Download Unit 5.1 Review (2)

Unit 5 Infectious
Disease
Lesson 5.1 Infection
How are infectious diseases spread through a
population?

Bacteria and Viruses:





Fungus:


Spread by eating contaminated food or by vectors, like
mosquitoes and malaria
Helminthes:


Grow in warm/damp areas and can spread through spores
in the air, skin to skin contact, or sharing unwashed
clothes
Protozoa:


Most common infectious agents
Bacteria are prokaryotic organisms that can survive on
their own
Virus are not cellular and need a host to reproduce
Spread from contact with a contaminated person or thing
and through the air
Parasitic worms that are transmitted through under
cooked meats and eating fecal matter
Prions:

Mutated proteins that can happen randomly or by infected
human tissue
What is aseptic technique?
 These are techniques used to maintain
a sterile environment when working
with bacteria.
 Important to reduce spread of bacteria
and contamination
 Aseptic techniques include
 Wearing goggles, gloves, and aprons/lab
coats
 Using Bleach solution to clear your area
before and after use
 Keep the petri dish closed as much as
possible
 Use a flame to sterilize slides and loops
before use
 Wash hands and forearms
How can an unknown sample of bacteria be
identified?
 Colony Morphology
 Grow bacteria on Petri Dishes in
isolated colonies
 Analyze the specific characteristics
of colony growth to help determine
bacteria species
 Gram Staining
 Stain bacteria first with grams
stain and then safranin.
 Gram + will stain purple and Gram
– will stain pink
 Chemical Tests
 A variety of chemical tests can be
used to help identify bacteria since
each species reacts differently to
certain tests.
How can an unknown sample of bacteria be
identified?
 Gram Staining Continued
 Gram + have thick peptidoglycan wall
that absorbs purple stain
 Gram – have thin peptidoglycan wall
with an outer lipid membrane. The lipid
membrane washes off and then the cell
wall is stained pink
 Bacteria shape
 Gram staining allows us to see the
shape on the individual bacteria
 Coccus – Circle
 Bacilli – Rods
 Spirilla - Spiral
How does the immune system function to
protect the human body from foreign
invaders?
Nonspecific Defense
 Defense mechanisms against
all types of foreign invaders
 They do not remember or
focus on a specific type of
invader
 First Line
 Skin – protective layer
against foreign objects
 Mucus – Lines lungs and other
inner surfaces that traps and
helps expel foreign objects
 Nose Hair – Filters air and
traps foreign particles
How does the immune system function to
protect the human body from foreign
invaders?
Nonspecific Defense
 Second Line
 Inflammation – Blood
rushes to the area bringing
phagocytes and other
white blood cells to the
area. Also helps to retain
the infection in one area
 Phagocytes – have
receptors that seek out
pathogens (bad foreign
invaders) and once bound
to it the phagocyte eats
the pathogen.
 Phagocytes can also lead
into specific defense by
presenting the antigen
How does the immune system function to
protect the human body from foreign
invaders?
Specific Defense
 Defense against
specific invaders
through the use of
antigens and
antibodies
 This comes into play
after the invader gets
past the nonspecific
defense
 Two main cells are T-
cells and B-cells
How does the immune system function to
protect the human body from foreign
invaders?
Specific Defense
 Antigens are proteins
on the pathogens that
tells human cells what
they are.
 The phagocyte
presents the antigen to
helper T-cells that will
produce proteins to
activate B-cells
How does the immune system
function to protect the human
body from foreign invaders?
Specific Defense

B-cells are activated by T-cells and also
connects to pathogen antigens

B-cells produce plasma cells that make
antibodies specific to the antigen.

The antibodies attach to the antigen and
mark it for phagocytes to destroy.

B-cells also produce memory cells that
will “remember” same antigen so if the
pathogen invades again the immune
response will be faster