There are four longitudinal collection canals, two dorso-lateral and two ventro-lateral, running along the length of the worm, with a transverse canal linking the ventral ones at the posterior of each segment. When the proglottids begin to detach, these canals open to the exterior through the terminal segment.The main nerve centre of a cestode is a cerebral ganglion in its scolex. Nerves emanate from the ganglion to supply the general body muscular and sensory endings, with two lateral nerve cords running the length of the strobila. The cirrus and vagina are innervated, and sensory endings around the genital pore are more plentiful than in other areas. Sensory function includes both tactoreception (touch) and chemoreception (smell or taste). Proglottids
Once anchored to the hosts intestinal wall, tapeworms absorb nutrients through their surface as their food flows past them. Cestodes are unable to synthesise lipids, which they use for reproduction, and are therefore entirely dependent on their hosts.The tapeworm body is composed of a series of segments called proglottids. These are produced from the neck by mitotic growth, which is followed by transverse constriction. The segments become larger and more mature as they are displaced backwards by newer segments. Each proglottid contains an independent reproductive tract, and like some other flatworms, cestodes excrete waste through flame cells (protonephridia) located in the proglottids. The sum of the proglottids is called a strobila, which is thin and resembles a strip of tape; from this is derived the common name "tapeworm".
As pressure increases in the skull, herniation of the brain can occur, which is a squeezing of the brain across the internal structures of the skull. This can lead to headache, nausea, vomiting, confusion, seizures, brain stem compression and respiratory arrest, and non-cardiogenic accumulation of fluid in the lungs. This is usually fatal if not immediately treated. Symptom severity depends on how fast and how severe the drop in blood sodium level is. A gradual drop, even to very low levels, may be tolerated well if it occurs over several days or weeks, because of neuronal adaptation. The presence of underlying neurological disease such as a seizure disorder or non-neurological metabolic abnormalities, also affects the severity of neurologic symptoms. Chronic hyponatremia can lead to such complications as neurological impairments. These neurological impairments most often affect gait (walking) and attention, and can lead to increased reaction time and falls. Hyponatremia, by interfering with bone metabolism, has been linked with a doubled risk of osteoporosis and an increased risk of bone fracture. Causes
The specific causes of hyponatremia are generally divided into those with low tonicity (lower than normal concentration of solutes), without low tonicity, and falsely low sodiums. Those with low tonicity are then grouped by whether the person has high fluid volume, normal fluid volume, or low fluid volume. Too little sodium in the diet alone is very rarely the cause of hyponatremia. High volume
Both sodium and water content increase: Increase in sodium content leads to hypervolemia and water content to hyponatremia.