单元 2 - 2C

The nose is a prominent facial feature located in the center of the face, above the mouth, and between the eyes. It serves as a passage for air during breathing and is responsible for the sense of smell. The nose consists of external and internal structures, including the nostrils, nasal cavity, nasal septum, and nasal cartilage. It plays a vital role in the respiratory system by filtering, warming, and humidifying the air we breathe. The shape and size of the nose can vary greatly among individuals and are influenced by genetics and ethnic background. Apart from its functional role, the nose also contributes to facial aesthetics and expressions, making it an important aspect of overall facial appearance.

The tongue is a muscular organ located in the mouth that plays a vital role in various functions, including tasting, chewing, swallowing, and speech production. It is composed of muscles covered by a mucous membrane and contains taste buds that allow for the perception of different flavors. The tongue also helps manipulate food during chewing and forms sounds by interacting with the teeth, palate, and other speech organs.

The eye is a complex sensory organ that enables vision in humans. It consists of several parts working together to capture and process visual information. The front part of the eye includes the transparent cornea and the colored iris, which controls the amount of light entering the eye through the pupil. Behind the iris is the crystalline lens, which focuses light onto the retina at the back of the eye. The retina contains specialized cells called photoreceptors that convert light into electrical signals, which are then sent to the brain via the optic nerve. The eye also has structures such as the sclera, the white outer layer, and the conjunctiva, a thin membrane covering the front of the eye.

The ear is a sensory organ located on the sides of the head, responsible for both hearing and maintaining balance. It consists of three main parts: the outer ear, middle ear, and inner ear. The outer ear includes the visible part called the auricle or pinna and the ear canal, which leads to the eardrum. The middle ear contains the eardrum and three tiny bones called the ossicles, which transmit sound vibrations to the inner ear. The inner ear houses the cochlea, a spiral-shaped structure responsible for converting sound into electrical signals that can be interpreted by the brain. In addition to hearing, the ear also plays a crucial role in our sense of balance and spatial orientation.