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brain
question | answer |
---|---|
why is the brain often compared to a computer? | because it can simultaneously recieve and process enormous amounts of info, and then organize, integrate, file and store the info. before making output response |
brain size is ___directly correllated with intelligence | not |
typical human brain has a volume of | 1200 cc and |
a typical brain weighs around | 3 pounds |
four major regions of the brain | cerebrum, diencephalon, brainstem, and cerebellum |
when viewed superiorly the cerebrum is divided into two halves, called | leftand right cerebral hemispheres |
each hemisphere may be further subdivided into | five functional areas called lobes |
outer surface of an adult brain exhibits folds called | gyri (singular gyrus) |
the outer surface of an adult brain exhibits shallow depression between gyri called | sulci (singular sulcus |
the brain is associated with ___ pairs of cranial nerves | 12 |
what are the two directional terms used to describebrain anatomy? | rostral (anterior) and caudal(posterior) |
rostral means | toward the nose |
terms synonomous with rostral | cranial or superior or anterior |
caudal means | towards the tail |
synonomous with caudal | posterior, inferior |
the the human embryo the brain orms the ___ of hte neural tube, which undergoes ___ growth rates in different regions | front part, disproportionate |
by the fifth week of development a totatl of __ regions appear | five: tellencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon |
telencephalon | forms the cerebrum |
diencephalon | eventually formsthe thalamus, hypothalamus, and epithalamus |
during the embryonic and fetal periods the telencephalon... | grows rapidly and surrounds the diencephalon |
mesencephalon | which formsa short section of the brian stem between the diencephalon and pons |
metencephalon | eventually forms the pons and cerebellum |
myelencephalon | eventually forms the medulla oblongata1 |
as the future brain develops, its surface folds, execially in the ___, oleading to the formation of adult ___ and ____. | telencephalon, sulci and gyri |
what detwermine the boundadries of the brains's cavvities? | the bends and creases that occur in the developing brain |
what is necessary in order to fit the massive amount of brain tissue within the confines ofthe cranial cavity? | bends, creases and folds in the telencephalon |
why is it that when the fetus is borns the brain closely resembles that of an adult? | because most of the gyri and sulci develop late in the fetal development |
what are the two distinct tissue areass whcih are recognized within the brain and spinal cord | gray matter, and white matter |
gray matter houses: | motor neuron and interneuron cell bodies, dendriteds, branching axon terminals, unmyelinated axons |
whit matter deriveds its color from | myelin in the nyelinated axons |
white matter yhouses: | myelinated axons, dendrites adn associated neuroglial cells |
what forms from mihrating peripheral neurons? | an outer superficial region of gray matter |
cortex | external sheets of gray matter that cover the surface of most of the adult brain (cerebrum and cerebellum) |
the whit matter of the brain lies ___ to the gray matter of the cortex | deep |
medulla | inner region of white matter |
sudden decelerations (car crashes) can cause what to occur? | gray and white matter int he brain to shear at the interface |
in the spinal cord how are the white and grey matter organized? | white matter as its outer layer and gray matter at its center |
the brain is prootected and isolated by multiple structures | bony cranium (rigid support), meninges, csf(cushioning), bb barrier(prevent entry of harmful chem) |
meninges | three connective tissue layers that separate the soft tissue of the brain from the bones of the cranium, enclose and protect bv tha tsupply the brain and ocntain and circulate csf. also forms some of the veins that drain blood from teh brain |
what are the three layers of the meninges | dura mater, arachnoid mater, pia mater |
sura mater | most external of the neninges |
dura mater is composed of | tough, dense connective tissue with two fibrous layers, strongest of the meninges |
two layers of the dura mater | periosteal layer, meningeal layer |
periosteal layer | more superficial layer, forms the periosteum fo the cranial bones |
meningeal layer | lies deep to the periosteal layer |
the meningeal layer is usually fused to the ___ except in specific areas where the two layers separate to form large, blood-filled spaces called ______ | periosteal layer, dural venous sinuses |
dural venous sinuses | triangular in cross section , do not have vvalves to regulate venous flow (unlike most veins) |
dural venous sinuses are in essence, | large veins that drain blood from teh brain and transport the blood to the internal jugular veins |
