Homeostasis and Transport across membranes Ch 5 p

Homeostasis and Transport across membranes Ch 5 p 94

Types of Transport �Passive Transport �Diffusion �Osmosis �Facilitated diffusion �Active Transport �Cell membrane pumps �Endocytosis �Exocytosis Movement across a membrane depends on BOTH the concentrations of particles AND their size, shape and if they dissolve in lipids!

Passive Transport �Diffusion – the movement of particles from an area of high concentration to an area of low concentration �Movement down its concentration gradient �Happens naturally due to kinetic energy of molecules � Dye in a glass of water (where would it happen faster – hot water or cold water? ) �Movement of particles happens until EQUILIBRIUM is reached as long as the particles… …can move thru the substance or across the membrane

Passive Transport �Osmosis – the movement of WATER from an area of high concentration to low concentration �Hypertonic: get your energy OUT �Hypotonic: Hypo the Hippo �Isotonic: equal

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Passive Transport �Facilitated Diffusion – the movement of particles is assisted by carrier proteins in the cell membrane.

Active Transport �Cell Membrane pumps �Sodium (Na)-potassium (K) pumps �“Na Na NAAA Na, Na Na NAAA Na HEY Good bye” �Our cells need the potassium in them. It doesn’t care if there isn’t a lot outside the cell, it just wants to bring in as much as it can. � Sodium sneaks in the cell, and isn’t needed. SO…the cell uses energy to kick out the Na and bring in the K

Active Transport

Active Transport �Endocytosis: endo=in cyto=cell �Pinocytosis “to drink” brings in fluid �Phagocytosis “to eat” brings in large particles or cells �The cell membrane forms a divit and wraps around until it connects on the other side, forming a vessicle.

Active Transport �Exocytosis: Exo=exit cyto=cell �When a vesicle that has formed in the cell, attaches to the cell membrane and opens up, releasing its contents out of the cell.

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