Molecules in Our Bodies

pH

pH = Power of Hydrogen

Logarithmic Scale: 0-14

Shows concentration of H+ ions in water

Water dissociates into H+ and OH-

10^-7 H+ in normal water: pH 7 = neutral

Acids (0-6) and Bases (8-14)

Controls enzymes and reactions

FeedbackHomeostasis: We must maintain a stable internal environment (balance).

Positive vs. Negative Feedback

Example: TemperatureIs temperature a positive or

negativefeedback loop?

Molecules help us maintain balance!

Digestion

• How do we get energy and nutrition from our food?40.3 (p. 828) and 41.2 (p. 849)

• Why do we pee?44.2 (p.927)

(also 44.4 - kidneys)

Respiration

• How do we get oxygen to our cells and get rid of the carbon dioxide waste? 42.7 (p.891)

Health/Immunity

• What is the role of chemical receptors in our immune system’s ability to fight off disease?

43.2 (p.903)

• How does the misrecognition of molecules create allergies and autoimmune diseases?43.5 (p.916)

Reproduction• Why do women get periods? 46.4 (p.973)

• How do hormones control the development of a zygote into an embryo? 47.1 (p. 989)

Growing Up

• How do hormones communicate with your cells to regulate growth and reproduction?45.2 (p. 945)

Processing Information

• How do brain cells send signals?48.3 and 48.4 (p.1017)