Reading 2 Flashcards
______________ consists of the brain and the spinal cord, which occupy the cranium and the vertebral canal, respectively
Central Nervous system (CNS):
___________the part of the nervous system outside the CNS, consists mainly of the nerves that extend from the brain and spinal cord.
Peripheral Nervous system (PNS):
______________ carry signals to and from the brain
spinal nerves: carry signals to and from the spinal cord.
Cranial nerves:
____________ areas where neurons are clustered
Sensory or afferent division: signals are picked up by sensory receptors located throughout the body and carried by nerve fibers of the PNS into the CNS
Ganglia:
_____________ signals are carried away from the CNS by nerve fibers of the PNS to innervate the muscles and glands, causing these organs either to contract or to secrete (efferent means “carrying away”)
Motor or efferent division:
The four main divisions of the PNS
somatic sensory, visceral sensory, somatic motor, visceral motor
____________ (the sensory innervation of the outer tube: skin, body wall, and limbs);
somatic sensory
________________ (the sensory innervation of the viscera)
visceral sensory
________________r (the motor innervation of the outer tube, specifically skeletal muscles); and
somatic motor, or voluntary moto
______________the involuntary motor innervation of the inner tube, specifically smooth muscle, cardiac muscle, and glands, as well as some outer tube structures: arrector pili muscles, smooth muscle in the vessels, and sweat glands).
visceral motor:
______________ are the senses whose receptors are spread widely throughout the outer tube of the body\
General somatic senses:
_____________a sense that detects the amount of stretch in muscles, tendons, and joint capsules.
Proprioception:
______________are the somatic senses whose receptors are confined to relatively small areas rather than spread widely throughout the body
Special somatic sense:
_______________ include stretch, pain, and temperature, which can be felt widely in the digestive and urinary tracts, reproductive organs, and other viscera
General visceral senses:
____________ These senses, referred to also as the chemical senses, have their sensory receptors localized to the tongue and nasal cavity, respectively.
special visceral sense
_______________part of the PNS stimulates contraction of the skeletal muscles in the body. Because we have voluntary control over the contraction of our skeletal muscles,
Somatic motor:
__________________ part of the PNS regulates the contraction of smooth and cardiac muscle and secretion by the body’s many glands.
Visceral motor:
______________: which are the basic structural units of the nervous syste
Neuron:
These signals are transmitted along the plasma membrane, or neurilemma, in the form of nerve impulses, or _____________
action potentials
_____________: is also called a soma the largest part of the neuron. all consist of a single nucleus surrounded by cytoplasm
Cell Body:
_____________: substance is large clusters of rough endoplasmic reticulum and free ribosomes that stain darkly with basic dyes. These cellular organelles continually renew the membranes of the cell and the protein components of the cytosol
chromatophilic substance:
_____________: are bundles of intermediate filaments (neurofilaments) that run in a network between the chromatophilic substance.
Neurofibrals:
______________: clusters of cell bodies that lay on the cell body
Ganglia:
____________ function as receptive sites, providing an enlarged surface area for receiving signals from other neurons. By definition, dendrites conduct electrical signals toward the cell body.
Dendrites:
__________ The site at which neurons communicate
Synapse:
___________________ The neuron that conducts signals toward a synapse is called the
Presynaptic neuron:
_______________ the neuron that transmits signals away from the synapse is called
Postsynaptic neuron:
_____________ Most synapses occur between the terminal boutons of one neuron and the dendrites of another neuron
Axodendritic synapses:
____________These are membrane-bound sacs filled with neurotransmitters, the molecules that transmit signals across the synapse.
Synaptic vesicles:
_______________ are abundant in the terminal bouton because the secretion of neurotransmitters requires a great deal of energy.
Mitochondria
____________ are thin processes of uniform diameter throughout their length. By definition, axons are impulse generators and conductors that transmit nerve impulses away from their cell body.
Axons
____________ any long axon terminal
Nerve fiber:
___________ extend from the axon at more or less right angles.
axon collaterals,:
__________ undivided or has collaterals, it usually branches profusely at its end, called the terminal arborization.
Terminal arborization:
______________ axon terminals were the nerve impulse arrive
terminal boutons:
A nerve impulse is typically generated where the axon extends from the ______________
axon hillock and is conducted along the axon to the terminal boutons,
The neurotransmitters: ____________ the neurons or target organ that are in close contact with the axon boutons.
excite or inhibit
_____________the plasma membranes of the two neurons are separated by
Synaptic cleft:
______________ have numerous dendrites and a single axon. However, some small multipolar neurons have no axon and rely strictly on their dendrites for conducting signals. Well over 99% of neurons in the body belong to the multipolar class.
multipolar neurons:
_____________are neurons with two protrusions or processes. These very rare neurons occur in some of the special sensory organs (inner ear, olfactory epithelium of the nose, retina of the eye), where they mostly serve as sensory neurons.
Bipolare neurons:
___________ have a short, single process that emerges from the cell body and divides like an inverted T into two long branches. Unipolar neurons are found in sensory ganglia in the PNS, where they function as sensory neurons. The short, single process near the neuron cell body divides into two longer branches.
