1.Human anatomyMedium
Which carpal bone is most commonly fractured, typically after a fall on an outstretched hand?
- APisiform
- BLunate
- CHamate
- DScaphoid
Anatomy and Physiology: cram pack
Formula sheets, the key method steps for every topic and 4 practice problems, with full solutions at the back.
1Practice problems
2.Human anatomyHard
Which coronary artery most often supplies the sinoatrial (SA) node?
- ALeft anterior descending artery
- BCircumflex artery
- CLeft main coronary artery
- DRight coronary artery
3.Human physiologyMedium
Which receptors respond mainly to a fall in arterial oxygen levels?
- ABaroreceptors in the carotid sinus
- BStretch receptors in the lungs
- CCentral chemoreceptors in the medulla
- DPeripheral chemoreceptors in the carotid and aortic bodies
4.Human physiologyHard
A young woman has muscle weakness that gets worse with repeated use and improves with an acetylcholinesterase inhibitor. What is the most likely mechanism?
- ALoss of motor neurons in the spinal cord
- BAntibodies against acetylcholine receptors at the neuromuscular junction
- CDemyelination of central nervous system tracts
- DA defect in the dystrophin protein of muscle
2Solutions
1.Human anatomy
Answer: D · Scaphoid
Why this is the answer
The scaphoid is the most often fractured carpal bone. Tenderness in the anatomical snuffbox is a key clinical sign.
Answer
D · Scaphoid
2.Human anatomy
Answer: D · Right coronary artery
Why this is the answer
The SA nodal artery arises from the right coronary artery in roughly 60% of people and from the circumflex artery in the rest.
Answer
D · Right coronary artery
3.Human physiology
Answer: D · Peripheral chemoreceptors in the carotid and aortic bodies
Why this is the answer
The carotid and aortic bodies detect low PaO₂ (and also high CO₂ and H⁺). The central chemoreceptors respond to CO₂ but not directly to oxygen.
Answer
D · Peripheral chemoreceptors in the carotid and aortic bodies
4.Human physiology
Answer: B · Antibodies against acetylcholine receptors at the neuromuscular junction
Why this is the answer
In myasthenia gravis, autoantibodies reduce the number of functional acetylcholine receptors. Blocking acetylcholinesterase leaves more ACh to bind the remaining receptors.
Answer
B · Antibodies against acetylcholine receptors at the neuromuscular junction
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