Biology - Diseases

First 4 topics of 2.8

What is a Pathogen

A micro-organism that causes disease. Includes micro-organisms such as bacteria, viruses, protists, and fungi

A - Cell membrane

B - Cytoplasm

C - Cell wall

Virus

How are Pathogens transferred?

By contact, aerosol, body fluids, water, insects and contaminated foods

Blood, saliva and semen

How to prevent AIDS

Condoms, disposable gloves when in contact with contaminated blood

Antiviral agents

Disadvantage of antiviral agents

Only prevent the multiplication of the virus inside cells

Must be taken throughout life

What is Chlamydia caused by?

Bacteria that is spread during sexual intercourse via the vagina or urethra

What happens if Chlamydia is untreated?

Cause infertility in adults

Could cause conjunctivitis in babies if the mother is infected

Could spread to the babies lung

How to prevent Chlamydia or the spread?

Condoms

Antibiotics

How is Malaria spread?

Single-celled organism called Plasmodium

Spread via female mosquitoes

Bite humans and goes into the bloodstream

Why and how does Malaria affect humans?

Causes a fever when it destroys red blood cells in humans

Prevention methods of Malaria

Killing plasmodium with anti-malarial drugs

Vaccines

Killing mosquitoes with Insecticides

Releasing infertile male mosquitoes

Biological control of mosquitoes

How does our body prevent the entry of microbes? (2 in detail)

Intact Skin

• Physical barrier

• Tough outer layer has little water, which microbes need for growth

• Natural bacteria living take up nutrients, so pathogens can’t grow

  Blood Clotting

• Seals wounds and stops microbes from entering when skin is cut

White cells in the blood help to defend the body against microbes by:

• Ingesting bacteria

• producing antibodies which inactivate particular bacteria or viruses

• producing antitoxins which counteract the toxins released by bacteria.

Phagocytosis

Ingest the microbe and then break it down when its inside the cell

What happens when there’s a foreign antigen?

White blood cells called Lymphocytes will secrete antibodies against it

Release specific antibodies against it

Swells and divides repeatedly by mitosis to produce a huge clone of cells

What cells are made from White blood cells?

Most become plasma cells - produce antibodies

Some form clones of smaller, long-living memory cells

Primary Immune Response

Response that takes place the first time an individual encounters an antigen

Secondary Immune Response

Response that takes place the second time an individual encounters an antigen

What is different in Secondary Immune Response?

• Response of lymphocytes is faster

• More antibodies are produced

• Response lasts for longer

This is due to memory cells that can multiply rapidly and produce antibodies very quickly following the second invasion

Why can people get the flu multiple times?

• Antigens on the surface of the flu virus mutate and change rapidly

• Memory cells produced from before are no use

Antigen

A protein found on the outside surface of a pathogen with a specific shape

Memory cells

• Lymphocytes are produced in response to the specific antigens on a pathogen.

• After pathogen is removed, some cells remain

• These are called memory cells. If the same pathogen enters the immune system for a second time, the response is much more rapid