Systems of Defense

Animal Systems

Yesterday, you illustrated a diagram of skin in your notebook!

What are the three layers found in skin?

Contains keratin for elasticity and waterproofing

Contains melanin for pigmentation

Functional layer of skin that contains nerve cells, blood vessels, hair follicles, and specialized skin cells.

Made mostly of fat Lies beneath the dermis

acting as a shock absorber and an insulator.

Anchors the skin to underlying organs

A

B

C

Yesterday, you illustrated a diagram of skin in your notebook!

What are the three layers found in skin?

Why do we need skin?

•Protection from injury

•1st Line of Defense against Disease

•Prevents the body from drying out

Now let’s look at your diagram of the structure of bone.

Yellow bone marrowSpongy bone

Compact bone

Blood vessels

Periosteum

•Porous inner corefilled with red bone marrow•Production of blood cells and platelets begins

•Hard outer covering

•Made of fat for energy storage.

•Tough exterior membrane •Contains blood vessels

•Supplies nutrients to the bone

Now let’s look at your diagram of the structure of bone.

Bone marrowSpongy bone

Compact bone

Blood vessels

Periosteum

Why do we need bones?•Provides shape & support

•Protects internal organs

•Along with muscles, enables movement.

Both of these provide defense and protection to the animal.

What do we need protection from?Injury & Illness

How do they protect us?Provides a physical barrier

A physical barrier from what???

PATHOGENS!!!

Skin and mucous membranes are the 1st Line of Defense against pathogens!

What are pathogens?An agent that causes disease.

Examples: viruses, bacteria, fungi, protists, allergens

How does the body recognize pathogens?

Body cells have surface markers that indicate they belong in the body.

When a pathogen infects a body cell, the infected body cell displays an antigen on the surface.

The antigen triggers an immune response. Like little red flags

Like an ID Badge

Let’s look at a few pathogens in more detail!!!

Viruses

Non-living. Why?Needs a host cell to replicateDo not grow, metabolize, or

maintain homeostasis.Only pathogenic (causes disease).Viruses are specific to certain kinds of cells.

Ex: HIV infects only Helper T cellsBefore a virus can replicate, it must infect a living

cell, called the host cell.

Let’s review!

Virus Replication

Once in a host, the virus can take one of two paths.

1. Lytic Cycle 2. Lysogenic Cycle

Virus Replication- Lytic Cycle

Infection

Replication

Cell destruction

Virus Replication- Lysogenic Cycle

Results in two infected host cells.

Each time the cell divides, the provirus also divides.

Virus gene is inserted into host chromosome (called a provirus).

Does not destroy host cell.

Common Viral Infections

Cold sores Herpes

Influenza (the flu) HIV/AIDS

SARS Small pox

Viral pneumonia Warts

Chicken pox Hepatitis

BacteriaRemember Bacteria?

Prokaryotes-No nucleusObtain energy by autotrophy (photosynthetic or

chemosynthetic) or heterotrophyCan be harmful (cause disease) or helpful (food-making,

mining, nitrogen fixing for the environment)

Let’s review!

How do Bacteria cause disease?

Bacteria can cause disease by metabolizing nutrients in their host (competition for resources) or by releasing toxins, which damage the host.

Bacteria are identified by their shape and cell wall type.

Important Bacterial Infections

Ear infections Upper Respiratory Infection

Cavities Stomach Ulcers

Tuberculosis Impetigo

Carbuncles Food Poisoning

How can we treat infections?

Only bacterial infections can be treated with an antibiotic.

Why? Let’s look at the word—

Unfortunately, viruses can only be treated with rest and fluids until your immune system destroys the cells infected with viruses.

ANTIBIOTICagainst life

What other methods are used to protect against pathogens?

Prevention by vaccines!

How does it work? A weakened or heat-killed strain of a virus or

bacteria is injected into your body. Your immune system responds to the vaccine by

creating B cells, the memory cells. If the pathogen enters your body again, it is quickly

recognized and destroyed.

Viruses Bacteria

Draw this t-chart on the left side of your IN.

Complete the t-chart by comparing and contrasting viruses and bacteria..

What happens if the pathogen gets past the 1st Line of Defense?

Draw a four square diagram in your notebook on the next right hand side.

Inflammatory Response

Label the four boxes as shown below.

Temperature Response

Complement System White Blood Cells

What happens if the pathogen gets past the 1st Line of Defense?

Temperature Response

Complement System White Blood Cells

Inflammatory Response

•Local blood vessels dilate. •Increased blood flow to the area brings more white blood cells

What happens if the pathogen gets past the 1st Line of Defense?

Inflammatory Response

Complement System White Blood Cells

Temperature Response

•Fever. •Bacteria can only grow within a certain temperature range. A fever raises the temperature so the bacteria cannot survive.

What happens if the pathogen gets past the 1st Line of Defense?

Temperature ResponseInflammatory Response

White Blood CellsComplement System

•Made of about 20 different proteins •Travels the bloodstream punching holes in the cell membranes of pathogens. • Interferon, a protein released by virus-infected cells, prevents viruses from making proteins and RNA.

What happens if the pathogen gets past the 1st Line of Defense?

Temperature Response

Complement System

Inflammatory Response

White Blood Cells

•Neutrophils-engulfs and destroys pathogens•Macrophages-ingest and kills pathogens and clears dead cells and debris •Natural Killer Cells-attacks cells infected with pathogens, punctures their cell membranes

What happens if the pathogen gets past the 1st Line of Defense?

2nd Line of DefenseTemperature Response•Fever. •Bacteria can only grow within a certain temperature range. A fever raises the temperature so the bacteria cannot survive.

Complement System•Made of about 20 different proteins •Travels the bloodstream punching holes in the cell membranes of pathogens. •Interferon, a protein released by virus-infected cells, prevents viruses from making proteins and RNA.

White Blood Cells•Neutrophils-engulfs and destroys pathogens• Macrophages-ingest and kills pathogens and clears dead cells and debris• Natural Killer Cells-attacks cells infected with pathogens, punctures their cell membranes

Inflammatory Response•Local blood vessels dilate. •Increased blood flow to the area brings more white blood cells

What happens if the pathogen gets past the 1st Line of Defense?

2nd Line of DefenseTemperature Response•Fever. •Bacteria can only grow within a certain temperature range. A fever raises the temperature so the bacteria cannot survive.

Complement System•Made of about 20 different proteins •Travels the bloodstream punching holes in the cell membranes of pathogens. •Interferon, a protein released by virus-infected cells, prevents viruses from making proteins and RNA.

White Blood Cells•Neutrophils-engulfs and destroys pathogens• Macrophages-ingest and kills pathogens and clears dead cells and debris• Natural Killer Cells-attacks cells infected with pathogens, punctures their cell membranes

Inflammatory Response•Local blood vessels dilate. •Increased blood flow to the area brings more white blood cells

What if the 2nd Line of Defense doesn’t stop the pathogen?

Specific Immune Response- 3rd Line of Defense

What does it mean to be SPECIFIC?

def: of a special or particular kind

Then what is a specific immune response?

So how does it work? Helper T cells recognize

the antigens that are given off by macrophages that

have ingested pathogens.

The helper T cells then activate B cells and

cytotoxic t cells.

B cells become memory cells that help recognize the

pathogen as soon as it is reintroduced to the body.

Cytotoxic T cells destroy infected cells

Reflection:

On the left hand side of your IN, write a description of the body defenses that are involved in the following scenario:

Joe was slicing an apple when

the knife slipped and sliced his thumb.

Ouch!