Membrane and Transport and Neurons

faster

As cell grows, its volume increases _____ than its surface 

large

Cells need a _____ surface area (membrane) to volume (cytoplasm) ratio 

amphipathic

polar and nonpolar regions

unsaturated hydrocarbon tails

(plants) kinked hydrocarbon tails prevent packing which allow for membrane fluidity

saturated hydrocarbon tails

(plants) hydrocarbon tails pack together which increases membrane viscosity

viscosity

state of being semifluid or thick

integral membrane protein

embedded within the membrane. spans from outside to inside cell

peripheral membrane protein

surface protein. bound to surface

passive transport

molecules move from high to low concentration until it reaches dynamic equilibrium. no energy required

simple diffusion

small, nonpolar molecules move between phospholipids. typically gases

osmosis

diffusion of water across a membrane. some use aquaporins (transport proteins)

hypotonic solution

- Low solute concentration 

- Hyposmotic (low osmolarity) 

- Net flow of H₂O into cell → cell to swell and possibly burst

- More solvent outside cell

isotonic solution

- Same solute concentration inside and outside cell

- Isosmotic 

hypertonic solution

- High solute concentration 

- Hyperosmotic (high osmolarity) 

- Net flow of H₂O out of the cell → cell shrinks

- less solvent outside the cell 

lysed

hypotonic animal cell

shriveled

hypertonic animal cell

turgid

hypotonic animal cell

flaccid

isotonic plant cell

plasmolyzed

hypertonic animal cell

facilitated diffusion

use of transport proteins for diffusion. includes polar molecules, ions, and bigger molecules

channel protein

a channel through which water molecules or a specific solute can pass

active transport

use of energy to move molecules from low to high concentration (via transport proteins)

pumps

proteins that use ATP to force molecules against their gradient

endocytosis

enter cell

pinocytosis

“pinch” and “cell drinking”. cell takes in water and dissolved solutes

receptor mediated endocytosis

Specific molecules bind to receptors which trigger endocytosis of receptors and molecules 

phagocytosis

engulfing. ex: white blood cells engulf pathogens

exocytosis

exit cell. Vesicle fuses within membrane and releases its contents

dendrite

receive messages/stimuli

axon

pathway for impulse

synaptic terminal

end, secrete neurotransmitters

cell body

perform metabolic functions

synapse

gap/space between neurons

myelin sheath

protects/covers/insulates axon

node of ranvier

gap between schwann cells (axon exposed) 

schwann cell

forms myelin sheath and guides new axon growth