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Nutrition and Metabolism > Metals: Role in physiology and pathology > Flashcards

Metals: Role in physiology and pathology Flashcards

1
Q

Where is Na found?

A

Mostly found in blood and in ECF (extracellular fluid)
*Mostly excreted in urine

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2
Q

What are the Physiological functions of sodium?

A

Essential nutrient
Helps in:
➢ maintaining normal cellular homeostasis
➢ Regulating fluid and electrolyte balance and blood pressure. Main regulator of ECF volume (through its osmotic action) including plasma volume
➢ transporting nutrients and substrates through plasma membranes
Important for the excitability of muscle and nerve cells

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3
Q

What are sodium associated diseases when you’re low in Na?

A

Too low Na in serum = Hyponatremia (serum Na <136 mmol/L)
Electrolyte* abnormality
*Serum ** Na concentration depends on **ratio of total body solutes **(e.g., total body sodium and total body potassium) to total body water
*Hyponatremia= imbalanced ratio; total body water> total body sodium (body solutes)

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4
Q

What are sodium associated diseases when you’re high in Na?

A
  • Cause: limited access to water or impaired thirst mechanism
  • Decrease in total body water relative to electrolytes
  • “Water problem,” not a problem of Na homeostasis
  • Water leaves cells and enters blood (aiming to dilute it and lower Na levels)

Too much Na in diet= facial puffiness, high blood pressure, heart disease and stroke
It can also causeCa loss (increases Ca excretion), some of which can be from bone

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5
Q

Where is potassium located?

A

Mostly inside the cells than outside; present in all body tissues
Mostly excreted in urine, 10% in sweat and stool
K has a strong relationship with Na

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6
Q

Physiological functions to Potassium?

A
  • Essential for normal cell function
  • Maintains intracellular fluid volume and transmembrane electrochemical gradients
  • Helps preserve acid-base balance and maintain isotonicity and electrodynamic cellular function
  • Activates many enzymes e.g., pyruvate kinase
  • Essential for transmission of nerve impulses, contraction of cardiac muscles, skeletal and smooth muscles, tissue synthesis, gastric secretion, and renal function
  • Relaxes walls of blood vessels,lowers blood pressure
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7
Q

Disease low potassium in blood?
Cause?

A
  • Low levels of K in blood= Hypokalemia (< around 3 mmol/L)
    Cause 1: excessive K loss in urine (due to medications that increase urination)
    These medications are often prescribed for high blood pressure or heart disease
    Cause 2:** Low K intake**; associated with increased blood pressure and higher risk of stroke
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8
Q

Disease high potassium in blood?
Cause?

A

High levels of K in blood= Hyperkalemia (> 6.0 mmol/L)
Can be life-threatening
Heart muscle activity may be reduced, weakness, paralysis in feet or respiratory muscles

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9
Q

Where is Magnesium located?

A

50% of body’s magnesium is in bone
Very little in blood

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10
Q

What physiological functions in Magnesium?

A
  • Cofactor in various structures/enzymes that regulate reactions
  • Protein synthesis, muscle and nerve function, blood pressure regulation
  • Required for energy production, oxidative phosphorylation, and glycolysis, and DNA, RNA and glutathione
  • Regulates insulin secretion in pancreatic beta cells
  • Critical for phosphorylation of insulin receptor
  • Contributes to formation (structural development) of bone and teeth
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11
Q

What is low levels in magnesium?

A

**Too low **= Hypomagnesemia (<1.46 mg/dL)
Occurs in chronic disease, alcohol abuse, gastrointestinal/renal losses, deficiency or when Mg homeostasis is disturbed

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12
Q

Diseases when magnesium is too low?
Cause?
Why?

A

Low Mg (deficiency)= Hypomagnesemia can cause hypocalcemia
* Low Mg impairs the Mg-dependent adenyl cyclase generation of cAMP
* This decreases release of parathyroid hormone (PTH)
* Since PTH regulates Ca levels, Ca levels are decreased
* Normally Mg affects electrical activity of myocardium and vascular tone
* Hypomagnesemia patients are at risk of cardiac arrhythmias

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13
Q

Diseases when magnesium is too low?
Cause?
Why?

A

Too high=Hypermagnesemia
Major cause is renal failure
Cardiovascular and neurological complications

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14
Q

Where is calcium found?

A

About 99% of body’scalciumis stored in bones and teeth
Cells (muscle cells) and blood also containca (bound to albumin or exist as ionized Ca)

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15
Q

Physiological functions of calcuim?
Cause?

