Chapter 6: Nervous System Flashcards
(143 cards)
1
Q
This system provides an animal with sensitivity to environmental energy and thereby awareness of self and surroundings. It is a part of the body where all the activities are being processed. It initiates and controls movement of most secretions, thus, responsible for the all inborn and learned behavior.
A
nervous system
2
Q
This system is unique in the vast complexity of the control actions it can perform. It receives literally millions of bits of information from the different sensory organs and then integrates all these to determine the response to be made by the body. Thus, it is responsible for sending, receiving, and processing nerve impulses. All of the body‟s muscles and organs rely upon these nerve impulses to function.
A
nervous system
3
Q
A highly organized collection of cells known as the ? constitute the nervous system which is found in all higher forms of animals
A
neurons
4
Q
The nerve cells collect information by means of?
A
receptors
5
Q
Receptors coordinate the information with internal activities of the organism in the process known as?
A
integration
6
Q
What system consists of the brain and the spinal cord, is the integrating and communicating center of the body?
A
central nervous system (CNS)
7
Q
The entire CNS is enclosed in a protective membrane called the?
A
meninges
8
Q
What system consists of the spinal and cranial nerves, including associated nerve roots and ganglia?
A
peripheral nervous system (PNS)
9
Q
Nerves and ganglia innervating viscera are designated as what system?
A
autonomic nervous system (ANS)
10
Q
ANS is composed of what two systems?
A
sympathetic nervous system (thoraco-lumbar) and the parasympathetic (cranio-sacral) nervous systems
11
Q
What is a bundle of nerve processes outside the CNS. It is a collection of nerve fibers ensheathed or myelinated by neuroglia and divided into one or more fascicles by connective tissue.
A
Nerve
12
Q
What are bundles of nerve processes within the brain and the spinal cord?
A
Tracts or fasciculi
13
Q
What are group of nerve cell bodies within the brain and the spinal cord. It should not be confused with the central body of the cell that is also called nucleus.
A
Nuclei
14
Q
What transmit electrochemical impulses?
A
Nerve cells or neurons
15
Q
What are responsible for the structural and nutritional support of neurons, electrical insulation, and enhancement of impulse conduction velocity along axons. It is the connective and supportive tissue of the CNS.
A
Supporting cells or neuroglia (“nerve glue”) or glial cells
16
Q
What is the basic structural and functional unit of the nervous tissue. Its primary function is to receive stimuli from the internal (interoreceptive) and external (exteroreceptive) environment. The subsequent transmission of information to the effector organs of the body is also an integral part of its function. This form the highly complex intercommunicating network of nerve cells that receive and conduct impulses along their neutral pathways or axons to the CNS for analysis, integration, interpretation, or response. The action of muscles or glands of the body provide the appropriate response to a given stimulus.
A
Neuron
17
Q
Which zone excitation is initiated?
A
Dendritic zone
18
Q
What are short, highly branched processes of neurons that collect incoming messages from the synapse and carry them toward the cell body.
A
Dendrites (from Gr. dendron which means tree)
19
Q
Which zone excitation is transmitted to another cell. It is also branched and has terminal expansions for storage and release of transmitter molecules.
A
Telodendritic zone
20
Q
The plasma membrane of axon is called?
A
axolemma
21
Q
Cytoplasm of axon is called?
A
axoplasm
22
Q
The axon or axis cylinder originates from the ? of the cell body, a conical region devoid of chromatophilic substance.
A
axon hillock
23
Q
Axon of most neurons has a myelin sheath formed by the supporting cells and interrupted by gaps called?
A
nodes of Ranvier
24
Q
What nurtures the nerve cell. It has a nucleus, cytoplasm and plasmalemma surrounding the nucleus.
A
Cell body (cyton, soma or perikaryon)
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These organelles of the neuronal cell bodies are slender, interlacing threads coursing through the cytoplasm of neuronal cell body from one dendrite to another or into the axon.
Neurofibrils
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These organelles of the neuronal cell bodies appear as lumps of basophilic material in the perikaryon. It is composed of blocks of stacked rER and ribosomal aggregations (RNA).
Nissl bodies or chromophillic substances
27
What is a coat of white, fatty tissue that covers nerves of the peripheral nervous system. It is covered by a membrane called neurolemma or Schwann‟s cell. It acts like insulation on a wire and greatly promotes speed and reliability of nerve impulse conduction.
