Movement of Water and Solutes

List the transmembrane proteins in order from the fastest to slowest rate.

pore, channel, solute carrier, ATP-dependent

What opens/closes the gate in channel proteins?

electrical, chemical, or mechanical signals

What are the three types of solute-carriers?

uniporters, symporters, antiporters

Function of uniporters?

transport a single molecule across the membrane

Function of symporters?

couple the movement of two or more molecules or ions across the membrane in the same direction

Functions of antiporters?

couple the movement of two or more molecules or ions across the membrane in opposite directions

Function of ATP-dependent proteins?

use ATP to drive the movement of molecules/ions across the membrane

What is diffusion?

the process by which molecules move from areas of high concentration to low concentration

What are the requirements for diffusion?

must be a concentration gradient for a solute, membrane must have some permeability, area available for diffusion

As we ___ the concentration gradient, the ___ the diffusion rate

increase, higher

Facilitated diffusion must have what?

a transporter

What happens in facilitated diffusion?

Eventually you reach a maximal flux

What is primary active transport?

uses the energy of ATP to move solutes against their concentration gradient

What is secondary active transport?

uses the energy of an electrochemical gradient to move another solute against its own electrochemical gradient

What is passive transport?

follows the direction of the electrochemical gradient

What is paracellular transport?

movement of solutes and fluid through intercellular gaps, between cells

Intracellular fluid has ___ Na+ and ___ K+ concentration compared to extracellular fluid

low, high

What is conductance?

a measure of how easily something can move across a cell membrane

How does water cross cell membranes?

osmosis

Isotonic solution

cells do not change volume

Hypotonic solution

cells swell

Hypertonic solution

cells shrink

Vesicular Transport can be

endocytosis and exocytosis

What is endocytosis?

the membrane pinches off to form a vesicle that contains a small volume of extracellular fluid. The vesicle is then internalized

What are the functions of endocytosis?

entry of large nutrients, the endocytosis of hormone-receptor complexes ends signaling processes, remove portions of the cell membrane

What is exocytosis?

vesicles formed inside the cell fuse with the membrane, releasing intracellular contents to the outside

What are the functions of exocytosis?

selective export of macromolecules, helps insert vesicle-bound proteins into the membrane, insert portions of the cell membrane

What is transcytosis?

endocytosis on one side of the cell, followed by exocytosis on the other side

What are the 3 mechanisms of endocytosis?

pinocytosis, phagocytosis, receptor-mediated endocytosis

What is pinocytosis?

the formation of endocytotic vesicles for nonspecific uptake of solutes and water

What is phagocytosis?

When a cell engulfs and destroys large particles and microorganisms

What is receptor-mediated endocytosis?

ensures that the desired extracellular components are internalized

What are the two types of exocytosis?

constitutive and regulated

What is constitutive exocytosis?

continuous secretion of a specific compound

What is regulated exocytosis?

exocytosis in response to a stimulus

The SNARE complex

membrane proteins target the secretatory vesicle to the membrane

What triggers the SNARE complex process?

an increase in intracellular Ca2+

function of epithelial cells?

form a dynamic barrier that moves substances in and out of the body

Epithelial cells connect to one another via

tight junctions

the function of tight junctions in epithelial cells

prevents water and solute movement around cells

What defines the boundary between the apical and basolateral domains of the membrane?

tight junctions

List the epithelial cell junctions

adhering junctions, desmosomes and hemidesmosomes, gap junctions, tight junctions

Provide mechanical adhesion by linking the cytoskeleton of neighboring cells

adhering junctions, desmosomes and hemidesmosomes

Intercellular connections that allow the movement of small molecules and electrical current between cells

gap junctions

form a pathway from one side of the cell to the other

Tight junctions (paracellular pathway)

What is vectorial transport?

the transport of something through the epithelial

transport from the apical to the basolateral side

absorption or reabsorption

transport from the basolateral to the apical side is called

secretion