Chapter 3 : Diffusion, Osmosis,`] and Permeability of Plasma Membrane

what materials are restricted to passing through plasma membrane freely?

size

electrical charge

molecular shape

lipid solubility

what kind of charge does the plasma membrane have?

has negative charge

what are the different ways substances can transport into plasma membrane?

passive processes : diffusion, osmosis, carrier-mediated transport (facilitated)

active processes : vesicular transport, carrier-mediated transport (active)

what is diffusion?

passive movement from an area with high concentration to an area with low concentration

what are the 5 factors that influence the rate of diffusion?

distance

ion and molecule size : smaller → faster

temperature : more heat → faster

concentration gradient : steeper → faster

electrical forces : opposites attract, likes repel

what is simple diffusion?

does not require a carrier protein / channel

lipid-solubles and gases

what is channel-mediated diffusion?

requires carrier protein / channel for bigger molecules

water-soluble compounds / ions

(still moves from high concentration to low concentration)

what is osmosis?

diffusion of water that moves to higher solute concentrations

what is osmotic pressure?

pulling water

what part of the body provides osmotic forces?

glucose / proteins pull fluid back to bloodstream to return to herat

what is hydrostatic pressure?

pushes water

what part of the body provides hydrostatic pressure?

heart because it is constantly pumping blood (maintains blood pressure / hydrostatic pressure) and pushes blood out of bloodstream to rest of body

why is osmotic and hydrostatic pressure important?

how water / fluid moves throughout body by theses forces telling where fluid needs to go

does osmosis occur more rapidly or slower than solute diffusion?

more rapidly because water can cross through abundant water channels (aquaporins)

what is a hypotonic solution?

exterior of cell has a lower concentration than interior of cell

what happens to a cell in a hypotonic solution?

water goes into cell because the solute concentration is greater on the inside of cell

cells swells

what happens if the cell swells too much?

lead to hemolysis (cell explodes)

what is a hypertonic solution?

exterior of cell has a higher concentration than the interior of cell

what happens to a cell in a hypertonic solution?

water goes outside cell because the solute concentration is greater on the outside of cell

cell shrinks (crenation)

what is carrior-mediated transport?

using proteins to transport molecules into plasma membrane

what are the two types of carrier-mediated transport?

facilitated diffusion

active transport

what is facilitated diffusion?

passive transport that requires carrier proteins to transport molecules that are too big to fit through channel proteins

what is active transport?

requires energy (ATP) to move substrates against concentration gradient

what are exchange pumps in active transport?

moves two ions in opposite directions at same time

which element is concentrated on the inside of cell?

which element is concentrated on the outside of cell

what do sodium-potassium exchange pumps do?

pumps sodium out against concentration gradient

pumps potassium inside against concentration gradient

what percent of ATP goes to operating pumps?

70% - 90% of ATP

what happens if cells are sick or fail to make ATP?

pumps are the first infected

what type of charge does every cell develop?

negative charges

why is it important that cells develop negative charges?

neurons / muscles communicate via electrical signal

charge present is vital to maintain cell’s health