Maintaining Homeostasis Passive and Active Transport

Lesson Objectives Understand how equilibrium is established as a result of diffusion. Distinguish between diffusion and osmosis.

Cellular Membrane Membrane: function is to control what enters and exits the cell Selectively permeable

Homeostasis All living cells exists in a liquid environment Internal conditions need to remain constant Homeostasis Equilibrium=everything is balanced Maintain homeostasis by regulating movement of molecules across the membrane Passive Transport (no energy required) Active Transport (energy required)

Passive Transport: Diffusion Movement of materials across the cell membrane without using energy Diffusion: Movement of material/molecules from an area of high concentration to an area of low concentration Concentration Gradient

Passive Transport: Osmosis When water diffuses across the cell membrane http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.htm l

Effects of Osmosis on Cells Hypotonic: Hypertonic: Isotonic: Lower solute concentration outside of the cell Higher solute concentration outside of the cell Concentration is the same inside and out Water moves into the cell Water moves out of the cell Water moves in and out Cell swells Cell Shrinks

How does water move? “Salt Sucks”

How does water move? “Salt Sucks”

How does water move? “Salt Sucks”

Osmosis In Nature Cytolysis: in a hypotonic solution red blood cells will continue to swell until they burst Penicillin killing bacteria Contractile Vacuole: organelle in protist cells that pumps excess water out http://www.youtube.com/watch?v=pahUt0RCKYc&feature=related Turgor Pressure: water pressure placed on the cell wall to give plant cell its shape Plants wilting if solution is hypertonic Don’t drink salt water Diarrhea Something in stools that is drawing out the water

Facilitated Diffusion Movement of particles from higher concentration to lower concentration Large molecules may require “help”, they use carrier proteins Nervous system uses Na and Ca pumps

Lesson Objectives Distinguish between passive and active transport. Explain how sodium-potassium pumps operate. Compare and contrast endocytosis and exocytosis.

Active Transport Active Transport Passive Transport: down concentration gradient

Active Transport Passive Active

Active Transport Requires energy to move molecules up their concentration gradient Low concentration to high concentration Sodium-Potassium Pump Exocytosis Endocytosis

Cell Membrane Pumps Requires a carrier protein 3 Na-2 K Requires energy http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodium_potassium_p ump_works.html

Endocytosis Phagocytosis Pinocytosis

Exocytosis