<P> There are two categories of nerve cells that are found in the nerve nets of Hydra: ganglion and sensory . While ganglion cells are normally found near the basal ends of the epithelial cells, sensory cells generally extend in an apical direction from the muscle processes of the basal ends . While Ganglia generally provide intermediary connections between different neurological structures within a nervous system, sensory cells serve in detecting different stimuli which could include light, sound, touch or temperature . </P> <P> There are many subsets of neurons within a nerve net and their placement is highly position specific . Every subset of a neuron has a constant and regional distribution . In a Hydra, cell bodies of epidermal sensory cells are usually found around the mouth at the hypostome's apical tip, neurite's are usually directed down the sides of the hypostome in a radial direction, and ganglion cells are found in the hypostome's basal region (in between tentacles and just below the head). Nerve nets contain intermediate neurons which allow for modulation of neural activity which occurs between the sensation of the stimulus and motor output . </P> <P> Each sensory neuron within a nerve net responds to each stimulus, like odors or tactile stimuli . The motor neurons communicate with cells via chemical synapse to produce a certain reaction to a given stimulus, therefore a stronger stimulus produces a stronger reaction from the organism . If a particular stimulus is larger than another, then more receptors of the sensory cells (which detect stimuli) will be stimulated which will ultimately trigger a larger response . In a typical unmyelinated axon, the action potential is conducted at a rate of about 5 meters per second, compared to a myelinated human neural fiber which conducts at around 120 meters per second . </P> <P> While nerve nets use hormones, the total physiology isn't very well understood . Hormones normally found in vertebrates have been identified in nerve net tissues . Whether they serve the same function as those found in vertebrates isn't known and little research has been performed to solve the question . Hormones such as steroids, neuropeptides, indolamines, and other iodinated organic compounds have been seen in tissues of cnidarians . These hormones play a role in multiple pathways in vertebrae neurophysiology and endocrine system including reward and complex biochemical stimulation pathways for regulation of lipid synthesis or similar sex steroids . </P>

How many specialized neurons are in a nerve net