Diseases
A 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 throat
2. fungus – ex: ringworm
3. protist – ex: malaria
4. virus – ex: cold
1. Bacteria
Bacteria is alive and can be killed = antibiotics
Less than 1% of all bacteria cause disease.
2. Fungi
Example – Athletes Foot
Example - Ringworm
3. Protists
Example - Malaria
4. Viruses
Viruses are so small they can make bacteria sick
(they kill bacteria)!
Viruses are smaller than bacteria
Viruses 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 Bacteria
Cocci (round) Streptococcus
Strep Throat
Bacillius anthracis. (rod shape)
Anthrax
Spirillum minus
Spiral shape
Rat 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 – false
Pod – 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
Infectious
Noninfectious
Colds - caused by a virus
infection in the respiratory
system.
Diabetes - is a problem of the
pancreas and the insulin it
makes.
Flu (Influenza) - a highly
contagious viral infection
of the digestive system.
Asthma - Involves the
respiratory system
Strep throat - bacterial
infection of the throat
Athlete’s foot - a common
fungal infection of the
skin of the feet.
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.