Neuro Unit 5.7: Understanding addiction as a chronic disease
Disease Unit
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Transcript of Disease Unit
Disease Unit Ms. Powell’s
8th Grade Science Class
Types of Disease Causing Organisms
Virus Bacteria (includes Rickettsia) Protozoa (includes trypanosomes) Fungus Worms
Viruses A small nonliving particle that invades and
reproduces inside a living cell Considered nonliving because:
Viruses are not made of cells Do not use energy to grow and developor to respond to their environment Do not make food, take in food or produce waste
Have ability to multiply when inside a living cell
Virus Vocabulary Host: a living thing that provides a source of
energy for a virus or other organism Parasite: organisms that live on or in a host
and cause harm to the host Active virus: enters a cell and immediately
begins to multiply Hidden virus: the genetic material lies dormant in
a cell for a period of time before becoming active Ex. Cold sore virus (Herpes) lies dormant in nerve
cells
Potential Hosts of Viruses No organisms are safe from viruses Viruses can attack:
Plants, Animals, Bacteria, Protists, Fungi
Viruses are generally very host specific Ex. A plant virus does not attack people
Naming Viruses Viruses are not living organisms Scientists name the virus for the disease it causes
Ex. Polio
Scientists name the virus for the organism it infects Ex. Tomato mosaic virus
Scientists name the virus after themselves Epstein–Barr virus ( causes mono)
Virus Appearance Very small (smaller than a bacteria -750
nm) 22 to 250 nanometers
Shape: round, rod shaped, bricklike, threadlike, robotlike or bulletlike
Structure of a Virus Two basic parts:
Outer coat that protects the virus Made of protein Protein shape allows virus to lock onto certain cells Cell surface and virus coat is like a “lock and key fit”
– makes virus specific to certain cells
Inner core made of genetic material Analogy: chocolate covered cherry
Structure of Viruses
Parts of a Virus
Virus Photos
Rhinovirus (Common Cold)
Hepatitis B
How Viruses Multiply Once inside the cell the virus’s genetic
material takes over the cell’s functions The genetic material tells the cell to
produce the virus’s proteins and genetic material
These proteins and genetic material are assembled into new viruses that are released from the cell
How Viruses Multiply
How HIV Invades a Human Cell
Herpes zoster Shingles/Chickenpox
Virus: Smallpox
Polio Virus: Neuromuscular Damage
Bacteria Are unicellular microorganisms. Are typically a few micrometres long Are prokaryotes – their cells do not have
nuclei Shapes: spherical, rodlike or spiral
Bacteria Rod Shape,
Spherical,
Spiral
Bacteria Two types:
archaebacteria – ancient bacteria Live in hot springs and other extreme
environments Eubacteria – live everywhere else
Bacteria (blue and purple rods) and other microorganisms lurk in a kitchen sponge
Bubonic Plague: Bubos –swollen gland
Rickettsia Rickettsia species are a type of bacteria Are carried as parasites by many ticks,
fleas, and lice Cause diseases such as
Rocky Mountain spotted fever, and typhus in humans
Rickettsia: Lyme Disease: “Bull’s Eye” Rash at Site to Tick Bite
Rickettsia: Rocky Mountain Spotted Fever Rash
Rocky Mountain Spotted Fever
Typhus
Protozoan Parasites Protozoa (in Greek proto = first and zoa =
animals) are single-celled eukaryotes (organisms whose cells have nuclei)
Commonly show characteristics usually associated with animals
Most notably mobility and heterotrophy
4 Types of Protozoa Dinoflagellates Cilliates Sporozoans Amoeba
4 Types of Protozoa - Locomotion Flagellates are cells with one or more whip-like
tail called flagella. (trypanosomes?) Ciliates –use hair-like cilia to move (malaria) Amoeba move by means of temporary
projections called pseudopods, Sporozoans spore-forming, parasites of animals.
Motile structures such as flagella or pseudopods are absent
Protozoa: Life Cycle of Malaria
Mosquito Transmission of Malaria
Protozoa - Trypanosomes Undergo a complex lifecycle which may
include several different morphological forms
Often transmitted by invertebrates. African Sleeping Sickness/Tsetse fly Chagas Disease, Triatome bug
Tsetse Fly
African Sleeping Sickness
Trypanosome and Red Blood Cells
Trypanosomiasis – Parasite Seen in Blood Sample
Fungal Diseases Eukaryotic organisms (nucleus in cell) Digest their food externally, absorbing
nutrient molecules into their cells. Related to yeasts, molds, and mushrooms Ringworm, Athletes foot, Nail fungus
Fungus: Ringworm
Helminths - Parasitic worms Intestinal parasites - tape worm, pin worm
Onchocerciasis/River Blindness is an infection caused by the parasite Onchocerca volvulus (worm)
Spread by the bite of an infected blackfly. Lymphatic filariasis
African River Blindness - ParsiticWorm
Parasitic Worm: Lymphatic Filariasis
Parasitic worm
Parasitic Worm: Liver Fluke