Nervous Tissue

Nervous tissue is a vital component of the human body's communication system, enabling us to perceive and respond to stimuli. However, like all other tissues, it is vulnerable to disorders and diseases that can significantly impact our neurological functioning. Homeostatic Imbalances: Alzheimer's disease manifests as a gradual decline in memory and cognitive abilities, attributed to the buildup of amyloid plaques and neurofibrillary tangles in the brain. Parkinson's disease arises from the...

The myelin sheath is a multilayered lipid and protein covering that insulates the axon of a neuron, enhancing the speed of nerve impulse conduction. Axons without this sheath are referred to as unmyelinated. Two types of neuroglia, Schwann cells in the peripheral nervous system (PNS) and oligodendrocytes in the central nervous system (CNS) are responsible for producing myelin sheaths. Schwann cells begin to form myelin sheaths around axons during fetal development. They wrap around a small...

Overview The nervous system is the collection of specialized cells responsible for maintaining an organism’s internal environment and coordinating the interaction of an organism with the external world—from the control of essential functions such as heart rate and breathing to the movement needed to escape danger. Parts of the Nervous System The vertebrate nervous system is divided into two major parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS...

Neurons, the fundamental units of the nervous system, can be classified based on both their structural and functional characteristics. Structurally, neurons are categorized into three main types: multipolar, bipolar, and unipolar (or pseudounipolar). Multipolar neurons, which are the most common type in the brain and spinal cord, as well as all motor neurons, possess multiple dendrites and a single axon. Bipolar neurons, on the other hand, have one primary dendrite and one axon. They are...

In the CNS, neurogenesis, the birth of new neurons from stem cells, is limited to the hippocampus in adults. In other regions of the brain and spinal cord, neurogenesis is almost non-existent due to inhibitory influences from neuroglia, especially oligodendrocytes, and the absence of growth-stimulating cues. The myelin produced by oligodendrocytes in the CNS inhibits neuronal regeneration. Furthermore, astrocytes proliferate rapidly after neuronal damage, forming scar tissue that physically...