Midterm Flashcards
T/F: The sodium channel has two gates, one for activation, and one for inactivation.
True
Initial depolarization widens the channel, opening the activation gate
Inactivation gate closes and allows the channel to reset - refractory period
What is the local anesthetic mode of action?
Block the influence of stimulation (depolarization) on Na+ permeability
What is the specific receptor theory of nerve blockade?
Anesthetic agent accesses and blocks channel from the intracellular side
Charged agents only block stimulated nerves
What is a phasic block?
Means only stimulated nerves are blocked
What are the three parts to the chemical structure of local anesthetic?
- Aromatic group (hydrophobic)
- Intermediate chain (amide or ester)
- Amino group (hydrophilic)
The aqueous distribution constant (Q) reflects the ability to penetrate hydrophobic tissue and correlates with the _________ of the LA.
duration
The dissociation constant (pKa) is the proportion of ionized to un-ionized molecules and correlates with the ___________ of the LA.
onset
In what order do are sensations affected by LA?
- dull pain
- warmth
- cold
- sharp pain
- touch
- pressure
- proprioception
What is the normal pH of anesthetics?
4-6
T/F: Most anesthetic compounds come with a vasoconstrictor.
True
T/F: All local anesthetics are vasodilators.
True
This is why vasoconstrictors (epinephrine) are in the carps
T/F: Anesthetic that is bound to protein will have the strongest effect.
False
No effect
What are some conditions that will increase and decrease binding of LA to proteins?
Increase: MI, cancer, trauma, surgery, chronic pain
Decrease: Pregnancy, oral contraceptives, estrogen supplementation, acidosis, increasing dose
Unbound LA will distribute to the ______ first.
lungs
How long will it take unbound LA to distribute to the muscle?
15 minutes
__________ anesthetics are broken down by circulating plasma pseudocholinesterase.
Ester-type
___________ anesthetics are broken down by hepatic metabolism.
Amide-type anesthetics
What will be the systemic vascular effects at moderate concentration of LA?
Decreased HR, cardiac output, PVR
The more ____________ an anesthetic is, the greater the risk for cardiac toxicity.
lipophilic
What processes decrease under sympathetic stimulation?
Disestive and secretory actions
Alpha receptors stimulate __________ or smooth muscle in blood vessels.
contraction
_________ receptors are found in the heart and produce cardiac stimulation.
Beta-1
What will happen under activation of alpha-1, beta-1, and beta-2 receptors?
Alpha-1: increase blood pressure
Beta-1: Increase heart rate
Beta-2: Decrease blood pressure
Why is antioxidant found in the LA carp?
To protect the vasoconstrictor
Why is HCl or NaOH found in some carpules?
pH adjusting agent
What are the 4 major reasons for adding vasoconstrictor to the carp?
- Hemostasis
- Slow CV absorption -> lower toxicity risk
- Stays where its put -> longer duration
What are the three types of sympathomimetic drugs (vasoconstrictors)?
- Direct acting - directly on receptors
- Indirect acting - use NE release
- Mixed
T/F: Epinephrine is a direct acting sympathomimetic drug.
True
T/F: A 1:50,000 concentration of vasoconstrictor is more potent than a 1:100,000 concentration.
True
What is the volume of a carp?
1.7 ml
What is the maximum epinephrine dose for an ASA I patient per appointment? Patient with heart disease?
0.2 mg; 0.04 mg
T/F: The beta effects of epinephrine predominate.
True
Which antioxidant is added with epinephrine?
Sodium bisulfite