cell physioloy 1: ions, fluids, electricity

Question 1

What is a solvent? What does it tend to be in biology and in the lab?

Answer 1

• solvent = fluid present
• BIOLOGICAL SYSTEMS: always water
• LAB: can be organic fluids

Question 2

What is a solute?

Answer 2

particles dissolved in the solvent

Question 3

What are the 4 fluid compartments of the body?

Answer 3

• plasma
• intracellular
• interstitial
• transcellular

Question 4

Describe the plasma compartment of our body?

Answer 4

• it is Na+ based

Question 5

Describe the intracellular compartment of our bodies?

Answer 5

• K+ based
• lots of proteins (anions)

Question 6

Describe the interstitial fluid compartment of our bodies

Answer 6

• plasma
• lacks blood proteins (anions)

Question 7

Describe the transcellular fluid compartment of our bodies

Answer 7

• in the lumen of tubes and organs
• cerebrospinal fluid, urine in bladder, chyme in GI tract

Question 8

What are electrolytes?

Answer 8

ionised components of living fluid (e.g all the ions)

Question 9

List the major cations in our bodies

Answer 9

• Na+
• K+
• Ca2+
• H+
• Mg2+

Question 10

List the major anions in our bodies?

Answer 10

• OH-
• Cl-
• HCO3-
• [SO4]2-
• [PO4]3-

Question 11

What do ions do?

Answer 11

• start cellular processes
• act as second messengers

Question 12

What are some of the cellular processes ions do?

Answer 12

• create energy
• move water
• activate enzymes
• control transmembrane voltage

Question 13

What are some of the things that can happen if tou have the wrong ion concentrations?

Answer 13

• cardiac arrhythmias
• tics and other nervous dysfunctions
• seizures
• bone deformities
• oedema

Question 14

What are some causes of ion imbalance?

Answer 14

• trauma + haemorrhage
• diabetes
• kidney dysfunctions
• hormonal imbalances
• extensive D & V

Question 15

What is voltage?

Answer 15

difference in potential energy between 2 points in an electrical field

Question 16

What is the formula for voltage

Answer 16

V = I (current) x R

Question 17

What is the formula for current?

Answer 17

I = g (conductance) x V

Question 18

What is conductance (g)?

Answer 18

reciprocal of resistance

Question 19

What are the two forces working on each ion?

Answer 19

• chemical force
• electrical force

Question 20

Describe the chemical force that works on ions

Answer 20

• based on difference in concentrations ACROSS the membrane

Question 21

Describe the electrical force that works on ions

Answer 21

• 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

Question 22

What is net force?

Answer 22

chemical + electrical force

Question 23

What are the 5 ways ions can cross membranes?

Answer 23

• channels
• pumps
• exchangers
• co-transporters
• leak