A
  • Formation of bone and teeth (makes up most of the structure- keeps tissue rigid, strong, flexible)
  • Small fraction of Ca in blood, ECF, and other tissues-

Here, it mediates blood vessel contraction/dilation, muscle contraction, blood clotting, nerve transmission, and hormonal secretion

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16
Q

What happens when there is a lack of calcuim?

A
  • rickets in children
  • osteoporosis in adult life (brittle bones)
  • dental changes
  • cataracts
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17
Q

What is Hypocalcemia?

A

Low levels of Ca in blood

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18
Q

What is Hypercalcemia?

A

High levels of Ca in blood

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19
Q

What iS FMM?

A

Familial hypocalciuric hypercalcemia (FHH): inherited disorder
Causes high levels of calcium in blood and low- moderate levels of calcium in urine
FHH-usually do not show symptoms
Diagnosis is by chance
Weakness, fatigue…

20
Q

What are trace elements?
Examples?

A
  • Essential for life; for numerous metal-dependent enzyme and protein activities
  • Required in a minimal amount to maintain health
  • 13 trace elements have been identified that affect health
  • Established role: iron, zinc, iodine, copper, selenium,chromium, manganese, molybdenum
  • Controversial role: vanadium, silicon, boron, nickel
  • No proven role in health but known for its toxicity: Arsenic
  • Requirements are usually met through diet.
21
Q

Where is iron found?

A
  • In the circulation –e.g bound to haemoglobin, ferritin (iron storage protein) and transferrin (iron-carrier protein)
  • Also, deposited in higher amounts in tissues during disease states
22
Q

Functions of Iron?

A
  • Essential component of haemoglobin (transfer oxygen from the lungs to tissues)
  • Myoglobin, provides oxygen, supports muscle metabolism
  • Essential for neurological/physiological development, cellular functions
23
Q

What are the diffrent types of iron?
Where is this found?

A

Dietary iron = haem and non-haem
Non-haem iron : in plants and iron-fortified foods
Haem iron (iron + protoporphyrin IX):
about 10% to 15% of total iron intake in western world
Seafood, poultry contain both haem and non- haem iron
* No physiological mechanism to remove excess iron

24
Q

What is primary iron overload?
Whats the treatment?

A

Primary iron overload (inherited)- Haemochromatosis - mutations in genes that regulate hepcidin or ferroportin (cellular iron exporter)

Treatment - Phlebotomy

25
Q

What is primary iron overload?
Whats the treatment?

A

Secondary iron overload – ** Mild to moderate, due to other conditions e.g alcohol-associated liver disease** or transfusion or **excessive dietary consumption **
Treatment-iron chelating agents e.g deferoxamine (intramuscular, subcutaneous, intravenous), deferiprone (oral)

26
Q

What is secondary iron overload?
Whats the treatment?

A

Secondary iron overload – Mild to moderate, due to other conditions e.g alcohol-associated liver disease or transfusion or excessive dietary consumption

Treatment-iron chelating agents e.g deferoxamine (intramuscular, subcutaneous, intravenous), deferiprone (oral)

27
Q

What is a iron deficient anaemia?
Causes?

A
  • Iron deficiency anaemia= anaemia due to iron deficiency
  • Anaemia = Low RBC count or low haemoglobin (diagnosis)
  • Women are more affected than men

Causes: decreased intake, impaired absorption, increaseddemand, gastrointestinal bleeding

Treatment: Ferrous sulphate, ferrous gluconate, IV

28
Q

What is the iron essential?

A

Iron is essential for haemoglobin synthesis
Low iron bioavailability = low hemoglobin synthesis=iron-deficiency anemia

Treatment: Ferrous sulphate, ferrous gluconate, IV

29
Q

Where is Zinc found?

A

Present in blood, in all tissues- highest in muscle, bone, then liver

30
Q

What is the role of zinc?

A
  1. Formation of DNA, RNA, and proteins
  2. Stabilizes ribosomes, cell membranes
  3. Decreases lipid peroxidation and subsequent free radicals
  4. Required for spermatogenesis, embryogenesis, and fetal growth
31
Q

What is a disorder of zinc metabolism?

A

Acrodermatitis enteropathica (AE):a disorder of zinc metabolism, example of zinc deficiency disease

Rare autosomal recessive condition resulting in severe zinc deficiency
ZIP-4 = transmembrane zinc uptake protein
Transports **zinc ions **from extracellular region or lumen into cytoplasm
Mutation results in defective zinc absorption in duodenum and jejunum

Acquired zinc deficiency due to malabsorption syndromes, liver or kidney disease, dietary habits, can present with clinical features simulating AE

32
Q

How is Zinc distribution regulated?

