Cell physiology of Ions 1 Flashcards
What is a solvent?
the fluid present
What is the solute?
the particles dissolved in the solvent
What is Ionic Gradient?
the difference in concentration of ions between two points in space
How much of the body is water?
60%
How much of the water in our body is in our intracellular fluid?
2/3
How much of the water in our body is in our extracellular fluid?
1/3
What does the extracellular fluid consist of?
Interstitial fluid 3/4 + Plasma 1/4
List the four fluid compartments of the body?
plasma, interstitial, intracellular and transceullar
What is the chemical composition of plasma?
Na+
What is the composition of interstitial fluid?
plasma + lack of blood proteins
What is the composition of intracellular fluid?
potassium based + lots of proteins (anions)
Where can transcellular fluid be found?
in the lumen of tubes and organs
Give examples of Transcellular fluid.
CSF, Urine, chyme (GI Tract)
What is Diffusion?
The process of solute molecules passively moving down their concentration gradient
What does diffusion not involve the movement of ?
the solvent
What is Osmosis?
the process of water molecules passively moving down their concentration gradient
What is an Ion?
an charged atom or molecule
What is a cation?
a positively charged ion
What is an anion?
a negatively charged Ion
What are electrolytes ?
ionised components of living fluid
List 5 cations.
Na+, K+, Ca2+, H+, Mg2+
List 5 anions.
OH-, Cl-, HCO3-, SO4-, PO4- (phosphate)
What 2 things is phosphate important for?
in reactions involving ATP and in the Bone
Why is sulphate important?
structurally in glycosaminoglycans (molecule which make connective tissue and bone)
Where can we find Ions (6) ?
Free in a solution Tightly bound to another molecule Sequestered behind a membrane organelle In teeth/bones Buffered- non specifically bound Chelated - specifically bound
Explain how ions cross the membrane via Channels
Channels- membrane proteins which open and close to specific ions. Using a pore
Explain how ions cross the membrane via Co-Transporters.
Co-Transporters- 2 ions will attach to a protein which moves them both through membrane. Down conc. gradient.
Explain how ions cross the membrane via Pumps.
Pumps- SLOWEST only active one membrane proteins which use ATP to pump ions across the membrane (usually against conc gradient)
K+ Na+ ATPase
Explain how ions cross the membrane via exchangers.
one ion goes out another goes in. CL, HC03-
Explain how ions cross the membrane via Leak.
unexplained movement of ions.
What 2 main jobs do ions do?
They start cellular processes + Act as second messengers
Explain how second messengers work in fertilisation?
Ca2+
sperm hits the outside of the egg, which leads to Ca2+ increase inside the egg.
Explain how second messengers work in muscle contraction?
neural signal –> muscle. a signal is sent across the membrane which triggers an increase in intracellular calcium
Explain how second messengers work in exocytosis?
stimulated from outside the cell
what 4 things can Ions do?
create energy ATP
move water
activate enzymes
control transmembrane voltage
What Ion does water usually follow?
Chloride
High levels of calcium stimulates which enzyme used to phosphorylate other proteins?
Protein Kinase C
What is oedema?
collection of fluid in the extracellular space
What Is voltage?
a potential difference between 2 points in space of an electric field
What is the equation for voltage?
V = I x R
or
I = g xV
(g is conductance)
Which Ions form the majority of those found inside and outside the cell?
Potassium (cation) inside cell, Sodium (cation) outside of cell
What does the movement of Ions across the cell membrane lead to?
electrical currents
What is the sign for membrane potential?
Vm. (Reality)
What is the sign for resting membrane potential?
RMP or Vrest. (hypothetical)
What are the 2 forces on each Ion?
Chemical force
Electrical force
What is the chemical force on an Ion?
the difference in concentration across the membrane
What is chemical force also known as in Ions?
diffusional force
What measurement is electrical force based on in Ions?
Vm membrane potential
What is electrical force in Ions?
a few positive charges are unpaired with negative charges on the same side of the membrane
