one-celled organisms that can be free-living or
parasitic in nature. They are able to multiply in humans, which contributes to
their survival and also permits serious infections to develop from just a single
organism. Transmission of protozoa that live in a human's intestine to another
human typically occurs through a fecal-oral route (for example, contaminated
food or water or person-to-person contact). Protozoa that live in the blood or
tissue of humans are transmitted to other humans by an arthropod vector (for
example, through the bite of a mosquito or sand fly).
The protozoa that are infectious to humans can be classified into four groups
based on their mode of movement:
•Sarcodina – the amoeba, e.g., Entamoeba
•Mastigophora – the flagellates, e.g., Giardia, Leishmania
•Ciliophora – the ciliates, e.g., Balantidium
•Sporozoa – organisms whose adult stage is not motile
e.g., Plasmodium, Cryptosporidium

81. Helminthes
Helminths are large, multicellular organisms that are generally visible to the naked eye in
their adult stages. Like protozoa, helminths can be either free-living or parasitic in
nature. In their adult form, helminths cannot multiply in humans. There are three main
groups of helminths (derived from the Greek word for worms) that are human parasites:
•Flatworms (platyhelminths) – these include the trematodes (flukes) and cestodes
(tapeworms).
•Thorny-headed worms (acanthocephalins) – the adult forms of these worms reside in
the gastrointestinal tract. The acanthocephala are thought to be intermediate between
the cestodes and nematodes.
•Roundworms (nematodes) – the adult forms of these worms can reside in the
gastrointestinal tract, blood, lymphatic system or subcutaneous tissues. Alternatively, the
immature (larval) states can cause disease through their infection of various body
tissues. Some consider the helminths to also include the segmented worms (annelids)—
the only ones important medically are the leeches. Of note, these organisms are not
typically considered parasites.

83. Ectoparasites
Although the term ectoparasites can broadly include blood-
sucking arthropods such as mosquitoes (because they are
dependent on a blood meal from a human host for their
survival), this term is generally used more narrowly to refer to
organisms such as ticks, fleas, lice, and mites that attach or
burrow into the skin and remain there for relatively long
periods of time (e.g., weeks to months). Arthropods are
important in causing diseases in their own right, but are even
more important as vectors, or transmitters, of many different
pathogens that in turn cause tremendous morbidity and
mortality from the diseases they cause.

85. Malaria
• Malaria is a life-threatening disease caused by
parasites that are transmitted to people through the
bites of infected female Anopheles mosquitoes.
• In 2015, 95 countries and territories had ongoing
malaria transmission,
• About 3.2 billion people – almost half of the world’s
population – are at risk of malaria.
• Malaria is preventable and curable, and increased
efforts are dramatically reducing the malaria
burden in many places.

86. • Between 2000 and 2015, malaria incidence among
populations at risk (the rate of new cases) fell by
37% globally. In that same period, malaria death
rates among populations at risk fell by 60% globally
among all age groups, and by 65% among children
under 5.
• Sub-Saharan Africa carries a disproportionately
high share of the global malaria burden. In 2015,
the region was home to 88% of malaria cases and
90% of malaria deaths.

87. • Malaria is caused by Plasmodium parasites. The
parasites are spread to people through the bites of
infected female Anopheles mosquitoes, called
"malaria vectors." There are 5 parasite species that
cause malaria in humans, and 2 of these species
– P. falciparum and P. vivax – pose the greatest
threat.
• P. falciparum is the most prevalent malaria parasite
on the African continent. It is responsible for most
malaria-related deaths globally.
• P. vivax is the dominant malaria parasite in most
countries outside of sub-Saharan Africa.

90. How would you eliminate
Malaria?

95. Vocabulary Cards
• Diseases caused by fungi
• Diseases caused by protozoans
• Diseases caused by multi-cellular
parasites or carried by them
• Diseases caused by prions
• Facts on malaria
• Cards should have some general
information for test usage. You will be
asked about some specifics about
well known diseases.