BERNSETIN PHSC 2301 Transport

all biological systems are composed of cells and cells are surrounded by a selective ______________________

plasma membrane

plasma membrane regulates exchange of different substance between the cell and the ______________

interstitial fluid

types of transport

passive, active, coupled, endocytosis

types of passive trasnport

simple diffusion, facilitated diffusion, osmosis, filtration

random process of movement of any molecules from one location to another through the random thermal motion

diffusion

amount of substance crossing biological membrane in a time

flux

net flux between two compartments is always from an area of _______ concentration of any substance to an area of _____ concentration

higher, lower

diffusion of a molecule across biological membrane depends upon ________________ of the substance

molecular weight

heavier molecules diffuse faster than lighter molecules (true or false)

false (heavier diffuse slower)

law stating that the net diffusion rate of a gas across a fluid membrane is proportional to the difference in partial pressure, proportional to the area of the membrane, and inversely proportional to the thickness of the membrane

RT - DS (Co-Ci)/change in X

- RT - rate of transport

- (Co-Ci) - concentration gradient across the membrane

- S - surface area of diffusion

- D - diffusion coefficient

- change in x - distance of diffusion

fick's law

D = kbT/6pinr

D = diffusion coefficient

Kb = Boltzmann's constant

T = absolute temperature

r = molecular radius

n = viscosity of the medium

stokes-einstein equation

speed of diffusion across the unit area of the membrane

permeability

P = KD/∆X

∆X = distance of diffusion

D = diffusion coefficient, which depends on a variety of factors (size of solute and medium viscosity)

K = permeability coefficient

permeability coefficient

oxygen, carbon dioxide, water, and anesthetic gases have very _________ permeability

high

water, oxygen, carbon dioxide has a permeability constant of 10^-4 - 10^-6 which takes about how long

0.5-5 seconds

urea has a permeability constant of 10^-6 which takes about how long

10 minutes

glucose, amino acids have a permeability constant of 10^-7 which takes about how long

1.4 hour

Cl- has a permeability constant of 10^-11 which takes about how long

1.6 years

K+ and Na+ has a permeability constant of 1-^-13 which takes about how long

160 years

___________ substances (oxygen, carbon dioxide, fatty acids, lipid soluble hormones) diffuse directly across phospholipid bilayer of biological membranes

non polar (non-ionized)

____________ substances must pass biological membrane through the selective ion channels, which are typically formed by integral proteins. most channels are characterized by similar design. proteins are configured to create a transmembrane water-filled channel. water-filled pore allow ions to diffuse across the membrane

polar (ionized)

channels are formed by ________ proteins

integral

what are examples of membrane channels

selective ion channels, porins, aquaporins

three types of selective ion channels

voltage-gated, ligand-sensitive, mechanosensitive

selective ion channels are remarkably selective; difference in charge and size of ions is ________ and allows passage of only one type of ion

small

a sodium ion channel is for sodium ions only (true or false)

true

there is a positive charge at the entrance to selective ion channels (true or false)

false (negative charge)

narrow region acts as selectivity filter and contains carboxyl and carbonyl groups (true or false)

true

transport rate for selective ion channels is 10^6-10^8 ions/second (true or false)

true

selective filter for potassium is

0.3 nm

less specific selective ion channel that is formed by transmembrane proteins - porins

pores

pores form a ____________ which is water-filled pore

beta barrel

ionic channels are larger than pores (true or false)

false (pores are 1.2 nm)

what allows passage of hydrophilic solutes: anions, cations, ATP, cAMP, and IP3

pores

size of a pore limits size of a solute; gating controlled by Ca2+, H+, voltage, and anesthetics (true or false)

true

what is the transport rate for pores

10^3 molecules/second

selective ion channel that allows rapid passage of water in specialized cells and has thirteen family membranes

aquaporins (AQPs)

prokaryotes and eukaryotes have aquaporins (true or false)

false (prokaryotes do not contain aquaporins)

AQP channels are formed with _______________ side chains inside the channel

hydrophilic

channel diameter of aquarporin is what

0.3 nm (H2O = 0.1nm)

transport rate for aquaporin is what

10^9 molecules/second

transport rate for aquaporin

10^9

transport rate for sodium channel

10^8

transport rate for potassium channel

10^7

transport rate for calcium channel

10^6

facilitated diffusion kinetics is analogous to ________ kinetics

enzymes

metabolic energy (ATP) is not required for facilitated diffusion (true or false)

true

when molecules are too polar or too large, they are transported across the biological membrane through the mechanism of what

facilitated diffusion

receptor site on the transporter is characterized by chemical specificity and the binding receptor on the transporter is characterized by what

competition

facilitated diffusion occurs through the

membrane trasnporters

facilitated diffusion is charactered by what

saturation kinetics

transport rate for facilitated diffusion is

10^2 molecules/second

water is small and polar and can diffuse through the _______________ or through _______________ (aquaporins)

lipid bilayer, protein channels

movement of water across a semipermeable membrane that moves to the area of higher salt concentration

osmosis

osmosis across semipemrmeable membrane leads to increase in the volume in the compartment with ________ solute concentration

higher

increase in pressure within the compartment that has higher solute concentration that can prevent further water entry

osmotic pressure

movement of protein-free plasma across the capillary wall; occurs in all the capillaries

filtration

driving force for filtration across the capillary wall is what

hydrostatic pressure

both blood and interstitial fluid contain dissolved solutes and create what

osmotic pressure

hydrostatic pressure in the capillaries is _______ than the osmotic pressure of the blood

greater

filtration is also determined by _________________, type of capillaries, type of tissue, and size of the pores in the capillary

molecular weight

movement of ions and molecules against concentration and electrochemical gradients; moving from a red of lower concentration to area of higher concentration that requires an input of energy

active transprot

active transport is provided by the trasnporter (pump) with the continuous supply of energy (ATP) hydrolysis of ATP with ATPase is the direct source of energy for the function of the__________. any inhibition of ATP synthesis of ATPase blocks operation of the pumps

pumps

doesn't matter how many pumps there are per cell for active transport since transporters span the biological membranes (true or false)

false (specific number of pumps)

binding of the ion.molecule to receptor site on carrier protein stimulates the breakdown of _________ and results in ____________ of the protein

ATP, phosphorylation

transporting systems provide _________ transport of calcium, hydrogen, sodium and potassium

active

one of the most important pumps that is identified in all animal cells and is the first pump to be documented

Na+/K+ ATPase pump

subunits of Na+/K+ ATPase pump

two alpha, two beta

alpha or beta subunits in Na+/K+ ATPase pump is the transmembrane protein with binding sites for atp on the cytoplasmic side

alpha

molecular weight of alpha subunit in Na+/K+ ATPase pump

100,000

molecular weight of beta subunit in Na+/K+ ATPase pump

40,000-60,000 (located outside of alpha subunits)

secondary active transport and transports sodium, glucose/amino acids, and water

epithelial transport coupled transport

water moves through extracellular spaces between the cells

paracellular pathway

water moves across the luminal and basolateral membranes

transcellular pathway

active sodium transport _________ the osmolarity

increases

water moves toward ________ osmolarity in basolateral spaces

increased