Maintaining Homeostasis Passive and Active Transport Lesson Objectives

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. mcgrawhill. com/sites/0072495855/student_view 0/chapter 2/animation__how_osmosis_works. html

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

How does water move? “Salt Sucks”

How does water move? “Salt Sucks”

How does water move? “Salt Sucks” v v

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=pah. Ut 0 RCKYc&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 Passive Transport: down concentration gradient Active Transport

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. mcgrawhill. com/sites/0072495855/student_view 0/chapter 2/animation__how_the_sodium_potassium_p ump_works. html

Endocytosis • Phagocytosis • Pinocytosis

Exocytosis