cell communication, signalling + permeability

what are used for cell communication

hormones and neurotransmitters

how do cells communicate

hormones and neurotransmitters are:

-released by exocytosis

-travel to target cells via bloodstream

-target cells have complimentary receptors to detect

how do drugs work?

drugs bind to target cell receptors to trigger a response or prevent the cell from working

below 0 degree effect on membrane

permeability increases

explain permeability at below freezing temps?

-molecules have low kinetic energy

-low kinetic energy → phospholipids become closely packed → rigid membranes

-rigid membranes → proteins deform and create gaps in membrane

-gaps in membrane → leakage of substances → increased permeability

in the membrane, if team gets TOO low

-ice crystals can form

-crystals can puncture the membrane → creates gaps that increase permeability

between 0 and 45 degree effect on membrane

membrane becomes partially permeable

explain permeability between 0 and 45 degrees

-kinetic energy of components increases

-components move further apart → increased fluidity

increased fluidity = increased permeability

above 45 degree effect on membrane

permeability rapidly increases

explain permeability above 45 degree effect on membrane

-proteins in the membrane denature and unravel

-water in cytoplasm expands → increased pressure on membrane

-pressure on membrane → gaps in bilayer

what is permeability

measure of a materials ability to allow fluids/substances to pass through it