Chapter 6: interactions between cells and the extracellular environment

true or false: the membrane is selectively permeable

true

What is diffusion?

passive movement of solue down its concentration gradient from te region of higher concentration to region of lower concentration

What is simple diffusion?

due to random thermal motion

What is facilitated diffusion?

requires carrier molecule or transporter like GLUT for glucose

What is a carrier protein?

located in the membrane allow passie transport (no ATP required) of glucose into the cell. glucose binds to the carrier and then diffuses down (along,with) it concentration gradient

What is osmosis?

diffusion of water down its concentrationn gradient

solvent and solute make what

solution

What is osmolarity?

total solute concentrattion of a solution (all solutes)

what does osmolarity determine ?

water movement

What is tonicity?

refers to relative concentrations of two solutions which creates osmotic pressure and affects the volume of a cell

What is isotonic?

equal osmolarities for internal and external solutions

What is hypertonic?

higher osmolarity in the external solution

What is hypotonic?

lower osmolarity in the external solution

what is primary active transport

transport of a solute against its concentration gradientt requiring ATP

What type of membrane is required for osmosis to occur ?

selectively permeable membrane

How does osmolarity affect the movement of water in osmosis

What're moves from a region of lower osmolarity to a region of high osmolarity

What is osmolarity?

Total solute concentration of a solution which is the sum of all molarities of solute per liter

What happens when two solutions have equal osmolarity ?

Two solutions have equal osmolarity they also have equal water concentration

What is tonicity?

Refers to the relative concentrations of two solutions which creates osmotic pressure and affects the volume of a cell

What are three types of tonicity and their functions

Hypertonic: higher osmolarity in the external solution

Hypotonic: lower osmolarity in the external solution

Isotonic: equal osmolarity for internal and external solutions

What is primary active transport ?

The transport of a solute against its concentration gradient requiring ATP. The solute is transported by a carrier protein which as Na+/K+ pump

How does the Na+/K+ pump work?

Exchanges 3 intracellular Na+ for 2 K+ ions, creating a change difference across the membrane

What is epithelial transport ?

Refers to the movements of substances across epithelial cell

What is bulk transport?

Refers to the movement of large amounts of material into or out of a cell.

What are the two main types of bulk transport ?

endocytosis: the cell membrane folds in to form vesicles that bring fluid or particles into the cell

Exocytosis: vesicles fuse with the cell membrane to relapse their contents outside the cell

What is membrane potential

The difference in charge across the cell membrane. The inside of the cell s negatively charges compared to the outside mainly due to unequal concentrations of ion like Na+ and K+

How does the Na+/K+ pup contribute to membrane potential ?

The Na+/K+ pump moves 3 Na+ ions out of the cell for every 2 K+ ions moved into the cell making the insider of the cell more negative and contributing to the membrane potential

What is the typical resting membrane potential in cells

Between -65Mv and -85mV

What role do chemical signal play in cell signaling ?

Chemical signals are molecules related by cells to travel to a target cell where they bind to receptors triggering a physiological response