University:
Davenport University
Course:
BIOL 115 | Anatomy and Physiology with Human Disease I
Academic year:

2021
Views:

402

Pages:

13
Author:

Shyanne Johnson

11.2 Neuroglia • Nervous tissue histology • Nervous tissue consists of two principal cell types – Neuroglia (glial cells): small cells that surround and wrap delicate neurons – Neurons (nerve cells): excitable cells that transmit electrical signals Neuroglia of the CNS (1 of 6) • Four main neuroglia support CNS neurons – Astrocytes – Microglial cells – Ependymal cells – Oligodendrocytes Neuroglia of the CNS (2 of 6) • Astrocytes – Most abundant, versatile, and highly branched of glial cells – Cling to neurons, synaptic endings, and capillaries Neuroglia of the CNS (3 of 6) • Astrocytes (cont.) – Functions include:  Support and brace neurons  Play role in exchanges between capillaries and neurons  Guide migration of young neurons  Control chemical environment around neurons  Respond to nerve impulses and neurotransmitters  Influence neuronal functioning  Participate in information processing in brain Neuroglia (1 of 5) Figure 11.4a Neuroglia. Neuroglia of the CNS (4 of 6) • Microglial cells – Small, ovoid cells with thorny processes that touch and monitor neurons – Migrate toward injured neurons – Can transform to phagocytize microorganisms and neuronal debris Neuroglia (2 of 5) Figure 11.4b Neuroglia. Neuroglia of the CNS (5 of 6) • Ependymal cells – Range in shape from squamous to columnar – May be ciliated  Cilia beat to circulate CSF – Line the central cavities of the brain and spinal column – Form permeable barrier between cerebrospinal fluid (CSF) in cavities and tissue fluid bathing CNS cells Neuroglia (3 of 5) Figure 11.4c Neuroglia. Neuroglia of the CNS (6 of 6) • Oligodendrocytes – Branched cells – Processes wrap CNS nerve fibers, forming insulating myelin sheaths in thicker nerve fibers Neuroglia (4 of 5) Figure 11.4d Neuroglia. Neuroglia of PNS • Two major neuroglia seen in PNS • Satellite cells – Surround neuron cell bodies in PNS – Function similar to astrocytes of CNS • Schwann cells (neurolemmocytes) – Surround all peripheral nerve fibers and form myelin sheaths in thicker nerve fibers  Similar function as oligodendrocytes – Vital to regeneration of damaged peripheral nerve fibers Neuroglia (5 of 5) Figure 11.4e Neuroglia.