Toxic agents Flashcards
Metallothioneins:
Metallothioneins (MTs) are a family of small, highly conserved, cysteine-rich metal-binding proteins that are important for zinc and copper homeostasis, protection against oxidative stress, and buffering against toxic heavy metals
D: provide high-affinity binding of copper and mercury.
Transferrin
Iron
ceruloplasmin
Copper
metallothioneins
Zinc
albumin
nonspecific metal binding.
LEAST likely to chelate metals?
-Cl
What is the mechanism of toxicity of arsenic (As)?
inhibition of mitochondrial respiration.
Lead’s toxicity is largely due to its ability to mimic and interfere with normal functioning of which of the following ions?
Ca2+
Which of the following statements regarding mercury (Hg) toxicity is FALSE?
Mercury vapor inhalation is characterized by fatigue and bradycardia.
Wilson disease
- Urinary excretion of copper is high.
- There is impaired biliary excretion of copper.
- The disease can be treated with liver transplantation.
- This is an autosomal recessive disorder
Metals and medical therapy
- There are elevated levels of aluminum in the brains of Alzheimer’s patients.
- Lithium is used to treat depression.
- Chronic nephrotoxicity is a common result of excess aluminum exposure.
- Platinum salts can cause an allergic dermatitis.
Humans consume food to provide energy needed to
drive cellular functions including digestion, metabolism, pumping blood, nerve activity, and muscle contractions
Neural control of energy balance
may involve a balance between leptin’s action on orexigenic versus anorexigenic peptide expression.
Excess calories may be…
stored as glycogen in the liver.
Metabolic syndrome is a constellation of actions including…
Excess caloric intake
may lead to nonalcoholic steatohepatitis.
Although dieting may effectively reduce body weight,
toxicity may result from a loss of required nutrients.
Body mass index
may be defined as body weight divided by height squared.
Def. calories ++
- The set-point hypothesis proposes that food intake and energy expenditure are coordinately regulated by defined regions in the brain that signal to maintain a relatively constant level of energy reserve and body weight.
- Hormonal messages generated by the endocrine cells of the pancreas, adipose tissue, and GI tract are involved in orchestrating multiple responses associated with caloric intake and caloric utilization.
- Caloric content of foods generally assumes factors of 4, 9, and 4 for carbohydrate, fat, and protein.
- Liver, adipose, muscle, and other tissues adapt to excess caloric loads.
Animal toxins
- The kidneys are responsible for the excretion of metabolized venom.
- Venoms can be absorbed by facilitated diffusion.
- Most venom fractions distribute unequally throughout the body.
- Venom receptor sites exhibit highly variable degrees of sensitivity
Scorpion venoms do
- Affect potassium channels.
- affect sodium channels.
- affect chloride channels.
- affect initial depolarization of the action potential.
widow spiders
Alpha-latrotoxin stimulates increased exocytosis from nerve terminals
commonly caused by tick envenomation
- Rocky Mountain spotted fever.
- Lyme disease.
- Q fever.
- ehrlichiosis.
characteristic Lepidoptera envenomation?
- increased prothrombin time.
- decreased fibrinogen levels.
- increased risk of hemorrhaging.
- decreased plasminogen levels.
A species of which of the following animals produces a venom that contains 60% formic acid?
Ants
Which animals has a venom containing histamine and mast cell-degranulating peptide that is known for causing hypersensitivity reactions?
Bees
Which enzymes is not typically found in snake venoms?
histaminase
Plant toxins
- genetic variability plays a role in the toxicity of a plant.
- young plants may have a higher toxin concentration than older plants.
- the weather can influence the toxicity of plants.
- soil composition can alter a plant’s production of toxin.
Activation
Capsaicin
