• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/31

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

31 Cards in this Set

  • Front
  • Back
list 4 main functions of plasma membrane
communication, intercellular connection, physical barrier, selective permeability,
which molecules cna readily diffuse across lipid bilayer?
- small non polar molecules, oxygen, CO2, Nitrogen
- small uncharged molecules, water, ethanol,
list main ntracellular ions
K = 140 mM

CL= 5mM
Na = 10 mM
Ca = 0.1 nM
list main exttra cellular ions
Na = 145 mM
Cl = 125 mM

K= 4mM
Ca = 1.6mM
what is the difference between transporter and channel?
Transporter has moving parts, transfers moleules from one side of the membrane to teh other by changing its shape
Channel forms hydrophilic pores in the membrane that allows passage of small molecules ( ions)
what is different name of passive transport ?
facilitated diffusion
describe passive transport
molecules move down their concentration gradient from high to low,
does not require energy
describe active transport
molecules move against their concentration gradient,
requires energy
referred as pumps
describe two states of passive transporter
state A - binding site for the solute are exposed to the outside membrane
state B - the binding sites are exposed to the inside of the membrane
These transitions occur randomly and independent of whether solute is bound,
give example of passive transporter
glucose uniporter GLUT
what are 3 methods of active transport?
coupled transport
ATP-driven pumps
light -driven pumps
what is coupled transport?
couples the transport of one molecule down its concentration gradient with the transport of another molecule up its concentration gradient
describe ATP driven transport
couples transport of molecules up
its concentration gradient with ATP hydrolysis
what are two types of coupled transport?
symport and antiport
give example of symporters
SGLT1 in small intestine and
SGLT2 in proximal tubules of nephron
couples transport of Na+ ions down its concentration gradient with transport of glucose against its concentration gradient
describe glucose absorption in the small intestine
enterocytes have 2 different transporters
apical surface has sodium dependent glucose transporter
and basal surface - has passive glucose transporter(uniporter)
give example of antiporters
Na+Ca2+ Exchanger
found in plasma membrane
helps regulate intracellular Ca level
uses energy of the Na movement down its gradient to move Ca out of the cell against gradient
how the resting potential is maintained?
due to Na-K pump found in plasma membrane of all cells
requires energy from ATP
responsible for one third of cells energy expenditure and even 2/3 in neurons
how Na -K pump works?
transport 3 Na out and 2 K in per cycle
maintains net negative charge near the inner side of the plasma membrane
what are the 2 mechanisms by which intracellular Ca concentration is kept low?
1) sodium-calcium exchanger (NCX)
2) Ca pumps

both are examples of active transport - NCX uses energy from electrochemical gradietns and Ca pump from ATP
what are characteristics of ion channels?
- posses ion selectivity
- gated
what does it mean that channel is gated?
normally closed but open for a brief time in response to a specific stimulus
what are the types of gated channels?
voltage gated
ligand gated
stress gated
where can we find voltage-gated channels?
neurons,
muscles
egg cells
describe voltage gated channels
opening of voltage gated ion channels is controled by membrane potential.
Changes above a certain threshold produce enough force to cause a conformation change in the channel resulting in opening it or closing
what is role of voltage gated Na channels?
responsible for creation and propagation of action potential
what is role of voltage gated Ca channels?
muscle excitation and contraction
what is role of voltage gated K channels?
involved in repolarization following action potential
describe ligand - gated channels
opening of this channels is controlled by binding of molecule ( ligand) to the channel ( receptor)
The ligand binding site can face either the outside or the inside
- they convert chemical signal into electrical signal
where can we find ligand gated channels?
on the surface of some neurons and at the postsynaptic side of neuromuscular junction
- binds acetylcholine, and this opens the channel and allow for influx of Na and outflow of K along their electrochemical gradients
describe stress-gated channels
auditory hair cells of the inner ear have projectionsc called sterocilia
- stress gated ion channels on one stereocilia are connected to those on adjacent stereocilia through a linking filament
sound vibrations cause the basilar membrane to vibrate , the stereocila tilt , opening fo stress gated channels , causing ions to flow into the hair cells ,
this results in electrical signal that is transmitted to the auditory nerve