Exam 3 Flashcards
(___) iron is primarily from (___) sources while (___) iron is from mostly (___) sources
Heme, Animal, non-heme, plant
What is heme iron derived from?
Hemoglobin and myoglobin. It must first be removed from the porphyrin ring structure via hydrolysis (proteases)
How is heme absorbed across the brush border?
With the help of heme carrier protein (HCP1) and PCFT.
In the (___) the heme porphyrin ring is hydrolyzed by (___) into (___) iron and protoporphyrin
enterocyte
heme oxygenase
ferrous
Non-heme iron in the stomach is released with the help of (___) and (___) into its (___) form
HCl
proteases
Fe3+ (with some Fe2+)**
**3+ = ferric iron
Three enzymes to reduce ferric iron at the brush border
cytochrome b reductase 1
Ferric cupric reductase
STEAP 2
DMT1 can transport which minerals?
Zn, Mn, Cu, Ni, and Pb
What happens to DMT1 when iron stores are high
more is synthesized, and less when iron stores are low
go back for inhibitors and enhancers
xxx
Without this mineral, Iron cannot beoxidized to the ferrix state and transported out of the liver.
Copper
primary regulator of iron
hepcidin, released when stores of iron are adequate or high
Iron sensor of the body
HFe-TfR2 complex (transferrin receptor 2)
cornerstone of internal iron circuit
ferroportin
ferroportin function
export iron into the plasma from the duodenum (absorption control)
These two cells control the release of iron recovered from red blood cell catabolism and from stores.
Macrophages and hepatocytes
Iron overload storage form
hemosiderin
Three main sites for iron storage
liver, spleen, and bone marrow
Cofactor for monooxygenases, dioxygenases, peroxidases, and oxireductases
Iron
Vitamin C and Iron
C releases ferric iron from ferritin and reduces iron to the ferrous form
Copper and Iron
Cu deficiency causes Fe deficiency. Cu is needed for the ferroxidase activity of hephaestin and ceruloplasmin
Zinc and Iron
Zinc inhibits iron absorption and v/v minerals ingested together at a 2:1 ratio favoring non-heme iron
Vitamin A and Iron
low A causes increased Fe accumulation in the spleen and liver; also altered RBC morphology
Lead and iron
Lead reduces heme synthesis, associated with iron deficiency anemia
Stages of iron deficiency
1) iron stores being to srop (plasma ferritin as index of depletion)
2) Iron stores depleted
3) plasma iron declines and iron available to bone marrow for hemoglobing drops
4) Anemia, rbc synth drops
ZIP 4
Zinc carrier to cross brush border membrane into cytosol. Degraded by high Zinc intake
Acrodermatitis enteropathica
caused by a ZIP 4 mutation
characterized by poor absorption and skin lesions
Minerals that can absorb by diffusion
Zinc
transport of zinc in the blood is mostly handled by…
albumin
Stored zinc is bound to…
thionein as metallothionein
Stored zinc from these locations is poorly organized, even when intake is low
liver, kidneys, muscle, skin, and bones.
When zinc is low what happens to plasma zinc?
when intake is low, the less crucial plasma zinc enzymes and mettalothionein can be catabolized for ionic zinc
Vitamin A and Zinc
zinc is important in making RBC’s which are needed to transport retinol. Without retinol, night blindness can occur.
Copper and Zinc
Zinc toxicity can induce Cu deficiency
Calcium and Zinc
compete for common absorption sites
Cadmium and Zinc
if Cadmium is high it prevents Zinc from binding to regular sites
Cu1+
cuprous
Fe2+
ferric
Cu2+
cupric
Fe3+
ferrous
Most food Cu is the (___) form
cupric 2+
Primary supplemental form of Cu
copper sulfate
Most Cu absorption happens in the (___) form
cuprous 1+
Copper transporters
Ctr 1 and DMT (which co-transports with H+)
ATP7B
moves Cu 1+ to the golgi network where it is incorporated into the ceruloplasmin
Cu is stored in (___) in the (___)
Mettalothionein, liver
Wilson’s Disease
mutation of ATP7B where it is either absent or dysfunctional. This disrupts Cu excretion into the bile and then into the ceruloplasmin. Copper builds up in the liver
D2
ergocalciferol
D3
cholecalciferol; typical supplemented form, also synthesized by skin.
D synthesized in the skin goes to…
the blood bound to DBP
D from the diet is…
incorporated into the chylomicrons, enters the lymphatic system, and then enters the blood
D in the blood goes to
the liver
D in the liver
Converted to calcidiol (much of which is released into the blood).
What picks up most of the calcidiol from the blood and why
the kidneys when triggered by PTH
Calcidiol is hydroxylated to the active form (___) which is regulated by (___) and (___)
calcitriol
FGF
PTH
Rickets
vitamin D deficiency
Regulation of calcium is handled by three hormones
calcitriol
PTH
calcitonin
In response to low plasma Ca, (___) is excreted
PTH
In the intestine, (___) reacts with vitamin d receptors to induce transcription to code for (___)
Calcitriol
calbindin
Role of calcitonin in Ca regulation
lower serum Ca when the levels are high
Sodium levels
- Low: 140 mg or less per serving
- Very Low: 35mg or less
- Sodium Free: Less than 5mg per serving
Serum sodium maintained by
ADH aldosterone atrial natriuretic hormone renin angiotensin
membrane potential
concentration differences between K+ and Na+ across cell membranes to create an electrochemical gradient
Magnesium absorption is enhanced by
vitamin D and carbohydrates, D is not essential
Phosphorous absorption is increased by
PTH
High phosphorous stimulates (___) to suppress (___). doing so decreases the serum concentration of (___)
FGF23
Calcitriol
Calcium
Three parts responsible for ECF volume and osmolarity maintenance
Hypothalamus
Renin-angtiotensis-aldosterone system
kidneys
Angiotensis II triggers the adrenal cortex to release (___) which tells the kidneys to excrete (___) and retain (___).
aldosterone
K
Na
Vasopressin is released by (___) in response to (___) and tells the (___) to retain more water
the hypothalamus
angiotensin II
kidneys
Responsible for tissue growth, cell-mediated immunity, assistance in insulin function and conversion of retinol to reinaldehyde
Zinc
Ceruloplasmin, superoxide dismutase, cytochrome c oxidase and others, tyrosine metabolism, nerve and immune function
Copper
Calcium metabolism and enhanced absorption, cell differentiation, bone development
Vitamin D
Enhance Ca absorption from guts and retention from kidneys, cause Ca bone mobilization
Calcitriol
Skeleton and blood clot formation, nerve transmission, muscle contraction
Calcium
Glucose co-transport, fluid balance maintenance, nerve transmission, muscle contraction
Sodium
Maintain electrolyte and pH balance, decrease Ca excretion, nerve tissue
Potassium
Bone structure, glycolysis, kreb cycle
Magnesium
Bone mineralization, DNA / RNA component, energy storage and transfer
Phosphorous
