Chapter 2 - Functional Neuroanatomy Flashcards
Phrenology
studying the shape of the head
Gross neuroanatomy
features of the nervous system visible to the naked
central nervous system (CNS
consists of the brain and spinal cord.
peripheral nervous system
all parts of the nervous system found outside the skull and spinal column
peripheral nervous system three components:
The peripheral nervous system consists of nerves, or bundles of axons, and has three components: 1. Cranial nerves–connected to the brain 2. Spinal nerves–also called somatic nerves, connected to the spinal cord 3. Autonomic nervous system–primarily controls glands and internal organs
Spinal nerves or somatic nerves two distinct branches, or roots:
Spinal nerves or somatic nerves–31 pairs Each spinal nerve is the fusion of two distinct branches, or roots: 1. Dorsal (back) root–carries sensory information from the body to the spinal cord 2. Ventral (front) root–carries motor information from the spinal cord to the muscles
Preganglionic neurons
run from the CNS to the autonomic ganglia.
Postganglionic neurons
run from the autonomic ganglia to targets in the body.
autonomic ganglia
A Group of neurons that are located outside the CNS.
The autonomic nervous system And the three major divisions:
spans the central and peripheral nervous systems. The autonomic nervous system has three major divisions: 1. Sympathetic nervous system 2. Parasympathetic nervous system 3. Enteric nervous system
Neurons
or nerve cells, are the most important part of the nervous system
Glial cells
provide support for neurons.
Neuron doctrine
states that: The brain is composed of independent cells. Information is transmitted from cell to cell across synapses.
A neuron has four zones
- Input zone–receives information from other cells through dendrites 2. Integration zone–cell body (or soma) region where inputs are combined and transformed 3. Conduction zone–single axon leads away from the cell body and transmits the electrical impulse 4. Output zone–axon terminals at the end of the axon communicate activity to other cells
Functions of Neurons
- Motoneurons (motor neurons) stimulate muscles or glands. 2. Sensory neurons respond to environmental stimuli, such as light, odor, or touch. 3. Interneurons receive input from and send input to other neurons
Glial Cells Four types
Glial cells support neuronal activity 1. Astrocytes–star-shaped cells with many processes that receive neuronal input and monitor activity 2. Microglial cells, or microglia–small cells that remove debris from injured cells 3. Oligodendrocytes are glial cells that form myelin sheath in the brain and spinal cord. 4. Schwann cells provide myelin to cells outside the brain and spinal cord. Glial cells respond to injury by edema, or swelling, and are also susceptible to tumors.
Myelination
Myelination–the process in which glial cells wrap axons with a fatty sheath, myelin, to insulate and speed conduction
Nodes of Ranvier
gaps between sections of myelin where the axon is exposed
Multiple sclerosis
a demyelinating disease
Synapses three components
Synapses have three components: 1. Presynaptic membrane–on the axon terminal of the presynaptic neuron 2. Postsynaptic membrane–on the dendrite or cell body of the postsynaptic neuron 3. Synaptic cleft–a gap that separates the membranes
Golgi stains
fill the whole cell, including details, but only stain a small proportion of neurons. Fluorescent molecule injections give a similar result.
Nissl stains
outline all cell bodies because the dyes are attracted to RNA, which encircles the nucleus.
glial cells
Also called glia or neuroglia. Nonneuronal brain cells that provide structural, nutritional, and other types of support to the brain. Glial cells are of clinical interest for several reasons. Unlike neurons, glial cells continue to divide throughout life, and consequently they form many of the types of tumors that arise in the brain. Some glial cells, especially astrocytes, respond to brain injury by changing in size—that is, by swelling.
neuron doctrine
The hypothesis that the brain is composed of separate cells that are distinct structurally, metabolically, and functionally. 1) the brain is composed of separate neurons and other cells that are independent structurally, metabolically, and functionally; and (2) Information is transmitted from cell to cell across tiny gaps.
