Revision Questions - week 3 Flashcards
3 metabolism pathways of alcohol
ADH pathway – low to moderate intake 3-7drinks per week)
MEOS pathway – moderate to excessive intake (7-14 drinks per week)
Catalase pathway in peroxisomes - excessive intake (<14 drinks per week)
ADH pathway
- occurs in gastric cells and mainly hepatocytes
- converts ethanol to actaldehyde
- NAD+ reduced to form NADH
- acetaldehyde moves to mitcohondria and is metabolized by ALDH2 to acetate
- acetate leaves mitochondria to extra hepatic tissue for further metabolism to actely coa
acetyl coa can then be used for ketone body production or lipogenesis or CAC)
MEOS pathway
- Occurs in hepatocytes
- Activated when ADH cannot keep up
- Requires oxidation of NADPH to NADP+ and consumes ATP
- same outcome as ADH as well as free radicals
assists in building a tolerance to alcohol over time
Catalase pathway in peroxisomes
- In hepatocytes and other cells
- Oxidation occurs in peroxisome via peroxisomal catalase
- uses hydrogen peroxides to form acetaldehyde and H2O
- same outcome as ADH
What is the reason for alcohol intolerance?
caused by a genetic condition in which the body can’t break down alcohol efficiently
What does 5% alcohol volumes mean?
0.05g of alcohol per 100ml
How much alcohol is in a standard drink? What is this based on?
10g alcohol assuming liver metabolises 10g of alcohol per hour
How is the concentration of alcohol in a beverage determined?
Percentage of pure alcohol in a beverage
How many standard drinks are contained in 1L of bear at 4.5% alcohol volumes
1000 *0.045 *0.789=?
What is the J curve and what does it say?
refers to a dose response relationship
In alcohol context
- 0 exposure - no benefit
- optimal dose - optimal benefit (it is an association) e.g. cardiovascualr health - antioxidant high HDL, better endothial function
- high dose - no extra heatlh beneift and increase health risk e.g. liver failure
What are typical acute effects of alcohol abuse?
- Chronic liver disease
- Wernicke-Korsakoff Syndrome
- Fat soluble vitamin deficiencies: A,D, E and K
- Decrease absorption of minerals
What are the typical outcomes of chronic alcoholism on the liver?
Cirrhosis can be due to:
- Increased concentration of acetaldehyde
- Accumulation of fat in liver resulting in cellular inflammation and damage overtime
- Production of free radicals from excessive alcohol metabolism, and reduced activity of antioxidant factors due to poor nutrition
What are the outcomes of chronic alcoholism on nutrition status?
Protein and energy malnutrition and deficiencies of vitamins and minerals
What is Wernicke Korsakoff syndrome? Describe the reasons it develops and the outcomes.
Thiamin deficiency because of chronic alcohol abuse (decrease thiamin intake and absorption and increased excretion in urine)
What is BAL? What does a BAL of 0.07 mean? How long does it take to return to a BAL of 0.00?
- BAL is blood alcohol level
- BAL 0.07 means 0.07g of alcohol in 100ml of blood
- Takes an hour to break down 5-10grams
Describe the mechanisms by which the body increases water volume and thus increases blood pressure
RAAS
Describe the mechanisms by which the body decreases water volume and thus reduces blood pressure
ANF
RAAS
- Renin is an enzyme secreted by the kidney when sodium or blood volume are decreased, leading to decreased blood pressure (BP)
- Renin converts Angiotensinogen (from liver) to Angiotensin I
- Angiotensin I (is 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 (secreted from adrenal cortex) stimulates Na+ reabsorption
- Results in increased ECF osmolality
- Promotes fluid retention (water follows Na+) • Increases BP by increasing the water volume
ANF
- released by atrial myocytes
(heart) in response to raised blood pressure - acts to reduce water and sodium load in the circulation by promoting sodium excretion to return BP to normal
How is body water compartmentalised? What are the various components?
- 4L blood and lymph
- 11L interstial fluid
- 25L fluid found inside every type of cell
What are electrolytes? Which electrolytes are found in the ECF and in the ICF?
- Electrolytes are compounds that separate into ions in water and are able to conduct electrical current
- ICF electrolytes – potassium, magnesium, phosphate and sulfate
- ECF electrolytes – sodium, calcium, chloride and bicarbonate
What are the effects of dehydration on the body?
ranges from thirst to death (e.g. tingling in arms, dizziness, increas weakeness, muscle cramps)
What are the effects of hyper- hydration on the body?
– Concentration of electrolytes is diluted, especially sodium = hyponatremia
– Water from diluted blood is pulled into cells by osmosis
– Diluted blood and swollen cells can cause headache, blurred vision, muscle cramps
What is the role of water in physiology?
- Blood volume, transport of nutrients and O2
- Precursor of body fluids: saliva, joint lubrication, bile etc
- Solvent to metabolic and biochemical processes
- Temperature regulation
• High specific heat: rises slowly, resists temperature fluctuations
• Sweat: 99% H2O. Heat energy from skin evaporates sweat - Waste products removal: compounds are made water soluble (conjugated in enterocytes and hepatocytes) for clearance via urine
What are the NRVs for water?
NRV is the adequate intake
determined by looking at population studies
consumed as fluids
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+
symptoms of dehydration at 4%
- Dry mouth
- Reduced blood volume and blood pressure (BP)
- Impaired performance
- Headache
- Reduced urine
- Fatigue
symptoms of dehydration at 7-10%
Very dry mouth Sunken dry eyes Low urine volume Dizziness and poor balance Rapid heart beat Rapid and feeble pulse Exhaustion Delirium and collapse
Absopriton of alcohol
20% in stomach
80% SI
not digested
