A & P 1551 - Nervous Tissue & The Spinal Cord and Spinal Nerves-College of Dupage

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111 terms · College of Dupage: A & P 1551; Skarbek; Chapters 12 & 13 (Principles of A & P, 12th edition, Tortora)

Three functions of Nervous System:

Sensory, integrative & motor function

Sensory Function:

sensory receptors that detect stimuli

Integrative function:

Processing of information

Motor function:

carries out the responses

Two divisions of Neverous system:

Central and Peripheral Nervous Systems

Central nervous system:

Made up of brain and spinal cord

Peripheral Nervous system:

all nervous tissue outside the central nervous system; two catagories

Two categories of Peripheral Nervous system:

Somatic and autonomic nervous systems

Somatic nervous system:

mostly responsible for voluntary functions; skeletal muscles

Autonomic Nervous System:

involuntary automatic functions; heart, digestion, respiration; to subdivisions

Two subdivisions of autonomic nervous system:

Sympathetic and parasympathetic divisions


one nerve cell

Cell body:

Part of neuron that has nucleus, cytoplasm and typical organelles


part of neuron-projections that send messages to the cell body


part of neuron-long projection that sends messages away from cell body; every neuron has one one "of these"

Axon terminals:

part of neuron-branches at end of axon

Synaptic end bulbs:

part of neuron-bulb shaped structures filled with neurotransmitters


a type of neuroglia of CNS that physically protects neurons ; plays role in learning and memory


a type of neuroglia of CNS; responsible for productin the myelin sheath


a type of neuroglia of CNS; phagocytes that help fight foreign substances

Ependymal Cells:

a type of neuroglia of CNS; produce cerebrospinal fluid; helps with circulation

Schwann cells:

type of neuroglia of PNS; cells that surround axons

Satellite cells:

type of neuroglia of PNS; provides structural support; involved with nutrient exchange between cells and interstitial fluid

Two types of neuroglia that produce myelin sheaths:

Schwann cells and oligodendrocytes of CNS

Myelin sheath:

A multi-layered lipid and protein covering that surronds axons


the outer nucleated cytoplasmic layer of the schwann cell, which encloses the myelin sheath

Nodes of ranvier:

gaps in myelin sheath that occur between schwann cells; increases nerve signal transmission


white fatty substance produced by oligodendrocytes and schwann cells

Potassium ion:


Sodium ion:


Ion channels:

4 types of chanels that allow ions (K+ and Na+) to pass in and out of a cell

Electrochemical gradient:

Ions move from areas of higher concentration to areas of lower concentration

Resting membrane potential:

an excess of unused ions that store potential energy, that line the outer wall of the plasma membrane

Unequal distribution of ions in Extra Cellular Fluid & Cytosol:

contributes to resting membrane potential; plasma membrane has more K+ leakage channels that allow for more K+ to diffuse down concentration gradient out of cell into ECF

Inability of anions to leave cell:

contributes to resting membrane potential because they are attached to nondiffusible molecules such as ATP

Electrogenic nature of Na/K ATPases:

contributes to resting membrane potential by pumping out Na+ as fast as it leaks in

The two main phases of an action potential:

depolarizing and repolarizing phases

Depolarizing Phase:

negative membrane potential becomes less negative, reaches 0, then becomes positive

Repolarizing Phase:

membrane potential is restored to resting state

Refractory period:

perior of time after action potential when another impulse can not be generated

Two types of propagation of nerve impulses:

continuous and saltatory conduction

Continuous conduction:

step by step depolarization and repolarization of each adjacent segment of the plasma membrane

Saltatory conduction:

special mode of action potential propagation that occurs along myelinated axons because of uneven distriution of voltage-gated channels

Electrical Synapses:

have gap junctions that have connexons which connect cytosol of two cells, which allows faster communication

Chemical synapses:

synaptic cleft w/neurotransmitters that chemically transmit messages from one neuron to another

Excitatory and Inhibitory postsynaptic potentials:

are types of action potentials that neurotransmitters will cause

Excitatory postsynaptic potential:

causes excitation of the effector (which is the structure that carries out the response)

Inhibitory postsynaptic potential:

Neurostansmitter moves post synaptic further away from threshold


A small molecule neurotransmitter that works at the neuromuscular junction; excitatory or inhibitory

