0506 intro to acid base regulation VY Flashcards

1
Q

What is the bronsted definition of an acid and base

A

Acid - any chemical substance that can donate a hydrogen ion. Base - any chemical substance that can accept a hydrogen ion

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2
Q

What is pH (what does it quantify, what is the formula)? What does a pH shift of 1 indicate

A

pH is a measure of the amount of free hydrogen ions, pH = -log [H+}. A pH shift of 1 = a 10 fold change in [H+]

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3
Q

Even a small change in internal pH can affect the biological activity of an organism. What are some biological components that can be affected?

A

Enzymes, ligands, ion channels, transporters, and structural proteins are all sensitive to pH changes

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4
Q

What is the significance of a bell curve shape of enzymatic activity when graph across a pH axis

A

It shows the optimal pH level of activity for a certain enzyme. It is important because it demonstrates that enzymes have an optimal level of normal activity and deviations from this pH will have consequences in terms of enzyme efficiency

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5
Q

What is the key principle behind acid-base balance in our body

A

The amount of acid excreted per day must equal the amount produced per day

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6
Q

What is the pH value of arterial blood plasma? What are 2 areas of the body with low and high pH

A

Blood plasma is 7.4pH. Low pH is anywhere that is acidic (Gastric secretions in stomach, lysosomes, etc). High pH is anywhere that is basic (e.g. pancreatic fluid in pancreas)

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7
Q

What is the definition of a buffer? Why are they so biologically significant

A

A buffer is any substance that reversibly consumes or release H+. They are very important in biological systems because they contribute to pH homeostassis (minimise pH changes)

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8
Q

Describe the pattern of undissociated acid, free anion and free H+ you would see in a strong acid

A

High free anion and free H+. Low undissociated acid

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9
Q

Describe the pattern of undissociated acid, free anion and free H+ you would see in a weak acid

A

Low free anion and H+. high undissociated acid

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10
Q

What are monoprotic and polyprotic acids? How many equivalence points do each have

A

Monoprotic acids are acids that can only donate one proton (hydrogen ion). They have one equivalence point. Polyprotic acids are acids that can donate more than one proteon. They have multiple equivalence points

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11
Q

What is buffering power? Why is the optimal pH in terms of buffering power important?

A

Buffering power describes the number of moles of a strong acid or base that is needed to shift the pH by 1. Optimal pH for buffering power is important because that is when a buffer is most effective at regulating pH changes

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12
Q

What is the advantage (in terms of buffering power) of having multiple buffers rather than one buffer in our bodies

A

Multiple buffers often have multiple optimal pH ranges (in terms of buffering power). This means that our body is more capable of counteracting pH change over a wider scale of pH values because we have a variery of buffers

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13
Q

Where would you expect to find buffers in our body

A

Interstitial fluid, blood, intracellular fluid, urine, bone

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14
Q

How does CO2 make our bodies more acidic

A

Although CO2 is not originally an acid nor a base (no pH change), as it enters water, a series of reaction means it produce H+ ions . CO2 +H2O => H+ and HCO3-

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15
Q

Using the nernst equation, why might cytosolic pH (pH inside a cell) be lower than the predicted value based on an extracellular pH and membrane potnetial

A

Because our cells have active mechanisms to extrude H+. This is how they regulate intracellular pH. The nernst equation does not account for this

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16
Q

Describe an intracellular response to HCl being administered into a cell (acidosis)

A

Na/H exchanger pumps out H+ and brings in Na, lowering intracellular [H+]

17
Q

What is the affect of a higher than normal pH value in the extracellular environment on the Na/H exchanger on a cell membrane

A

A high extracellular pH would stimulate the exchanger (pumping our H+ ions to lower extracellular pH). Vice versa for a low extracellular pH

18
Q

Describe an intracellular response to KOH being administered into a cell (alkalosis)

A

A HCO3-/CL exchanger removes HCO3- and pumps in Cl-, lowering intracellular concentration of [HCO3-]

19
Q

What is the affect of a higher than normal pH value in the extracellular environment on the HCO3-/Cl- on a cell membrane

A

A high extracellular pH would inhibit the exchanger (AS there is already a basic extracellular environment). Vice versa for a low extracellular pH

20
Q

What is the affect of an acidic and basic extracellular environment on intracellular response to acidosis

A

Acidic extracellular environment means intracellular regulation of acidosis will be slower (longer to neutralise). Basic extracellular environment means intracellular regulation of acidosis will be faster (faster to neutralise)