Week 3- Alcohol & Water Balance Flashcards
Alcohol Absorption
- Absorption is rapid, as it does not require digestion: in the stomach (~20%) and small intestine (80%) by simple diffusion
- Cannot be stored has priority over all other energy sources in metabolism (is toxic for the body)
Alcohol energy value
7kcal or 29kJ per gram of alcohol
Standard drink
10g of alcohol in Australia
Alcohol by volume
number of millilitres (mL) of pure ethanol present in 100 mL
What is the rationale to qualify this quantity a standard alcoholic drink in Australia
Based on the assumption that the liver metabolises 10g of alcohol per hour (varies between 5-10g depending on body size and sex)
BAL/BAC
Blood alcohol level/content
What does a BAL of 0.07 mean in terms of alcohol concentration?
A BAL of 0.07 means that there is 0.07g of alcohol in 100mL of the person’s blood
The person will be
- Talkative, acts and feels self confident,
impaired judgement and movement, inhibition reduced
Alcohol Concentration effects by BAL/BAC
0.01-0.05 (0.01-0.05g/100mL): talkative, relaxed, more confident
0.05-0.08 (0.05-0.08g/100mL): Talkative, acts and feels self confident,impaired judgement and movement, inhibition reduced
0.08-0.15(0.08-0.15g/100mL): Speech slurred, impaired balance and coordination, reflexes slowed, visual attention impaired, unstable emotions, nausea and vomiting
0.15-0.30 (0.15-0.3g/100mL): Unable to walk without help, apathetic, sleepy, laboured breathing, unable to remember events, loss of bladder control, possible loss of consciousness
>0.3g /100mL: Coma, death
Australian Guidelines 1
Guideline 1: Reducing the risk of alcohol-related harm over a lifetime
- For healthy men and women, drinking no more than two standard drinks on any day reduces the lifetime risk of harm from alcohol-related disease or injury.
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Australian Guidelines 2
Guideline 2: Reducing the risk of injury on a single occasion of drinking
- For healthy men and women, drinking no more than four standard drinks on a single occasion reduces the risk of alcohol-related injury arising from that occasion.
Australian Guidelines 3
Guideline 3: Children and young people under 18 years of age
For children and young people under 18 years of age, not drinking alcohol is the safest option.
Australian Guidelines 4
Guideline 4: Pregnancy and breastfeeding
Maternal alcohol consumption can harm the developing fetus or breastfeeding baby.
- For women who are pregnant or planning a pregnancy, not drinking is the safest option.
- For women who are breastfeeding, not drinking is the safest option
Binge drinking
Drinking with the intention of getting absolutely intoxicated in a short period of time
ICF
Intracellular fluid
- 2/3 of body water
ECF
Extracellular fluid
- interstitial and intravascular (plasma)
- increased in obesity
Body fluid also contains
- solutes: electrolytes
- cations and anions
Water distribution changes with growth and ageing
- total water decreases
- ICF increases
- ECF decreases
in adult …% of body weight
55%
Lean bodies have more water as % body weight
obese individuals
Water balance
– Sodium-potassium-ATPase pump (active transport)
• Used to move ions against their concentration gradient
- high concentration Na+ outside cell
- high concentration K inside cell
• Water follows Na+
Electrolytes in ICF and ECF
screenshotted
Electrolytes
elements that separate into ions in water make the water able to conduct electrical current. Include sodium, chloride, calcium and potassium etc. Electrolytes composition of plasma is similar to that of sea water. Concentration of Cl- parallels that of Na+.
Functions
- Blood volume
- Precursor of bodyfluids
- Solvent tometabolic and biochemical processes
- Temperature regulation
- Waste products removal:
Blood Volume
transport of nutrients and O2
Precursor of body fluids
saliva, joint lubrication, bile…
Temperature Regulation
- High specific heat: rises slowly, resists temperature fluctuations
- Sweat: 99% H2O. Heat energy from skin evaporates sweat
Waste product removal
compounds are made water soluble (conjugated in enterocytes and hepatocytes) for clearance via urine
needs
– Vary with body size, physical activity, environmental
conditions and dietary intake
Kidneys are the …
main regulatory units for water balance, responding to biochemical signals
Nephrons
= functional unit – Bowman’s capsule – Glomerulus and capillary network – Proximal convoluted tubule – Distal convoluted tubule – Collecting duct • Urine formation: glomerular filtrate, reabsorption of compounds into blood • 99.5% of Na is reabsorbed • Active reabsorption of Na+ results in passive reabsorption of Cl-, HCO3- and water
Biochemistry in low bp - RAS
- Renin is an enzyme secreted by the kidney when sodium or blood volume are decreased, leading to decreased blood pressure (BP)
- Renin converts Angiotensinogen (produced by the liver) to Angiotensin I
- Angiotensin I (inactive), converted to angiotensin II (active) by angiotensin converting enzyme (ACE)
- Angiotensin II causes restriction of small blood vessels resulting in increased BP
- Angiotensin II also promotes release of aldosterone from the adrenal cortex
Aldosterone Pathway
- Aldosterone (secreted from adrenal cortex) stimulates Na+ reabsorption
- Results in increased ECF osmolality
- Promotes fluid retention because water follows Na+ • Increases BP by increasing the water volume
ADH pathway
- The output of urine is also controlled by the hypothalamus, which triggers the posterior pituitary gland to secrete anti-diuretic hormone (ADH, also known as vasopressin)
- ADH is released when body water is low (perceived as low BP by baroreceptors)
- ADH increases water permeability of distal convoluted tubule and collecting duct in the kidneys
- ADH thus promotes water reabsorption / reducing urine output, resulting in raised blood volume and BP
biochemistry in high BP
- Atrial natriuretic factor (ANF), released by atrial myocytes (heart) in response to raised blood pressure
- ANF acts to reduce water and sodium concentration in the circulation by promoting sodium excretion, and thus water to return BP to normal by reducing the blood volume
ADH
- released in response to increased solutes concentration in the blood.