epidural space | the dura mater and bones of the skull can be separated by it, contains the arteries and veins that nourish the meninges and bones of the cranium |
arachnoid mater | lies immediately internal to the dura mater |
why is the arachnoid mater named accordingly? | because arachnoid means like a s pider or resembling a spider's web and this meninx is so named because it is partiallly composed of a delicate web o callagen and elastic fibers |
subdural space | potential located between the arachnoid and overlying dura mater |
subarachnoid s pace | immediately deep to the arachnoid mater, the spider web-like extensions of the arachnoid extend throug this space from the arachnoid to the underlying pia mater |
pia mater | is the innermost of hte cranial meninges |
pia mater is composed of | delicate connective tissue that itghtly adheres to the brain and nfollows every contour of the brain surface |
cranial dural septa | double layers of dura mater (meningeal layer of the dura mater extends as flat partitions (septa) into the cranial cavity) |
function fof the cranial dural septa | membranous partitions separate specific parts of the brain and provide additional stabilization and support fro the entire brain |
four cranial dural septa | falx cerebri, tentorium cerebelli, falx cerebelli, diphragma sellae |
largenst of the four dural septa | falx cerebri |
describe the falx cerebri | sickle-shaped vertical fold fo dura mater, located int he midsagittal plane, projects into the longitudinal fissure between the left and right cerebral hemispheres |
anterior attachment of falx cerebri? | crista galli aof ethmoid |
posterior attachment sit e for the falx cerebri | superior portion fo the tentorium cerebelli |
reunning within the margins of the falx cerebri are | several dural vvenous sinuses |
describe the tentorium cerebelli | horizontally oriented fold of dura mater athat separates the occipital lobe and temporal lobes of fhte cerebrum from the cerebellum |
what runs within the posterior border of the tentorium cerebelli? | dural venous sinus |
the anterior surface of the tentorium cerebelli has a | tentorial notch |
tentorial notch | small gap or opening, allows passage fo the brainstem |
tentorial incisure | tentorial notch |
describe the falx cerebelli | extend in toeh midsagittal line inferior to eht tentoriiumm cerebelli, sickle-shaped vertical partition atha tdivides the left and righ tcerebellar hemishperes |
what runs in the posterior vertical border of the falx cerebelli | tiny dural venous sinus |
smallest of hte dural septa is the | diphragma sellae |
diphragma sellae forms a | roof ofve rhte sella trucica of hte sphenoid bone |
a smallopening within the diphragman sellae allos for the passage of the | thin stalk taht attaches the pituitary gland within the sella turcicca to the base ofthe yypothalamus located just above |
the brain ventriclesare | cavities or expansions within the brain that are deried from the lumen (opening) of the embryonic neural tube |
where are the brain ventricles derived from? | the lumen (opening) of the embryonic neural tube |
the ventricles are ___ with one another as well as the ___ of the spinal cord | contiguous, central canal |
whare the four ventricles in the brain? | two lateral ventricles, third ventricle, fourth ventricle |
allof the ventricles in the brain contain | csf |
where are the two lateral ventricles located | in the cerebrum (one in the right, one in the left cerebral hemisphere) |
whare are the two lateral ventricles separated by? | a thin medial partion called the septum pellucidum |
thir ventricle | smaller chamber located within the diencephalon |
each lateral ventricle communicates with the | third ventricle |
fourth ventricle | shaped like a tetrahedron, located between the pons and the ecerebellum |
the fourth ventricle narrows at its ___ end before it merges with the ____ int he spinal cord | inferior, central canal |
csf | clear, colorless liquid circulates int eh ventricles and subarachnoid space |
csf bathes the -_____ of the cns and completely surrounds it. | exposed surfaces |
importan functions of the csf. | buoyancy, protection, environmental stability |
the csf provides buoyancy so that the brain? | floats, |
the floating of the brain reduces its | apparent weight by more than 95% and preventsin it form being crushed under its own weight |
when csf is removed during spinal taps, many persons complain of headaches, caused in part by a | loss of the cushoinning buoyancy |
how does the csf protect | by creating liquid cushion to protect the brain from sudden mvmnts |
how does the csf provide environmental stability? | by transporting nutrients, chemical messengers and removing wates |
where are wastes and excess csf eventually transported? | into the venous circulation |
csf is formed by | the choroid plexi in each of the four ventricles |
