Tutor profile: Richard T.
Explain the scientific and pharmacokinetic evidence basis for why people should not take Benadryl (generic diphenhydramine) PO (by mouth) right before you drive?
Diphenhydramine is a histamine (i.e. H1) receptor antagonist that binds to histamine receptors throughout the body. The liver metabolizes diphenhydramine and it is excreted through the urine unchanged, but the half-life and the duration of action are the most important properties. Some sources say that diphenhydramine in its PO form has a half-life ranging from 3.4-9.2 hours. This means that it takes close to 4 hours minimum and 9 hours maximum for the drug to get to half its concentration within your blood stream. People who take Benadryl before they drive feel drowsy less than one hour after they take it. The same effect (not necessarily the same duration of action) can be said for other first-generation antihistamines such as chlorpheniramine, which is found in some over-the-counter decongestants. The drug can have a lasting effect from 2-3 hours, which is why it is best to take a Benadryl when one arrives home inside their dwelling. Some people could fall asleep within the first half hour after taking it and can be more sensitive or less sensitive to its effects. Because of this drowsiness, its use as a sleep aid and for fighting allergies at night is a good use of this medication. Benadryl: Great for sleep and allergies, but not for driving.
Trace the denaturation of a protein from quaternary, to tertiary, to secondary, to primary structure. Remember to include the specific types of intermolecular interactions that make up each of these structures in your answer. Include also under what general conditions a protein may denature.
A protein denatures when it is exposed to extremes in pH, salinity (salt concentration), temperature variations (hot or cold), changes in concentration of surrounding solutes, or addition of solutes that break up protein structure such as urea or detergents such as sodium dodecyl sulfate (SDS). The specific conditions vary depending upon the type of protein and the various ranges of each extreme that can be tolerated. In layman's terms: some like it hot, some like it acidic, others like it cold, and others are flexible. When a quaternary protein structure is denatured, the spatial arrangement of its protein subunits is disrupted. This basically means that the proteins can be in a shape that appears disorganized with disconnected parts of tertiary structure. Quaternary protein structure consists of multiple subunits that can be either globular or fibrous. Tertiary structure denaturation involves disrupting three major intermolecular interactions: 1. Covalent interactions between amino acid side chains (disulfide bridges between cysteine groups for example). 2. Non-covalent dipole-dipole interactions between polar amino acid side chains and the surrounding solvent (usually water). 3. Van der Waals (induced dipole) interactions between non-polar amino acid side chains. Secondary structure denaturation involves the disruption of hydrogen bonds between alpha-helices and beta-pleated sheets. A random coil configuration results, which is not stable. Our hair and spider silk would not hold up respectively. (Collagen is made of three alpha-helices bound together while spider silk is made up of beta-pleated sheets). Primary structure is the only structure that does not denature. Covalent peptide bonds hold this configuration together.
What are the main muscles of facial expression? What nerve are they innervated by? What are their basic actions?
The main muscles of facial expression are the frontalis, the orbicularis oculi, the orbicularis oris, the levator palpebrae superiorus, the risorius, the buccinator, and the zygomaticus major and minor. The names of the muscles and their actions are listed as follows: 1. The frontalis muscle allows us to raise our eyebrows superiorly, in other words elevate them. It is that thing done when people raise their eyebrows after lowering their sunglasses. 2. The orbicularis oculi and levator palpebrae superioris close and open the eyelids respectively. If the light is too much, the orbicularis oculi closes the eye. If you need to see, the levator palpebrae superioris is involved in elevating the eyelid. 3. The risorius is the "smirk" muscle, allowing us to pull up the corners of the mouth laterally. The zygomaticus major and minor help us smile, drawing up the angles of the mouth upward and laterally. This is the muscle best reserved for Joker from Batman. 4. The buccinator pulls the cheeks of our mouth inward (medially). This is the muscle we use primarily when we make a fish face. The orbicularis oris is what allows us to purse our lips, such as when kissing or whistling.
needs and Richard will reply soon.