USC bridge course 1.6 acids and bases
Acids and bases
Are electrolytes that can donate an electron and can dissolve or dissociate in water.
- Are proton donors- in water the ionize or release a hydrogen ions (H+) and anions. bare protons (have no electrons) in detectable amounts in solution.
i.e.: HCl -> H+ + Cl-
- important acids or molecules in our body: HCl (hydrochloric acid), HC2H3O2 (acetic acid/HAc), and H2CO3 (Carbonic acid).
- molecular formula for an acid has H+ written first.
- Are proton acceptors, they collect H+ ions in solutions. Common inorganic bases are hydroxides ie: magnesium hydroxide and sodium hydroxide.
- Dissolve in water to form hydroxyl ions and cations. NaOH -> Na+ +OH-
Cation Hydroxyl ion
- Important bases in the body is bicarbonate (HCO3-) and ammonia (NH3) is a waste product of protein breakdown.
- When acids and bases mix together they React with each other in displacement reactions to form water and salt: NaOH + HCl -> NaCl + H2O
- This is also a neutralization reaction because the joining of H+ and OH- to form water neutralizes the solution.
- Measure of acid or base (hydrogen ion concentration). Acidic solutions have a high H+ but a low pH. Acid is 0-6.99
- neutral pH is equal number of H+ and OH- ions. Neutral solutions pH is 7
- alkaline or base solutions have a low H+ but high pH. Range is 7.01 to 14.
- Blood ph is about 7.4
Physiological pH range
- important to maintain our body in this range for biologic reactions to take place.
- pH change interferes with cell function and may damage living tissue.
- Slight change in pH can be fatal
- pH is regulated by kidneys lungs and chemical buffers.
- Regulated by kidneys and lungs and chemical systems help prevent excessive changes in body pH.
- Acidity involves only free H+ in solution, not H+ bound to anions.
- Can resist abrupt and large swings in pH by releasing H+ ions if pH rises or can bind H+ ions if pH falls.
- Converts strong acids or bases that are completely dissociated info weak ones that are slightly dissociated. I.e.: buffer system in our blood is the carbonic acid-bicarbonate system. H+ ions respond to neutralize the blood.
How does the carbonic acid-bicarbonate system help to maintain homeostasis of the blood?
As blood pH rises or becomes alkaline, carbonic acid dissociates.
If blood pH drops or becomes more acidic bicarbonate ions begin to bind with protons
pH and oxygen transport
Oxygen binds to the iron containing heme group in Hgb via noncovalent interactions (charge-dipole). Under appropriate circumstances this interaction is broken and O2 can be released from the molecule
A decrease in the amount of O2 associated with Hgb and other respiratory compounds in response to a lowered blood pH resulting from an increased concentration of CO2 in the blood.
Low pH induces Hgb to release O2.
Net effect: release O2 in tissues RBCs take up CO2.
A substance that is very acidic may have a pH of 1 or 2. This means that the acidic substance has:
A high concentration of H+ ions
A buffer will release H+ ions if the blood pH:
Rises or becomes more basic.