neuron or nerve cell
The basic unit of the nervous system, each composed of a cell body, receptive extension(s) (dendrites), and a transmitting extension (axon).
synapse
The tiny gap between neurons where information is passed from one to the other.
mitochondrion
A cellular organelle that provides metabolic energy for the cell’s processes
cell nucleus
The spherical central structure of a cell that contains the chromosomes
ribosomes
Structures in the cell body where genetic information is translated to produce proteins
axon
A single extension from the nerve cell that carries nerve impulses from the cell body to other neurons. The axon has two quite different functions: rapid transmission of electrical signals along the outside of the axon, and the much slower transportation of substances inside the axon, to and from the axon terminals.
dendrite
One of the extensions of the cell body that are the receptive surfaces of the neuron.
input zone
The part of a neuron that receives information, from other neurons or from specialized sensory structures. Usually corresponds to the cell’s dendrites.
cell body or soma
The region of a neuron that is defined by the presence of the cell nucleus.
integration zone
The part of the neuron that initiates nerve electrical activity, described in detail in Chapter 3. Usually corresponds to the neuron’s axon hillock
conduction zone
The part of the neuron over which the nerve’s electrical signal may be actively propagated. Usually corresponds to the cell’s axon.
axon terminal
Also called synaptic bouton. The end of an axon or axon collateral, which forms a synapse on a neuron or other target cell.
output zone
The part of a neuron, usually corresponding to the axon terminals, at which the cell sends information to another cell.
multipolar neuron
A nerve cell that has many dendrites and a single axon
bipolar neuron
A nerve cell that has a single dendrite at one end and a single axon at the other end
unipolar neuron
Also called monopolar neuron. A nerve cell with a single branch that leaves the cell body and then extends in two directions; one end is the receptive pole, the other end the output zone.
motoneuron
Also called motor neuron. A nerve cell that transmits motor messages, stimulating a muscle or gland.
sensory neuron
A neuron that is directly affected by changes in the environment, such as light, odor, or touch.
interneuron
A neuron that is neither a sensory neuron nor a motoneuron; it receives input from and sends output to other neurons.
arborization
The elaborate branching of the dendrites of some neurons.
presynaptic
Referring to the region of the synapse that releases neurotransmitter.
presynaptic membrane
Referring to the region of a synapse that receives and responds to neurotransmitter
postsynaptic membrane
The specialized membrane on the surface of the cell that receives information by responding to neurotransmitter from a presynaptic neuron.
neural plasticity
Also called neuroplasticity. The ability of the nervous system to change in response to experience or the environment. Studding the dendrites of many neurons are outgrowths called dendritic spines that, by effectively increasing the surface area of the dendrites, allow for extra synaptic contacts. Both the number and structure of dendritic spines may be rapidly altered by experience, such as training or exposure to sensory stimuli
synaptic cleft
The space between the presynaptic and postsynaptic elements.
synaptic vesicle
A small, spherical structure that contains molecules of neurotransmitter.
neurotransmitter
Also called synaptic transmitter, chemical transmitter, or simply transmitter. The chemical released from the presynaptic axon terminal that serves as the basis of communication between neurons.
receptor
Also called receptor molecule. A protein that binds and reacts to molecules of a neurotransmitter or hormone.
astrocyte
A star-shaped glial cell with numerous processes (extensions) that run in all directions. Astrocytes receive synapses directly from neurons and also surround and monitor the activity of nearby neuronal synapses. They may then communicate among themselves and with the neighboring neurons to modulate the neurons’ responses
microglial cells
Also called microglia. Extremely small glial cells that remove cellular debris from injured or dead cells. But we are beginning to realize that microglial cells are involved in more than just damage control: for example, microglial cells appear to be a key component of neural pain systems They are also important for the maintenance of synapses; interference with this function is associated with the development of Alzheimer’s and other dementias
axon hillock
A cone-shaped area from which the axon originates out of the cell body. Functionally, the integration zone of the neuron.
