Basically, the nervous system of animals is a highly complex part of the body. It transmits signals to various parts of the body and also coordinates animal actions. It is also responsible for the coordination of sensory information.
Cerebrum
Generally, the cerebrum is the largest part of the brain. It controls movements, speech, emotions, memory, and reasoning. The brain also receives nerve signals from the body and interprets these signals. The brain sends new signals to other parts of the nervous system based on the information it receives.
The cerebrum has several lobes. Each lobe is responsible for a specific function. Each lobe is divided into areas that serve that function. There are four major lobes: the frontal lobe, the parietal lobe, the temporal lobe, and the limbic lobe.
The frontal lobe is located in front of the head. It contains Broca’s area, which is associated with speech. It also contains the areas related to emotions, learning, memory, and personality.
The parietal lobe is located between the frontal and temporal lobes. It is surrounded by the corpus callosum, a curved, elongated part of the brain that joins the two hemispheres. It has connections to the hypothalamus, which controls appetite and thirst. It is also connected to the limbic lobe, which is found on the medial margin of the hemisphere.
The limbic lobe is found on the medial margin of the cerebral hemisphere. It contains the substantia nigra, a large midbrain nucleus that synthesizes dopamine. It also receives input from the thalamic nuclei, which influence distinct regions of the cerebral cortex involved with motor function.
Sub-cortical and cortical regions of the brain
Among the major regions of the brain are the cortical and sub-cortical regions. Each of these regions is functionally organized. Each is responsible for a particular type of information. The cortical region carries out cognitive functions while the sub-cortical region functions in learning and consciousness.
The cortical region is the outermost layer of the brain and is divided into several types of cortices. It is considered the most organized area of the brain. The cortex is composed of supporting cells and neurons. It processes sensory input and processes visual, auditory, and somatosensory information. It also carries out mental activity and storage of memory. The cortex is also responsible for the execution of the language.
The sub-cortical region consists of several groups of cerebral nuclei. It includes the amygdala, globus pallidus, striatum, hippocampus, and hypothalamus. The hippocampus receives input from the cortex, the insula, and the rhinal (olfactory) cortices. It is also considered a motor control area. The basal ganglia are also part of the subcortical region. These areas are thought to contribute to motor control and learning.
The spinal cord is a long, cylindrical structure that contains white matter. It is enclosed by 31 pairs of spinal nerves that transmit sensory information from internal sites and external sites to the brain.
Gray and white matter
Unlike white matter, which forms outside the spinal cord, gray matter is found in the spinal cord. It forms a butterfly-shaped portion of the central spinal cord and contains the anterior horn and lateral horn. This gray matter is often referred to as the cerebellum, and it is essential for precise motor control. It also contains more neurons than all other parts of the brain combined.
Grey matter is located in the cerebellum, the brainstem, the brain stem, and the subthalamus. It is also present in the cerebrum, which contains deep gray matter called nuclei. It is mainly composed of neuronal cell bodies and axons.
The gray matter of the brain is composed of neuronal cell bodies and glial cells. These cells are supportive of the neurons and provide them with nourishment and energy. In addition, these cells may influence neuron communication.
Axons are long, spindly appendages of some neurons that carry signals from one neuron to another. The axons are wrapped in myelin, a white fat layer that provides insulation. The axons are usually a few hundred micrometers to over a meter in length.
The brain is an extremely complex organ. Both gray and white matter is critical for the efficient operation of the neural networks that process information. However, the relationship between these two components of the brain is less understood.
Dendrites
Among the most important structural and functional ramifications of a neuron are its dendrites. Dendrites are special structures that receive synaptic inputs and release neurotransmitters. They may also serve as sites of propagation for APs. Dendritic properties are influenced by many biophysical and morphological parameters.
The shape of a dendritic arbor is related to the mode of connectivity between neurons. Some neurons show unipolar morphology, while others exhibit asymmetric morphology. Other neurons exhibit passive dendrites. These morphological characteristics may be a factor influencing the likelihood of externalization.
The geometry of an axon is influenced by the distribution of voltage-gated sodium channels. In some neuronal types, axonal properties are not correlated with dendritic properties.
