Search
-
- Glossary
Brain stem
The "trunk" of the brain, to which all other brain structures are "attached," so to speak. From bottom to top, it comprises the medulla oblongata, the pons, and the mesencephalon. It transitions into the spinal cord below. It is a center for vital functions such as breathing and heartbeat and contains ascending and descending pathways between the cerebrum, cerebellum, and spinal cord.
-
- Glossary
Histology
Histology is the study of tissue. It involves examining tissue samples. The tissue is processed and stained using various methods and cut into thin sections that can be examined under a microscope.
-
- Glossary
Homo economicus
A term from economics describing the idea that people always act according to the maxim of optimizing their own utility. However, the motive is not primarily selfish, but rather rational. This view of human nature contrasts with that of Homo reciprocans, which assumes that people prioritize cooperative behavior.
-
- Glossary
Homeostasis
Homeostasis is the ability of an organism to maintain internal conditions such as metabolism, body temperature, blood pressure, etc. at a relatively constant level. The maintenance of homeostasis is controlled by the autonomic nervous system, meaning that humans cannot directly influence its regulation at will.
-
- Glossary
Homunculus
In the brain, every part of the body is represented in precisely defined locations, both sensorily and motorically. Body parts with a high density of sensory receptors (fingertips, tongue) are represented more prominently than those with a lower receptor density (back, legs). Neural maps are developed, e.g., of the hand or face. If these maps are graphically assigned to their body parts, the result is a homunculus, i.e., a small human being. The size of its respective body parts reflects their motor capabilities or sensitivity. This makes the homunculus appear strangely distorted.
-
- Glossary
Auditory pathway
The auditory pathway refers to the nerve fibers that transmit acoustic information from the inner ear to the primary auditory cortex. In humans, the auditory pathway consists of five switching points: the spiral ganglion, the auditory nuclei in the brainstem, the inferior colliculus, the medial geniculate body of the thalamus, and the primary auditory cortex.
-
- Glossary
Horizontal cell
Horizontal cells are nerve cells in the retina. They form a lateral connection between photoreceptors and bipolar cells. In this way, they increase the contrast of what is seen.
-
- Glossary
Hormone
Hormones are chemical messengers in the body. They serve to transmit information between organs and cells, usually slowly, e.g., to regulate blood sugar levels. Many hormones are produced in glandular cells and released into the blood. At their destination, e.g., an organ, they dock at binding sites and trigger processes inside the cell. Hormones have a broader effect than neurotransmitters; they can influence various functions in many cells of the body.
-
- Glossary
Auditory nerve
The hair cells of the organ of Corti stimulate neurons in the spiral ganglion, which is located in the cavity of the cochlea. Their axons form the auditory nerve, which transmits electrical impulses from the inner ear to the brain. Together with the vestibular nerve (nervus vestibularis), the auditory nerve forms the VIII cranial nerve.
-
- Glossary
Cornea
The cornea is the transparent front part of the outer layer of the eye. It is involved in refracting light, ensuring that the image of a distant object falls on the point of sharpest vision on the retina.
