Biochem Flashcards
Micro nutrients vs macro nutrients
Micro - single molecules
Macro - polymers - carbs, proteins, lipids, nucleotides
Essential amino acids
– Phenylalanine, histidine, isoleucine, lysine, leucine, methionine, threonine, valine and tryptophan
– Cysteine, glycine, arginine are also essential for premature babies
Examples of important AA as precursors
– His -> histamine
– Trp -> serotonin, melatonin
– Phe -> Tyr -> DOPA -> dopamine -> epinephrine
How do potassium, sodium and chlorine move through the body?
between cells and cell compartments, actively pumped rather than passive diffusion
Concentrations of potassium and sodium inside and outside cells
Intracellular - K high, Na low
Extracellular - K low, Na High
Example of symporter and anti-porter
Symporter - potassium in one direction and chlorine in same direction
Antiporter - sodium in one direction, potassium in other direction
How does the kidney maintain Na/K balance in plasma?
– Renin activates angiotensin I, which is converted to angiotensin II (by ACE), causing the secretion of aldosterone which increases reabsorption of Na and vasoconstriction ⇒ Na retained
What is hyponatremia and hypokalaemia?
Hyponatremia (low Na+)
– Can result in headaches, seizures and coma.
– Due to low Na diet and diuretic drugs, extreme fluid loss, e.g. diarrhoea.
Hypokalemia (low K+)
– Can result in weakness and muscle cramps, cardiac
arrhythmias or paralysis in extreme cases.
– Due to diuretics, or excessive diarrhoea or vomiting (e.g. bulimia)
Consequence of XS liquorice consumption
Hypokalemia it blocks 11beta-hydroxysteroid dehydrogenase
How is vitamin D involved in calcium regulation?
• During low calcium intake:
– Parathyroid gland secretes parathyroid hormone PTH
– PTH stimulates 1-hydroxylase
– PTH + calcitriol stimulate osteoclasts to mobilise bone and increase calcium resorption by kidneys
Consequences of vitamin D deficiency
- Rickets
- Osteomalacia
Vitamin B1, 2, 3 deficiency
Vitamin B1:
Beriberi, abnormal blood sugar, depression, fatigue, vomiting, gastrointestinal disorders.
Vitamin B2:
Light sensitivity, cracks / inflammation of lips, tongue, corners of mouth, dizziness, insomnia
Vitamin B3:
Pellagra (dementia, death), nausea, vomiting, fatigue, dermatitis, loss of appetite, swollen red tongue, Greater risk for some non-melanoma skin cancers.
Deficiency and XS B12?
Def: pernicious anaemia
XS: liver disease
– also used to reverse cyanide poisoning