the choroid plexi are formed | by the ependymal cells that line the ventricles and the bearby blood capillaries |
csf is essentially a filtrate of | plasma, in that it contains proteins and salts (ions) |
the choroid plexi produce csf at a rate of | 500 milliliter (ml) perday |
the csf eventually leave sth ventricles and enter the | subarachnoid space, where the total volume f the csf at at any given moment ranges between 100 ml and 160 ml |
because of teh constant changing ranges of csf, this means that? | excess csf is continuously removed fromteh subarachnoid space so the fluid will not accumulate and compress or damage the nervous tissue |
arachnoid villi | fingerlike extensions of the arachnoid project throug the dura mater into the dural venous sinuses |
arachnoid granulations | collections of arachnoid villi (visible) |
excess csf moves across the arachnoid membrane at the arachnoid villii to return to the | blood within the dural venous sinuses |
summarize. CSF is produced by ___ in the ____, flows throug the ___, enters into the ______ and the central canal, anas is evventually drained back into the blood via the ________ that empty into the dural venous sinuses. | choroid plexi, ventricles, ventricles, subarachnoid space, arachnoid villi |
what is protected by the bbb? | nervous tissue, |
astrocytes envelop brain capillaries and reduce | capillary permeablilty |
bbb helps to prevent hazardous | material from diffusing across the capillary wall. |
usually only ____ compounds can diffuse across the capillary wall and into the fluids of the CNS to reach the _____. | lipid-soluble, brain neurons |
where is the bbb markedly reduced or missing in the brain? | choroid plexi (necessary permeabliility to produce csf), hypothalamus and pineal glands (so they have acccess to blood stream to directly release their hormones into the plasma) |
cerebrum | telencephalon |
location of conscious though processes and the origin of all complex intellectual functions | cerebrum/telencephalon |
telencephalon is readily identified as the two large | hemispheres on the superior aspect of the brain. |
what are the functions of teh telencephalon (cerebrum)? | center of your intelligence, reasoning, sensory perception, thought, memory and judgment, volulntary motor, visual and auditory activities |
andy believes that you can kill what type of individuals for organ donation? | if they do not bave cerebral hemisphyeres, not a human person |
outer gray layer off the telencephalon is the _____ and the inner white matter was the _____> | cerebral cortex, cerebral medulla |
there surface of the cerebrum contains? | gyri, sulci and deeper grooves called fissures |
the two halves of the cerebrum | left and right cerebral hemispheres |
the paired cerebral hemispheres are separated by a deep | longitudinal fissure |
the longitudinal fissure extends along | the midsagittal plane |
are the cerebral hemispheres separate from one another? | yes except at a few locations (corpus collusum) where tracts of white matter allow for communication between them. |
corpus callosum | largest whit matter tract between lft and right hemispheres of cerebrum, connects the hemispheres and provides the main method of communication between these hemispheres |
what are the three points that should be kept in mind with respect to the cerebral hemispheres? | 1. overlap of functions (no precise location of function) 2. project commands and recieve info from opposite side of body. 3. the sheres are mirror images, one can play a greater role in certain body activities. |
why is it difficult to assign a precise function to a specific region of the brain? | there is considerable overlap of function |
both cerebral hemispheres receive their sensory info from, and project motor commoands to? | the opposite side fothe body, vice versa. |
the two cerebral hemispheres appear as mirror images, one hemisphere can play a greater role in? | controlling certain body activities |
which hemisphere is more important in controlling speech and understanding spoken word? | left hemisphere of telencephalon/cerebrum |
each cerebral hemisphere is divided into five lobes, what are they? | frontal lobe, parietal, temporal, occipital, insula |
where does the frontal lobe lie? | lies deep to the grontal bone and forms the anterior part of the cerebral hemisphere |
the grontal lobe is primarily concerned with? | voluntary motor functions of skeletal muscles, concentration, verbal communications, decision making, planning, personality |
parietal lobe lies where and forms what part of cerebral hemisphere? | lies internal to the parietal bone and forms superoposterior part of hemisphere |
the parietal lobe is involved with? | general sensory functions such as evaluating hte shpae and texture of objects being touched |
where does the temporal lobe lie? | internal to the temporal bone |
the temporal lobe is involved with? | hearing, interpreting speech and language, smell |
