BCM Phys Lecture 1: Water, pH- Acid/Base

Question 1

What kind of bonds form between water molecules

Answer 1

HYDROGEN BONDS

Question 2

Explain why water molecules are very polar.

Answer 2

Oxygen has a higher electron affinity/stronger attraction for shared e- than H does.

O has a partial negative charge. H has partial positive charge.

Question 3

Five molecules of water form to create a ______ structure.

Answer 3

Tetrahedral structure by H bonding.

Question 4

What are some molecules that can H bond?

Answer 4

O, N, F

Question 5

What kind of water molecule organization occurs in ice?

Answer 5

Hexogonal water formation, which is a much more open structure. Ice is less dense than water which is why it floats

Question 6

Define the following terms:

1. Electrolyte
2. Amphipathic
3. Cation
4. Anion

Answer 6

Electrolyte: Dissociation of Molecules in water

Amphipathic: compounds that have both polar and nonpolar groups

Cations: positively charged ions

Anions: negatively charged ions

Question 7

In the partial dissociation of a weak electrolyte, what is the Keq’ eqn?

Answer 7

Keq’ = [H+][A-]/[HA]

Question 8

Water is a strong/weak electrolyte? How does water dissociate and what is the corresponding eqn?

Answer 8

Water is a WEAK electrolyte.

HOH<-> H+ + OH-

Keq = 1.8 x 10^(-16)

Note: [OH-][H+] = 1.0 x 10^ -14

Question 9

Proton donor is a _____.

Proton acceptor is a ______.

Answer 9

Proton donor is a weak acid

Proton acceptor is a weak base.

Question 10

Describe the relationship between [H+], pH, and pOH

Answer 10

Note: pH = -log[H+]

pH+pOH= 14

10^-pH = [H+]

Question 11

What are the pH values/ranges for some of the biological fluids? Example: blood, gastric juice, pancrease, urine

Answer 11

Question 12

How can you use Keq to identify the stregnth of an acid?

Answer 12

The tendency of the conjugate acid to release a proton can be assessed from Keq’. The smaller the value of Keq, the less tendency to give up the proton (and the weaker the acid)

Question 13

What is the Henderson Hasselbach equation?

Answer 13

Note: there are equal amounts of conjugate acid and conjugate base if the pH equals the pKa

Question 14

Give the equation for carbonic acid. What is really treated as the acid? And then what is the important pKa value that we glean from it to solve HH problems.

Answer 14

Carbonic acid does not last long AT ALL, thus CO2 is essentially treated as the acid.

The important pKa in this equation is that:

([H+][HCO3-])/[CO2] has a pK value of 6.1.

Question 15

Blood buffers try to keep the pH of blood at ____.

Name the blood buffers.

What happens when the bases in blood are used up?

Answer 15

pH around 7.4

HCO3- (bicarb), Hemoglobin, and HPO4- are blood buffers

When the bases are utilized, blood pH will drop significantly

Question 16

The concentrations of both ____ and ___ and pH of blood are therefore important values in clinical practice to determine acid/base status of patients.

pH less than ____ is acidosis

pH greater than _____ is alkanosis.

Answer 16

Concentrations of HCO3- and CO2

pH < 7.35 is acidosis

pH > 7.45 is alkanosis

Question 17

Metabolic acidosis occurs when_____.

Metabolic alkanosis occurs when____.

Answer 17

Metabolic acidosis: excess/buildup of organic acids (like ketone bodies in diabetes, hypoxia) OR loss of HCO3- like in diarrhea, uremia, chronic kidney failure

Metabolic alkanosis: retention of HCO3- and ingestion of bases

Question 18

Respiratory acidosis occurs when______.

Respiratory alkanosis occurs when_____.

Answer 18

Respiratory acidosis: retention of CO2 (like in emphysema, asthma, polio, morbid obesity)

Respiratory alkanosis: hyperventilation and OD on aspirin

Question 19

What are the two transport systems in the human body that transport CO2 to the lungs?

What’s the percent of total Co2 produced by cells and transported to the lungs for each system respectively?

Answer 19

There is “isohydric transport” of CO2, where CO2 is transported as HCO3- (bicarb). Roughly 70-80 % of CO2 produced by cells is transported to the lungs via this system.

The other system is “transport of CO2 as Carbamino-Hb”, and roughly 15-20% of CO2 produced by cellss is transported to the lungs via this system.