PHYLUM NEMERTEA
saadiaPHYLUM NEMERTEA There are nine hundred species of nemerteans. They are elongate, flattened worms. They are found in marine mud and sand. They have a long proboscis. Therefore, nemerteans are…
How is the vertebrate brain related to spinal cord?
rubabEvolution of the vertebrate nervous system included development of a single. tubular nerve cord above the notochord. During early evolution, the nerve cord underwent expansion, regional modification, and specialization into…
Describe nervous system in various invertebrate groups with special reference to the evolutionary trends.
Although no real nervous system is present in protozoa and sponges, coordination and reaction to external and internal stimuli such as, to light, temperature, chemicals etc do occur Only animals…
How is an action potential transmitted between neurons?
When an action potential passes down an axon to its terminal, it must cross a small gap, the synapse (Gr. synapsis, contact, union), separating it from another neuron or an…
What is saltatory conduction?
Saltatory Conduction is different means of speeding the propagation of action potentials has evolved in vertebrates. Many axons in vertebrate nervous systems are myelinated, that is, coated with insulating layers…
CLASS CESTOIDEA: THE TAPEWORMS
CLASS CESTOIDEA: THE TAPEWORMS It is the most highly specialized class of flatworms. The members of cestoidae are commonly called tapeworms. It has 3,500 species. All are endoparasites. They live…
Phases of action potential & role of gated ion channels
Stages / Phases of Action Potential: 1. All cells have a membrane potential; however, only certain kinds of cells, including neurons and muscle cells, have the ability to generate changes…
Class Trematoda : Flukes (trematodes, perforated form)
CLASS TREMATODA: Flukes (trematodes, perforated form) This class has eight thousand species of parasitic flatworms. Trematoda are collectively called flukes. They are wide and flat shaped. 1. Habitat: Almost all…
sidraWhat do you mean by resting membrane potential? How is a resting membrane maintained?
Resting membrane potential can be defined as the potential difference that results from the separation of charges along the plasma membrane of a neuron or other excitable cell. A resting…