Taste and Smell

The Tongue – sense of taste (gustatory)

Your tongue is covered by thousands of little tiny bumps, which you have probably always called your “taste buds”. The tiny bumps that coat the surface of your tongue are small structures called papillae. Four different types of papillae cover the regions of the tongue: foliate (sides of the tongue), vallate (back of the tongue), fungiform (midline of the tongue) and filiform (front of the tongue, lacks taste buds).

Sensory receptors, taste buds, are located on the sides of the papillae (Figure 1). Food molecules or other chemicals that enter the taste bud through the small opening (taste pore) are detected by sensory receptor cells. This sensory input is relayed to the brain by one of three cranial nerves [facial (VII), glossopharyngeal (IX), and vagus (X)].

Figure 1: Taste buds with and without illustration overlay

Olfactory Epithelium – sense of smell (olfaction)

The inside of your nasal passages is lined with olfactory epithelium. This mucous-producing epithelium is heavily ciliated (Figure 2). The mucus and cilia help to trap particles (dust, pollen, bacteria, viruses). This ciliated pseudostratified epithelium contains sensory receptor cells that relay sensory input from odor molecules to your brain by the olfactory nerve (cranial nerve I).

Figure 2: Olfactory epithelium with and without illustration overlay

Chapter Illustrations By:

Juan Manuel Ramiro-Diaz, Ph.D.