Class Notes (837,698)
Canada (510,399)
Biology (2,272)
BIOL 354 (37)
Lecture 7

Lecture 7 Summary.docx

2 Pages
196 Views
Unlock Document

Department
Biology
Course
BIOL 354
Professor
Bruce Greenberg
Semester
Summer

Description
BIOL354 – Environmental Toxicology I Spring 2012 Lecture 7 – Toxicokinetics - Review: K owis octanol-water partition coefficient, vessel w/ octanol & water + sample -> centrifuge -> [] Toxicity Pathways (Exposure -> Toxicity) - Bioaccumulation: Net accumulation per organism from all sources. Exposure route (Air, Water, Soil/sediments, and Food) is specie specific. o Bioaccumulation Phase: Max [Toxicant] per tissue increase until a steady state plateau. o Depurination Phase: [Toxicant] per tissue decreases through depuration of DNA, sharply at first, slows down as the [Toxicant] decreases. - Bioconcentration: Net accumulation per organism from water only. (Aquatic toxicology) o ( ) ⁄ o Fish exposed to chemical (constant over time), monitor chemical in tissue until equilibrium o Lipophilicity/owof the contaminant -> Bioconcentration @ adipose & liver tissues  Chemicals: Hydrophilic/Lipophobic, Hydrophobic/Lipophilic, Amphipathic (both)  Usually the major factor that determines BCF  High Kow Partitions preferentially to lipids (e.g. Dioxins, PCBs, MeHg -> High BCF until bioavailability limited by solubility of the compound)  Low Kow Partitions preferentially to water (e.g. Metals -> Low BCF) - Biomagnification o [Toxicant] increases as trophic level increases o Toxicant must be able to bioconcentrate & persists within in tissues of the prey - Toxicokinetics (ADBE): Relationship b/w systemic exposure of [Toxicant] in an organism & its toxicity o Absorption/Uptake -> Distribution (systemic) -> Biotransformation -> Excretion/Elimination Absorption/Uptake - Mechanisms for Uptake (4): Gills (Low Kow, Guts (High Kow, Lungs (Low Kow, & Skin/Mucus membrane o Route of uptake depends on the organism, the contaminant & the external environment o The chemical/toxicant must interact with tissues/cells - Pathways after Uptake (3): o Pathway & Speed of transportation after uptake depends on the chemical’s hydrophilicity, lipophilicity ow ) & molecular size 1) Lipid: Passive diffusion across the phospholipid bilayer 2) Aqueous: Passive or active transport via integral membrane transport proteins i. Channel proteins: Non-specific (e.g. Calcium Channels) [Passive] 1. Physically blocked by ligands that are similar in radii 2. Cd permeability low, few enters, rest blocks & -Ca uptake significantly ii. Carrier proteins: Specific -> conformational change (e.g. Porin -> Sucrose) [Active] 3) Endocytotic: Active ingestion of large polar molecules (*Ingested Contaminants) i. Invagination of plasma membrane -> formation of intracellular vesicles Distribution via circulatory system - Lipophilic (High ow) associates with blood cells ostHydrophilic (LoowK ) dissolved in plasma/cytoplasm - Physiochemical properties of toxicant determines 1 tissue they interact with => destination o Liver, Kidney, Adipose tissue & Rarely Bones o Vertebrates: All blood from GI go to the hepatic portal system of the liver 1 for filtration  If owis high (Lipophilic), toxicant biotransformed/metabolized by hepatocytes to increase solubility (2 phases), secreted into the intestines for excretion BIOL354 – Environmental Toxicology I
More Less

Related notes for BIOL 354

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit