Ca-pump and Ion Transport Channels in Cellular Absorption

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What is the primary factor influencing absorption through endothelial pores in intramuscular, subcutaneous, and intradermal routes of exposure?

Lipid solubility

Site of skin thickness

Surface area

Blood flow (correct)

What is the bioavailability of a drug administered intravenously?

50%

Ranges from 0 to 100%

100% (correct)

35%

Why is it essential to understand bioavailability and extent of absorption for xenobiotics?

To determine the optimal dose for therapeutic effects

To assess the risk of toxic effects (correct)

To identify the most suitable route of administration

To evaluate the efficacy of detoxification pathways

What is the primary mechanism of destruction of lidocaine in the body?

Destruction in gastric acid (B) Signup and view all the answers

What is the term for the phenomenon where a drug is destroyed or metabolized before it reaches the systemic circulation?

First Pass Effect (C) Signup and view all the answers

Which route of exposure has a large surface area?

Intraperitoneal (B) Signup and view all the answers

What is the primary factor influencing the absorption of xenobiotics through the skin?

Lipid solubility (B) Signup and view all the answers

What is the primary factor determining the selective transport of ions through ion channels?

Size and ionic charge (D) Signup and view all the answers

Which of the following is an example of a cation transport channel?

Epithelial calcium channel type 2 (ECaC2) (B) Signup and view all the answers

What is the primary mechanism of lead absorption from the intestine to the blood?

Active transport via the epithelial calcium channel type 2 (ECaC2) (A) Signup and view all the answers

What is the primary effect of lead poisoning on children?

Neurologic damage and IQ reduction (D) Signup and view all the answers

What is the primary prevention strategy for chronic lead poisoning?

Taking calcium supplements and maintaining a diet rich in milk and protein (D) Signup and view all the answers

What is the radioactive isotope of iodine that can cause thyroid cancer?

I-131 (D) Signup and view all the answers

What was the event that led to the series of equipment failures and releases of radioactive materials at the Fukushima I Nuclear Power Plant?

Tōhoku earthquake and tsunami (C) Signup and view all the answers

What is the primary mechanism by which lead enters the blood from the gut?

Epithelial calcium transporter (C) Signup and view all the answers

What is the primary target tissue for blood lead toxicity?

Brain (B) Signup and view all the answers

Which of the following xenobiotics is NOT sequestered in adipose tissue?

Aflatoxin (B) Signup and view all the answers

What is the purpose of depot sequestration and mobilization in the context of xenobiotic toxicity?

To reduce the toxicity of xenobiotics by sequestering them in depot stores (C) Signup and view all the answers

Which of the following xenobiotics is characterized by a short-acting effect due to re-distribution from the brain to fat?

Thiopental (B) Signup and view all the answers

What is the primary consequence of depot mobilization of sequestered xenobiotics during pregnancy and breast feeding?

Redistribution of xenobiotics to the fetus or breast milk (D) Signup and view all the answers

What is the primary mechanism of elimination for xenobiotics such as ammonia and volatile organic compounds?

Exhalation through the lungs (C) Signup and view all the answers

What is the primary reason for the low bioavailability of certain xenobiotics in extracellular fluid?

Binding to albumin reduces their availability (D) Signup and view all the answers

Which of the following statements about brain capillaries is true?

Their cell membrane is sealed shut, preventing the passage of toxic substances (B) Signup and view all the answers

What is the effect of tolbutamide binding to plasma albumin?

It increases the bioavailability of tolbutamide (B) Signup and view all the answers

What is the purpose of the blood-brain barrier (BBB)?

To protect the brain from toxic substances in the blood (B) Signup and view all the answers

What is the effect of competition-displacement between xenobiotics on their bioavailability?

It increases the bioavailability of one xenobiotic and decreases the bioavailability of the other (B) Signup and view all the answers

What is the purpose of sequestration in animals?

To store toxicants in inert tissues, reducing their toxic effects (B) Signup and view all the answers

What is the difference between normal blood capillaries and brain capillaries?

Normal blood capillaries are fenestrated, while brain capillaries are unfenestrated (C) Signup and view all the answers

What is the primary mechanism of excretion for water-soluble toxicants with a molecular weight of less than 70,000?

Passive transport through the kidney (A) Signup and view all the answers

Which of the following elimination routes involves both filtration and reabsorption processes?

Kidney (D) Signup and view all the answers

What is the primary function of the liver in the elimination of toxicants?

Metabolism of lipid-soluble toxicants to more water-soluble molecules (A) Signup and view all the answers

What is the significance of mother's milk as an elimination route?

It is an important route of transfer of toxicants to babies and from animals to humans (A) Signup and view all the answers

What is the mechanism of excretion of conjugates with high molecular weight?

Active transport into bile (A) Signup and view all the answers

What is the fate of lipid-soluble and non-ionized toxicants in the body?

They are reabsorbed into the bloodstream, leading to systematic toxicity (B) Signup and view all the answers

What is the primary route of elimination for gases and volatile liquids?

Lung (C) Signup and view all the answers

What is the role of the GIT in the elimination of toxicants?

It is involved in the excretion of toxicants through simple diffusion (C) Signup and view all the answers

What is the significance of sweat and saliva as elimination routes?

They are minor routes of elimination for lipid-soluble toxicants (C) Signup and view all the answers