Transcript Antibiotics

Defense against Infectious
Disease
CH. 10
Defense against Pathogens
 God has wonderfully equipped the human body to
resist disease
 Our body’s system of defenses is a solid testimony
against evolution

Defenses could not have developed over long periods of time;
we would all be dead
 God has also given man resources and an innovative
mind to develop medicines and therapy to
overcome pathogens
Foreign Invaders
 Called Pathogens
 Viruses, bacteria or
other living things that
cause disease/immune
response.
 Antigens
 Toxins that pathogens
produce that cause
harm to an organism.
3 Types of Defense
 Structural Defenses
 Nonspecific Defenses
 Specific Defenses
Structural Defense
First Line of Defense The Skin
•
Provides Physical and Chemical barriers
 Physical –

tough dead cells, made of indigestible keratin, and other
layers of tightly packed cells
Chemical –





tears
sweat
mucous linings
Stomach acid
Structural Defenses
 Natural “Flora”

These are bacteria that live in our intestines and benefit
us by breaking down some of our food and providing
nutrients

These non-pathogenic organisms occupy the areas in our
GI tract that pathogens would like to occupy if they could

However, certain antibiotics could destroy this natural
flora and leave the intestines vulnerable to pathogenic
invasion
Second Line of Defense –
Nonspecific Immune Response
Should a pathogen get past the skin…
 These are defenses the body uses no matter what the invader
may be. These defenses include:

Inflammation - caused by release of Histamine from leukocytes



Fever
 The fever (high temp) kills invaders by inhibiting their growth.
 Boosts chemical reactions that are needed to activate the 3 rd line of
defense
Swelling – caused by fluid moving into damaged area
 Fever and swelling can also cause – redness to occur
Phagocytosis – done by Macrophages*
 *Macrophage: A phagocytic cell found in the liver, spleen, brain and
lungs. Travels to all areas of the body to find and eat pathogens.
Third Line of Defense Specific Immune Response
 If pathogens make it past the first 2 lines of
defense then…
 A specific response to a pathogen/antigen is begun
by the IMMUNE SYSTEM

The system in the body responsible for maintaining
homeostasis by recognizing harmful from non-harmful
organisms and produces an appropriate response.
Parts of the Immune System
1.
2.
3.
4.
Blood - White Blood Cells in
particular.
Lymph nodes
Thymus Gland – Produces T
Lymphocytes
Bone Marrow – Produces B
Lymphocytes
Immune Response
 The immune system has 2 main components:
 Chemicals called antibodies
 Several kinds of special cells, each with a specific job
 Antibodies are small “Y” shaped chemicals that
circulate the body and attach to different pathogens
and antigens
The Pathway of Specific Immune Response
Step 1
Pathogens eaten by Macrophage
Step 2
Displays portion of Pathogen
on surface
Step 3
Pathogens
Helper-T cell recognizes
Pathogen
What is Immunity?
Immunity
 Immunity
 The ability of the body
to fight infection and/or
foreign invaders by
producing antibodies or
killing infected cells.
 After defeating a certain
pathogen/infection, cells
in the immune system
develop a “chemical
memory” so that if that
pathogen ever invades
again, the immune
response will begin
almost immediately
Primary .vs. Secondary Immune Response
Autoimmune Disease
 Autoimmune diseases are diseases where the immune
system begins to attack itself.
 Ex:
Rheumatoid Arthritis – crippling disease of the joints.
 Lupus – disease of blood and organs.
 Multiple Sclerosis – disease of nervous system

 Cause(s):
unknown
 Cures/Treatments: No known cures. Usually treated with
drugs.
Medical Control of Disease
 Sometimes, despite the awesomeness of our body’s
defense, physicians may prescribe various chemicals
to help
 Chemotherapy – the use of chemical agents to treat
or prevent disease




Antibiotics
Antiviral drugs
Antihistamines
vaccines
Antibiotics
 Antibiotics (“against – life”) – are chemicals designed
to either destroy or disrupt the metabolic pathways of
bacteria or other living pathogens


Bactericidal (killing bacteria)
Bacteriostatic (inhibiting the growth of bacteria)
 Antibiotics were discovered by accident by an English
bacteriologist named Sir Alexander Fleming in 1929


He came back to his lab from vacation and notice a mold
growing in the middle of a petri dish culture and a ring around
the mold were no bacteria grew
He called the chemical produced by the Penicillium mold
penicillin
Antibiotics
 Common antibiotics:
 Penicillin and cephalosporin – inhibit synthesis of cell wall
components
 Erythromycin and tetracycline – interfere with protein
synthesis
 Rifampin – inhibits RNA synthesis
 Unfortunately, antibiotics are often not very specific
in which bacteria they kill

These are called broad-spectrum antibiotics
Antibiotic Resistance
 After penicillin was discovered, physicians started
using antibiotics as a “cure-all” for any and every
type of infection

For a time, it worked
 Unfortunately, once the populations of pathogens
killed by antibiotics, the pathogens that were
naturally resistance began to thrive
 Now, scientists work to create antibiotics that are
more specific to certain pathogens are more careful
to regulate dosages and strength
Allergies
Allergy
- An exaggerated response by the immune system to an allergen.
Allergen: a normally harmless substance that causes an allergic
reaction.
ex: dust, pollen, mould, food, insect stings
Types of Allergic reactions
There are two types of allergic reactions.
a. Immediate – occurs within seconds and normally lasts for about 30
mins.
b. Delayed – takes longer to react and can last for a much longer time.
What happens during an allergic reaction?

During an allergic reaction antibodies cause histamines to be released
from certain cells.
Histamines cause:
a. Swelling of tissues
b. Release of fluids (runny noses and eyes)
c. muscle spasms (some cases)
Anaphylaxis or anaphylactic shock:
This is the sudden and severe allergic reaction to a substance that can
cause death.
Treatments for Allergies
1.
Avoidance of material – especially food.
2.
Epinephrine – “epi – pen”
3.
Antihistamines -- benadryl
This powerpoint was kindly donated to
www.worldofteaching.com
http://www.worldofteaching.com is home to over a
thousand powerpoints submitted by teachers. This is a
completely free site and requires no registration. Please
visit and I hope it will help in your teaching.