3.1

substance in greater concentration on one side of a semipermeable membrane will move down concentration if it can

O2 diffuses into cell because generally higher concentration is outside cell

CO2 diffuses out of cell because generally more concentration is inside cell

large polar or ionic molecules cannot easily cross bilayer

very small polar molecule (H2O) can diffuse due to size

charge atoms or molecules of any cannot cross bilayer

repelled by hydrophobic tails

most solutes dissolved in H2O cannot pass freely through lipid bilayer

movement restricted to protein channels + specialized transport mechanisms

process used for those substances that cannot cross due to size, charge, +/or polarity

two “type”

specialized carrier proteins transfer molecules into cell to facility its inward diffusion

membrane proteins form channels or gateways so substances can move down their concentration gradient

diffusion of H2O through a semipermeable membrane

2 solutions have same concentration of solutes

cells must maintain equal concentration of H2O inside + outside to function

solution with higher concentration of solutes

H2O tends to diffuse into

cells will shrivel as H2O leaves cell

solution with lower concentration of solutes

H2O tends to diffuse out

cells will swell + risk bursting

uses a hydrostatic pressure gradient to push fluid + solutes in from area of higher pressure to area of lower pressure

movement of plasma + substances out of capillaries + into surrounding tissue

mechanism that kidneys use to remove water from bloodstream

ATP needed to move substance across a membrane

often against its concentration gradient

often with help of protein “pumps”

through endocytosis (process of cell ingesting material)

maintains high concentration of sodium ion outside of cell

maintains electrical gradient

concentration of NA+ outside and K+ inside cell

difference in electrical charge across a space

opens passive sodium channel

concentration gradient of sodium drives sodium into cell

process of cell ingesting material

material ingested is enveloped in a portion of cell membrane

material ingested becomes independent intracellular vesicle

large particles

fluid with dissolved substances

portion of cell membrane with receptors for specific substance (ligand)

cell membrane envelopes receptor-ligand complex

exporting material using vesicular transport

substances produce in cell package for transport

membrane-bound vesicles fuse with cell membrane

vesicle releases it contention into interstitial fluid

secretion of digestive enzymes

release of hormones

immune cells produce histamine