Nervous Tissue Histology PDF

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Summary

NERVOUS TISSUE Central Nervous System: Brain and Spinal Cord 2 major parts Central Nervous System Consist of the brain and spinal cord which are surrounded and protected the cranium and vertebral bones. Peripheral Nervous System Located outside the CNS and consist of cranial, spinal and peripheral n...

Description

NERVOUS TISSUE

Central Nervous System: Brain and Spinal Cord 2 major parts -

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Central Nervous System – Consist of the brain and spinal cord which are surrounded and protected by the cranium and vertebral bones. Peripheral Nervous System – Located outside the CNS and consist of cranial, spinal and peripheral nerves that conduct information to and from the CNS.

Arachnoid Villi -

Types of Neurons in the Central Nervous System -

Protective Layers of the Central Nervous System -

Dura Matter – Outermost meningeal layer. It is a tough, strong and thick layer of dense connective tissue fibers. Arachnoid Matter – Deep to the Dura Matter. A more delicate connective tissue. Pia Matter – Innermost meningeal layer. Contains numerous blood vessel and adhere directly to the surfaces of the brain and spinal cord.

Cerebrospinal Fluid -

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It is a clear, colorless fluid that cushions the brain and spinal cords and gives them buoyancy as a means of protection from physical injuries. Continually produced by the choroid plexuses in the lateral, third, and fourth ventricles or cavities of the brain, with the majority of the fluid produced in the lateral ventricles. Important for homeostasis and brain metabolism.

Small, thin-walled arachnoid extensions that penetrate the dura matter and project into the blood-filled venous sinuses located between the periosteal and meningeal layers of dura matter.

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Multipolar Neurons – These are the most common type in the CNS and includes all motor neuron and interneurons of the brain, cerebellum and spinal cord. Bipolar Neurons – These are not as common and purely sensory neurons. Unipolar Neurons – Most neuron in the adult organism that exhibit only one process leaving the cell body were initially bipolar during embryonic development.

Myelin Sheath and Myelination of Axons Myelin Sheath -

Successive layers of modified cell membrane and forms a lipid-rich, insulating sheath around the axon. Extends from the initial segments pf the axon to the terminal branches.

Nodes of Ranvier -

Gaps in myelin sheath between myelinating cells.

Shwann Cells Choroid Plexuses -

Small, vascular extension of dilated and fenestrated capillaries that penetrate the interior of brain ventricles.

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Specialized cells that surrounds axon in PNS.

NERVOUS TISSUE

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Either Myelinate individual peripheral axons and extend along their length, from their origin to their termination in the muscle or glands.

Gray and White Matter -

Gray matter of the CNS consists of neurons, their dendrites and the supportive cells call Neuroglia. White Matter – devoid of neuronal cell bodies and consists primarily of myelinated axons, some unmyelinated axon, the supportive neuroglial oligodendrocytes and blood vessels.

Synapses -

Are specialized sites for chemical or electrical transmission for communication between neurons, interneurons, and effector cells, such as the muscles fibers or glands.

Neuroglia -

Highly branched supportive, nonneuronal cells in the CNS that surround the neurons, their axons, and dendrites. Four types: Astrocytes, Oligodendrocytes, Microglia and Ependymal Cells.

Neurons, Interneurons, Axons and Dendrites -

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Somatic Afferent fibers conduct impulses from the body surface and body organs, such as muscles, tendons and joints. Visceral Afferent fibers conduct impulses from internal organs, glands and blood vessels. Neurons are highly specialized for irritability, conductivity and synthesis of neuroactive substances such as neurotransmitters and neurohormones.

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Dendritic Spines – connects synapses with axon terminals from other neurons. Axon hillock – funnel shaped region of the cell body where axons arises. Initial Segment – located between axon hillock and where myelination starts....