Chap 3: Anatomy Of The Nervous System Flashcards
The peripheral nervous system (PNS)
The division that is located outside the skull and spine
Composed of the somatic nervous system and autonomic nervous system
Central nervous system (CNS)
The division of the nervous system that is located within the skull and spine
Composed of the brain and the spinal cord
The brain is part of the CNS located in the skull
The spinal cord is the part that is located in the spine
The somatic nervous system (SNS)
The part of the PNS that interacts with the external environment. It is composed of the afferent nerves that carry sensory signals from the skin, skeletal muscles, joint ps, eyes, ears, and so on to the CNS
Autonomic nervous system (ANS)
The part of the PNS that regulated the body’s Internal environment
Afferent vs. Efferent
Afferent is going towards something in this case going toward the CNS they begin with (a) (advance, approach, arrive)
Efferent is going away from something which begins with (e) (exit, embark, escape)
Sympathetic nerves
Those autonomic motor nerves that project from the CNS in the lumbar (small of the back) and thoracic (chest area) regions of the spinal cord
Parasympathetic nerves
Those autonomic motor nerves that project from the brain and sacral (lower back) region of the spinal cord
The Three Meninges
It encases the brain and spinal cord which are the most protected organs in the body
The outer meninx is the tough membrane called the dura mater (tough mother)
Arachnoid membrane
Is immediately inside the dura mater (spider weblike membrane)
Subarachnoid space
Beneath the arachnoid membrane, which contains many large blood vessels and cerebrospinal fluid
Pia mater
Innermost meninx, which adheres to the surface of the CNS
Cerebrospinal fluid (CSF)
Protects the CNS,which fills the subarachnoid space, the central of the spinal cord & the cerebral ventricles of the brain
Central canal
A small central channel that runs the length of the spinal cord
Cerebral ventricles
Are the four large internal chambers of the brain: the two lateral ventricles, the third ventricle, and the fourth ventricle
Choroid plexuses
Networks of capillaries (small blood vessels) that protrude into the ventricles from the pia mater. It continuously produces cerebrospinal fluid
Cerebral aqueduct
Connects the third and fourth ventricles
Hydrocephalus
Produced by the buildup of fluid in the ventricles causing the walls of the ventricles and the brain to expand
It’s treated by draining the excess fluid from the ventricles and trying to remove the obstruction
Blood brain barrier
It’s a mechanism that impedes the passage of many toxic substances from the blood into the brain
Neurons
Cells that are specialized for the reception, conduction, and transmission of electrochemical signals
Cell membrane
The semipermeable membrane that encloses the neuron
Dendrites
The short processes emanating from the cell body, which receive most of the synaptic contacts from other neurons
Axon hillock
The cone shaped religion at the junction between the axion and the cell body
Axon
The long narrow process that projects from the cell body
Cell body
The metabolic center of the neuron, also called the soma
Myelin
The fatty insulation around many axons
Nodes of ranvier
The gaps between sections of myelin
Buttons
The buttonlike endings of the axon branches, which release chemicals into synapses
Synapses
The gaps between adjacent neurons across which chemical signals are transmitted
Endoplasmic reticulum
A system of folded membranes in the cell body; rough portions (those with ribosomes) play a role in the synthesis of proteins; smooth portions (those without ribosomes) play a role in the synthesis of fats
Nucleus
The spherical DNA containing structure of the cell body
Mitochondria
Sites of aerobic (oxygen consuming) energy release
Cytoplasm
The clear internal fluid of the cell
Ribosomes
Internal cellular structures on which proteins are synthesized; they are located on the endoplasmic reticulum
Golgi complex
A connected system of membranes that packages molecules in vesicles
Microtubles
Tubules responsible for the rapid transport of material throughout neurons
Synaptic vesicles
Spherical membrane packages that store neurotransmitter molecules ready for release near synapses
Neurotransmitters
Molecules that are released from active neurons and influence the activity of other cells
Neuron cell membrane
The neuron cell membrane is composed of a lipid bilayer, or two layers of fat molecules
Classes of neurons
A way of classifying neurons that is based on the number of processes (projections) emanating from their cell bodies
Multipolar neuron
A neuron with more than two processes extending from its cell body
Unipolar neuron
A neuron with one process extending from its cell body
Bipolar neuron
A neuron with two processes extending from its cell body
Interneurons
Neurons with a short axon or no axon at all, their function is to integrate the neural activity within a single brain structure, not to conduct signals from one structure to another
Nuclei (singular nucleus)
It’s in the central nervous system clusters of cell bodies
