What are the 4 main structures of the nervous system?
The nervous system consists of the brain, spinal cord, sensory organs, and all of the nerves that connect these organs with the rest of the body. Together, these organs are responsible for the control of the body and communication among its parts.
What are the key structures of the nervous system?
The nervous system has two main parts:
- The central nervous system is made up of the brain and spinal cord.
- The peripheral nervous system is made up of nerves that branch off from the spinal cord and extend to all parts of the body.
Does amphioxus have dorsal nerve cord?
On the evolutionary road to vertebrates, amphioxus occupies a key position to tackle this exciting issue. Its “simple” nervous system basically consists of a dorsal nerve cord and a diffuse net of peripheral neurons, which contrasts greatly with the complexity of vertebrate nervous systems.
What are the 3 main parts of the nervous system?
The nervous system is made up of the central nervous system and the peripheral nervous system:
- The brain and the spinal cord are the central nervous system.
- The nerves that go through the whole body make up the peripheral nervous system.
What structures in the amphioxus are typically vertebrate?
Amphioxus is a prototypical vertebrate, with many homologs of vertebrate organs. These amphioxus structures include the pituitary, pineal organ, striated axial muscles, kidneys, liver, thyroid gland, nerve cord, and pancreatic islet cells.
What are the early nervous system structures called?
neural plate
The first sign of the nervous system is the appearance of a thin strip of cells along the center of the back, called the neural plate. The inner portion of the neural plate is destined to become the central nervous system (CNS), while the outer portion will become the peripheral nervous system (PNS).
What are the 6 stages of nervous system development?
Physio (6 Stages of Neuronal Development)
- Neurogenesis.
- Cell Migration.
- Cell Differentiation.
- Synpatogenesis.
- Neuronal Cell Death.
- Synapse Rearrangement.
Which is the excretory structure of amphioxus?
The excretory organs of Amphioxus occur as segmentally arranged structures throughout the pharyngeal region and may be divided into three components: the solenocytes, the renal tubule, and the renal glomerulus. The solenocytes possess foot processes that rest upon the coelomic surface of the ligamentum denticulatum.
What are the features of amphioxus?
Amphioxus is an amazing animal and possesses a notochord, dorsal tubelike nerve cord, pharyngeal gill slits, postanal tail, and segmented somites, which are assumed to be present only in the common chordate ancestor. Its embryonic development has feature of invertebrates and vertebrates, as noted by Kowalevsky (1867).
Do amphioxus CNS cells produce neurochemicals?
Although the central nervous system (CNS) of amphioxus comprises only about 20,000 neurons (as compared to billions in vertebrates), the developmental genetics and neuroanatomy of amphioxus are strikingly vertebrate-like. In the present study, we mapped the distribution of amphioxus CNS cells producing distinctive neurochemicals.
What is an amphioxus transverse?
“A highly schematic transverse section of amphioxus through the central nervous system and the top portion of the notochord, showing various sensory and motor cell types and the composition of the dorsal nerves.
Why is amphioxus important to vertebrates?
As such, amphioxus is of key importance to investigations vertebrate organization. The nervous system is of special interest originated. One has little recourse except to conduct investigations of amphioxus and other protochordates. This was the comparative zoologists of the day.
What are the characteristics of excretory system of amphioxus?
Excretory system • Lacks kidney • Excretion occurs through solenocytes • Solenocytes of Amphioxus are closely resemble the protonephridia of flatworm or annelids (Parallel evolution) 1. Protonephridia : • Simple, closed, ciliated sac like and thin walled ectodermal tubules present on pharyngeal wall on each gill.