22 下列有關耳蝸（cochlea）之敘述，何者錯誤？

耳蝸內有三個螺旋狀之腔室，包括前庭階（scala vestibuli），中階（scala media）和鼓膜階（scala tympani）

中階又稱耳蝸管（cochlear duct），內含柯蒂氏器（organ of Corti）

中階內之液體成份與細胞外液類似為一低鈉液體，稱為外淋巴液（perilymph）

內淋巴液（endolymph）由血管紋（stria vascularis）所產生，含有高濃度的鉀離子

ANS C

Perilymph is an extracellular fluid located within the cochlea (part of the ear) in two of its three compartments; the scala tympani and scala vestibuli. The ionic composition of perilymph is comparable to that of plasma and cerebrospinal fluid. The major cation in perilymph is sodium: the values of sodium and potassium concentration in the perilymph were 138 mM and 6.9 mMrespectively.

IT IS HYPERNATREMIC!

The third compartment of the ear, the cochlear duct (or scala media) contains endolymph. Perilymph and endolymph have unique ionic compositions suited to their functions in regulating electrochemical impulses of hair cells. The electric potential of endolymph is ~80-90 mV more positive than perilymph due to a higher concentration of K compared to Na.

THINK OF THE THE PERILYMPH AND ENDOLYMPH, LIKE THE EXTRACELLULAR AND INTRACELLULAR SPACE:

OUTSIDE: MORE Na

INSIDE: MORE k