For example, in cerebellar Purkinje neurons, sodium channels are distributed differently in the dendrites and axons. This may have an impact on AP generation. Axons of these neurons show a higher density of sodium channels than dopaminergic neurons. Alternatively, the shape of the dendritic arbor may be related to the mode of connectivity between neurons.
There is a large difference between the morphology of primary and secondary dendrites. Primary dendrites are generally unbranched, while secondary dendrites have a few branching points. The density of SD sodium channels is also different in these two types.
Amino acid neurotransmitters
Almost all nervous system functions are dependent on amino acid neurotransmitters. Some amino acids are also important for other functions of the body. For instance, glutamate is one of the most important excitatory neurotransmitters in the brain and is involved in learning and memory.
Amino acids can also serve as precursors for neurotransmitters. For example, glycine and glutamate are precursors for GABA. Amino acid neurotransmitters are essential for the structure and function of the brain and nervous system.
The most common excitatory neurotransmitters in the CNS are glutamate and GABA. These neurotransmitters are linked to energy homeostasis and are tightly coupled with the body’s energy metabolism. They are also implicated in neurodegenerative disorders, including Alzheimer’s disease.
Amino acids are involved in most nervous system functions, including learning and memory. Glutamate is an excitatory neurotransmitter that acts on NMDA receptors. GABA adds an important functional property to glutamate.
Glycine is an inhibitory neurotransmitter and plays a role in sensory processing and auditory information. It is also involved in appetite suppression and sleep-wake cycles. In addition, glycine has an important role in learning. It is also found in high concentrations in the brain.
Gamma-aminobutyric acid is another neurotransmitter. It is known to have a calming effect. It is thought to play a key role in controlling nerve cell hyperactivity. It is also associated with a higher risk for schizophrenia and cognitive deficits.
Blood-brain barrier
During development, the Blood-brain barrier (BBB) between the brain and the nervous system is established. This cellular barrier acts as a gatekeeper, preventing xenobiotics and chemicals from entering the brain and promoting the clearance of toxins and waste products. During neurological disease, BBB disruption leads to immune infiltration and neuronal dysfunction. This disruption can be chronic or acute. Inflammatory cytokines, reactive oxygen species (ROS), and glutamate are responsible for the disruption.
The BBB has a distinct endothelial composition. BBB endothelium has higher levels of mitochondria than vascular endothelial cells (ECs) from other tissues. This higher mitochondrial content is crucial to the metabolic work capability of the BBB.
The BBB also controls the passage of molecules and nutrients between the brain and the nervous system. Various specialized transporters move small molecules and water-soluble nutrients across the BBB. Most transporters are ATP-independent and belong to the specialized transporter (SLC) superfamily.
The BBB also has a special arrangement of tight junctions. These junctions are called adherens junctions (AJ) and guide the distribution of Interendothelial TJs. They are also anchored by the zona occludens.
These junctions are important in maintaining the ion balance at the BBB. They are also involved in the regulation of permeability.
Memory
Several different brain regions are involved in memory, including the hippocampus, prefrontal cortex, amygdala, cerebellum, and striatum. Each of these regions is involved in different types of memory.
Declarative memory is the most common type of memory. This involves remembering facts, events, and categories of learned information. The hippocampus is a key part of the declarative memory process.
In addition to the hippocampus, the amygdala and cerebellum are important for semantic memory. Some research suggests that semantic memories are stored in the temporal lobe.
The limbic system is involved in the memory of emotions and feelings. It is also important for motivation and olfaction. It also plays a crucial role in the storage of sensory memories.
Procedural memory is the memory of how to perform certain tasks. It is also related to the cerebellum, which coordinates fine motions. It is compromised in Huntington’s disease and Parkinson’s disease.
Semantic memory involves the memory of learned cognitive maps and mathematical tables. This is done by using a synaptic mechanism. This involves the regulation of membrane channels in the postsynaptic neuron.
Implicit memory is a form of learning that occurs during the performance of various tasks. It can result in enhanced performance or a change in behavioral choices. This is a type of memory that is evolutionarily primitive.
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