A

Predominantly regulated by its intestinal absorption
(balanced with endogenous loss through feaces-excess zinc secreted into intestine
Distribution is controlled at cellular and systemic levels through coordinated regulation through ZIP family and ZnT family of transporters

33
Q

Zinc deficiency cause and treatment?

A

Zinc deficiency can be inherited or acquired
Treatment: oral supplementation- zinc acetate, zinc gluconate, or zinc sulfate

34
Q

What is RMI? Safe level of zinc?

A

Recommended daily adult intake of zinc= 15 mg
Toxicity symptoms do not become evident until intake exceeds approximately 1to 2 g of zinc
High levels could be via gastrointestinal, dermal, respiratory, and parenteral routes

35
Q

How can high levels be caused dermally and parenteral?

A

Dermally - Zinc oxide toxicity can occur through the skin -from overuse of makeup, sunscreen, and ointments
Parenteral - Excessive amounts of denture cream can lead to zinc overdose (and secondary copper
deficiency)

36
Q

How can high levels of zinc be caused respiratorily?
What are the symptoms?

A
  • Respiratory stress after zinc smoke inhalation
  • Metal fume fever
  • Inhalation of zinc oxide (occupational exposure e.g welding) can lead to “metal fume fever“-flu-like symptoms with cough.
  • Smoke bombs containing zinc chloride can
    cause chest pain, airway irritation and ARDS
37
Q

Symptoms if high levels of zinc in gastrointestinal tract?

A
  • Nausea
  • Epigastic pain
  • Vomiting
  • Diarrhea

Loss of appetite

38
Q

Symptoms if high levels of zinc in brain?

A
  • Lethargy
  • Neuronal defects

HEADACHES

39
Q

What Copper function?

A
  1. Required for growth, cardiovascular integrity, lung elasticity, neovascularization, neuroendocrine function, iron metabolism
  2. Essential cofactor for enzmes:
    * cytochrome c oxidase in the mitochondria (energy production)
    * lysyl oxidase in connective tissue (connective tissue synthesis)
    * dopamine monooxygenase in brain
    * ceruloplasmin (iron metabolism)
    * apo-copper-zinc superoxide dismutase (apoCuZnSOD), protects against free-radical damage to proteins, membrane lipids and nucleic acids.
40
Q

How is copper distributed?

24

A
41
Q

What is the disease linked to copper deficinecy
How is it caused?

How is it dicovered?

25

A
  • General diagnosis =measure serum copper, serum ceruloplasmin and 24-h urine copper levels.
  • Genetic disease- Menkes Disease-X-linked recessive pattern
  • Mutations in ATP7A (regulates copper levels)= poor distribution of copper
  • Copper accumulates in small intestine, kidneys, but low in brain and other tissues
42
Q

Effects of copper deficiency?

A
  • Acquired Copper deficiency is not common in humans
  • Effects of copper deficiency=anaemia, hypopigmentation, hypercholesterolemia, connective tissue
    disorders, osteoporosis, abnormal lipid metabolism, increased risk of infection
43
Q

Treatment for copper deficiency

A
  • Copper injections
    Treatment: oral or intravenous copper replacement in the form of copper gluconate, copper sulfate or
    copper chloride.
44
Q

What is copper overload disease?
How is it casued?

A

Wilson disease- rare genetic disorder, impairs copper transport
* Mutation in ATP7B (copper transport protein in liver)
* (normally loads copper onto apo-ceruloplasmin; transports
excess copper into bile for excretion)
* Decreased copper secretion into bile
* Body cannot get rid of extra copper. Impaired clearance
* Copper accumulates in liver, other organs, eyes and brain
* Neurologic and liver damage (cirrhosis)
* Also, there is impaired incorporation of copper in
ceruloplasmin, so may show low serum levels of
ceruloplasmin

45
Q

Treatment of copper overload?

A
  • Treatment: copper chelation therapy or high doses of zinc can prevent permanent organ damage (results in decreased copper
    absorption from diet)
46
Q

How does chronic exposure to high levels of copper to occur? Symptoms?

26

A
  • Acquired copper toxicity is rare in healthy people, but found in
    those consuming stagnant water in copper pipes
  • Chronic exposure to high levels of copper= liver damage and
    gastrointestinal symptoms (e.g., abdominal pain, cramps,
    nausea, diarrhea, and vomiting)

Nutrition and Metabolism (14 decks)

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