Unit 8 Concept 2 - Disease

homeostasis

stability of the internal environment and the mechanisms that maintain the stability

• Homeostasis is constantly threatened.

• If an organism doesn’t respond to these threats(stimuli) it can result in disease or death

what can disrupt homeostasis

• viruses, bacteria, fungi, + other parasites invade/hijack cells or tissues

germ theory

• Disease is caused by the presence of pathogenic microorganisms.

  • Many scientists contributed to this understanding, but Pasteur and Koch are the two most recognized for their contributions.

louis pasteur

• Discovered that fermentation and decay were caused by living microorganisms 🡪 this led to the development of the pasteurization process

robert koch

• Discovered a universal method for determining whether a specific bacterium causes a certain disease (isolating the bacterium, growing it in a medium, inserting it into healthy cells to see reaction)

causes of disease

• Presence of disease-causing bacteria, viruses, or fungi cause Infectious Diseases

• Hereditary factors (non-infectious)

  • Genes you inherit from your parents

• Environmental factors (non-infectious)

  • Ex. Toxic substances, poor nutrition, unhealthy habits, exposure to mutagens, etc.

  • These can show up right away or have effects years down the road (ex. second hand smoke)

• Gene mutations (non-infectious) → uncontrolled cell division = cancer

why are bacteria and viruses such threats

• They can live in a variety of environments.

• We can’t see them.

• They reproduce SO FAST!  

This allows them to evolve adaptations in populations quickly

How do bacteria cause disease

• Invade the organism

• Challenge the immune system

• Use healthy cells for food 🡪 a breakdown of healthy cells and tissues

• Release toxins that can travel to different tissues throughout the body, once in the bloodstream

how do viruses cause disease

• Viruses target specific tissues

• Invade target cells

• Hijack their protein expression mechanisms

• Copy themselves