Cell Physiology of Ions 1 Ions, Fluids, Electricity Flashcards
What are the Fluid Compartments of the body? (4)
- Plasma - Na+ based
- Interstitial fluid - Na+, based but lacks blood proteins (anions)
- Intracellular fluid - K+ based, contains lots of proteins (anions)
- Transcellular Fluid - in the lumen of tubes and organs e.g urine, chyme
Name some important ions in the body, in terms of anions and cations?
Cations include Na+, K+, Ca2+, H+, Mg2+
Anions include OH-, Cl-, HCO3-, [SO4]2-, [PO4]3-, charged proteins
What are the different ways ions can exist in the body in terms of binding, name from weakest to strongest? (6)
- Free in solution
- Buffered (non-specific)
- Chelated (in coordinate bonds)
- Tightly bound
- Sequestered - behind organelles
- Teeth, Bones
What are the different ways ions can pass through a membrane? (5)
- Channels
- Pump
- Leak
- Co-transport
- Exchangers
What are some functions of ions? (7)
- Start cellular processes
- Act as second messenger
- Transmit information across the cell
- Activate Enzymes
- Control Transmembrane voltage
- Create ATP
- Move water
What are examples of things that can happen due to ion imbalance? (5)
- Cardiac Arrhythmias
- Nervous dysfunctions e.g Tics
- Bone deformities
- Oedema
- Seizures
What can cause ion imbalances, name at least 5? (8)
- Haemmorhage, Trauma
- Extensive Diarrheoa and Vomiting
- Hormonal imbalances
- Diabetes
- Vitamin D imbalances
- Poisons
- Kidney Dysfunction
- Diuretics
What is voltage? (2)
- The potential energy difference between 2 points in an electrical field.
- This means it is the driving force for movement of charged particles.
What are the formulas for voltage? (2)
V = I (current) x (R) Resistance
Conductance (g) is the reciprocal of resistance. Therefore [I = g x V]
What is the main rules of ion balance? (3)
- Any ion that leaves the cell must be replaced by another ion of same type coming into the cell.
- Energy is used to re-establish ionic gradients across membranes e.g Na+/K+ Pump
- Concentration of positive and negative ions must “nearly” balance.
What role does Carbonic Anhydrase play in maintaining blood pH? (3)
It is an enzyme that catalyses the reversible reaction CO2 + H2O -> H2CO3 -> H+ + HCO3-. Creating acid and base.
This is important as:
- H+ is charged and cannot readily cross cell membrane so indirectly helps process of H+ crossing cell membrane and epithelia.
- Helps indirectly transport Co2 around the body as it is poorly soluble in blood. H+ and HCO3- are.
How is Carbonic Anhydrase used to maintain Homeostasis in:
- Red Blood cells
- Lungs
- Gastric Parietal Cells
- Pancreas (4)
- Red Blood Cells = “Chloride shift” for removing H+ ions from muscle.
- Lungs = Removing CO2 from the blood
- Gastric Parietal cells = Secreting Acid into Stomach
- Pancreas = Secreting bicarbonate
Describe how Carbonic anhydrase catalyses the formation of HCL into stomach in the gastric parietal cell? (6)
- CO2 and H2O enter cell through basolateral membrane.
- CA catalyses reaction to H+ and HCO3-.
- H+ is exchanged for K+, entering stomach lumen through the apical membrane.
- HCO3- is exchanged for Cl- through the basolateral membrane
- Cl- is transported into lumen via apical membrane.
- H+ and CL- form HCL in lumen.
