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Toxicology > Heavy Metals > Flashcards

Heavy Metals Flashcards

1
Q

____ Lead is more readily absorbed than ____ lead

A

Organic lead is more readily absorbed than metallic lead

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2
Q

What is the most common source of lead exposure

A

Lead based paint
Aerial emission from combustion of leaded fuel
Batteries
Insecticide/herbicide

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3
Q

Which species is most likely to have lead toxicosis

A

Birds, water fowl

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4
Q

What does lead displace

A

Calcium and Zinc

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5
Q

Why are younger animals more sensitive to lead

A

Greater GIT absorption

Immature BBB

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6
Q

Which species are more resistant to lead

A

Goat, Swine, Chicken

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7
Q

What 3 things decrease lead absorption

A

Calcium, zinc, protein

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8
Q

How is lead absorbed

A

Active transport using same carrier protein as calcium

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9
Q

If patient is deficient in _____ then lead is more readily absorbed

A

Calcium
Vit D
Zinc
Iron

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10
Q

Lead absorption is increased by

A

GIT acidity

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11
Q

How long does lead bind to proteins in soft tissue

A

4-6 weeks

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12
Q

What is Metallothionein

A

Chelating liver protein

Sequesters metal ions

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13
Q

Where can lead be reserved for years

A

bone matrix

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14
Q

Lead targets which tissues

A

GIT, Blood, CNS

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15
Q

Chronic exposure to lead at low doses inhibits ___ leading to ___

A

Heme Synthesis leading to anemia

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16
Q

Lead alters the release of

A

Neurotransmitters (dopamine, acetylcholine, GABA)

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17
Q

Hematologic signs of lead

A

Anemia, basophilic stippling
Antemortem - whole blood >0.35
Postmortem – Kidney, liver >10ppm

18
Q

CNS signs of lead

A

Anxiety, vocalization, head pressing, manic behavior, seizures

19
Q

Lead signs in birds

A

Peripheral neuropathy, chronic wasting

20
Q

Which chelating agent is better

A

Calcium disodium EDTA

21
Q

What are some concerns with chelating agents

A 
Renal injury (don't treat >5 days)
Binds other minerals (supplement Zinc)
22
Q

What can be used with Ca-EDTA to enhance excretion and why

A

Dimercaprol - crosses BBB

23
Q

Lead lines do not represent ____

A

lead deposits in bone

24
Q

What increases zinc release and absorption

A

Acid - both

Absorption – AAs, peptides, chelating agents

25
Q

What decreases zinc absorption

A

Dietary fiber, phytate (P), Ca

26
Q

Excess zinc interferes with absorption and use of

A

Cu and Fe

27
Q

Rapid accumulation of zinc occurs in which organs

A

Pancreas, liver, kidney, spleen

28
Q

Clinical signs of zinc in GI, Blood and Kidney

A

GI - vomit, anorexia, lethargy, pain, diarrhea, pica
Blood - Hemolytic anemia (hemolysis), icterus, hemoglobinuria
Renal - Azotemia (BUN), hypophos

29
Q

What type of tube is used for zinc analysis

A

Trace elements tube - dark blue top

30
Q

What can chelation therapy cause with zinc

A

May increase zinc redistribution and absorption

** can use Ca-EDTA after removal of source

31
Q

Which species milk contains no iron

A

Pig

32
Q

What deficiency in sows increases risk of iron toxicity in piglets

A

Selenium and Vit E

33
Q

Is organic or inorganic iron more toxic

A

Organic is less irritant

34
Q

Why is little iron normally excreted

A

It is bound to transferrin and transported to bone marrow for hemoglobin synthesis

35
Q

Free iron ions are very reactive and cause _____ and direct damage to _____

A

Cause free radical lipid peroxidation and direct damage to cell membranes

36
Q

The primary effects of iron are on which systems

A

Cadiovascular, GI and liver – leads to shock and death

37
Q

Clinical signs for acute iron toxicosis

A

Severe depression, shock, acidosis and death within hours

38
Q

Stages of acute iron toxicosis

A 
Stage 1 (0-6 hr) - GI upset
Stage 2 (6-24 hr) - apparent recovery
Stage 3 (12-96 hr) - Most severe signs due to metabolic effects
Stage 4 (2-6 wks) - GI obstruction due to fibrosis
39
Q

How long after ingestion of iron is GI decontamination effective

A

Within 4 hrs

40
Q

______ is not effective but ____ can be used to precipitate iron

A

Activated charcoal

Milk of magnesia

41
Q

For iron toxicosis when is chelation therapy warranted and what is used

A

Has ingested >60 mg/kg, serum iron is >500 mcg/dL

Deferoxamine (rapid injection can cause hypotension and cardiac arrhythmias)

Toxicology (8 decks)

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