Brain
The human brain is located together with the cerebrospinal fluid (liquor) in the bony skull. It is directly connected to the spinal cord via the brain stem. In addition, numerous nerve fibers run through various openings in the base of the skull to the individual muscles and sensory organs. The human brain consists of two brain hemispheres, each of which is divided into four lobes:
- Frontal (frontal) lobes: centers of personality & drive control
- Temporal lobe (temporal lobe): Hearing center, speech center
- Parietal lobe (parietal lobe): Center for spatial thinking
- Occipital lobe (occipital lobe): Visual center
The sense organs
The eyes are an important sense organ. Seeing is one of the five human senses along with hearing, tasting, smelling and feeling. When light falls on the human eye, it is converted into electrical impulses in the area of the retina, whereby the stimulus is then transmitted to various visual centers in the brain.
Information about the proximity, color, size and movement of an object is also processed. The nose contains the olfactory cells that are present in the area of the nasal mucosa, the so-called olfactory epithelium. Humans have about 10 million olfactory cells, which transmit olfactory information to the brain.
The nose also provides access to the airways. During nasal breathing, the inhaled air is to be warmed, moistened and cleaned (by special cilia in the area of the nasal mucous membrane) before it reaches the lower airways (including the lungs). The mouth is the first station of the digestive tract.Here the food is crushed and partly digested by enzymes of the saliva before it reaches the esophagus by swallowing.
There are also numerous taste buds on the tongue, which can differentiate between the qualities bitter, sour, salty and sweet, and can pass on the taste information to the brain. Air can also pass through the mouth into the respiratory tract, which is then directed into the windpipe (trachea). The ear contains both the hearing and the balance organs.
Sound waves enter the ear via the auditory canal, causing the eardrum to vibrate. By striking the ossicles (hammer, anvil and stirrup), the sound stimulus is transmitted to the cochlea, from where the information then reaches the brain via the auditory nerve. The organ of equilibrium in the inner ear enables the body to recognize its position in space and, together with the information from the eyes, to coordinate movements, for example.