Nervous tissue is a highly specialized tissue that forms the nervous system, responsible for coordinating and controlling many body activities.
It consists of neurons and supporting cells known as neuroglia or glial cells.
Nervous tissue is essential for sensing stimuli, transmitting signals, and regulating bodily functions.
Structure of Nervous Tissue
1. Neurons
I. Cell Body (Soma): Contains the nucleus and other organelles. It is the metabolic center of the neuron.
II. Dendrites: Branched extensions from the cell body that receive signals from other neurons and conduct impulses toward the cell body.
III. Axon: A long, singular projection that transmits impulses away from the cell body to other neurons, muscles, or glands. The axon can be covered with a myelin sheath, which increases the speed of signal transmission.
IV. Axon Terminals: The endings of the axon that release neurotransmitters to communicate with other cells across synapses.
2. Neuroglia (Glial Cells)
I. Astrocytes: Star-shaped cells that provide structural support, regulate blood flow, maintain the blood-brain barrier, and influence synaptic activity.
II. Microglia: Act as the immune cells of the central nervous system, providing defense against pathogens and cleaning up cellular debris.
III. Oligodendrocytes: Produce the myelin sheath in the central nervous system.
IV. Schwann Cells: Produce the myelin sheath in the peripheral nervous system.
V. Ependymal Cells: Line the ventricles of the brain and the central canal of the spinal cord, involved in the production and circulation of cerebrospinal fluid.
VI. Satellite Cells: Surround neuron cell bodies in the peripheral nervous system, providing support and nutrients.
Types of Nervous Tissue
1. Gray Matter
Location: Found in the brain (cerebral cortex and basal nuclei) and spinal cord (central region).
Components: Consists mainly of neuron cell bodies, dendrites, and unmyelinated axons.
Function: Involved in muscle control, sensory perception, decision making, and emotions.
2. White Matter
Location: Found in deeper tissues of the brain and the outer portion of the spinal cord.
Components: Consists primarily of myelinated axons.
Function: Responsible for the transmission of signals between different parts of the brain and between the brain and spinal cord.
Functions of Nervous Tissue
1. Sensory Input:
Detects internal and external stimuli through sensory receptors and transmits this information to the central nervous system.
2. Integration:
Processes and interprets sensory input, deciding what action, if any, should be taken.
3. Motor Output:
Sends signals to muscles and glands to elicit a response, such as muscle contraction or hormone release.
4. Homeostasis:
Regulates and maintains stable internal conditions, such as temperature and pH balance, through feedback mechanisms.
5. Mental Activity:
Facilitates cognitive functions such as thinking, memory, learning, and emotions.