Anatomy & Physiology Flashcards

The Circle of Willis provides collateral circulation to the brain. Which artery connects the two anterior cerebral arteries?

Answer: Anterior communicating artery

The anterior communicating artery is a short vessel connecting the left and right anterior cerebral arteries, completing the anterior part of the Circle of Willis.

Which enzyme converts angiotensin I to angiotensin II in the renin-angiotensin-aldosterone system?

Answer: Angiotensin-converting enzyme (ACE)

ACE (Angiotensin-Converting Enzyme), found predominantly in pulmonary endothelium, cleaves angiotensin I to produce the active vasoconstrictor angiotensin II.

What is the primary function of surfactant produced by type II pneumocytes in the alveoli?

Answer: To reduce alveolar surface tension and prevent collapse

Pulmonary surfactant reduces alveolar surface tension, preventing alveolar collapse (atelectasis) at end-expiration, and is critical for normal lung compliance.

The hepatic portal vein drains venous blood to the liver from which organs?

Answer: Gastrointestinal tract and spleen

The hepatic portal vein carries nutrient-rich and potentially toxic venous blood from the gastrointestinal tract (stomach to rectum) and spleen to the liver for processing.

Which nerve innervates the diaphragm and originates from cervical spinal levels C3, C4, and C5?

Answer: Phrenic nerve

The phrenic nerve (C3, C4, C5 — 'keeps the diaphragm alive') provides motor and sensory innervation to the diaphragm, the primary muscle of respiration.

In the cardiac cycle, what does the P wave on an ECG represent?

Answer: Atrial depolarisation

The P wave on an ECG reflects the electrical depolarisation of the atria, which triggers atrial contraction and occurs just before the PR interval and QRS complex.