What structures conduct nerve impulses?
Neurons, or nerve cells, carry out the functions of the nervous system by conducting nerve impulses. They are highly specialized and amitotic.
What tissue layers do cnidarians have?
Cnidarians consist of two cell layers: an outer ectoderm and an inner endoderm (the gastrodermis) that lines the coelenteron.
What is the nervous system of a cnidarian?
The basic plan of the cnidarian nervous system is that of a nerve net which, at some locations, has condensed to form nerve plexuses, or circular or longitudinal nerve tracts which may be syncytia.
Why do cnidarians have a nerve net?
In the cnidarian body, the nerve net serves as a sensory locator; neuron cells stretch all around the animal’s body and allow the cnidarian to detect chemical changes, to capture prey, and to move in response to a stimulus. This kind of expansive nerve net is also known as a diffuse nerve net.
What do the nerve cells of cnidarians make up?
Cnidarians contain specialized cells known as cnidocytes (“stinging cells”), which contain organelles called nematocysts (stingers). These cells are present around the mouth and tentacles, serving to immobilize prey with toxins contained within the cells. Nematocysts contain coiled threads that may bear barbs.
What is the movement of cnidarians?
However, most do so weakly and are carried passively by currents over long distances. Polyps are generally sedentary. Pennatulacean colonies move slowly across soft substrata by action of their inflatable peduncle (a stalk that attaches to the strata in the lower end and to the polyp body on the higher end).
Do cnidarians have a nerve net?
Cnidarians are considered “nerve net animals” even though their nervous systems include various forms of condensation and centralization.
What does a nerve ring do?
n. In echinoderms, a bundle of nerve cells encircling the mouth and connecting to radial nerves. It functions to relay the sensory and motor signals throughout the body.
How is a nerve impulse conducted describe the process?
In electrical synapses, two neurons are connected through channel proteins for transmitting a nerve impulse. The nerve impulse travels across the membrane of the axon in the form of an electrical signal. The signal is transmitted in the form of ions and therefore it is much faster than chemical synapses.
What is the function of cnidarians in the nervous system?
A gastrovascualar cavity is present in them. Nervous system in the form of a nerve network is present. Specialized cells called cnidocytes are present. They are used for defense, feeding and attachment. Cnidarians possess diploblastic and tissue-level organization. Cells organize into tissues. The tissues carry out specific functions.
Are there ganglia or ganglia in a cnidarian?
Ganglia or other accumulations of nerve cell bodies are not found in cnidarians, but there are gap junctions between neurons and between neurons and effectors, which allow the transmission of nerve impulses.
What are the two cell layers of a cnidarian?
Cnidarians consist of two cell layers: an outer ectoderm and an inner endoderm (the gastrodermis) that lines the coelenteron. Between these is sandwiched the mesoglea, a largely noncellular layer composed of a jellylike material permeated by a complex network of supporting fibres that may be microscopically thin or very thick.
Where are the muscles located in a cnidarian?
Muscles in cnidarians are extensions of the bases of ectodermal and endodermal cells. Individual muscle cells are relatively long and may occur in dense tracts in jellyfish or sea anemones. Most cnidarian muscles, however, are thin sheets at the base of ectodermal and endodermal layers.