water = nonionic compound. it is converted to ions in a process called ionization. water separates...
TRANSCRIPT
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).
ALL LIFE PROCESSES DEPEND ON THIS TINY IONIZATION PROCESS…
Imagine a water molecule that picks up a positively charged hydrogen proton.
When this happens, this water molecule becomes positively charged.
The water molecule that gave up the hydrogen proton becomes negatively charged
because one 1 electron remained behind.
The level of H+ and OH— ions in solution
is known as the pH scale
The proton exchange results in 2 water molecules out of every 1 billion splitting into a
positively charged H3O+ (called hydronium) ion and a negatively charge OH- (called hydroxide) ion.
Pure water, contains hydronium ions equal to 1 x 10-7 moles per liter (0.0000001 moles per liter).
In other words, the number of hydronium ions Is 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 substances
to water.
A proton donor is known as an acidacid. AcidsAcids increase the
[H+] ions in solution.
A basebase functions as a proton acceptor,
it reduces the concentration of [H+] in solution
and increases the concentration of [OH--] ions.
1 X 10-1 [H+] = pH 1 HCl or stomach acid
1 X 10-13 [OH--] = pH 1 HCl or stomach acid
[H+]
pH 1 pH 7 pH 14
[OH—]
What happens to the pH of the solution if the level of [H+] increases?
What happens to the pH of the solution if the level of [OH–] increases?
CO2
What does exhalinginto the water
add to the water?H2O
Bromothymol Blue added
CO2How does this
‘change’ the water?
Why?
CO2 + H2O H2CO3
Carbonic Acid
H2OCO2
Buffer Systems—a buffer is a moleculethat tends to either bind or release hydrogen ions
in order to maintain a particular pH
What happens when the reactions go to the right?
What happens if the reactions go to the left?
Carbonic acid
BicarbonateIon
CarbonateIon
H2CO3
HCO3 --
= carbonic acid (H+ donor) responds to a rise in pH
= bicarbonate (H+ acceptor) responds to a drop in pH
[H+]
pH 1 pH 7 pH 14
Carbonic acid
BicarbonateIon
A diabetic’s blood pH dropped to 7.23. Why?The body enters a starving state due to no insulin output; body burns stored 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 accumulate causing the pH of blood to increase = alkalosis
What happens during HYPOventilation?Carbon dioxide in blood increases; more H+ ions will accumulate causing the pH of blood to decrease
Maintaining blood pH—why?
Acidosis or Alkalosis = death
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 brain because there is less buffering ability in CSF than in blood. The low pH (excess H+ ions) stimulates neurons in the medullary respiratory centers to fire more impulses to the diaphragm to increase the rate and depth of breathing.
What do the kidneys do?Regulates HCO3- ions in blood loss of HCO3- ions in blood = decrease blood pH = metabolic acidosis gain of HCO3- ions in blood = increase blood pH = metabolic alkalosis
Parietal Cells of the stomach secrete HCl into the stomachto disrupt the extracellular matrix and kills most bacteria that are swallowed up with food…
HCl converts inactive pepsinogen (whichis secreted by chief cells of the stomach)into active pepsin
Pepsin begins the chemical digestionof proteins by splitting the polypeptidesinto smaller polypeptides…
pH in the Digestive System, producing HCl
Lumen of the
Stomach
Esophagus“peristalsis”
Small Intestine
H2CO3
HCO3
= carbonic acid (H+ donor) responds to a rise in pH
= bicarbonate (H+ acceptor) responds to a drop in pH
[H+]
pH 1 pH 7 pH 14
The Stomach—secretion of HClMovement of molecules by active transport or facilitated diffusion
Cl-
HCO3-
Cl-
H+
HCl
CO2+ H2O
H2CO3
H+HCO3-
CapillaryBloodvessel
Parietal cell
Lumen of stomach
Cl-
+
Bicarbonate ion
Carbonic Acid
H2CO3 HCO3- H++
Buffer system in place to regulate pH
Carbonic Acid Bicarbonate Hydrogen ion