Chapter 35: Immune System &
Disease
Ms. Carballosa
Biology
Heart
• In groups label the parts of the heart:
– Right and left atrium
– Tricuspid valve
– Right and Left Ventricle
– Septum
– Mitral Valve
Pathogens
35.1 Infectious Disease
• Pasteur & Koch came up with
the germ theory of disease:
infectious diseases occur when
microorganisms cause
physiological changes that
disrupt normal body function
– Can be caused by viruses,
bacteria, fungi, protists and
parasites
– Except for parasites, all others
known as pathogens
35.1 Infectious Disease
• Koch’s Postulates:
– 1. Pathogen must always be
found in sick body but not
healthy body
– 2. Pathogen can be isolated &
grown in lab
– 3. If pathogen infects healthy
host, should produce sickness
– 4. Pathogen can be isolated from
new host & looks identical
35.1 Infectious Disease
• What’s the different between a symbiont
and pathogen?
– Symbionts are either harmless or beneficial
– Pathogens destroy host cells, release
poisons, block blood flow, and take up hosts
nutrients
35.1 Infectious Disease
• Diseases spread through coughing,
sneezing, physical contact, exchange of
body fluids, contaminated
water/food/animals
35.1 Infectious Disease
• Natural selection favors pathogens with
adaptations that help them spread from
host to host
– Coughing, sneezing, body-to-body contact,
sexual activity, drug usage, poor sanitation
– Best way to avoid infection is to constantly
wash your hands!
35.1 Infectious Disease
• Those pathogens that thrive in both
human and animal hosts are known as
zoonosis
– West Nile virus, Mad cow disease, Lyme
disease, Ebola
– Carriers of the disease who don’t get sick
are known as vectors
Let’s Practice!
• Worksheet 35.1
• Answer using complete sentences when
necessary.
35.2Nonspecific Defenses
• Include skin, tears and other secretions,
inflammatory response, interferon's and
fever
– First line of defense: skin, which is the most
widespread defense
35.2Nonspecific Defenses
• Pathogens can enter through the mouth,
nose or eyes which are protected by
saliva, mucus and tears
– Contains lysozyme which breaks down
bacterial cell walls
– Stomach secretions (acid) also protect
35.2Nonspecific Defenses
• Second line of defense includes
inflammatory response, fever, and
Interferons (IFNs) are proteins made and
released by host cells in response to the
presence of pathogens such as viruses,
bacteria, parasites or tumor cells.
35.2Nonspecific Defenses
• Inflammatory response causes areas to
become red and painful because of
histamines (release by mast cells to
increase flow of blood and fluids to the
area)
– White blood cells (phagocytes) will then
engulf and destroy bacteria
35.2Nonspecific Defenses
• Interferon's inhibit synthesis of viral
proteins
– Aka “interfere” with viral growth, slowing
down the production of new viruses
35.2Nonspecific Defenses
• Fever increases body temperature to
slow down or stop the growth of some
pathogens
– Sometimes also speeds up several parts of
the immune response
35.2 Specific Defenses
• Specific defenses distinguish between
“self” and “other” and inactivate / kill
any foreign substance or cell that enters
the body
– Nonspecific = general threat
– Specific = particular pathogen
35.2 Specific Defenses
• Recognizes specific chemical markers on
own cells – own secret password
– If the marker is not recognized, will attack
and remember it for later as “non-self” so
that it can kill it quickly if it enters the body
again: immune response
35.2 Specific Defenses
• Antigens are any foreign substances that
can stimulate an immune response
– Found on the outer surface (the “flag”)
– Immune system responds by increasing # of
cells to attack or produce proteins called
antibodies
35.2 Specific Defenses
• Antibodies tag antigens for destruction
by immune cells (the “alert!!”)
• The shape of each antibody allows it to
bind to only one antigen – very specific
35.2 Specific Defenses
• Main working cells of the immune system
are
– B lymphocyte cells: grow and mature in red
bone marrow; have antibodies on them;
attack in body fluids
– T lymphocyte cells: grow in red bone
marrow but mature in thymus; have to be
presented with antigen to attack
Worksheet 35.2
• Due At 2:05 PM
• STAY ON TASK
• Start on your homework if done with
classwork early.
35.3 Fighting Infectious Disease
• Vaccination: injecting a weakened form
of a pathogen, or of a similar but less
dangerous pathogen, to produce
immunity
– Jenner
35.3 Fighting Infectious Disease
• Vaccination stimulates the immune
system with an antigen. The immune
system produces memory B cells and T
cells that quicken and strengthen the
body’s response to repeated infection
35.3 Fighting Infectious Disease
• 2 types of immunity:
– Active: natural / deliberate exposure to
antigen
– Passive: antibodies are produced by other
individual or animal and passed through
pregnancy, breast milk, or injection (only
gives TEMPORARY immunity)
35.3 Fighting Infectious Disease
• 1900 – 30% deaths related to infectious
diseases
• 2005 - <5% deaths “ “
• How? Public health has prevented disease
by monitoring & regulating food and water,
providing vaccinations, and promoting
healthy behaviors
35.3 Fighting Infectious Disease
• Antibiotics can kill bacteria (but CANNOT
kill viruses) and some antiviral
medications can slow down viral activity
– Alexander Fleming – discovered first
antibiotic, penicillin
35.3 Fighting Infectious Disease
• We had mostly wiped out polio in the
U.S. & eliminated smallpox globally, but
now it’s back! Why?
– Human / animal interaction
– Misuse of medications leads to resistance by
pathogens