查看Ch15 Sensory Transduction的源代码

=== 半规管检测头部的角加速度 ===

<b style=color:#0ae>The semicircular canals detect the angular acceleration of the head</b>

Semicircular canals (see Fig. 15-17B) also sense acceleration, but not the linear acceleration that the otolithic organs prefer. Angular acceleration generated by sudden head rotations is the primary stimulus for the semicircular canals. Shake your head side to side or nod it up and down. Each rotation of your head will excite some of your canals and inhibit others.

半规管（见图 15-17B）也可以感应到加速度，但不能感应耳石器官喜欢的线性加速度。头部突然旋转产生的角加速度是半规管的主要检测目标。左右摇头或上下点头，你头每旋转一次都会刺激你的一些半规管并抑制其他半规管。


The semicircular canals stimulate their hair cells differently than the otolithic organs. In each canal, the hair cells are clustered within a sensory epithelium (the crista ampullaris) that is located in a bulge along the canal called the ampulla (see Fig. 15-18C). The hair bundles—all of which have the same orientation—project into a gelatinous, domeshaped structure called the cupula, which spans the lumen of the ampulla. The cupula contains no otoconia, and its mucopolysaccharides have the same density as the surrounding endolymph. Thus, the cupula is not sensitive to linear acceleration. However, with a sudden rotation of the canal, the endolymph tends to stay behind because of its inertia. N15-4 The endolymph exerts a force on the movable cupula, much like wind on a sail. This force bows the cupula, which bends the hairs and (depending on the direction of rotation) either excites or suppresses the release of transmitter from the hair cells onto the sensory axons of the vestibular nerve. This arrangement makes the semicircular canals very sensitive to angular acceleration of the head. N15-7

半规管刺激其毛细胞的方式与耳石器官不同。在每个管中，毛细胞聚集在感觉上皮（壶腹嵴）内，该感觉上皮位于沿根管的凸起中，称为壶腹（见图 15-18C）。这些发束（所有发束都具有相同的方向）投射成一个称为壶腹的凝胶状圆顶状结构，该结构跨越壶腹腔。壶腹菌不含耳石，其粘多糖与周围的内淋巴液具有相同的密度。因此，壶腹帽对线性加速度不敏感。然而，随着根管的突然旋转，由于其惯性，内淋巴液往往会留在后面[N15-4]。内淋巴液对可移动的壶腹肌施加力，很像风吹在帆上。这种力使壶盖弯曲，使毛发弯曲并（取决于旋转方向）激发或抑制从毛细胞释放到前庭神经感觉轴突上的递质。这种排列使半规管对头部的角加速度非常敏感[N15-7]。


Each side of the head has three semicircular canals that lie in approximately orthogonal planes. The anterior canal is tilted ~41 degrees anterolaterally from the sagittal plane, the posterior canal is tilted ~56 degrees posterolaterally from the sagittal plane, and the lateral canal is tipped ~25 degrees back from the horizontal plane. Because each canal best senses rotation about a particular axis, the three together give a good representation of all possible angles of head rotation. This complete representation is further ensured because each canal is paired with another on the opposite side of the head. Each member of a pair sits within the same plane and responds to rotation about the same axis. However, whereas rotation excites the hair cells of one canal, it inhibits the canals of its contralateral axis mate. This push-pull arrangement presumably increases the sensitivity of detection.

头部的每一侧都有三个半规管，位于大致正交的平面上。前管从矢状面向前外侧倾斜约 41 度，后管从矢状面向后外侧倾斜约 56 度，外侧管从水平面向后倾斜约 25 度。因为每个耳道最能感知围绕特定轴的旋转，所以这三个管一起可以很好地表示头部旋转的所有可能角度。这种完整的表示得到了进一步的保证，因为每个根管都与头部另一侧的另一个根管配对。对中的每个成员都位于同一平面内，并响应绕同一轴的旋转。然而，虽然旋转会激发一个管的毛细胞，但它会抑制其对侧轴配合的根管。这种推挽式布置可能增加了检测的灵敏度。

<br>