Father Pacini corpuscles
Father Pacini bodies , also called Pacinian bodies or lamellar bodies ( Latin Corpusculum lamellosum ), are mechanoreceptors of the skin that adapt quickly and convey vibration sensations particularly well . They are named after the German anatomist Abraham Vater (1684–1751) and the Italian anatomist Filippo Pacini (1812–1883).
Occurrence
In humans, the Vater-Pacini corpuscles are mainly located in the subcutis , especially the palms and soles of the feet and the proximal phalanges of the fingers and toes. They are also found on the large tendon plates, in the pancreas , periosteum , vaginal wall , in the retroperitoneal space and in the tissue around the urinary bladder .
construction
The receptor is formed by the non-medullary end of a medullary nerve fiber that is surrounded by 40–60 onion-skin-like lamellae made of flattened perineural cells and a connective tissue capsule. The lamellar bodies reach a size of up to 2 mm.
The non-medullary end of the neuron represents the sensor. Mechanically activated ion channels, a mechanical deformation of the lamellae triggers a generator potential that is passed on electrotonically. This conversion of the mechanical stimulus into a change in electrical potential is called “transduction”. When a threshold is exceeded, the receptor potential is converted into an action potential by opening potential-dependent sodium channels (“transformation”).
The Vater-Pacini corpuscle is one of the rapidly adapting receptors. It reacts to (positive and negative) accelerations and is therefore suitable as a vibration detector. The highest sensitivity is with a vibration of around 300 Hz, where a deformation of a few micrometers is sufficient to excite the receptors.
Neural interconnection
The action potential of the associated sensitive neuron, the perikaryon of which is located in a spinal ganglion , is passed on via its axon without switching in the posterior cord on the same side of the spinal cord to the posterior cord nuclei in the medullary brain ( nucleus gracilis for the lower, nucleus cuneatus for the upper half of the body) and there to the second neuron interconnected. Its efferent fibers join the medial loop path ( lemniscus medialis ). This path crosses in the further course in the brain stem to the opposite side and reaches the thalamic nuclei . After switching over again, the information then reaches the sensitive areas of the cerebral cortex .
Krause bodies
The smaller variant of the Vater-Pacini corpuscle is also called the Krause corpuscle .
literature
- Schmidt, Schaible (Ed.): Neuro- and Sensory Physiology , Springer, 2000, ISBN 3-540-41347-2
- Kandel et al. (Ed.): Neurosciences , Spectrum 1995, ISBN 3-86025-391-3