Chapter 7, The Nervous System

Front 1

Axon Terminal

Back 1

Axon terminals are distal terminations of the branches of an axon. An axon nerve fiber is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses (called "action potentials") away from the neuron's cell body, or soma, in order to transmit those impulses to other neurons.

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Dentrite

Back 2

are the branched projections of a neuron that act to conduct the electrochemical stimulation received from other neural cells to the cell body, or soma, of the neuron from which the dendrites project.

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Myelin Sheath

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It is essential for the proper functioning of the nervous system

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Afferent Neuron

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afferent neurons (otherwise known as sensory or receptor neurons), carry nerve impulses from receptors or sense organs towards the central nervous system. This term can also be used to describe relative connections between structures. Afferent neurons communicate with specialized interneurons. The opposite activity of direction or flow is efferent.

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Association Neuron

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multipolar neuron which connects afferent neurons and efferent neurons in neural pathways. Found within the central nervous system and the enteric nervous system.

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Cutaneous Recpetor

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A cutaneous receptor is a type of sensory receptor found in the dermis or epidermis. They are a part of the somatosensory system

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Efferent Neuron

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carry nerve impulses away from the central nervous system to effectors such as muscles or glands

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Ganglion

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ganglia are composed mainly of somata and dendritic structures which are bundled or connected together. Ganglia often interconnect with other ganglia to form a complex system of ganglia known as a plexus. Ganglia provide relay points and intermediary connections between different neurological structures in the body, such as the peripheral and central nervous systems.

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Neuroglia

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are non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the brain, and for neurons in other parts of the nervous system such as in the autonomous nervous system

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Neurotransmitters

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endogenous chemicals that transmit signals from a neuron to a target cell across a synapse

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Nerve

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an enclosed, cable-like bundle of peripheral axons. Nerves are found only in the peripheral nervous system.

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Nodes of Ranvier

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formed between the myelin sheaths generated by different cells. A myelin sheath is a many-layered coating, largely composed of a fatty substance called myelin, that wraps around the axon of a neuron and very efficiently insulates it. At nodes of Ranvier, the axonal membrane is uninsulated and therefore capable of generating electrical activity.

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Proprioceptors

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the sense of the relative position of neighbouring parts of the body and strength of effort being employed in movement.

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Schwann cells

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the principal glia of the peripheral nervous system (PNS). Glial cells function to support neurons and in the PNS

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Synapse

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structure that permits a neuron to pass an electrical or chemical signal to another cell

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Stimuli

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detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity

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Neural Tract

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connects one part of the nervous system with another and usually consists of bundles of elongated, myelin-insulated neurons, known collectively as white matter. Neural pathways serve to connect relatively distant areas of the brain or nervous system, compared to the local communication of grey matter.

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Depolarization

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a change in a cell's membrane potential, making it more positive, or less negative. In neurons and some other cells, a large enough depolarization may result in an action potential.

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Refractory Period

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a period of time during which an organ or cell is incapable of repeating a particular action.It most commonly refers to electrically excitable muscle cells or neurons.

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Somatic Reflex

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a group of nuclei of varied origin in the brains of vertebrates that act as a cohesive functional unit.

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Hypothalamus

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a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland

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Pons

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a structure located on the brain stem. It is superior to the medulla oblongata, inferior to the midbrain, and ventral to the cerebellum.

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Dura Mater

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the outermost of the three layers of the meninges surrounding the brain and spinal cord.

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Arachnoid mater

Back 24

one of the three meninges, the membranes that cover the brain and spinal cord. It is interposed between the two other meninges, the more superficial dura mater and the deeper pia mater, and is separated from the pia mater by the subarachnoid space.

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Choroid Plexus

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structure in the ventricles of the brain where cerebrospinal fluid (CSF) is produced. The choroid plexus consists of modified ependymal cells.

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Cerebral Aqueduct

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contains cerebrospinal fluid (CSF), is within the mesencephalon (or midbrain) and connects the third ventricle in the diencephalon to the fourth ventricle in the mesencephalon, which is between the pons and cerebellum.

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Concussion

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most common type of traumatic brain injury.

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Contusion

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a bruise, a type of relatively minor hematoma of tissue[1] in which capillaries and sometimes venules are damaged by trauma, allowing blood to seep into the surrounding interstitial tissues.

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Intracranial Hemorrhage

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a blood vessel within the skull is ruptured or leaks. It can result from physical trauma (as occurs in head injury) or nontraumatic causes (as occurs in hemorrhagic stroke) such as a ruptured aneurysm.

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Cerebral Edema

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an excess accumulation of water in the intracellular or extracellular spaces of the brain.

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Endoneurium

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a layer of delicate connective tissue made up of endoneurial cells that encloses the myelin sheath of a spinal cord nerve fiber.

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Perineurium

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composed of connective tissue, which has a distinctly lamellar arrangement consisting of roughly 7-8 concentric layers. The perineurium is cellular, and is composed of perineurial cells, which are epithelioid myofibroblasts.

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Epineurium

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the outermost layer of connective tissue surrounding a peripheral nerve. It is made of dense irregular connective tissue and usually contains multiple nerve fascicles as well as blood vessels which supply the nerve.

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Axillary Nerve

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a nerve of the human body, that comes off the of the brachial plexus at the level of the axilla (armpit) and carries nerve fibers from C5 and C6.

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Musculocutaneous Nerve

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arises from the lateral cord of the brachial plexus, opposite the lower border of the Pectoralis major, its fibers being derived from C5, C6 and C7.

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Median Nerve

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It is in the upper limb. It is one of the five main nerves originating from the brachial plexus.

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Radial Nerve

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a nerve in the human body that supplies the upper limb. It supplies the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm and the associated joints and overlying skin.

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Ulnar Nerve

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The nerve is the largest unprotected nerve in the human body. This nerve is directly connected to the little finger, and the adjacent half of the ring finger

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Autonomic ganglion

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clusters of neuronal cell bodies and their dendrites and are essentially a junction between autonomic nerves originating from the central nervous system and autonomic nerves innervating their target organs in the periphery.