Axon

of progenitors in the epithelium, the specification of neurons and glia, the growth and guidance of axons and dendrites, and the development and refinement of electrical and chemical synapses. In the central nervous system (CNS), stem cells reside throughout life in the forebrain, continuing to generate neurons and glia in the subventricular zone (SVZ) surrounding the lateral ventricle and in the dentate gyrus of the hippocampus. The SVZ is known to be the major site of Neurogenesis in the adult mammalian brain. Throughout life neurons spawn from the neural stem cells that are localized in specialized niches. The apical ependymal niche and the basal vasculature niche are…

proteins are synthesized in the cell body and are transported down the axon by anterograde to the synaptic terminal. The proteins at the synaptic terminal which have reached the end of their lifetime are then transported back to the cell body by the retrograde transport for degradation and recycling. 2. Can depolarization occur without an action potential being created? Explain An action potential begins when a depolarization increases the membrane voltage so that it crosses a threshold value.…

myelin and how does it affect the transmission of nerve impulses? Identify the cells responsible for the formation of myelin. Covering some axons is a multilayered lipid and protein called myelin sheath, this helps to insulate the axon and speed up nerve impulses. (Tortora pg. 407) An axon that is surrounded by myelin sheath, whether in the central nervous system (CNS) or the peripheral nervous system (PNS), is said to be “myelinated”, while the bare axon is “unmyelinated”. Action potentials…

Myelin is imperative for the functioning of adequate conduction velocity speed in axons. Myelin is made of water, lipids and proteins and appears white in color. This combination of lipids and proteins form a whitish protective cover or sheath over the axon of numerous nerve fibers. This sheath covering the axon speeds up the impulses that are being conducted, which is important in the transmission of impulses in our body. Without myelin speeding up conduction, the impulses would decelerate.…

Summary: In the visual perception: neural processing chapter it first started talking about how neurons work and what parts make up the neurons. The neurons contain three parts which are dendrites, axon, and the axon terminal. Dendrites are the structures that receive electrical messages from other neurons. In order for neurons to work, they will have to receive stimuli through their synaptic receptors. Once the dendrites receive the electrical messages from the other neurons it will transfer it…

length of the axon can be different. For example, the axons in the brain are shorter (Pastorino and Doyle-Portillio, 2015). The axon carries the neural impulse away from the cell body. Several structures to note that are present on the axon include the myelin sheath and the nodes of Ranvier. The myelin sheath helps with the insulation of the neural impulse and the nodes of Ranvier are the spaces that are uncovered by the myelin sheath. Once the neural impulse reaches the end of the axon, the…

leave the central nervous system. The pyramidal and extrapyramidal tracts consist of UMNs. Since UMN do not leave the neuraxis they have to synapse with LMN to carry messages to the muscles. LMN is spinal and cranial nerves. The cell bodies of LMN are located in the brainstem but their axons are able to leave the CNS and synapse with the muscles of the body. During speech, muscles receive impute from both pyramidal and extrapyramidal systems.…

What is the all-or-nothing principle, and how does it work? In order to fully understand the all-or-nothing principle, one must first know what an action potential is and its relevance to the all-or-nothing principle. Therefore, an action potential is a very short wave of positive electrical charge that travels down an axon. In connection to the all-or-nothing principle, it is important to know that the action potential obeys the all-or-nothing principle. The all-or-nothing principle states that…

PNS include all the neural tissue outside the CNS. Neuron are the nerve cells which receive the stimulus from each part of the body and send it to the CNS. A neuron consist of body cell, dendrites, axon,myelin sheath and telodendrites. Normal neuron requires all the structure works together forming a good nervous system. The damages of any…

mitochondria can become stationary and in mature axons of the central nervous system (CNS), the majority of the mitochondria become stationary with only about 20-30% remaining motile. With this reduction in mitochondrial transport, mature CNS axons fail to regrow after injury, resulting in neurological impairment. Previous studies suggest that mature CNS neurons have lost their growth capacity and to recover from an injury, neurons need to quickly reform an active growth cone where damaged…