Unipolar neurons:
One of these branches runs centrally into the CNS and is called ____________ the other branch extends peripherally to the receptors and is called the ______________
the central process
peripheral process.
___________ They transmit impulses toward the CNS from sensory receptors in the PNS. Most sensory neurons are pseudounipolar, and their cell bodies are in ganglia outside the CNS. The peripheral process extends from a sensory receptor; the central process terminates in the CNS
Sensory Neurons:
______________These neurons carry impulses away from the CNS to effector organs (muscles and glands). Motor neurons are multipolar, and their cell bodies are located in the CNS (except for some neurons of the autonomic nervous system)
Motor Neurons:
_______________lay between sensory neurons and motor neurons. link together into chains that form complex neuronal pathways. The fact that interneurons make up 99.98% of the neurons of the body reflects the vast amount of information processed in the human CNS.
Interneurons:
_____________ All neurons associate closely with non-nervous supporting cells
Neuroglia:
____________ are the most abundant CNS neuroglia.
Astrocytes
____________ are defensive cells in the CNS.
Microglial cells
____________ cerebrospinal fluid-filled cavities.
Ependymal cells line
____________have processes that form myelin sheaths around long axons in the CNS.
Oligodendrocytes
____________ surround neuron cell bodies within ganglia. Their name comes from a fancied resemblance to the moons, or satellites, around a planet.
Satellite cells
______________ surround all axons in the PNS and form myelin sheaths around many of these axons.
Schwann cells
_____________ are produced by oligodendrocytes in the CNS and Schwann cells in the PNS. These sheaths are segmented structures that are composed of the lipoprotein myelin and surround the thicker axons of the body.
Myelin sheaths
________________: myelinated axons, nerve impulses do not travel along the myelin-covered regions of the axonal membrane but instead jump from the membrane of one myelin sheath gap to the next in a way that greatly speeds impulse conduction.
Myelin sheaths gaps nodes of Rainer
In contrast, thin, slowly conducting axons lack a myelin sheath and are called ______________
nonmyelinated axons
_____________ is a gray-colored zone that surrounds the hollow central cavity of the CNS. In the spinal cord it is a butterfly-shaped region in which the dorsal half contains cell bodies of interneurons and the ventral half contains cell bodies of motor neurons
Grey Matter:
gray matter is the site where _____________
neuron cell bodies are clustered
____________ contains no neuron cell bodies but millions of axons and neuroglia. Its white color comes from the myelin sheaths around many of the axons.
White matter:
____________ axon destinations in the white matter matter
Tracts:
__________an additional layer of gray matter located superficially
Cortex:
__________ is a cablelike organ in the peripheral nervous system
Nerve:
__________ Covering the Schwann cells is a delicate layer of loose connective tissue
endoneurium:
__________Groups of axons are bound into bundles called nerve
Fascicles:
____________connective tissue wrapped around fascicles
perineurium:
______________Finally, the whole nerve is surrounded by a tough fibrous sheath
epineurium:
__________ is a nerve cell
A neuron
__________ is a long axon
A nerve fiber
_____________ a collection of axons in the PNS.
A nerve is
________________ are simple chains of neurons that cause our simplest, reflexive behaviors and reflect the basic structural plan of the nervous system.
Reflex arcs
___________ are defined as rapid, automatic motor responses to stimuli. Reflexes are unlearned, unpremeditated, and involuntary.
reflex
____________ is the site where the stimulus acts.
The receptor:
______________are located at the terminal end of the peripheral process of a sensory neuron.
Receptors
The sensory neuron transmits the afferent impulses to _________________
the CNS.
______________ consists of one or more synapses in the gray matter of the CNS In the simplest reflex arcs, the integration center is a single synapse between a sensory neuron and a motor neuron. In more complex reflexes, it can involve multiple synapses that send signals through long chains of interneurons to other portions of the CNS, for instance, to portions of the brain.
The integration center
The motor neuron conducts efferent impulses from ___________ to ________________
the integration center to an effector.
________________ is the muscle or gland cell that responds to the efferent impulses by contracting or secreting.
The effector
______________ there is no interneuron between the sensory neuron and the motor neuron; thus, as its name implies, there is only one synapse in this reflex arc.
monosynaptic reflex:
_____________ in which one or more interneurons are part of the reflex pathway between the sensory and motor neurons.
Polysynaptic reflexes:
_________________ one presynaptic neuron synapses with several other neurons
Diverging circuit:
_____________: When many neurons synapse on a single postsynaptic neuron,
Convergign circuit:
________________one neuron in the circuit receives feedback from another neuron in the same circuit.
reverberating circuit,
Neurons that synapse one-on-one in a sequence are said to be joined in ______________________
series, and the processing is called serial processing
The second way of processing information is___________________
along neurons joined in parallel. Information from a single neuron is sent along two or more parallel pathways. This is called parallel processing.
You don’t generally feel pain until after you have reflexively moved your hand away because
the CNS needs time to process the information. In response to the pain, the motor area of your brain may initiate a nonreflexive motor response
_________________ is a progressive disease that destroys patches of myelin in the brain and spinal cord, disrupting neuronal signals in the CNS and leading to sensory disorders and weakened musculature.
Multiple sclerosis (MS)