Myelin sheath
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What are the small-constricted portion of the neuron‟s myelin sheath that separates the axon along the cells length. These narrowing, or gaps, is more permeable to potassium and sodium ions than the rest of the axon body. Consequently, these nodes allow nerve implies to be transmitted from the axon, where otherwise the impulses would be shielded by the insulating myelin sheath.
Nodes of Ranvier
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Myelinated axons between the gaps are called?
internodes
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The internodal transmission that leads to a node is referred to as?
paranode
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What are layers of the cells which cover the myelin sheath segments of some nerve cells, and constrict at the nodes of Ranvier. The neurons of the brain and spinal cord do not have such a cell layer covering their myelin sheaths. It provides a protected immediate environment for PNS neurons. They can become phagocytic in case of nerve damage.
Schwann’s cell (neurolemma, neurolemmocytes)
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What neurons conduct impulses from internal or external receptors to the CNS.
Sensory (afferent) neurons
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What neurons convey impulses from the CNS to the effector muscles or glands?
Motor (efferent) neurons
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What serve as intermediary cells and are located between sensory and motor neurons in the CNS?
Interneurons (mixed)
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What type of neurons usually have several dendrites to receive impulses, but only one axon to carry the signal away. It has a cell body within the dendritic zone. They are the most common type in the CNS and include motor neurons and interneurons of the brain and spinal cord.
Multipolar neurons
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What type of multipolar neuron are those with numerous dendrites and very long axon?
Golgi Type I
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What type of multipolar neuron are those with less dendrites and a short axon?
Golgi Type II
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What type of neuron have a cell body located within the axon. They have one dendrite and one axon that nerve impulses are received and transmitted only in one direction, from one pole of the neuron to the other. They are the receptor cells that are found in the retina of the eye, the organ of hearing in the inner ear, and the olfactory epithelium in the upper region of the nose. Bipolar neurons are not as common and are purely sensory neurons.
Bipolar neurons
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What type of neuron have a cell body that arise from a single axon and soon bifurcates. Like the bipolar neurons, they convey sensory information to the CNS. They are also sensory and are found numerous in the craniosacral ganglia of the body.
Unipolar neurons (Pseudo-unipolar)
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What are specialized junctions by which a stimulus is transmitted from a neuron to its target cell?
Synapses
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What are bulbous enlargement at synapes
Terminal bulbs
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What synapse is the most common, involving a synapse of an axon and dendrite?
Axodendritic synapse
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What synapse involves a synapse of an axon on the cell bod?
Axosomatic synapse
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What synapse involves telodendria (inhibitory effect) or a synapse on the initial segment?
Axoaxonic synapse
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What synapse does not involve telodendria?
Dendrodenritic synapse
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What membrane is the part of the terminal bouton membrane closest to the target cell. On stimulation, neurosecretory vesicles in the bouton fuse with the synaptic membrane and exocytose their neurotransmitters into the synaptic clef.
Presynaptic membrane
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What is a fluid-filled space between the pre - and postsynaptic membrane?
Synaptic cleft (Synaptic Gap)
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What membrane is a thickening of a plasma membrane of the next neuron or target cell?
Postsynaptic membrane
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What is highly branched, supportive, non-neuronal cells in the CNS that are located between the neurons. It comprises well over 90% of the cells that make up the nervous system. These cells do not conduct impulses and are morphologically and functionally different from the neurons
Neuroglia
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What line the ventricular cavities of the brain and the central canal of the spinal cord?
Ependymal cells
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What are the largest neuroglial cells and support the neurons, repair the CNS tissue after injury or disease, and form scar tissue after neuronal damage. In addition, the astrocytes may be involved in the energy metabolism and supporting metabolic exchanges between neurons and the capillaries of the CNS.
Astrocytes
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The white matter is said to contain what type of astrocytes?
fibrous astrocytes
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The gray matter is said to contain what type of astrocytes?
protoplasmic astrocytes
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Astrocyte processes terminate in expansions called?
end feet
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What neuroglia function by forming myelin sheaths around the axon in the CNS?
Oligodendrocytes
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What neuroglia are considered the macrophages of the CNS and are found throughout the CNS. When nervous tissue is injured or damage, microglia proliferates, become phagocytic, and remove dead tissue from the CNS.
