Ch.22 Immune System

Question 0

Infectious agents

Answer 0

Or (pathogens) cause damage or death to a host organism

Question 1

Function of the immune system

Answer 1

Protection from infectious agents and harmful substances

Question 2

Prions

Answer 2

Structure:
an abnormal form of a normally harmless protein found in the brain

Features:
Upon entering a healthy organism, it induces existing, properly folded membrane proteins to convert into the disease-associated, prion form.

Diseases:several fatal diseases of nervous tissue

Question 3

Viruses

Answer 3

Structure:
Not cells. Composed of a nucleic acid within a cuspid (protein coat), some have a lipid envelope. Small

Features:
Obligate intracellular parasites (must enter cells to reproduce).
Destroy cells when newly formed viruses exit
.
Diseases:
common cold, chicken pox, HIV, warts

Question 4

Bacteria

Answer 4

Structure:
Unicellular prokaryotes

Features:
Living organisms that require nutrients to survive.
When invade other organisms–cause damage by
destroying tissues or toxin release

Diseases:
staph, infection, tuberculosis(TB), Lyme disease

Question 5

Protozoans

Answer 5

Structure:
unicellular eukaryotes without a cell wall

Features:
Intracellular and extracellular parasites in order to obtain nutrients

Diseases:
malaria, giardiasis (“beaver fever“)

Question 6

Fungi

Answer 6

Structure:
multicellular eukaryotes (yeasts are an exception) with a cell wall
.
Features:
Release digestive enzymes to perform extracellualar digestion ,thus, inducing inflammation (redness and swelling)

Diseases:
ringworm, “athlete’s foot”, yeast infection

Question 7

Parasites

Answer 7

Structure:
multicellular eukaryotes without a cell wall (=animals)

Features:
Reside in host from which they take nourishment
Diseases:
Ex. roundworm and tapeworm infections (helminthosis)

Question 8

RADaR System

Answer 8

protective system of immune system

• Recognize
• Attack
• Destroy &
• Remember

Question 9

Cytokine

Answer 9

• small soluble proteins released from 1 cell & bind specific receptor of target cell in order to:
• regulate & facilitate immune system
• serve as weapons destroying cells
• influence non-immune cells
  (ex: nervous system) Interleukins (IL), Interferons (IFN), Colony-stimulating factors (CSF)

Question 10

1st line of defense

Answer 10

(Non specific external)

Barriers:skin & mucosa

Question 11

Skin

Answer 11

a) Physical barrier
b) Releases antomicrobial substances: IgA, lysozyme (enzyme damaging bacterial walls)
, sebum,lactic acid, etc.
c) Hosts norma floura (nonpathogenic microorganisms

Question 12

Mucosal membrane

Answer 12

(membranes lining openings):

a) Produce mucin (when hydrated, forms mucus)
b) Releases antimicrobial substances: (ex. IgA, lysozyme, lactic acid, HCl)
c) Hosts normal flora (nonpathogenic microorganisms)

Question 13

2nd line of defense

Answer 13

(Non specific internal)

2a: cells (phagocytes, NK, eosinophils)
2b: chemicals (interferon, complement)
2c: physiologic (inflammation and fever)

Question 14

If a pathogen enters our body, how does our body distinguish an invader from body’s own cells?

Answer 14

All cells have membrane surface molecules: carbohydrates (part of glycolipids and glycoproteins) and proteins. Many of these molecules are used for cell communication and help to distinguish your cells from invaders.

Question 15

Major histocompatibility complex
(MH1 class 1)

Answer 15

responsible for displaying fragments of the

normal cellular proteins as “badges” that identify each cell as belonging to the body.

Question 16

However, if the cell is infected by a pathogen, it will be displaying foreign
fragments that will act as a “red flag” …

Answer 16

=> the infected cell will be

attacked

Question 17

Sometimes, an abnormal cell (like, one that transformed into the cancer cell) will stop
producing MHC class 1 molecules in
order to “sneak” past the immune cells =>

Answer 17

the cancer cell will not be able to confirm its identity and will be attacked

Question 18

2nd line:cells

Answer 18

A variety of immune cells can identify invaders and destroy them using various methods:
A. Destruction by eating
B. Destruction by launching “chemical weapons”

Question 19

Destruction by eating

Answer 19

During an invasion, chemical signals attract
phagocytes (ex.neutrophils), which bind to the pathogen with the help of receptors, engulf & digest it
.

Question 20

Destruction by launching “chemical weapons”

Answer 20

Natural killer cells (NK cells)-circulate in blood and destroy a wide variety of unhealthy body
cells (infected by viruses, tumor cells) by:

-forming a pore in a cell by releasing Perforin
-initiating apoptosis(programmed death) by
release of enzymes into the pore

Eosinophils- destroy parasites by releasing enzymes and other substances (ex. neurotoxins)

Question 21

2nd line of defense: Chemicals

Answer 21

A.Interferons (IFN)

B.Complement System

Question 22

Interferons (IFN)

Answer 22

class of cytokines released by a virus-infected cell to prevent viral spread:

Bind to the receptors of the neighboring non-infected cells to prevent them from becoming infected (initiates production of
enzymes that slow down protein synthesis and enzymes that will break viral RNA if viral invasion happens)

-Bind to the receptors of the neighboring infected cells
and trigger their apoptosis

Stimulate macrophages and NK cells
to_______________virus-infected cells

Question 23

Complement System

Answer 23

30 proteins synthesized by liver and continuously released in inactive form in blood. Several mechanisms can be employed upon arrival of a pathogen (usually, bacteria)

Binding of a complement protein
\_\_\_\_\_\_\_\_\_\_\_\_
to the pathogen will
make it
more likely to be phag
ocytized
.
This process of “marking” a pathogen
for destruction is called “opsonization”.
K
illing a pathogen by forming a
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_in its plasma
membrane
-
membrane attack
complex (MAC).
\_\_\_\_\_\_\_\_\_\_\_\_
and
\_\_\_\_\_\_\_\_\_\_\_
\_\_
of v
arious
immune cells, triggering
inflammation