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
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