What are Neurons?
Neurons are the fundamental units of the CNS, specialized in transmitting electrical and chemical signals. They consist of a cell body (soma), dendrites that receive signals, and an axon that sends signals to other neurons or muscles.
What is the Role of Glial Cells?
Glial cells are non-neuronal cells that provide support and protection for neurons. They include astrocytes, oligodendrocytes, microglia, and ependymal cells, each with distinct functions such as forming the blood-brain barrier, producing myelin, and providing immune defense.
What is Myelin and Its Importance?
Myelin is a fatty substance produced by oligodendrocytes in the CNS. It forms a sheath around axons, facilitating the rapid conduction of electrical impulses. Loss of myelin, as seen in disorders like multiple sclerosis, severely impairs nerve function.
What are the Main Histological Layers of the Brain?
The brain is organized into several histological layers. The outermost layer, the
cerebral cortex, consists of gray matter containing neuron cell bodies, dendrites, and synapses. Beneath the cortex lies white matter, composed of myelinated axons that connect different brain regions.
What is the Structure of the Spinal Cord?
The
spinal cord is a cylindrical structure extending from the brainstem to the lumbar region. It is organized into an outer layer of white matter and an inner core of gray matter. The gray matter is butterfly-shaped and contains neuron cell bodies, while the white matter contains ascending and descending nerve tracts.
How is the Blood-Brain Barrier Formed?
The
blood-brain barrier (BBB) is formed by endothelial cells of the brain capillaries, astrocyte end-feet, and pericytes. It selectively restricts the passage of substances from the bloodstream into the brain, protecting neural tissue from toxins and pathogens.
What are Synapses and Their Function?
Synapses are junctions where neurons communicate with each other or with muscle cells. They can be electrical or chemical. Chemical synapses release neurotransmitters into the synaptic cleft, which bind to receptors on the postsynaptic cell, propagating the signal.
How Do Neurons Regenerate?
Neurons in the CNS have limited regenerative capacity. However,
neurogenesis can occur in specific regions like the hippocampus. Neural stem cells in these areas can differentiate into new neurons, which can integrate into existing circuits under certain conditions.
What are Common CNS Pathologies?
Various pathologies can affect the CNS, including neurodegenerative diseases like Alzheimer's and Parkinson's, demyelinating diseases like multiple sclerosis, and traumatic injuries. Histological examination is crucial for diagnosing these conditions and understanding their underlying mechanisms.