Microglial cells
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What are specialized Schwann‟s cells in craniospinal and autonomic ganglia where they form a one-cell-thick covering over the cell bodies of the neurons (ganglion cells). The nuclei are spheric with mottled chromatin. In sections, the nuclei typically appear as a „string of pearls” surrounding the much larger ganglion cell bodies
Satellite cells
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Such axons do not have a myelin sheath around them and are considered?
unmyelinated
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Axons that are surrounded by myelin sheath are considered?
myelinated
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What nerves originate from the spinal cord and exit the vertebral canal?
Spinal nerves
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What nerves originate from the brain and exit the cranial cavity
Cranial nerves
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What consists usually of thousands of axons, each sheathed by neurolemmocytes and all enveloped by connective tissue?
Nerve
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What is the proximal region of the nerve where axons are enveloped by neurolemmocytes and meninges?
Root
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What fibers are sensory since they conduct excitation to the CNS. These neurons have unipolar cell bodies in craniospinal ganglia. The dendritic zone is composed of receptors, or synaptic contacts on the sensory epithelium of a sense organ.
Afferent fibers
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What fibers come from axons of multipolar cell bodies located in the CNS or in autonomic ganglia?
Efferent fibers
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Which nerve fibers innervate the skin, skeletal muscles and joints?
Somatic nerve fibers
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Which nerve fibers innervate cardiac and smooth muscles and glands?
Visceral nerve fibers
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What nerves is composed of one to several nerve fascicles. It contains myelinated and unmyelinated axons, Schwann‟s cells, and fibroblast, but no neuron cell bodies.
peripheral nerve
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Each peripheral nerve is surrounded by a dense connective tissue or ?, branches of which penetrates the nerve and divides the nerve fibers into bundles or fascicles.
epineurium
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A nerve is delimited by ?, a sheath surrounding each fascicle.
perineurium
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Within the nerve fascicle, fibroblast and collagen fibers surrounding neurolemocytes constitute?
endoneurium
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This perineurium is an outer cell of moderately dense collagenous connective tissue.
Fibrous perineurium This perineurium
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This perineurium is an inner sleeve of multiple concentric layers of squamos epithelial cell. Collagen fibers are dispersed between the layers of each epithelial cell is enclosed in a basal lamina.
Perineural epithelium
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What are accumulations of peripheral nerve clusters of neuron cell bodies within a nerve fascicle?
Ganglia
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Which ganglia are spinal ganglia on dorsal roots and cranial nerve ganglia containing unipolar cell bodies of afferent neurons. The unipolar cell bodies are distributed around the fibers of the nerve, which course through the center of the ganglion. Each unipolar cell body gives rise to a single axon that may coil initially before joining the centrally connected fibers where the axon bifurcates into central and peripheral branches
Sensory ganglia (cranio-spinal)
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Which ganglia are produced by multipolar cell bodies accumulated within the autonomic nerve fascicles. Within visceral organs, there are terminal autonomic ganglia composed of only a few cell bodies.
Autonomic ganglia
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Postganglionic neurons are classified as:
if they synthesize and release acetylcholine
Cholinergic
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Postganglionic neurons are classified as:
if the neurotransmitter is noradrenaline. This postganglionic neurons can be identified by the presence of dense core synaptic vesicles. Some autonomic ganglia contain numerous large dense-core vesicles and release dopamine.
Adrenergic
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Which efferent neurons innervate skeletal muscle. One such neuron and all of the muscle fibers it innervates is regarded as a motor unit, since the muscle fibers it innervates contract as a unit when the neuron is excited
Somatic efferent neurons
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What syanpse consist of a presynaptic motor end-plate overlying the postsynaptic sole plate of a muscle fiber?
Neuromuscular synapses
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Cytoplasm that contains many mitochondria and numerous clear synaptic vesicles?
End-plate cytoplasm
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What is other type of somatic efferent neuron. It innervates small muscle fibers within muscle spindles.
fusimotor or gamma motor neuron
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synapse on postganglionic neurons in autonomic ganglia. The telodendria form end bulbs typical of interneuronal synapses.
Preganglionic autonomic neurons
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Which autonomic neurons have non-myelinated axons that innervate cardiac or smooth muscles or gland?
Postganglionic autonomic neurons
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What are individual, isolated stimulus detectors widely distributed in the body. It constitute the dendritic zone of an afferent neuron.
