Minerals Flashcards
Iron
Most common and widespread deficiency but the fourth most abundant mineral on earth. Exists as two ions Fe2+ and 3+. But 2+ is dangerous so has to be stored as 3+ or bound to proteins. Stored in the liver.
Myoglobin
Muscle
Haemoglobin
Red blood cell
Haem absorption
Account for 67% of iron in non-vegetarian diets
Haem is released from globin in small intestine
Enter enterocyte and then broken down to Fe3+
Iron absorption
Fe3+ is reduced to Fe+ by ascorbic acid and membrane bound to ferric reductase
Absorbed by DMT-1
In cell binds to ferritin transform to Fe3+
Leaves basolateral membrane (Ferritin -MTP1 or Transferrin - IREF-1)
Binds to transferrin in plasma
Ferritin
Fe3+ storage in all cells Ferroxidase activity to convert 2+ to 3+ Two subunit H and L 24 subunits - 450kDa and spherical shape Can bind to 4500 mol of Fe In enterocyte, hepatocyte and macrophage
Transferrin
Glycoprotein transfers Fe3+ in plasma Made in liver 2 similar binding points for Fe (1/9 have Fe at both, 4/9 at one and 4/9 at neither) Once at target cell transferrin receptor TfR1 - largest affinity TfR2 - Low affinity Iron enter cell by endocytosis Endosome becomes acidified and Fe3+ is released
Iron Metabolic function
Transport and storage of O2
And erythropoiesis
Erythropoiesis
Erythroblasts - immature
Reticulocytes - Immature and haem
Reticulocytes - lose nucleus
Erythrocytes
Iron deficiency
Reduce capacity of work
Impaired mental or motor development
Reduce immune status
Iron deficiency anaemia
Electrolytes and water
Electrolyte concentration depends on volume of urine
If drink less then solute volume becomes higher leading to water leaving plasma
Thirst
Water leave plasma Reduce blood pressure Registered by sensory neurone in kidney Triggers Renin-angiotensin aldosterone mechanism Increase angiotensin II Create sensation of thirst
Reabsorption of water
Low plasma volume Low blood pressure Baroreceptors detect Stimulate posterior pituitary Release ADH Increase water reabsorption in kidney
Sodium Absorption
Sodium hydrogen exchange along apical membrane known as Enac ion channel is distal ileum
Aldosterone causes more on apical membrane
Intracellular cAMP stimulate Enac and inhibit ubiquitin ligase
Sodium leaves basal lateral membrane via Na/K ATPAse
Aldosterone also encourage the reabsorption of Na+ in loop of henle
Hypernatremia
Dehydration
Thirst
confusion
Lethargy
Salt free IV to treat
Oral solution to treat
Hyponatremia
Solute loss
Water retention
Vomiting and Diarrhoea
Burnt skin
Neurological dysfunction
Brain swelling
Decreased blood pressure
Raise serum Na+ to treat
Potassium absorption
Potassium ions brought into cell in exchange for sodium
Increases amount in colonicite
Potassium pumped out the apical or the basolateral according to demand
Controlled by insulin – acts on sodium potassium ATPase
Mostly reabsorbed in proximal convuluted tubule depending on Na absorption in distal convoluted tubule
Potassium excretion
Potassium selected ion channels along apical membrane
Potassium Function
Osmotic pressure and electrolyte balance
Determines resting membrane potential
Nerve transmission
Essential for cardiovascular, respiratory, digestive, renal and endocrine
Co-factor for enzymes in energy metabolism
Potassium Deficiency
Hypokalaemia
Hypertension
Cardiovascular disease
Low bone mineral density
Chloride Parietal cells
Cl- enters parietal cell across basolateral membrane in exchange for HCO3-
H+ is secreted across luminal membrane via H+/K+ ATPase
Cl- follows H+ via Cl- channel is regulated by Ca2+ and cAMP
Chloride shift
Co2 diffuse from cell into erythrocyte
