Nervous Tissue Overview

Nervous Tissue Overview

• Nervous tissue is located in the brain, spinal cord, and nerves.
• Its primary function is to transmit nerve impulses, coordinating and integrating bodily functions.

Characteristics of Nervous Tissue

• Reacts to environmental changes.
• Neurons are the basic functional units of nervous tissue.

Types of Cells in the Nervous System

• Neurons: the smallest functional units in the nervous system.
• Supporting cells, known as neuroglia.
• Neural stem cells capable of differentiating into various cell types.

Repair and Regeneration

• The mature nervous system has a limited ability to repair itself.
• Mature neurons do not reproduce.

Stem Cells

• Stem cells in the CNS can give rise to different cell types.
• Key characteristics include self-renewal and differentiation into most neuron and glial types.

Neuron Facts

• The human nervous system contains more than 10 billion neurons.
• Neurons are responsible for receiving, processing information, and generating output.

Neuron Structure

• Components include the soma (cell body), dendrites, axons, and presynaptic terminals.
• The nucleus serves as the control center, housing genetic material and guiding metabolic activity.

Organelles in Neurons

• Mitochondria are responsible for energy metabolism, primarily ATP synthesis, distributed throughout the cell.
• Rough endoplasmic reticulum (Nissl substance) synthesizes and transports proteins, located in the soma.
• Smooth endoplasmic reticulum synthesizes and transports lipids, found throughout the cell.
• Ribosomes are responsible for protein and neurotransmitter synthesis, also located throughout the cell.
• The Golgi apparatus packages neurotransmitters and is situated in the soma.

Chemical Synapses

• A chemical synapse comprises the terminal button of the axon that contains neurotransmitters released into the synaptic gap, traveling to the dendrite of the following neuron.

Neurotransmitter Production

• Neurotransmitters are primarily produced in the soma and transported to the presynaptic terminal via axoplasmic transport.

Axoplasmic Transport

• Anterograde transport refers to movement from soma to terminals.
• Retrograde transport indicates movement from terminals to soma, with nitric oxide as the only retrograde neurotransmitter.

Types of Neurons

• Neurons can be classified by function (sensory, motor, interneurons) or structure (unipolar, bipolar, multipolar).
• Sensory (afferent) neurons carry messages from sense organs to the spinal cord and brain, typically unipolar.
• Motor (efferent) neurons transmit messages from the brain and spinal cord to muscles and glands, generally multipolar.
• Associative (interneurons) function as connectors between sensory and motor pathways.

Specialized Cells

• Purkinje cells in the cerebellum facilitate fine motor control and prevent jerky movements due to their extensive arborization.
• Pyramidal cells are found in the hippocampus, while double pyramidal cells are located in retinal sensory organs.