Receptors
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What nonencapsulated receptors are found throughout the body. They detect stimulation described as pain, warmth, cold or touch, as well as consciousness stimuli for reflex activity. They are associated by non-myelinated axons that branch extensively to innervate a wide area. The receptors are simply unsheathed terminal branches, enclosed by basal lamina.
Free nerve endings
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What nonencapsulated receptors detect body hairs being displaced, are derived from myelinated axons that branch extensively to innervate hundreds of fascicles?
Hair follicle terminals
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What nonencapsulated receptors are often collected at the base of a slight skin elevation called a tactile pad?
Non-encapsulated tactile corpuscles
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What encapsulated receptors are touch receptors found in the dermis of glabrous skin?
Encapsulated tactile corpuscles (corpuscles of Meissner)
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What encapsulated receptors are widely distributed throughout the body, sensitive to transient pressure such as in vibratory stimuli?
Lamellar corpuscles (corpuscles of Vater, corpuscles of Pacini)
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What encapsulated receptors vary in locations, size and shape. They are mechanoreceptors derived from myelinated axons having highly coiled terminal branches enclosed in a thin capsule of perineural epithelium.
Bulbous corpuscles (corpuscles of Krause, corpuscles of Golgi-Mazzoni, genital corpuscle)
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What encapsulated receptors are located at muscle-tendon junctions and are activated by tension.
Neurotendinous spindles (Golgi tendon organs)
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What encapsulated receptors are located in most muscles; consist of an elongate capsule of perineural epithelium containing afferent and efferent innervation and two kinds of intrafusal muscle fibers designated as: nuclear bag and nuclear chain fibers.
Neuromuscular spindles (muscle spindles)
94
What matter is formed by dense accumulations of nerve fibers individually enveloped by a myelin, white lipid-protein insulation. The high lipid content of myelin is responsible for the white appearance. This matter regions are divided functionally into tracts and fasciculi, based on the origin and destination of the nerve fibers.
white matter
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What matter lacks dense accumulations of myelin and is rich in cell perikarya, neuronal cell bodies, glial cells and neurophil?
gray matter
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Gray matter that coats the cerebellum and the cerebrum are called?
cortex
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The gray matter mass within the spinal cord, brainstem, cerebral and cerebellar white matter are generally called?
nuclei
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What is composed of paired cerebral hemispheres?
cerebrum
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What are the ridges called in the surface of each hemisphere?
Gyri
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What are the grooves called in the surface of each hemisphere?
Sulci
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In mammals, all the ventral cerebral cortex is designated as ?, since it is phylogenetically recent.
neocortex
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What layer of neocortex consists of predominantly neurophil oriented tangentially, composed of apical dendrites from pyramidal cells and telodendria from input fibers to the cortex?
Molecular layer
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What layer of neocortex the primary receptive layer for modality (sensory) specific input to the cortex; composed of small stellate neurons that form a thick layer in cortical sensory areas (e.g. visual area).
Internal granular layer
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What layer of neocortex is medium to very large pyramidal neurons; form a thick layer in the cortical motor area, where electrical stimulation elicits movement.
Internal pyramidal neurons
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What layer of neocortex many spindle-shaped neurons. Deep to this is cerebral white matter composed of nerve fiber going to and coming from the cortex.
Fusiform (multiform) layer
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The cerebellar surface, which features the folia (narrow ridges) separated by sulci, is coated by cortex. This regulates muscle tone, posture and movement so that these are expressed in an appropriate, coordinated pattern.
Cerebellum
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What cerebellar cortex layer is the most superficial and composed predominantly of neurophil?
Molecular layer
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What cerebellar cortex layer is situated adjacent to white matter, features densely packed granule cells - very small neurons with heterochromatic nuclei?
Granular cell layer
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What cerebellar cortex layer is a single layer of large cell bodies located at the interface of the molecular and granule cell layer?
Piriform cell layer
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What cells have elaborate dendritic trees that project into the molecular layer?
Piriform (Purkinje) cells
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What cell is another neuron found in the cerebellar cortex located at the piriform layer and its dendritic tree extends to the molecular layer?
