Iodine is actively concentrated in the thyroid and the radiation will destroy all tissue within 2-3mm causing focal, controlled destruction
How does down regulation of receptors occur?
Internalizing the receptors in lysosomes, recycling them, sequestering or degrading.
Part of normal cellular metabolism
Down Regulation of Receptors
Number of receptors decreases and therefore a reduction in the effect
Binds to the receptor to elicit a maximal response
Examples of non receptor biological reactions
Voltage Gated Channels
Targets for drug reaction are divided into what two categories
Common receptor for secretory and smooth muscle functions whre the changes occur over seconds.
Nonspecific drug effects occur in (physical/biological) interactions
Examples of nonspecific drug effects
Drug effects on Voltage Gated Channels
Blocking of ion channels can occur by the drug moleucle physically obstructing the channel to impair ion movment. Drug may also modulate the opening/or closing of the channel
The straight portion of the sigmoidal drug response curve falls between what range? This corresponds to what?
Steroids and thyroid hormones are examples of what type of receptor, new protein production starts over the course of hours
Mixed Agonist - Antagonist
Acts as an agonist in one type of receptor and as an antagonist on other types of receptors
Secondary to the intended effect and may be good or bad
Mimics the effect of the endogenous ligand
Responses to a drug that are harmful to the health or life of the animal
Maximal effect a drug can have
Types of pharmacodynamic receptors
Antacids (Direct Neutralizers)
Given orally they direct interact with acid in the GI tract, a form of physiologic antagonism
Drug effects on Enzymes
Drugs can be analogs that compete with the real substrate for binding to the enzyme, prodrugs where the drug needs to be metabolized into its active form or can act as false substrates which will lead to the formation of abnormal metabolites instead of active product.
Lethal Dose 50 (LD50)
Dose which kills 50% of animals
A partial agonist may never be able to achieve full efficacy
Molecules move through the body dragging water with them by osmosis until they are excreted
Will bind to the receptor but not cause as much effect as a full agonist, it does prevent anything else from binding to the receptor while docked there
Effective Concentration 50 (EC50)
Concentration at which a drug produces 50% of its maximal effect, only applies to in vitro preparations useful to compare the efficacy of different ligands
Onset of Action (Latent Period)
Time required after drug administration for a response to be observed
T/F: Endogenous neurotransmitters often bind to more than one type of receptor. The same signaling molecule can then cause different effects or have different affinity in different tissues or species.
A low therapeutic index indicates a (safe/dangerous) drug
Two drugs chemically inactivate each other