Anatomy and Physiology Flashcards

The brachial plexus arises from spinal nerve roots:

Answer: C5 to T1

The brachial plexus (C5 to T1) provides motor and sensory innervation to the entire upper extremity, including the arm used for IV access during sedation.

In which phase of the cardiac cycle do the coronary arteries receive most of their blood flow?

Answer: Diastole, when ventricular wall tension is lowest

Coronary perfusion occurs predominantly during diastole because systolic ventricular wall tension compresses the intramyocardial vessels, impeding flow.

The oxygen-hemoglobin dissociation curve shifts to the RIGHT in which condition, releasing more oxygen to tissues?

Answer: Hypercapnia (elevated CO2) and acidosis

Hypercapnia, acidosis, hyperthermia, and increased 2,3-DPG shift the curve rightward, decreasing hemoglobin oxygen affinity and facilitating tissue oxygen delivery.

Which cranial nerve carries preganglionic parasympathetic fibers to the parotid gland?

Answer: CN IX (glossopharyngeal)

CN IX (glossopharyngeal) carries preganglionic parasympathetic fibers via the lesser petrosal nerve to the otic ganglion, which innervates the parotid gland.

The portal circulation is clinically relevant to dental sedation because:

Answer: Orally absorbed drugs pass through the liver first, reducing bioavailability (first-pass effect)

The portal system drains GI tract blood to the liver before the systemic circulation, allowing the liver to metabolize orally absorbed drugs - the first-pass effect.

Which property allows CO2 to rapidly diffuse from the tissues into the bloodstream?

Answer: CO2 has high lipid solubility, crossing cell membranes approximately 20 times faster than O2

CO2 is highly lipid-soluble and diffuses across biological membranes approximately 20 times more rapidly than oxygen, facilitating rapid tissue-to-blood transfer.