Ganglia (singular ganglia)
In the peripheral nervous system
Oligodendrocytes
Are glial cells with extensions that wrap around the axons of some neurons of the central nervous system
Myelin
A fatty insulating substance, and the Myelin sheaths that they form increase the speed and efficiency of axonal conduction
Microglia
Make up a third class of glia cells, their smaller than other glia They respond to injury or disease by multiplying, engulfing cellular debris, and triggering inflammatory responses
Astocytes
Constitute a fourth class of glial cells, they are the largest glial cells and they are so named because they are star shaped
Nissl stain
The first neural staining procedure to overcome these shortcomings
Electron microscopy
A neuroanatomical technique that provides information about the details of neuronal structure
Anterograde tracing methods
Are used when an investigator wants to trace the paths of axons projecting away from cell bodies located in a particular area
Retrograde tracing methods
Work in reverse, they are used when an investigator wants to trace the paths of axons projecting into a particular area
Anterior
Means toward the nose end (the anterior end)
Posterior
Means toward the tail end (the posterior end)
Dorsal
Means toward the surface of the back or the top of the head (the dorsal surface)
Ventral
Means toward the surface of the chest or the bottom of the head (ventral surface)
Medial
Means toward the midline of the body
Lateral
Means away from the midline toward the body’s lateral surfaces
Cross section
A section cut at a right angle to any long, narrow structure, such as the spinal cord or a nerve
Gray matter
Is composed largely of cell bodies and unmyelinated interneurons
White matter
Composed largely of myelinated axons
Dorsal horns
The two dorsal arms of the spinal gray matter
Ventral horns
The two ventral arms
Spinal nerves
Are attached to the spinal cord, one on the left and one on the right-at 31 different levels of the spine
Dorsal root ganglia
Formed from all dorsal root axons, whether somatic or autonomic, are sensory (afferent) unipolar neurons with their cell bodies grouped together just outside the cord
Brain stem
The stem on which the cerebral hemispheres sit, it’s the other four divisions of the brain
Myelencephalon (or medulla)
The most posterior division of the brain, is composed largely of tracts carrying signals between the rest of the brain and the body
Reticular formation
It is a complex network of about 100 tiny nuclei that occupies the central core of the brain stem from the posterior boundary of the myelencephalon to the anterior boundary of the midbrain
Mesencephalon
Houses many ascending and descending tracts and part of the reticular formation
Pons
A bulge on the brain stems ventral surface
It’s the one major division of he metencephalon the other is the cerebellum (little brain)
Cerebellum
Is the large convoluted structure on the brain stems dorsal surface
Mesencephalon
Has two divisions which are the tectum and tegmentum
Tectum (roof)
Is the dorsal surface of the midbrain
Tegmentum
Is the division of the mesencephalon ventral to the tectum
Periaqueductal gray
Is the gray matter situated around the cerebral aqueduct, the duct connecting the third and fourth ventricles, it is of special interest because of its role in mediating the analgesic (pain reducing) effects of opiate drugs
Thalamus
Is the large, two lobes structure constitutes the top of the brain stem
Massa intermedia
Which runs through the ventricle
Sensory relay nuclei
Nuclei that receive signals from sensory receptors, process them, and then transmit them o the appropriate areas of sensory cortex
Hypothalamus
Below the anterior thalamus, plays a role in the regulation of several motivated behaviors (eating, sleep, & sexual behavior)
Pituitary gland
Which dangles from it on the ventral surface of the brain
Optic chasm
Is the point at which the optic nerves from each eye come together
Mammillary bodies
Which are often considered to be part of the hypothalamus, are a pair of spherical nuclei located on the inferior surface of the hypothalamus just behind the pituitary
Telencephalon
The largest division of the human brain, mediates the brains most complex functions
It initiates voluntary movements
Cerebral cortex
Mainly composed of small, unmyelinated neurons, it is gray and is often referred to as the gray matter
Central & lateral fissures
Partially divide each hemisphere into four lobes: frontal, parietal, temporal, & occipital lobe
Pyramidal cells
Are large multipolar neurons with pyramid shaped cell bodies, a large dendrite called an apical dendrite that extends from the apex of the pyramid straight toward the cortex surface and a very long axon
Stellate cells
Are small star shaped interneurons (neurons with a short axon or no axon)
Columnar organization
Neurons in a given vertical column of neocortex often form a mini circuit that performs a single function
Hippocampus
Is one important area of cortex that is not neocortex it has only three major layers
Septum
Is a midline nucleus that is located at the anterior tip of the cingulate cortex
