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  • Home
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    • Biology
    • Chemistry
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    • Pre-calculus & Calculus
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Unit 17: Immune System & Disease

Reading
OpenStax orange book: Read Ch. 17 - "The Immune System and Disease", and section 13.1 - "Prokaryotic diversity" (bacteria)
BJU: Read Ch. 10 - "Bacteria and viruses", and section 22B - "The lymphatic system and immunity"
OpenStax green book:  Ch. 42 The Immune System

Topics
  • Viruses
  • Immune system
  • Lymphatic system

Labs
  • ​​HHMI Virus Explorer weblab
  • Bio-Rad Microbes and Health lab (Yogurtness lab)
Picture
A virus invading a cell
Picture
A bacterium in all its glory
​Lecture outline
Viruses are not considered alive. They have no cell membrane, or internal organelles; and they do not divide. Instead, they invade a host cell, inject their DNA or RNA, and take over the machinery of the host cell to make copies of themselves. Viruses infect all types of organisms - animals, plants, bacteria, etc. 

Bacteria are living, single-celled organisms, about 1/1000ths the size of a human cell, but huge compared to viruses! All bacteria are prokaryotes (no nucleus, no organelles, divide by binary fission), but they are divided into two kingdoms - Archaebacteria and Eubacteria.

A breakdown of the immune system:

Type 1: Innate immunity (innate = what you're born with)
A)   Physical barriers
  • Skin
  • Mucous (in nose, throat, etc)
  • Cilia (sweeping action)
  • Stomach acid
  • Tears
  • Saliva
  • Urine
  • Other secretions
B)   Internal defenses
  • White blood cells (leukocyte = white + cell)
    • Neutrophils and macrophages migrate to area of infection and engulf and destroy invaders - known as phagocytosis
    • Eosinophils produce toxins
    • Natural killer cells police the blood and lymph, cause cell lysis of virus-infected cells
  • Inflammatory response - redness, heat, swelling
  • Fever - speeds up repair
  • Blood vessels dilate, become more permeable, allow soldiers, chemicals, clotting factors to move to the area

Type 2: Adaptive immunity (also known as specific or targeted or acquired immunity)
Your adaptive immune response kicks-in if your innate immune response (above) is insufficient.

The adaptive immune system responds to an antigen; antigens are foreign substances that provoke an immune response. 

Antigens are typically organic molecules not normally found in the body
  • Toxic molecules attached to the cells of bacteria, fungi, etc.
  • Various molecules which present on the surface of virus-infected cells
  • Chemicals in poison ivy, animal dander, detergents, cosmetics, etc.
  • Foreign molecules on pollen

B-cells and T-cells are types of white blood cells called lymphocytes

B-cells produce specific antibodies which circulate throughout the body and bind to antigens to 'tie them up' - so they can't bind to their target, and a macrophage can come along and eat it up. 
  • Antibodies are large Y-shaped proteins with two 'crab arms' that bind up antigens and clump them together. Your body has one billion(!) different antibodies, each with a unique shape, and each targeted to a different potential antigen. 
  • Antibodies are found in blood, lymph fluid, tears, saliva, breast milk, and other body fluids. 

Helper T-cells release chemicals that help other white blood cells recognize and destroy antigens

Cytotoxic T-cells release toxic chemicals that destroy target cells 
Immune System lecture slides
File Size: 3618 kb
File Type: ppt
Download File

We will watch the following video clips on bacteria, viruses, and the immune system.

​Homework
Immune System questions, posted in Canvas

kjohanson@nexgenacademy.org
Website by Sarah