Electrolytes

Question 1

Electrolytes

Answer 1

Saltsthat dissociate in solution and will carry an electric current; clinically used to mean the mineral salts of blood plasma and other body fluids.

Question 2

Common Electrolytes

Answer 2

Sodium, potassium, calcium,

magnesium , chloride, phosphorous

Question 3

Electrolytes function

Answer 3

help regulate kidney function and the retention of water.

Question 4

% of body weight that is water

Answer 4

Women: 45-50%
Men: 50 - 65%

Question 5

Daily fluid and electrolyte requirements:

Answer 5

2-3L water
50-100 mmol sodium
40-80 mmol potassium

Question 6

Daily fluid and electrolyte Requirements vary with

Answer 6

Age
Sex
Body fat content

Question 7

Normal urine output

Answer 7

> 1400 ml/day

Question 8

Water turnover

Answer 8

~ 5-10% in adults

3. 3L sedentary men
4. 5L active men

Question 9

Water requirements vary depending on

Answer 9

Dietary factors
    Physical activity level
    Environmental conditions
    Metabolism
    Health status

Question 10

UK Water intake recommendation

Answer 10

1.2L/ day for men & women

Question 11

Disease risk of unsafe water/poor sanitation

Answer 11

3.7 % of global burden of disease

6th cause of death) (1. 73m death

Question 12

Reduced availability of fresh water

Answer 12

783 million people lack access to drinking water.

2 billion people lack adequate sanitation.

By 2050 more than half the world will face water shortages

Question 13

Functions of water in the body

Answer 13

Maintaining cell structure
~ Forming a solvent within which chemical reactions in the body can take place

~ Physically transporting other nutrients and oxygen through the body via the bloodstream

~ Transporting white blood cells to fight infection via the lymphatic system

~ Enabling the body to get rid of waste products via the excretory systems, such as through the formation of urine.

~ Lubricants – synovial fluid in joints

~ Temperature regulation - sweating

Question 14

Distribution of body water

Answer 14

Total body water 45L

Extracellular fluid (outside cell)  15L
Blood or intravascular fluid    3L
Intracellular fluid (inside cell)              30L

Intercellular, interstitial or extravascular fluid 12L –>
–> Carries nutrients to the cells/ Collects waste products/ Changing water content

Question 15

Intracellular and extracellular electrolytes

Answer 15

extracellular: Na+ , Cl-, Ca++, HCO3-

Intracellular: K+, Mg++, PO4 ^3- , [protein]

Question 16

Body water gains

Answer 16

Food and drink

Metabolic water, by-product from oxidation of carbohydrates, protein and fats:

• 1g of carbohydrate produces 0.60g water
• 1g of protein produces 0.41g water
• 1g of fat produces 1.07g water

Question 17

Body water losses

Answer 17

Insensible water loss:

• Transepidermal water loss i.e lost through the skin and lungs
• Skin – occurs independently of sweating (350 ml/day)
• Lungs - Expired air saturated with water vapour (350 - 650 ml/d)

Water loss in sweat :
Perspiration: 100 – 5000 ml/day
Hot climates: 500-2500ml per hour

Water loss in urine:
Highly controlled by the kidneys ( 500-1400 ml/day)

Water loss in faeces (100 ml/day)

Question 18

Regulation of fluid balance

Answer 18

slide 14

Question 19

Anti-diuretic hormone (ADH)

Answer 19

• Secreted by the hypothalamus
• Causes the insertion of water channels into the membranes of cells lining the kidney collecting ducts, allowing water re-absorption to occur
• Without ADH, little water is reabsorbed in the kidney collecting ducts and dilute urine is excreted

Question 20

Anti-diuretic hormone (ADH) Secretion influenced by:

Answer 20

Receptors in the hypothalamus that are sensitive to increasing plasma osmolarity .
–> Increase ADH secretion

Stretch receptors in the atria of the heart - activated by a larger than normal volume of blood returning to the heart from the veins.
–> increase ADH secretion

Stretch receptors in the aorta and carotid arteries, which are stimulated when blood pressure falls.
–> decrease ADH secretion

Question 21

Abnormal water states

Answer 21

Hypotonic –> Water enters the cell; Cell expands and may finally burst.

hypertonic –> Water moves out of the cell. Cells shrink (crenation).

Isotonic - balanced

Question 22

Increased extracellular volume

Answer 22

Peripheral oedema:
Expansion of the extracellular volume by at least 2 L

Hyponatremia: cell swelling

Question 23

Cause of peripheral oedema:

Answer 23

Renal Sodium chloride retention
Heart failure
Hepatic cirrhosis
Nephrotic syndrome

Question 24

Cause of hyponatremia

Answer 24

# Loss of sodium from the extracellular fluid
# Addition of excess fluid to the extracellular fluid

The brain can’t increase its volume more than ~ 10% without causing brain injury and death.

Question 25

Protective mechanism against hyponatremia

Answer 25

If changes occur slowly the brain can transport electrolytes and organic solutes from cells into the extracellular compartments to prevent osmotic flow of water into the cells.

Question 26

Hypernatremia & cause

Answer 26

cell shrinking ``` # Loss of water from the extracellular fluid which concentrates sodium – dehydration # Excess sodium in the extracellular fluid ```

Question 27

Protective mechanism against Hypernatremia

Answer 27

promote intense thirst to protect against large increases in plasma and extracellular fluid sodium.

Question 28

mineral water

Answer 28

``` # clean water # must have at least 250 parts per million total dissolved solids. ```

Question 29

Traditional diet:

Answer 29

10-20 mmol/day Na, up to 200 mmol/day K Diet high in fruit and vegetables and no processed food. Fewer incidents of high blood press and cardiovascular disease

Question 30

Modern diet:

Answer 30

140-180 mmol/day Na, 30-70 mmol/day K Increases risk for hypertension, cardiovascular and kidney disease High potassium diet can protect against high sodium intake

Question 31

Sweat | [regulation/ problem/ solution]

Answer 31

contains sodium chloride Increased aldosterone secretion --> Increased re-absorption of sodium chloride from sweat Problem: Increased secretion of aldosterone causes increased potassium loss in urine and sweat. Athletes drinks contain enhanced sodium and potassium concentrations.