intro to cell mem transport Flashcards
what do the dendrites do
capture signals of other adjacent neurons
what is an axon
long tube that transmits info
how does the cns communicate
with action potentials
where and when does the reception of info occur
at the level of dendrites and right after the synapse
what different influences are considered for the treatment of info
inhibition (-) and excitation (+)
what structures transmits info
axon
from what neuron to what neuron does the signal direcxtion go
pre synaptic to post synaptic
what is proprioception
sense of body mvt provided thru cell mem exchange
why is an injury painful (explain what happens)
receptors have a deformation in their mem that will lead to an exhange of ions that will result in pain being felt because the signal has reached the brain
what makes up the lipid bilayer
lipid barrier
proteins
carbohydrates
what is the lipid bilayer permeable to
lipid-soluble substances(O, N, CO2, alcohol)
what is the lipid bilayer impermeable to
water and water soluble substances (ions, glucose, urea)
what does the lipid bilayer do
it forms a barrier to protect the neurons and to maintain a certain level of electrical potential
what are the two types of membrane proteins and what do they both transport
integral proteins and peripheral proteins transport water-soluble substances across the cell membrane
where are integral proteins on the membrane and what do they act as
protrude thru mem
act as pores & channels and substance carriers
where are peripheral proteins on the membrane and what do they act as
attached to one side of the mem (often attached to integral prot) much smaller than integral prot
acts as enzymes (regulates cell mem) and controller of transport through channels
what are the 2 basic processes of transport and which requires E
diffusion (no E) and active transport (E)
what are the two types of diffusiom
simple (lipid bilayer or channel prot) or facilated (carrier proteins)
what are the two places mol move thru in simple diffusion (which passes bigger mol)
interstices of lipid bilayer for lipid soluble substances
and thru protein channels for water and lipid insoluble mol (bigger mol)
what are the characteristics of selective permeability of ions or mol with diffusion thru protein channels
diameter of channel
shape of channel
diameter of substance (K+ > Na+)
nature of electrical charges along the surface of the channel
what are the different types of gates
voltage gating channels and ligand- gating channels
what do voltage gating channels respond to and what do they participate in
respond to electrical potential (changes will make the gate open or close)
participate in generation of a.p
what do chemical gating channels respond to and what do they participate in
respond to binding of another molecule with the channel
participate in synaptic transmission (receptors)
what are the steps of facilitated diffusion
mol diffuses by using a specific carrier protein => mol enters the pore and binds to binding point (connection btw carrier prot and transported mol.) of protein => a conformational change occurs so that the pore opens to the opposite side => mol is released
what is the role of facilitated diffusion
transporting large mol like glucose and amino acids
what is the diffusion rate in simple diffusion
proportional to the [ ] of transported substance (the higher the [ ] the faster the rate of diffusion)
what is the diffusion rate in facilitated diffusion
not proportional to the [ ] of the transported substance (diffusion rates approaches a max as the [ ] of the diffusing substance increases)
why is there a plateau in the diffusion rate of facilitated diffusion
bc carrier prot become saturated and only one can pass at a time
what are the two factors that affect net rate of diffusion
-[ ] diff (net mvt of mol from high [ ] to low [ ]; [ ]gradient)
-electrical pot diff (electrical charge of ions cause them to move thru the mem even tho no [ ] diff exists to cause mvt) (a [ ] diff of the ions will be developed in the direction opposite to the electrical pot)
what will negative charges do if positive inside and
will go inside if its more positive if started outside
why do mol or ions need energy for active transport across the mem tru a carrier prot
bc they are going against their [ ] and/or electrical gradient (flow is against the gradient so need to push harder)
what are the substances that can be transported thru mem by active transport and how can these substances also be transported by
Na+, K+, Fe2+, H+, Cl-, urate ions, sugars and amino acids
also transported by passive transport thru the process of diffusion depending on the need
what are the 2 types of active transports and what is the source of E used for both
primary active transport : ATP (used to activate pump)
secondary active transport: E is driven from the [ ] gradient of one of the 2 transported sub
what is an example of primary active transport and what gets moved in and out of the cell
Na+/K+ pump
3 Na+ go out and 2 K+ go in (against [ ] gradient)
what is the role of the Na+/K+ pump and what is the values at rest and how much E does it require
maintains [ ] diff across cell mem (more Na+ outside and more K+ inside
negative electrical potential inside the cell at rest (always negative but charge depends on the type of cell)
requires 1 to 2/3 of the cell’s E
what cause the conformational change in the Na+/K+ pump
the enzymatic ATPase activity
what is the net charge of the Na+/K+ pump
increase of 1 positive charge outside; electrogenic (transfer of 1 net + charge out of the cell)
how many sub are transported in secondary active transport and where does the E come from
2: principal and co-transported
E comes from the [ ] gradient of the principal sub
what are the 2 forms of secondary active transport and what is the main goal of secondary active transport
symport: the 2 sub move in same direction
antiport: the 2 sub move in opposite directions
Maintain homeostasis in the cell
what would be an example of symport s.a.t and where is the binding site for both
sodium (principal) and glucose(cotransported)
both bind on the carrier prot in the cell mem
what causes both Na and glucose to move together into the cell and when does that process start
the energy gradient of the Na+ (driving force and provides gradient E)
once both sub are attached to the carrier prot a conformational change occurs
where are the principal and counter-transported sub located in relation to the mem in antiport of s.a.t
opposite sides of the mem
where would Na+ bind and Ca2+ bind and where would they go when bound in antiport of s.a.t
Na+ binds on the ext side of the prot and Ca2+ (counter-transported sub) binds on the int side
w the gradient E, Na+ goes from out to inside and Ca2+ goes from inside to outside
Na+-Ca2+ antiport occurs thru ____ ___ ____ mem
almost all cell
Na+-H+ antiport occurs in several ____ especialltyimportant in the prox tubules of the kidney
tissues
mol are constantly kept with ___ [ ] inside and outside of cell and why is it important
unequal
important for the optimal functioning of the cell
what is the charge of extracellular fluid and what is it high in (AT REST)
postively charges and high in Na+, Ca2+ and Cl-
what is the charge of intracellular fluid and what is it high in (AT REST)
negatively charged and high in K+, Mg2+, proteins
