INI-CET 2018 — Physiology

Q: Curve A signifies which of the following?

Emphysema. ***Emphysema*** - Curve A shows a **leftward and upward shift** on the pressure-volume diagram, indicating **increased lung compliance** where lungs achieve higher volumes at lower pressures. - Characteristic of **emphysema** due to **destruction of alveolar walls** and **loss of elastic recoil**, making lungs easier to inflate but difficult to deflate. *Normal* - Represents the **baseline pressure-volume curve** with normal lung compliance and elastic recoil properties. - Shows typical relationship between **transpulmonary pressure** and lung volume in healthy lungs. *Pulmonary fibrosis* - Would demonstrate a **rightward shift** on the pressure-volume curve, indicating **decreased lung compliance** (stiffer lungs). - Characterized by **excessive collagen deposition** making lungs harder to inflate, requiring higher pressures for same volume. *Asthma* - Shows **near-normal static compliance** unlike emphysema because **elastic tissue remains intact**. - Primary pathology involves **airway hyperresponsiveness** and **bronchoconstriction**, not loss of lung elasticity. [Practice more Physiology PYQs on OnCourse]

Q: In the image shown below, which of the marked area is involved in relieving pain in response to massage?

Area A. ***A*** - Area A points to the **dorsal columns** (specifically the fasciculus gracilis and cuneatus) of the spinal cord, which carry **mechanoreceptive** and proprioceptive information. - Massage activates large diameter afferent fibers which transmit signals via the dorsal columns, inhibiting pain transmission through the **gate control theory of pain**. *B* - Area B points to the **dorsal horn** (specifically lamina I, II, and V), which is primarily involved in receiving and processing **nociceptive input**. - While integration of pain occurs here, it is not the primary pathway for the **modulatory effects of touch/pressure** from massage for pain relief. *C* - Area C indicates the **ventral horn** of the spinal cord, which contains **motor neurons** that control skeletal muscle activity. - It is involved in motor output, not directly in the sensory processing or modulation of pain signals from massage. *D* - Area D points to the **lateral white matter**, which contains various ascending and descending tracts, including the **spinothalamic tract** (primary pain pathway) and corticospinal tract. - While the spinothalamic tract carries pain signals, the direct pain-relieving effect of massage primarily involves activation of mechanoreceptors whose signals ascend via the dorsal columns. [Practice more Physiology PYQs on OnCourse]

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Curve A signifies which of the following?

In the image shown below, which of the marked area is involved in relieving pain in response to massage?