Mod.A. Bio Lec2:Homeostasis of pH

Question 1

pH

Answer 1

measure of The acidity or alkalinity of a

solution

Question 2

Acid

Answer 2

is a substance that acts as a

H+ (proton) donor

Question 3

Base

Answer 3

is a substance that combines
with a H+ i.e. H+ acceptor
OR : substances which produce
hydroxyl ions

Question 4

The homeostasis of the body fluids at a Normal arterial blood pH is between :

Answer 4

7.35-7.45

Question 5

If blood pH moves to much below 6.8 or above 7.8,

Answer 5

cells stop functioning and the patient dies

Question 6

The more H+ conc.

Answer 6

the more acidic the solution and the LOWER the pH

Question 7

The lower H+ conc.

Answer 7

the more alkaline the solution and the HIGHER the pH

Question 8

Sources of Hydrogen Ion

Answer 8

1-Metabolism of
carbohydrates
and fats
Produce CO2
(volatile acid)

2-metabolism of protein
التي تحتوي AA S أي
تنتج sullfer على
sulphuric acids

3-metabolism of
phospholipids
تنتج
phosphoric acid

Question 9

Types of acids: (2)

Answer 9

VOLATILE ACIDS. FIXED ACIDS

Question 10

Volatile acids:

Answer 10

Produced by oxidative metabolism
of CHO, Fat, and Protein.
Excreted through LUNGS as CO₂
gas

Question 11

Fixed acids:

Answer 11

Acids that do not leave solution, once produced they
remain in body fluids until eliminated by KIDNEYS
E.g. Sulfuric acid, phosphoric acid, and organic acids
are most important fixed acids in the body

Question 12

Why Is Normal pH Essential?

Answer 12

1-Maintain Body hemostasis Enzyme activity

2-Acid destroys cell membranes مثال : Lactate acid can destroy the cell membrane

3- Alteration of K+ levels. and Delivery of O2

Question 13

Acidosis:

Answer 13

Physiological state resulting from
abnormally low plasma pH
–Too much acid –Too little base
–Acidemia: plasma pH < 7.35

Question 14

Alkalosis:

Answer 14

Physiological state resulting from
abnormally high plasma pH
–Too much base –Too little acid
–Alkalemia: plasma pH > 7.45

Question 15

Rates of Compensation : 3

Answer 15

1•Buffers function almost instantaneously
2•Respiratory compensation take several minutes
3•Renal compensation may take several hours to days

Question 16

Buffer Systems

Answer 16

Is the systems that maintain a normal pH or resist changes in pH.

يعتبر* :First line of defense

مدة عمله * : act instantaneously short-term solution to the problem of excess H+.

Question 17

Most important buffers are :4

Answer 17

1-bicarbonate
2-phosphate
3-protein
4-ammonia

Question 18

most important

Extracellular buffer

Answer 18

bicarbonate

Question 19

a buffer is made up of

Answer 19

two compounds, called a buffer pair.

1- one of the pair is an acid 2- the second of the pair is a base

Question 20

Bicarbonate buffer system:

Answer 20

Most important buffer system in the plasma
• Buffer all fixed acid, but not volatile acid
• Buffer capacity is strong
مكان عمله * : in all tissues that contain carbonic anhydrase
(found mainly in erythrocytes and kidneys.).

Question 21

Phosphate buffer system:

Answer 21

1-not found in high
concentrations in all tissues.
2-Its concentration in
plasma is very low.
3-It is mainly an intracellular buffer and
a renal tubular buffer.

This buffer system consists of :
weak acid

1-dihydrogen phosphate ions (H2PO4
as hydrogen-ion donor

base

2-hydrogen phosphate ions (HPO4
as hydrogen-ion acceptor

Question 22

Most important buffer system in body cells.,Also in the blood. ?

Answer 22

protein buffer system

Question 23

in albumin:

Answer 23

16 histidine -

buffer in plasma.

Question 24

in hemoglobin:

Answer 24

38 histidines -

buffer in the RBC’s.

Question 25

Steps of Hb buffer system:

Answer 25

1- : CO2 diffuses across RBC membrane

2- As carbonic acid dissociates : يتكون

Bicarbonate ions
diffuse into plasma
 Hydrogen ions are
buffered by
hemoglobin molecules

Question 26

The lung regulates the ratio of [HC03

-]/[H2CO3] to approach

Answer 26

20/1

Question 27

The respiratory buffering system uses

Answer 27

bicarbonate

Question 28

how does the respiratory buffering system work:

Answer 28

Eliminate or Retain CO₂ (controls CO2 levels )

Hyperventilation :

leads to loss of CO2 and creates
alkaline conditions

Hypoventilation:

leads to retain of CO2 creates
acid conditions

Question 29

The renal buffer system uses

Answer 29

bicarbonate, phosphate and ammonium.

Question 30

Normal pCO2 level

Answer 30

35-45

Question 31

Normal HCO3 level

Answer 31

22-28

Question 32

Primary problems with C02 excretion are reflected in PC02;

these are called

Answer 32

Respiratory

Question 33

Primary problems with hydrogen ion production or excretion

are reflected in the [HC03-] and these are called

Answer 33

Metabolic