Eyes, ears, nose, tongue, body, etc. The brain is the center of all feelings. Eyes are vision, ears are hearing, nose is smell, tongue is taste, and all parts of the body are touch.

However, with the in-depth study of biology and human brain science, researchers have discovered several other senses of human beings. In addition to the "five senses", there are actually many sensory receptors everywhere in the human body, which play a very important role, such as keeping the body balanced and sending out hunger signals.

Generally speaking, receptors are divided into three categories according to their positions and stimuli:

1. External receptors: distributed in skin, mucosa, visual and auditory organs, etc. Accept external stimuli, such as physical stimuli and chemical stimuli such as touch, pressure, cutting, temperature, light and sound.

2. Endoreceptor: It is distributed in internal organs and blood vessels and receives physical or chemical stimuli applied to these organs, such as pressure, osmotic pressure, temperature, ion and compound concentration.

3, proprioceptors: distributed in muscles, tendons, joints and sensory organs of the inner ear, receiving the stimulation of body movement and balance.