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These neurons contain receptors, called olfactory receptors, that are activated by odor molecules in the air. The molecules in the air are detected by enlarged cilia and microvilli. [5] These sensory neurons produce action potentials. Their axons form the olfactory nerve, and they synapse directly onto neurons in the cerebral cortex (olfactory ...
There are two types of axons in the nervous system: myelinated and unmyelinated axons. [5] Myelin is a layer of a fatty insulating substance, which is formed by two types of glial cells: Schwann cells and oligodendrocytes. In the peripheral nervous system Schwann cells form the myelin sheath of a myelinated axon. Oligodendrocytes form the ...
Large motor neurons are first. Smaller sensory neurons together with glial cell differentiate at birth. [72] Adult neurogenesis can occur and studies of the age of human neurons suggest that this process occurs only for a minority of cells and that the vast majority of neurons in the neocortex form before birth and persist without replacement ...
The extensive dendritic tree of two hippocampal pyramidal neurons (magenta) with all incoming synapses genetically labeled (green spots). [2] Dendrites are one of two types of cytoplasmic processes that extrude from the cell body of a neuron, the other type being an axon. Axons can be distinguished from dendrites by several features including ...
A sensory system consists of sensory neurons (including the sensory receptor cells), neural pathways, and parts of the brain involved in sensory perception and interoception. Commonly recognized sensory systems are those for vision , hearing , touch , taste , smell , balance and visceral sensation.
(In fact, the types of neurons called amacrine cells have no axons, and communicate only via their dendrites.) Neural signals propagate along an axon in the form of electrochemical waves called action potentials, which produce cell-to-cell signals at points where axon terminals make synaptic contact with other cells. [40]
The cell bodies of sensory neurons known as first-order neurons are located in the dorsal root ganglia. [2] The axons of dorsal root ganglion neurons are known as afferents. In the peripheral nervous system, afferents refer to the axons that relay sensory information into the central nervous system (i.e. the brain and the spinal cord).
Bipolar neurons exist within the vestibular nerve as it is responsible for special sensory sensations including hearing, equilibrium and motion detection. The majority of the bipolar neurons belonging to the vestibular nerve exist within the vestibular ganglion with axons extending into the maculae of utricle and saccule as well as into the ...