axon collateral
A branch of an axon from a single neuron.
myelination
The process of myelin formation. The process of myelination continues for a long time in humans, 10–15 years after birth, and possibly throughout life.
myelin
The fatty insulation around an axon, formed by glial cells, that improves the speed of conduction of nerve impulses. • Purpose of myelin - a large increase in the speed with which electrical signals pass down the axon, jumping from one node to the next • the manner in which glial cells surround some synaptic contacts suggests that one of their roles is to insulate and isolate synapses to prevent one from affecting the other
innervate
To provide neural input.
edema
The swelling of tissue, especially in the brain, in response to injury. In the brain it is primarily due to glial cells It can damage neurons and is responsible for many symptoms of brain injuries
multiple sclerosis
Literally, “many scars”; a disorder characterized by widespread degeneration of myelin. Aka. demyelinating
axonal transport
The transportation of materials from the neuronal cell body to distant regions in the dendrites and axons, and from the axon terminals back to the cell body.
oligodendrocyte
A type of glial cell that forms myelin in the central nervous system.
Schwann cell
The glial cell that forms myelin in the peripheral nervous system.
node of Ranvier
A gap between successive segments of the myelin sheath where the axon membrane is exposed.
gross neuroanatomy
Anatomical features of the nervous system that are apparent to the naked eye
peripheral nervous system
The portion of the nervous system that includes all the nerves and neurons outside the brain and spinal cord
cranial nerve
A nerve that is connected directly to the brain. The 12 pairs of cranial nerves—1 left-sided and 1 right-sighted in each pair—serve the sensory and motor systems of the head and neck These nerves pass through small openings in the skull, directly entering or leaving the brain without ever joining the spinal cord.
spinal nerve
Also called somatic nerve. A nerve that emerges from the spinal cord. 31 pairs of nerves emerge at regularly spaced intervals through openings in the backbone One member of each pair of spinal nerves serves each side of the body. Each spinal nerve consists of the fusion of two distinct branches, called roots, which are functionally different. The dorsal (back) root and the ventral (front) root.
central nervous system (CNS)
The portion of the nervous system that includes the brain and the spinal cord.
nerve
A collection of axons bundled together outside the central nervous system.
motor nerve
A nerve that conveys neural activity to muscle tissue and causes it to contract.
sensory nerve
A nerve that conveys sensory information from the periphery into the central nervous system.
autonomic nervous system
The part of the peripheral nervous system that supplies neural connections to glands and to smooth muscles of internal organs. the brain’s main system for controlling the organs of the body.
dorsal root
The branch of a spinal nerve, entering the dorsal horn of the spinal cord, that carries sensory information from the peripheral nervous system to the spinal cord
ventral root
The branch of a spinal nerve, arising from the ventral horn of the spinal cord, that carries motor messages from the spinal cord to the peripheral nervous system.
cervical
Referring to the topmost 8 segments of the spinal cord, in the neck region.
autonomic ganglia
Collections of nerve cell bodies, belonging to the autonomic division of the peripheral nervous system, that are found in various locations and innervate the major organs. outside of the CNS
thoracic
Referring to the 12 spinal segments below the cervical (neck) portion of the spinal cord, corresponding to the chest.
lumbar
Referring to the 5 spinal segments that make up the upper part of the lower.
sympathetic nervous system
A component of the autonomic nervous system that arises from the thoracic and lumbar spinal cord. In general, sympathetic activation prepares the body for action: blood pressure increases, the pupils of the eyes widen, and the heart quickens. This set of reactions is sometimes called simply the “fight or flight” response.
sympathetic chain
A chain of ganglia that runs along each side of the spinal column; part of the sympathetic nervous system. Parasympathetic ganglia are not collected in a chain as sympathetic ganglia are. Rather, parasympathetic ganglia are dispersed throughout the body, usually positioned near the organs affected.