Two excitatory Amino Acids:

glutamate and asparate; act in CNS

Two inhibitory Amino Acids:

Gamma aminobutyric acid and glycine; act in CNS

Biogenic amines:

modified and decarboxylated amino acids that excite or inhibit receptors


excitatory or inhibitory; role in regulating mood


excitatory or inhibitory; very active in emotional responses, including addictive behaviors


excitatory or inhibitory; involved in mood, sleep cycle, appetite , sensory perception

Protective structures of the spinal cord:

Vertebral column and meninges

Vertebral column:

provides bony protection


connective tissue of spinal cord

Dura mater:

outer layer of the meninges; dense irregular connective tissue

Arachnoid mater:

middle layer of the meninges; made of collagen and elastic fibers

Pia Matter:

inner most layer of meninges; made of bundles of collagen fibers and elastic fibers; helps supply blood to cord

Internal anatomy of the spinal cord:

Anterior median fissure, posterior median sulcus, Central canal, Gray matter, White matter

Anterior median fissure:

very deep groove of internal spinal cord

Posterior median sulcus:

very shallow groove of internal spinal cord

Central canal:

tunnels through center of spinal canal; filled with CSF

Anterior gray horns:

gray matter of spinal cord containing somatic motor nuclei

Posterior gray horns:

gray matter of spinal cord containing somatic (voluntary) and automatic (involuntary) sensory nuclei

Lateral gray horns:

gray matter of spinal cord present in thoracic area, upper lumbar and sacral parts of spine; autonomic motor nuclei

White matter:

tracts that extend entire length of spinal cord; bundles of axons faciliate more efficient communication;

Sensory tracts of white matter:

carry information toward the brain

Motor tracts of white matter:

carry information away from the brain

Three tracts of white matter:

Anterior, posterior and lateral white columns

Formation of spinal nerves:

the anterior and posterior roots unite to form the spinal nerves

Posterior root of spine:

contains only sensory axons

Anterior root of spine:

contains only motor axons

Connective tissue of spinal nerves:

Epineurium, Perineurium, Fascicles & Endoneurium


connective tissue wrapping of individual axons (neurons)


bundles of wrapped axons


connective tissue that wraps fascicle of spinal nerves


connective tissue wrapping of entire spinal nerve


branches of spinal nerves

Posterior ramus:

branch of spinal nerve that serves muscles in the skin of posterior trunk

Anterior Ramus:

branch of spinal nerve that serves anterior trunk and some structures of the limbs

Meningeal branch:

branch of spinal nerves that enters and exits vertebral cavity to supply vetebrae, ligaments, blood vessels of spinal cord


divisions of the anterior rami

Intercostal nerves:

Anterior rami of spinal nerves T2-T12

Lateral & Anterior spinothalamic tracts:

convey impulses for temperature sensation, pain, etc


perception of the position of a body part, independent of vision

Discriminative touch:

ability to feel what part of body is being touched

Two point discrimination:

ability to distinguish the touching of two points of body, even when close together

Integration centers:

where info is processed by interneurons, determines response and sends to motor neurons

Direct pathways:

send impulses for precise voluntary movements

Three Direct Pathways:

lateral corticospinal , anterior corticospinal tract, and cortiobulbar tract

Indirect pathways:

involved with coordination of body movements, skeletal muscle tone, posture & equilibrium

Three Indirect Pathways:

Rubrospinal, tectospinal and vestibulospinal tracts


fast automatic sequence of actions in response to a stimulus

Spinal reflex:

integration takes place in spinal cord; no brain process required

Cranial reflex:

integration takes place in lower portion of brain; tracking portion of reading

Somatic reflex:

involves contraction of skeletal muscles

Autonomic visceral reflex:

reflexes not consciously perceived; heart rate


sensory receptor sensitive to mechanical stimuli, stretching of blood vessels, stretching or bending of deformation of tissue


sensory receptor that responds to change in temperature


sensory receptor that responds to pain


sensory receptor that responds to light


sensory receptor that responds to chemicals


sensory receptors responds to changes in osmotic pressure

Sensory Neurons:

carries sensory information

Integration center:

where information is processed and decisions are made

Motor neurons:

carries response information to effectors


Part of body that carries out responses

Three protective coverings of brain:

dura mater, arachnoid mater and pia mater

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