5/4 Agenda Homeostasis Review: osmosis, cell transport, signal transduction Homework: Study for AP Exam Sleep/Relax/Eat Well Do your best! You guys are awesome!

Homeostasis Overview Homeostasis is the natural balance your body keeps There are many ways your body maintains homeostasis Cell signaling Negative Feedback Mechanisms Cell transport Outside sources can cause a disruption in homeostasis Exercise Stress Food Infection Extreme Temperature All living organisms have methods for maintaining homeostasis

Osmosis Osmosis is the movement of water across a membrane Water moves from a low concentration of solute to a high concentration of solute Or moves from a high concentration of water to a low concentration of water Plants prefer a hypotonic environment to allow pressure against the cell wall so the plant will stand up straight If not, wilting will occur Animal cells need an isotonic solution so our cells stay the same size

Osmosis

Osmosis and IVs If normal red blood cells have a solute concentration of 0.095% NaCl, how would you design the IV solution? Why?

Cell Transport Active transport= requires ATP Moves against a concentration gradient Low to high Used to concentrate solution inside a cell Endocytosis/Exocytosis is an example Solute moves through membrane by pinching membrane and creating its own vesicle Passive transport= does not require ATP Moves from a high concentration of solute to a low concentration Facilitated Diffusion- an example of passive transport, but used a membrane protein to guide solute through Used for polar or charge particles, or larger particles

Body Temperature Regulation