cell physioloy 1: ions, fluids, electricity Flashcards
What is a solvent? What does it tend to be in biology and in the lab?
- solvent = fluid present
- BIOLOGICAL SYSTEMS: always water
- LAB: can be organic fluids
What is a solute?
particles dissolved in the solvent
What are the 4 fluid compartments of the body?
- plasma
- intracellular
- interstitial
- transcellular
Describe the plasma compartment of our body?
- it is Na+ based
Describe the intracellular compartment of our bodies?
- K+ based
- lots of proteins (anions)
Describe the interstitial fluid compartment of our bodies
- plasma
- lacks blood proteins (anions)
Describe the transcellular fluid compartment of our bodies
- in the lumen of tubes and organs
- cerebrospinal fluid, urine in bladder, chyme in GI tract
What are electrolytes?
ionised components of living fluid (e.g all the ions)
List the major cations in our bodies
- Na+
- K+
- Ca2+
- H+
- Mg2+
List the major anions in our bodies?
- OH-
- Cl-
- HCO3-
- [SO4]2-
- [PO4]3-
What do ions do?
- start cellular processes
- act as second messengers
What are some of the cellular processes ions do?
- create energy
- move water
- activate enzymes
- control transmembrane voltage
What are some of the things that can happen if tou have the wrong ion concentrations?
- cardiac arrhythmias
- tics and other nervous dysfunctions
- seizures
- bone deformities
- oedema
What are some causes of ion imbalance?
- trauma + haemorrhage
- diabetes
- kidney dysfunctions
- hormonal imbalances
- extensive D & V
What is voltage?
difference in potential energy between 2 points in an electrical field
What is the formula for voltage
V = I (current) x R
What is the formula for current?
I = g (conductance) x V
What is conductance (g)?
reciprocal of resistance
What are the two forces working on each ion?
- chemical force
- electrical force
Describe the chemical force that works on ions
- based on difference in concentrations ACROSS the membrane
Describe the electrical force that works on ions
- based on Vm (membrane potential, varies over time)
- based on few positive charges being UNPAIRED on the SAME SIDE of the membrane, so there are slightly more positive charges on one side of the membrane than the other
What is net force?
chemical + electrical force
What are the 5 ways ions can cross membranes?
- channels
- pumps
- exchangers
- co-transporters
- leak
