BMS02-1006 pH & Buffering

Question 1

pH

Answer 1

H conc

Question 2

What type of H

Answer 2

Free ones not bound ones

Question 3

Blood pH

Answer 3

7.35-7.45

Question 4

Living pH range

Answer 4

7-7.8

Question 5

What is out of normal range called? (2)

Answer 5

Acidosis

Alkalosis

Question 6

How do we get acids? (4)

Answer 6

Food
Protein breakdown
Incomplete ox of fat or glucose
Carbon dioxide

Question 7

What regulates pH in the body? (3)

Answer 7

Blood buffers
Lungs
Kidneys

Question 8

% of water in men, women, babies and elderly?

Answer 8

Babies - 73%
Elderly - 45%
Men - 60%
Women - 50%

Question 9

Molar of water?

Answer 9

55.6M

Question 10

When does pH = pKa

Answer 10

Half the equivelace point

Question 11

pKa=

Answer 11

-log Ka

Question 12

What is Ka

Answer 12

Diss constant

Question 13

What is pKa?

Answer 13

The pH when half the acid is diss, acid = conjugate base

Strong base and excess weak acid

Question 14

What does a low pKa indicate?

Answer 14

Strong acid

Question 15

Henderson-Hasselbalch equation

Answer 15

pH=pKa+log(A/HA)

Question 16

Buffer

Answer 16

Minimizes pH changes on addition of small volumes of acid or alkali

Question 17

What makes a buffer

Answer 17

Weak acid and base

Question 18

When does a buffer work best?

Answer 18

At its pKa therefore you know which pH it works best at

Question 19

Where does the HCO3- buffer act?

Answer 19

Blood and saliva

Question 20

What is the pKa of H2co3 to HCO3-

Answer 20

6.1

Question 21

What is the pKa of H2PO4 - to HPO4 2-

Answer 21

6.8

Question 22

What is H2CO3 proportional do?

Answer 22

pCO2

Question 23

Which is the only buffering AA?

Answer 23

Histidine

Question 24

Why don’t COOH and NH2 of AA buffer well?

Answer 24

COOH pKa 2.34

NH3 pKa 9.66

Question 25

Why does histidine buffer in Hb?

Answer 25

pKa changes when its not free as neighbouring groups affect it

Question 26

pKa in oxy and deoxy Hb

Answer 26

Oxy 6.8 | Deoxy 7.8

Question 27

Critical pH & value

Answer 27

Highest pH at which there is a net loss of mineral from the teeth 5.5

Question 28

Why is it only roughly 5.5?

Answer 28

Solubility of enamel varies with pH as its constantly in saliva which varies in Ca and K ions at times

Question 29

What does critical pH depend on?

Answer 29

Ionic product of CaP in saliva, which the amount of Ca decides

Question 30

What does this mean?

Answer 30

Changed the ions concentrations means you can lower the critical pH so it doesn't demineralise as quickly

Question 31

What happens in the conc of either ions is too high?

Answer 31

It become destabilised and forms a ppt known as calculus

Question 32

What is the stephans curve?

Answer 32

A way to asses carciogenicity (tooth decay causation) of different foods

Question 33

What are local anaesthetics?

Answer 33

Weak bases

Question 34

What are the 2 forms and why?

Answer 34

Unionised and ionised, the unionised is able to cross the membrane