Fluid and Water, Alcohol and Salt

Question 1

Name the 3 minerals/electrolytes in Salt

Answer 1

Sodium (Na)

Chlorine (Cl)

Potassium (K)

Question 2

What form is the majority of dietary salt in?

Answer 2

Sodium Chloride - NaCl

Question 3

Explain intake of Sodium (mg) Chloride (mg) and Sodium Chlorides (g) based on 1 mmol or 1g

Answer 3

1 mmol pf Sodium = 23mg

1 mmol of Chloride = 35.5 mg

Salt is NaCl in a ration of 1:1. The atomic mass of Salt is 23 + 35.5 = 58.5

1 g of Sodium = 2.5g of Salt

(58.5 / 23 = 2.54g)

Question 4

Explain the physiological function of sodium in the body

Answer 4

Na + = Principle cation in extracellular fluid

Transporter - substrates, phosphates, amino acids, glucose and galactose

Excitability of muscle/nerve cells

Question 5

Explain the physiological function of salt in the body

Answer 5

Maintaining acid-base equilibrium

Maintaining osmotic pressure

Control of body water balance metabolism is predominantly due to sodium

Question 6

Explain sodium metabolism

Answer 6

Sodium concentration is tightly regulated by kidney excretion and retention

If sodium intake increases:
Water is retained and ECF volume rises, BP increases
‘Natriuretic’ factors increases sodium (and water) excretion

If Sodium intake falls:
Water is excreted and ECF volume falls, BP decreases
Vasoconstriction and other factors act to increase sodium and water retention

Question 7

What is the RNI for sodium for adults 11+ years. How does this compare to children RNIs?

Answer 7

1.6g Sodium = 4g salt/day

In children, RNIs are lower to take account of lower body mass and kidney maturity

Question 8

Explain why the DRV for salt is 6g/day

Answer 8

6g salt per day is estimated to reduce CVD risk by 10% and stroke by 13%

6g salt a day is higher than RNI

6g salt a day recommended by COMA and reaffirmed by SACN as an achievable popular goal, rather than an idea consumption level

Question 9

Explain role of salt in health - salt produced by the body

Answer 9

Too little salt (uncommon) - caused by excess sweating may deplete salt but body soon adapts

Too much salt (very common)

Increases calcium excretion and may affect bone health

May directly stress a weekended heart

May aggravate kidney problems

raises blood pressure and may cause hypertension which is linked to increased CHD and stroke

Question 10

What is the normal blood pressure level?

Answer 10

120/80mmHg

Question 11

What blood pressure level is classed a hypertension?

Answer 11

Blood pressure greater than or equal to 140/90 mmHg

Question 12

Explain some of the functions of salt in our food

Answer 12

Flavour

Texture

Spoilage

Question 13

Explain what alcohol is functional and structure

Answer 13

One of the four macronutrients

Supplies energy

Considered a nutrient and drug

Ethanol - C2H5OH

Question 14

Where does ethanol come from?

Answer 14

Fermentation of CHO by yeast

Naturally occurring process

C6H12O6 —> 2 C2H5OH + 2CO2

Question 15

Explain absorption of alcohol

Answer 15

Rapidly absorbed (in blood <5 minutes)

Upper GI tract

Question 16

Explain the process of metabolism for alcohol

Answer 16

Stomach ‘first pass’

Small proportion of total ingestion

1.8g/hour

Enzyme - stomach alcohol dehydrogenases (ADH)

Reduced in gastritis, H pylori infection, medication

Genetic differences in stomach ADH

Question 17

Explain what ethanol and broken down into and the enzymes that do this

Answer 17

Ethanol to Acetaldehyde by the enzyme alcohol dehydrogenase

Acetaldehyde to acetate by the enzyme acetaldehyde dehydrogenase

Question 18

Explain nutritional content of alcohol

Answer 18

Energy ~ 7 kcal/g

Metabolism requires thiamine (Vitamin B1)

Increased intake of alcohol require more thiamine

Body has limited thiamine reserves

Question 19

Explain the impact on health on excessive alcohol intake

Answer 19

Liver damage, hepatitis and cirrhosis

GI tract damage, gastritis, pancreatitis

Cardiovascular disease, hypertension and stroke

Cancer e.g. mouth, oesophagus, breast, stomach

Brain damage, dementia, mental health, including depression

Obesity

Injuries following accidents, violence

Infertility, foetal alcohol syndrome

Question 20

Explain the impacts on health to drinking alcohol

Answer 20

Increased HDL cholesterol

Increases insulin sensitivity

Decreases inflammation

Possible effects on those at risk of diabetes

Question 21

Name the factors that affect alcohol consumption in the UK

Answer 21

Overall picture

Age

Gender

Income

Geographic location

Question 22

What percent of Earth’s water is fresh?

Answer 22

2.53%

Question 23

Explain how cholera spreads in water

Answer 23

Vibro cholerae - bacterium with flagellum

Lives in salt and fresh water

Only infects humans

Acute intestinal infection

1-5 day incubation period

Attaches to wall of gut and produces toxin

Gut wall produces diarrhoea

Dehydration

5-50% of cases results in death

Question 24

Explain Cryptosporidiosis

Answer 24

Single celled parasite

Ubiquitous

Causes morbidity in healthy people, fatal to people with deficient immune system

Question 25

Explain how water is treated in developed countries

Answer 25

Most methods of water treatment involve use of filtration at some stage to remove potentially harmful contaminants.

In developed countries, water treatment is carried out on a large scale.

In many developing countries that do not have the infrastructure in place to provide treated water the only practical method is to employ point-of-use treatments.

Question 26

Why is fluid (water) important in our bodies?

Answer 26

Water makes up about 60-70% of body weight

Question 27

Explain absorption and metabolism of water?

Answer 27

Digestion and absorption of water much quicker than food - liquids rapidly absorbed into the bloodstream.

Kidneys are continually producing urine, excess liquids are quickly eliminated via urine.

Water absorption can occur 5 minutesafter ingestion and peaks around 20 minutes after ingestion.

When water is drunk, it enters the stomach and quickly enters small intestine.

Nearly all water is absorbed into the bloodstream from small intestine.

Colon also absorbs some water.

Excess fluid absorbed in blood is filtered by kidneys, which produce urine that is transported to the bladder.

Question 28

Explain excretion of water?

Answer 28

Urine: After the kidneys process water, much of it is excreted throughurine (1-2 l/day but can vary

Sweat: When body needs to control its temperature, water lost in form ofsweat. Usually 800-1000ml/day. In hot climate can be 500ml/hr but can be as high as 2500ml/hr

Stool:Contains a certain amount of water that helps make it heavy enough to exit the body

Lungs: Water vapour ~ 300ml/day. Increased in very dry air or if hyperventilating

Insensible losses = losses from skin and lungs. Make up about half of losses

Question 29

Explain fluid requirements

Answer 29

Young infants: 150ml/kg

Toddlers: ~ 100ml/kg

Adult (18-60): 35 ml/kg

Adults (60 +) = 30ml/kg

Question 30

Why do children have higher fluid requirements?

Answer 30

Body Composition

Higher surface to mass ratio

Increased respiratory and metabolic rate

Immature renal function

Decreased thirst sensitivity

Body cooling and heat tolerance