DiseasesA disease is a condition that does not allow

the body to function normally.

• Diseases can affect either an individual organ or an entire body system.

• Diseases are divided into two groups—1. infectious (contagious)2. noninfectious.

Infectious Diseases

Infectious Diseases – (contagious) diseases that can be transferred from one another.

Pathogens – tiny organisms that cause an infectious disease (4 Types) -

1. bacteria – ex: strep throat2. fungus – ex: ringworm3. protist – ex: malaria4. virus – ex: cold

1. Bacteria

Bacteria is alive and can be killed = antibiotics

Less than 1% of all bacteria cause disease.

2. FungiExample – Athletes Foot

Example - Ringworm

3. ProtistsExample - Malaria

4. VirusesViruses are so small they can make bacteria sick

(they kill bacteria)!Viruses are smaller than bacteriaViruses can’t be cured – only treat symptoms like

fever, vomiting, headache

Where Do Pathogens Come From?

Pathogens come from 4 main sources:

1. another person

2. a contaminated object

3. an animal bite / insect bites

4. the environment

Our Body’s Defenses?

1st line of defense:

1. Skin – can’t get though unless skin is broken

2. Breathing passages – mucus traps and removes most pathogens.

3. Mouth and stomach – most pathogens swallowed are destroyed by saliva and stomach acid.

Our Body’s Defenses?

2nd line of defense – Immune System

1. White Blood Cells (WBC) – fight disease

2. Inflammation – enlarged blood vessels = more WBC. Area is red and swollen and can usually feel heat.

3. Fever – prevents pathogens from growing in body.

The Immune System

The immune system is responsible for distinguishing between the different kinds of pathogens and reacting to each according to its type.

Once a pathogen has entered the body, it works by damaging individual cells within the organs or, in some cases attacks an entire body system.

Bacteria are grouped by their shape.

Coccus or Cocci (pl) – round shaped

Bacillus or Bacilli (pl) – rod shaped

Spirillum or Spirilli (pl) – spiral shaped

Common BacteriaCocci (round) Streptococcus Strep Throat

Bacillius anthracis. (rod shape)

Anthrax

Spirillum minusSpiral shapeRat Bite Fever

.

Identify the Shapes

Protists are grouped by how they move and obtain

food.

Protists with pseudopods – move and eat by extending parts of the cell outwards with the rest of the cell following.

Pseudo – falsePod – foot

Amoeba

Protists with Cilia – move and capture food by using hundreds of small hair-like structures called cilia that whip and whirl around in the water.

Paramecium

Protists with Flagella – the flagella is a long whip-like structure that pulls the protist and pulls food into its mouth.

Euglena

•Can photosynthesize like plants•Can eat like an animal

Non-Infectious Diseases

Noninfectious diseases - are diseases that are NOT caused by pathogens in the body and are NOT spread from organism to organism.

These diseases are caused by a breakdown in an organ or organ system such as cardiovascular disease, allergies, diabetes, environmental factors or chemicals.

Common Diseases

InfectiousColds - caused by a virus

infection in the respiratory system.

Flu (Influenza) - a highly contagious viral infection of the digestive system.

Strep throat - bacterial infection of the throat

Athlete’s foot - a common fungal infection of the skin of the feet.

Noninfectious Diabetes - is a problem of the

pancreas and the insulin it makes.

Asthma - Involves the respiratory system

Parkinson’s disease - occurs when certain nerve cells in the brain die or become damaged.

Skin Cancer - Skin cancer is a disease in which cancer cells are found in the outer layers of your skin.