WEEK 1

Question 1

What are the statistics of total body water in men and women?

Answer 1

60% of body weight in men and 50% in women

Question 2

Intracellular fluid makes up how much of total body water?

Answer 2

2/3

Question 3

What is the statistic of interstitial fluid in the body?

Answer 3

Interstitial fluid volume is 3/4 of the extracellular fluid volume

Question 4

What are the statistics regarding interstitial fluid and extracellular fluid volume?

Answer 4

Interstitial fluid volume is 3/4 of the extracellular fluid volume (ECFV) and plasma is about 1/4 of the ECFV

Question 5

What happens with TBW regarding ageing?

Answer 5

TBW percentage decline with ageing

Question 6

What is the correlation between body fat and TBW?

Answer 6

as % of fat increases, TBW decreases

Question 7

What is the relationship between water and K+, Glucose, ATP and Proteins?

Answer 7

Water acts as a solvent for K+, Glucose, ATP and Proteins

Question 8

Describe the mechanism of why water is a dipolar molecule

Answer 8

Oxygen is more electronegative than hydrogen therefore the electrons shared in the covalent bond are attracted towards the Oxygen atom giving oxygen a partial -ve charge and hydrogen a partial +ve charge, making the molecule dipolar

Question 9

Knowing that H2O is a dipolar molecule, what does it readily dissolve?

Answer 9

Charged and polar biomolecules (e.g carboxylic acids, protonated amines, phosphate esters or anhydrides)

Question 10

Are biologically important gases such as CO2, O2 and N2 polar or non-polar?

Answer 10

non-polar

Question 11

Define ‘Hydrophilic’ molecules

Answer 11

Compounds that dissolve easily in water

Question 12

What does CO2 form in aqueous solution?

Answer 12

H2CO3 and is transported as the bicarbonate ion

Question 13

Explain the formation of H2O molecules

Answer 13

Tetrahedral arrangement of orbitals around the O2 atom allows each H2O molecule to form hydrogen bonds with as many as 4 neighbouring H2O molecules

Question 14

Explain the reasoning behind the change of state in H2O molecules

Answer 14

When there is more heat more disorganised molecules are in continuous motion, less bonds are formed, regular lattice structure is prevented which leads to a change in state
MORE HYDROGEN BONDS = MORE SOLID MATERIAL

Question 15

What is an electrolyte?

Answer 15

Ions capable of carrying an electrical charge

Question 16

What are the major cations (+) in the body?

Answer 16

Na, K, Ca and Mg

Question 17

What are the major anions (-) in the body?

Answer 17

Cl, HCO3, HPO4, SO4

Question 18

Knowing that electrolytes are unevenly distributed, where are Na+, Cl-, K+ and phosphates found in the body?

Answer 18

Na+ and Cl- are major in the extracellular fluid (ECF) and K+ and phosphates are major in cells

Question 19

What is serum osmolality affected by and what is its range?

Answer 19

Serum osmolality is affected by the concentration of blood chemicals and ranges from 275 to 295 most/kg

Question 20

What does “BUN” stand for?

Answer 20

Blood urea nitrogen

Question 21

What is the equation to calculate Serum osmolality?

Answer 21

2(Na) + Glucose/18 + BUN/1.8

Question 22

What is the difference between Isotonic solutions, Hypertonic solutions and Hypotonic solutions?

Answer 22

Isotonic solutions = Cells retain their normal size and shape since concentration of water is in equilibrium
Hypertonic solutions = Cells lose water and shrink since concentration of solutes is greater outside than inside the cell
Hypotonic solutions = Cells take on water by osmosis until they become bloated and burst since concentration of solutes is greater inside the cell than outside

Question 23

What is the difference between an acid and a base?

Answer 23

Acids are compounds that donate a hydrogen ion and bases are compounds that accept hydrogen ions

Question 24

What is the equation to calculate pH?

Answer 24

pH = log 1/[H+] or -log[H+]

Question 25

What are the causes of change in pH?

Answer 25

• Altered enzyme activity
• Membrane permeability
• CNS Activity
• Electrolyte distribution
• Increased myocardial irritability
• Decreased cellular viability
• Organ dysfunction

Question 26

What can happen in the body if the body pH increases or decreases?

Answer 26

pH decrease can lead to a loss of consciousness (depressed CNS) and pH increase (acidosis) can cause over excitability, tingling sensation and muscle twitches

Question 27

Define what a “Buffer” is

Answer 27

A substance or group of substances that tend to control the H+ ion concentration in solution by reacting with hydrogen ions of an acid added to the system and releasing hydrogen ions to a base added to the system. A buffer consists of a weak acid and its conjugate base.

Question 28

What are the fastest to slowest buffers in the human body?

Answer 28

Chemical buffer (a fraction of a second), Respiratory system (1-3 mins), Renal system (a few hours to a day)

Question 29

What are the two types of acids in the human body?

Answer 29

Volatile acids (CO2) and Non-volatile acids (Amino acids, fatty acids, nuclear acids)

Question 30

What are the different buffer systems in the body?

Answer 30

• Bicarbonate buffer
• Phosphate buffer
• Plasma proteins buffer
• Haemoglobin

Question 31

What is the role of the phosphate buffer?

Answer 31

Used in producing urine and is found in small concentrations in blood

Question 32

What is the role of buffers in plasma?

Answer 32

To carry H+ and CO2 out through the lungs

Question 33

What is the mechanism behind Diabetic Ketoacidosis?

Answer 33

Free fatty acids leave adipocytes (fat cells) that are converted by the liver to acetoacetic acid and B-hydroxybutyric acid that dissociate to produce H+ ions and anions. The H+ lowers her blood pH and a metabolic acidosis known as diabetic ketoacidosis (DKA) develops.

Question 34

Define ‘Osmolality’ and what it means to have high osmolality and low osmolality

Answer 34

Osmolality = The concentration of dissolved particles of chemicals and minerals

High osmolality means there are more particles in your serum and lower osmolality means the particles are more diluted. (Osmosis is from Low osmolality to High osmolality)