2 ALL LIFE PROCESSES DEPEND ON THIS TINY IONIZATION PROCESS… Water = nonionic compound. It is converted to ions in a process called ionization.Water separates when one of the OH bonds breaks.This results in a positively charged H+ (hydrogen ion)and a negatively charged OH— (hydroxide ion).Imagine a water molecule that picks up a positively charged hydrogen proton.When this happens, this water moleculebecomes positively charged. The water molecule that gave up the hydrogen proton becomes negatively chargedbecause one 1 electron remained behind.
3 The level of H+ and OH— ions in solution is known as the pH scale The proton exchange results in 2 water moleculesout of every 1 billion splitting into apositively charged H3O+ (called hydronium) ionand a negatively charge OH- (called hydroxide) ion. Pure water, contains hydronium ions equal to 1 x 10-7 moles per liter ( moles per liter). In other words, the number of hydronium ionsIs equal to number of hydroxide ions. Therefore, the hydroxide ions are equal to1 x 10-7 moles per liter.This equilibrium between hydronium and hydroxide ions is affected by the addition of substancesto water.The level of H+ and OH— ions in solutionis known as the pH scale
4 A proton donor is known as an acid. Acids increase the [H+] ions in solution. A base functions as a proton acceptor,it reduces the concentration of [H+] in solutionand increases the concentration of [OH--] ions.
5 1 X 10-1 [H+] = pH 1 HCl or stomach acid 1 X [OH--] = pH HCl or stomach acid
6 [H+] [OH—] pH 1 pH 7 pH 14 What happens to the pH of the solution if the level of [H+] increases?if the level of [OH–] increases?
7 CO2 What does exhaling into the water add to the water? H2O Bromothymol Blue added
8 CO2 CO2 + H2O How does this ‘change’ the water? Why? H2CO3 CO2 H2O Carbonic Acid
9 Buffer Systems—a buffer is a molecule that tends to either bind or release hydrogen ionsin order to maintain a particular pHBicarbonateIonCarbonateIonCarbonicacidWhat happens when the reactions go to the right?What happens if the reactions go to the left?
10 H2CO3 HCO3 -- = carbonic acid (H+ donor) responds to a rise in pH [H+] = bicarbonate (H+ acceptor) responds to a drop in pH
11 A diabetic’s blood pH dropped to 7.23. Why? BicarbonateIonCarbonicacidMaintaining blood pH—why?Acidosis or Alkalosis = deathA diabetic’s blood pH dropped to Why?The body enters a starving state due to no insulin output; body burnsstored fat for energy and ketones are released into the bloodstreamas a by-product/or waste product of fat metabolism. Ketones are acidic!What happens during HYPERventilation?Levels of Carbon dioxide decrease; less H+ ions will accumulatecausing the pH of blood to increase = alkalosisWhat happens during HYPOventilation?Carbon dioxide in blood increases; more H+ ions will accumulatecausing the pH of blood to decrease
12 What do the lungs do? In general, acids (H+ ions) are stimulating to neurons. As the carbon dioxide level in the blood increases,it also increases in the cerebrospinal fluid (CSF).This causes the pH to drop; especially in the brainbecause there is less buffering ability in CSF than in blood.The low pH (excess H+ ions) stimulates neurons in themedullary respiratory centers to fire more impulses to thediaphragm to increase the rate and depth of breathing.What do the kidneys do?Regulates HCO3- ions in bloodloss of HCO3- ions in blood = decrease blood pH = metabolic acidosisgain of HCO3- ions in blood = increase blood pH = metabolic alkalosis
13 pH in the Digestive System, producing HCl Parietal Cells of the stomachsecrete HCl into the stomachto disrupt the extracellular matrixand kills most bacteria thatare swallowed up with food…HCl converts inactive pepsinogen (whichis secreted by chief cells of the stomach)into active pepsinPepsin begins the chemical digestionof proteins by splitting the polypeptidesinto smaller polypeptides…
14 Esophagus“peristalsis”Lumen of the StomachSmall Intestine
15 H2CO3 HCO3 = carbonic acid (H+ donor) responds to a rise in pH [H+] = bicarbonate (H+ acceptor) responds to a drop in pH
16 The Stomach—secretion of HCl Movement of molecules by active transport or facilitated diffusionParietal cellLumen of stomachCl-Cl-Cl-+CO2H2OHClCapillaryBloodvesselCarbonic AcidH2CO3H+HCO3-+H+HCO3-Bicarbonate ion
17 H2CO3 H+ HCO3- + Buffer system in place to regulate pH Carbonic Acid BicarbonateHydrogen ionH2CO3H+HCO3-+Buffer system in place to regulate pH