Basket cell
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What is divided into segments based on the bilateral emergence of dorsal and ventral roots of spinal nerve?
spinal cord
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What surrounds by an H-shape profile of gray matter, which is in turn surrounded by white matter?
central canal
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Bilaterally, the spinal cord is divided by what fissures?
ventral median fissure and a dorsal median septum
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Column of the gray matter in the spinal cord contains somatic efferent neurons that innervate skeletal muscles. The volume of the cell bodies of these neurons is proportional to the volume of its axon and the size of the motor unit being innervated.
ventral gray column (horn)
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Which matter of spinal cord features a lateral gray column containing visceral efferent neurons that synapse in the autonomic ganglia?
intermediate gray matter
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Column of the gray matter in the spinal cord contains interneurons and neurons that project axons to distant segments or to the brain via white matter tracts?
dorsal gray column (horn)
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Which spinal matter is composed of fibers that belong to tracts (fasciculi); additionally fibers destined for spinal nerves traverse the white matter?
Spinal white matter
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Which spinal matter may be subdivided into nuclei, which generally are not distinct. The cord, and particularly the gray matter, is enlarged at the segments supplying limbs because of the increased nervous tissue necessitated by limb innervation. The gray matter contains interneurons, neurons that project their axons to the brain, and efferent neurons that sent their axons into the ventral roots.
Spinal gray matter
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Funiculus between the midline and dorsal root attachments?
Dorsal funiculus
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Funiculus between the midline and ventral root attachments?
Ventral funiculus
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Funiculus between dorsal and ventral root attachments?
Lateral funiculus
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What are membranes that envelope the brain, spinal cord and the roots of the peripheral nerves. It also envelop the entire optic nerve, which is actually CNS white matter. It provides a physical and phagocytic barrier and contains cerebrospinal fluid, which attenuates traumatic forces.
Meninges
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Which meningeal membrane matter consists of variously oriented space of collagen fibers that forms a thick, strong membrane. Elastic fibers, fibroblasts, nerves, lymph and blood vessel are also present.
Dura matter
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Spinal dura matter is surrounded by what space? within the vertebral canal.
epidural space
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Which meningeal membrane consists of a fine net collagen fiber coated both sides by leptomeningeal fibroblasts?
Arachnoid membrane
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What is the space contains cerebrospinal fluid, separates the arachnoid membrane and the pia matter?
subarachnoid space
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What are thin strands of the arachnoid membrane that traverse the subarachnoid space and join pia matter?
Arachnoid trabeculae
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As the vessels penetrate the CNS, an extension of the subarachnoid space extends around the vessel for a short distance, called a?
perivascular space
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What are microscopic pockets of arachnoid membrane that penetrates the venous sinus wall. The granulations act as valves that permit cerebrospinal fluid to drain from the sub-archnoid space into the bloodstream. The fluid can also drain into lymphatics of peripheral nerves.
arachnoid granulations
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What matter coats the entire CNS surface lining every sulcus and fissure?
Pia matter
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Bilaterally along the mid-lateral surface of the spinal cord, pial collagen is greatly thickened to form what ligaments? The ligament sends processes to the dura matter and thereby serves to suspend the spinal cord within the pachymeninx.
denticulate ligament
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Dura matter being thick and strong has been called?
pachymeninx
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What fluid is produced by choroid plexuses located in brain ventricles. It is produced by active secretion and ultrafiltration.
Cerebrospinal fluid (CSF)
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What is an expanded villiferous structure from each region of ventricles where its wall is formed only by ependyma and pia matter.
Choroid plexus
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The plexus consists of dense microvasculature in loose connective tissue coated by modified ependymal cells called?
choroid plexus epithelium
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What are group of nerve cell bodies outside the brain and the spinal cord. They are nerve enlargements produced by the presence of neuronal perikarya.
Ganglia
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Which regions of a single neuron are long, cylindrical processes with sparse branches that carry impulses away from the body of the neuron to the synapse. Collateral branches are those that emanate perpendicularly from the axon.
Axons
139
Neurons not connected with other functioning neurons or end organs are useless, and mechanisms have evolved to dispose them in a process termed?
transneuronal degeneration
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Which system comprises the cranial and spinal nerves, including all roots, branches and ganglia of the nerves?
peripheral nervous system
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What is an enlargement of a nerve produced by an accumulation of neuron cell bodies?
Ganglion
142
What may refer to a myelinated axon with its associated neurolemmocytes or to single non-myelinated axons?
Nerve fiber
143
The incoming telodendria often synapse on small neurons with short axons. These neurons are called ? since they interposed between the input and,the output of the nucleus.
interneurons
