sodium

Question 1

is sodium the main intra cellular or extracellular ion

Answer 1

major extracellular ion – so concs outside cell are higher

Question 2

Na conc in cells is low and varies with what and give an example

Answer 2

cell type
eg. 3-4 mmol/l in muscle and 20 mmol/l in red blood cells.

Question 3

does Total body sodium vary between the sexes

Answer 3

yes

Question 4

how many g of sodium is there in the average adult

Answer 4

90 - 100g

Question 5

what the conc of sodium in men and women in mmol/kg

Answer 5

adult male 52-60 mmol/kg
adult female 48-55 mmol/kg

Question 6

what percentage of body sodium is intracellular

Answer 6

10%

Question 7

what percentage of body sodium is extracellular

Answer 7

50%

Question 8

what percentage of body sodium is in skeleton

Answer 8

40%
(35-40 g)
(non-exchangable Na pool – i.e. not readily available)

Question 9

Sodium content of unprocessed foods varies between what

Answer 9

0.1 and 3.3 mmol/kg

Question 10

Processed foods have higher sodium content of what and why

Answer 10

11 to 48 mmol/100 g as is added

Question 11

what is sodium added to foods for

Answer 11

enhancing taste, and preservative as has antibacterial qualities (sodium nitrate).

Question 12

whats the link between processing level and sodium content

Answer 12

Higher the level of processing the higher the level of salt in the food

Question 13

what percentage of our salt in the diet comes from bread and cereals

Answer 13

30-35%

Question 14

what percenatge of diet intake of salt comes from salt addition during cooking or at table

Answer 14

35%

Question 15

what do requirements of sodium depend on

Answer 15

on amount of sweat produced, so varies from country to country due to their climate temp

Question 16

how much NaCl is adequate in temperate climates

Answer 16

2-3 g NaCl
(equivalent to LRNI; 4 g NaCl is equivalent to RNI)

Question 17

why is sodium often expressed as sodium chloride

Answer 17

sodium is always present as a salt so is why its always expressed as this as this is what we consume

Question 18

what are the RNI and LRNI for sodium on its own

Answer 18

LRNI: 25 mmol/d (conc) 575mg/d
RNI: 70 mmol/d (conc) 1 600 mg/d

Question 19

what is the UKs intake of salt and which gender consumes the most

Answer 19

9-10 g/d (men usually consume more than women).

Question 20

Excess sodium is normally excreted where

Answer 20

in the urine

Question 21

explain sodium content in different foods in relation to processing

Answer 21

Low salt options are natural food – such as buying eggs and cooking them at home. Buying them processed will have added salt. Same happens with ready made soups. Same happens with fruits and veg such as with buying pre baked potatoes and chips, and ready meals.

Pre made sauces and seasonings have added extra salt

Desserts and sweet snacks also have extra salt added

Question 22

what foods are fairly low in sodium

Answer 22

Wheat flour
Rice
Beef
Herring
Milk (cow)
Potatoes (boiled)
Carrots
Tomatoes (raw)

Question 23

what foods are high in sodium

Answer 23

processed foods
white bread
rice crispies
beef sausage
bacon
tinned carrots
salted butter

Question 24

what is the RNI for children under age 4 for sodium

Answer 24

500 mg/d equivalent to only 1.25 g salt/d

Question 25

why can babies under age 1 not consume sodium

Answer 25

as have undeveloped kidney function and so cannot handle Na+

Question 26

what happens to milk for babies as they cannot consume sodium

Answer 26

cow’s milk not suitable infant feed

breast milk provides about 500 mg NaCl/d, so human milk is fine

But 2-3 x this in cow’s milk than in breast milk

Infant formula/baby foods should be low salt. infant formulas removes the salt from the milk.
People who are unknowledged on this should be educated

Question 27

why do we need sodium

Answer 27

Regulates
- electrolyte balance
- acid/base balance – these are tightly regulated
- conductive capacity of nerves
- muscle contractions
- production of adrenaline
- production of amino acids

Most important cation (electrolyte) in maintaining the volume of extracellular fluid (and osmotic concentration of the intracellular fluid)

Question 28

what does changes in levels of sodium in extracellular fluid cause

Answer 28

movements of water into or out of cells
So if levels of sodium get high in extracellular fluid then it removes water out of tissues causing dehydration which is adverse to their function

Question 29

Sodium in body is regulated via the what

Answer 29

renin-angiotensin-aldosterone system, which is under homeostatic control. Its very readily absorbed so will easily enter body.

Question 30

what happens in states where sodium is depleted

Answer 30

aldosterone levels are increased and reduces urinary excretion of sodium.

Question 31

aldosterone levels are controlled by what and what does it do

Answer 31

not sodium levels

The system is activated by loss of blood volume which causes a fall in blood pressure e.g. due to dehydration; haemorrhage.
Aldosterone system will reduce the urinary excretion reducing loss of sodium so it can be take back into body, dragging water with it, so conc can increase

Question 32

describe high blood pressure

Answer 32

High blood pressures caused by generated force by the extra water and sodium in blood increasing the vein diameter and causing more force required to push the blood to the tissues

Question 33

what is the definition of hyponatraemia

Answer 33

low level plasma Na+
indicates severe Na+ depletion.

Question 34

what causes hypoantraemia

Answer 34

• e.g. excessive sweating (marathon in hot climate) – so why they take isotonic drinks
• e.g. fluid losses: diarrhoea#
• e.g. disease states: diabetes mellitus, Addison’s disease, medications renal failure –Na+ loss in urine

Question 35

Any reduced body sodium pool leads to reduced what

Answer 35

extracellular fluid volume.

Question 36

explain the impact of water excess and low sodium conc

Answer 36

ADH hormone controls excretion off water, ADH syndrome causes extra storage of water(cancers), renal failure, cirrhosis etc. – known as a dilutional hyponatraemia – low sodium conc as more water so diluting the sodium conc as in water excess.

Water excess cant occur by drinking too much water as we would pee it out. Something would have to disrupt the mechanism

Question 37

what is the definition of hypernatraemia

Answer 37

high level plasma Na+

Question 38

what does hypernatraemia indicate

Answer 38

H2O deficiency (rarely Na+ excess) i.e. Dehydration, but not always dehydration

Question 39

explain insufficient water intake in relation to Hypernatraemia