Co2 + H20 -> HCO3 -> H+ + HCO3-
HCO3- leave cell
Cl- replace HCO3-
Fluoride Absorption
Fluoride ions associate with H+
90% of fluoride is absorbed in the stomach
Fat increases digestion
Low protein decreases as urinate more frequently
Cations in diet also decrease absorption as associate with fluoride preventing
Fluoride function
Reduce dental caries
Improve tooth structure
Inhibit anaerobic glycolysis of oral bacteria
Fluoride acute toxicity
Nausea
Vomiting
Diarrhoea
Abdominal pain
Fluoride chronic toxicity
Fluorosis of teeth
Rare but can lead to skeletal fluorosis
Zinc Structure
Finger domains Bonds with other elements to get redox stability Structural motifs Involved in catalytic role Polarised Zn-bound to water Involved in all enzymes
Zinc function
Catalytic role
Ionisation
Polarisation
Displacement
Zinc Transporter
ZnT family
ZIP family
ZNTB
ZnT family
Reduce cytosolic zinc
6 transmembrane spanning domains
Intra and extra cellular loop
between 4 and 5 is histidine rich loop
ZIP family
Increase cytosolic zinc
8 transmembrane domains
Histidine rich loop too
ZnTB
Looks different to others
How it got into epithelial cell
Zinc deficiency
Skin lesions Diarrhoea Stunted growth Weakened immune Poor pregnancy
Iodine Absorption
I2 in diet reduced to I- gut
Absorbed in upper GIT via active transport NIS (Na+/I- symporter) transport
Controlled by iodine concentration
Uptaken by thyroid gland by NIS
Iodine function
Part of thyroid hormone
Thyroid hormone cascasde
Thyroid stimulating hormone
Stimulate thyroid hormone
Thyroglobulin iodinated to produce iodothyronine and diiodotyrosine
Combine to make thyroid hormone
Release into blood and bound to carrier proteins
Thyronine and Transthyretin bind to T4 at higher affinity than T3
T3 components
MIT and DIT
T4 components
DIT and DIT
Thyroid hormone function
T3 and T4 enter cell via ATP-dependent transport protein
T4 then converted to T3 in tissue - deiodinase enzyme
Binds to gene impacting basal metabolic rate
Iodine Deficiency Disorder
Worlds most prevalent cause of brain damage
Verge of eliminating
Starts before birth jeopardising Childs mental health
Iodine deficiency
Body notices lack of thyroid hormone
So produces more thyroid stimulating hormone
Swelling of thyroid hormone
Goitre and Cretinism
Copper absorption
30-40% absorbed depending on body’s need
Decreased with high intake of vitamin C, phytic acid and fibre
High iron and zinc interfere with absorption
Transport using plasma protein
-Ceruloplasmin
-Albumin
Taken up by target cells via membrane protein Ctr1
Excreted in bile
Copper function
Coenzyme
Ferroxidase - Fe2+ to Fe3+
Dopamine beta-hydroxylase (making noradrenaline)
Tyrosinase (pigmentation)
Cytochrome C
Lynyl oxidase (cross linkage of collagen)
Copper deficiency
Abnormal red blood cells
Non-iron anaemia
Increased susceptibility to infection
Iron toxicity - accumulate in liver because no transferrin
Wilsons Disease
Inherited recessive trait
Can not metabolise copper
Menkes Disease
Impaired copper distribution
High copper excretion
Die before 3 years old
Chromium Absorption
Passive diffusion
Ascorbic acid increase absorption
Cation mineral decrease absorption
Transported by transferrin or chromodulin
Chromium function
Chromium appears to inhibit the dephosphorylation of the insulin receptor leading to inpaired glucose regulation.
Increases the translocation of vesicles containing transferrin receptors – make iron available – didn’t understand the other part
Manganese FUnction
CHO metabolism
Role in bone formation
Manganese toxicity
Seen in individuals working in manganese mine
Sever psychiatric abnormalities
Upper level is 11mg/day
