Download The First and Second Lines of Defense Against Disease

The First and Second
Lines of Defense
Against Disease
BY JEFF HOFFMAN
What are the immune systems’ 1st & 2nd lines of Defense?
-The first 2 lines of response of the immune system are called INNATE
IMMUNITY.
-During the early stages of an infection, there is an inflammatory response
•Non-specific attack
•Phagocytes active ("eat" pathogen)
1ST LINE OF DEFENSE: SURFACE COVERAGE:
-The skin and mucous membranes protects the body from pathogens
-Skin is a cellular, dead layer that is dry and is low in pH (kills many
microorganisms)
-oil/sweat glands and tears help wash bacteria away
-Mucous membranes have lysozymes which breaks down bacteria
-some cells contain cilia which helps to filter out pathogens or other
particles
2nd LINE OF DEFENSE: NON-SPECIFIC RESPONSE:
-these are generalized, and random responses to pathogen infection
-they consist of various plasma proteins and WBC’s such as: neutrophils,
eosinophyls, basophils, mast cells, and macrophage
Inflammatory Response

Inflamation: is a response that is triggered by the damage of living
tissues. It is a natural defense mechanism that protects you from
injury and infection.

It localizes where the tissue damage is and eliminates it so that the
body can begin in the healing process.

Some symptoms of this response include: change in blood flow,
increased permeability of blood vessels, and the movement of
proteins, fluids and white blood cells from circulation to the injured
site.
Types of Inflammation

Acute Inflammation: This is inflammation that only lasts a few days

This is often benficial, and it usually causes uncomfortable sensations
such as the itchiness of an insect bite or the pain of a sore throat

This sensation is temporary and only lasts until the healing is finished.

Chronic Inflammation: this is long term and can last for months or even
years

the causes of this could be: failure to eliminate whatever caused acute
inflammation, a chronic irritant of low severeness that persists, an
autoimmune response which damages healthy tissue

Ex. Asthma, Tuberculosis, arthritis, Chron’s disease

Chronic inflammation over time can also cause harmful diseases like
cancer, periodontitis, and hay fever
Sequence of Inflammatory Events


The sequence of inflammatory events is:
insult by trauma or initial entry of bacteria

platelet adhesion, vasoconstriction of vessels

Vasodilation of vessels causing increased blood flow (redness, local
heat) to infected/damaged area

Filtration of fluid into tissues (causes swelling)

Exit of neutrophils (mature white blood cells) from vessels into tissues

Destruction of bacteria: phagocytosis with pus formation

Tissue repair
The Fever

-The Fever is another one of the body’s defense mechanisms to fight
infections.

Occurs When your body temperature rises because of an infection,

Fevers are caused by chemicals called pyrogens flowing in the
bloodstream. Pyrogens make their way to the hypothalamus in the
brain, which regulates body temperature. When pyrogens bind to
certain receptors in the hypothalamus, body temperature rises.

The main purpose of the fever is to raise the body’s temperature
enough to kill a certain bacteria that are sensitive to temperature
change.

The body’s normal temperature is about 37 degrees Celsius while an
oral temperature of 37.8 degrees Celsius would be considered a
fever
Question #1
 If
a person sprains their ankle, what type pf
inflammation is most likely to occur?
Question #2
 What
are the main structures of the first
line of defense?
Question #3
 What
is an example of something that
would result in chronic inflammation?