parasympathetic nervous system
A component of the autonomic nervous system that arises from both the cranial nerves and the sacral spinal cord. generally helps the body to relax, recuperate, and prepare for future action, sometimes called the “rest and digest” response.
sacral
Referring to the 5 spinal segments that make up the lower part of the lower back.
acetylcholine
A neurotransmitter produced and released by parasympathetic postganglionic neurons, by motoneurons, and by neurons throughout the brain. Which tends to slow down activity.
enteric nervous system
An extensive meshlike system of neurons that governs the functioning of the gut. plays a key role in maintaining fluid and nutrient balances in the body Part of the CNS
coccygeal
Referring to the lowest spinal vertebra (also known as the tailbone).
cerebral cortex
Sometimes called simply cortex. The outer covering of the cerebral hemispheres that consists largely of nerve cell bodies and their branches. The cortex is the seat of complex cognition.
preganglionic
Literally, “before the ganglion.” Referring to neurons in the autonomic nervous system that run from the central nervous system to the autonomic ganglia.
postganglionic
Literally, “after the ganglion.” Referring to neurons in the autonomic nervous system that run from the autonomic ganglia to various targets in the body.
frontal lobe
The most anterior portion of the cerebral cortex. important for movement and high-level cognition
parietal lobes
Large regions of cortex lying between the frontal and occipital lobes of each cerebral hemisphere. receive sensory information from the body and participate in spatial cognition.
temporal lobes
Large regions of coLarge lateral cortical regions of each cerebral hemisphere, continuous with the parietal lobes posteriorly, and separated from the frontal lobe by the Sylvian fissure Auditory information damage here can impair hearing the temporal lobes are also particularly associated with the sense of smell, and with aspects of learning and memory rtex covering much of the posterior part of each cerebral hemisphere.
religiosity
occipital lobes
Large regions of cortex covering much of the posterior part of each cerebral hemisphere. receive and process information from the eyes, giving rise to the sense of vision.
norepinephrine
Also called noradrenaline. A neurotransmitter produced and released by sympathetic postganglionic neurons to accelerate organ activity. Also produced in the brainstem and found in projections throughout the brain.
cerebral hemispheres
The right and left halves of the forebrain.
postcentral gyrus
The strip of parietal cortex, just behind the central sulcus, that receives somatosensory information from the entire body. contains a sensory map of the body The sense of touch
binding problem
precentral gyrus
The strip of frontal cortex, just in front of the central sulcus, that is crucial for motor control. the precentral gyrus contains an orderly map of the muscles of the body
gyrus
A ridged or raised portion of a convoluted brain surface.
white matter
A shiny layer underneath the cortex that consists largely of axons with white myelin sheaths. Which consists mostly of fiber tracts. It gains its appearance from the whitish fatty myelin that ensheathes and insulates the axons of many neurons. white matter mostly transmits information.
gray matter
Areas of the brain that are dominated by cell bodies and are devoid of myelin. on the exterior is dominated more by nerve cell bodies and dendrites, which are devoid of myelin. A simple view is that gray matter primarily processes information,
sulcus
A furrow of a convoluted brain surface.
Sylvian fissure aka Latteral fissure
Also called lateral sulcus. A deep fissure that demarcates the temporal lobe.
central sulcus
A fissure that divides the frontal lobe from the parietal lobe.
corpus callosum
The main band of axons that connects the two cerebral hemispheres.
neural tube
An embryonic structure with subdivisions that correspond to the future forebrain, midbrain, and hindbrain.
forebrain
Also called prosencephalon. The anterior division of the brain, containing the cerebral hemispheres, the thalamus, and the hypothalamus.
midbrain
Also called mesencephalon. The middle division of the brain.
cerebellum
A structure located at the back of the brain, dorsal to the pons, that is involved in the central regulation of movement. the surface of the cerebellum is elaborately convoluted, giving it more surface area The cerebellum has long been known to be crucial for motor coordination and control, but we now know it also participates in certain aspects of cognition, including learning.