Chapter 2-1 - Structure of neurons
Describe the bipolar neuron.
Bipolar neurons participate in sensory processes. They convey information in the auditory, visual, and olfactory systems. These neurons have two processes, one axon and one dendrite, and thus in some sense might be considered the prototypical neuron. Information comes in one end via the dendrite and leaves through the other end down the axon.
Describe the unipolar neuron.
The unipolar neuron has only one process extending away from the cell body. It can branch to form dendrites and axon terminals - a pattern common in invertebrate nervous system.
What is Golgi apparatus?
A complex of vesicles and folded membranes within the cytoplasm of most eukaryotic cells, involved in secretion and intracellular transport.
Describe dendrites and axons.
Dendrites are (usually) large treelike processes that receive inputs from other neurons at locations called synapses. The dendrites of a neurons are said to be postsynaptic. The axon situated before the synapse with respect to information flow is said to be presynaptic.
Describe axon terminals.
Electrical signals travel to the axon terminals, where synapses are located. These axons and axon terminals of the neuron are presynaptic with respect to the synapses they form. The axon terminals have specialized intracellular structures that enable communication via the release of neurotransmitters, the chemical substances that transmit the signal between neurons at chemical synapses.
What is endoplasmic reticulum? [endōˌplazmik rəˈtikyələm]
Endoplasmic reticulum (ER), in biology, a continuous membrane system that forms a series of flattened sacs within the cytoplasm of eukaryotic cells and serves multiple functions, being important particularly in the synthesis, folding, modification, and transport of proteins .
What is mitochondria? [maidəˈkändriə]
Mitochondria are rod-shaped organelles that can be considered the power generators of the cell, converting oxygen and nutrients into adenosine triphosphate (ATP). ATP is the chemical energy "currency" of the cell that powers the cell's metabolic activities.
Describe the multipolar neuron
Multipolar neurons exist in several areas of the nervous system and participate in motor and sensory processing. They have one axon but can have a few or many dendrites emerging from their cell bodies. The myriad of multipolar cells include spinal motor neurons, cortical sensory neurons such as stellate cells and pyramidal neurons, and some neurons of the autonomic nervous system. When we think about neurons in the brain, we are thinking about this class of neurons.
What are neurons?
Neurons are the basic signaling units. They are distinguished by their form, function, location, and interconnectivity within the nervous system.
Describe the pseudounipolar neuron.
Pseudounipolar neurons are so named because they have the appearance of unipolar neurons but where originally bipolar sensory neurons whose dendrites and axon have fused. An example is found in the dorsal-root ganglia of the spinal cord. These neurons are somatosensory cells that convey information from receptors in joints, muscles, and skin to the central nervous system.
What are ribosomes? [ˈraibəˌsoum]
Ribosomes are a cell structure that makes protein. Protein is needed for many cell functions such as repairing damage or directing chemical processes. Ribosomes can be found floating within the cytoplasm or attached to the endoplasmic reticulum.
Describe the soma
Soma is the cell body that contains the cellular machinery for the production of proteins and other cellular macromolecules. Like other cells, the neuron contains a nucleus, endoplasmic reticulum, ribosomes, mitochondria, Golgi apparatus, and other intracellular organelles.
How is the activity within a neuron and between neurons different?
The activity within a neuron involves changes in the electrical state, but at synapses the signal between neurons is usually mediated by chemical transmission. In limited circumstances some neurons signal to one another using electrical transmission at specialized electrical transmission at specialized electrical synapses.