occipital lobe forms what region of the hemispheres? | the posterior regions |
where is the occipital lobe located? | immediately underlies the occipital bong |
the occipital lobe is responsible for? | processing incoming visula information, storing visual memories |
insula | small lobe that can be visualized by pulling aside the temporal lobe |
the function of the insula | momory, interpretation of taste |
cerebral medulla | central white matter |
cerebral nuclei | masses of gray matter buried deep within the white matter |
coup-contrecoup injuries to the cerbrum occur when? | a blow to the head caused the brain to shift towards area of impact and injue itself by hitting the inner surface of the skull, then rebounding injuring itself again by hitting the skull on opposite side where orig. blow was delivered |
where is the diencephalon located? | sandwiched between inferior regions of hte cerebral hemispheres |
what does the diencephalon include? | hypothalamus, thalamus and epithalamus |
epithalamus forms | posterior roof of hte diencephalon and covers the third ventricle |
the posterior portion of the epithalamus houses the | pineal gland |
pineal gland | endocrine gland, secretes melatonin |
malatonin regulated | circadian-rhythm (day-night cycles) |
thalamus | paired oval masses of gray matter that lie on either side of the third ventricle |
thalamus forms | superolateral walls of the third ventricle |
the thalamus is the principal and final relay point for all | sensory information, except for olfaction, |
olfaction | sense of smell |
sense of smell is processed and projected to the | cerebral cortex |
the thalamus filters out | repetitieve or non-essential sights and sounds and clues in the cerebrum where the sensory info came from |
hypothalamus is what border of teh diencephalon? | anteroinferior |
infundibulum | extend inferiorly fromt he hypothalamus to the pituitary gland |
what connects the pituitary gland to the hypothalamus? | infundibulum |
what are the functions of the hypothalamus? | controls autonomic ns |
how does the hypothalamus control the autonomic ns? | projects descending axons to the inferior brain stem that inflence heart rate, bp, digestion, and respiration |
the hypothalamus is the master control of the | autonomic ns: endocrine system, thermostat, emotional resopnses, controls hunger, thirst center, regulates circadian-rythyms |
as the master of the endocrine system the hypothalamus secretes? | hormones that control the secretory activities of the ANTERIOR pituit gland. it also produces two hormones that are transported thorugh axons in the infundibulum and stored in the POSTERIOR pit. |
what are the two hormones secreted by the hypothalamus that are stored in the POSTERIOR pituitary gland? | antidiuretic hormone and oxytocin |
what regulates shivering and sweating? | hypothalamus, thermostat |
the limbic system | part of the brain that ocntrols emotional responses, where hypo is located |
emotional responses | pleasure, aggression, fear, rage, contantment, and sex drive |
the hypothalamus monitors nutrients and controls hunger, what nutrients? | glucose and aa |
as the body's thirst center, the hypo continuously monitors? | blood solute (dissolved substances) concentration and stimulates thirst or release of fluid |
how does the hypo regulate circadian rhythms? | acting in conjunction with pineal gland |
brainstem | bidirectional passageway for all nerve tracts extending between the cerebrum and the spinal cord |
the brainstem contains many | autonomic centers required for our survival |
three regions of the brain stem | mesencephalon, pons, medulla oblongata |
mesencephalon is located? | rostral (superior) portion of the brainstem, short section of the brain betwen the diencephalon and the pons |
the mesencephalon is concerned with? | visual and auditory reflexes, control of posture and mvmnt |
pons is located | bulging region on the anterior part of the brainstem, forms from part of the metencephalon |
the pons acts | to relay impulses, regulate breathing |
medulla oblongata if located where? | most caudal (inferior) part of the brainstem, continuous with the spinal cord inferiorly, formed from the myelencephalon |
the caudal portion of the medulla resembles the spinal cord with its | ounded shape and narrow central canal |
the central canal of the medulla oblongata (medulla) forms ___ as it extends rostrally (superiorly)? | enlarges and becomes the fourth ventricle |
all communication between the brain and spin cord involvees tract of nerve fibers that ascend or descend through the? | medulla oblongata |
what reults in control of the movements of the hemispheres of the opposite side of the body? | tract of nerve fibers, in teh caudal region of the medulla, cross to the opposite side of the brain, resulting in the crossoversi |
if the polic snipers want to disconnect the brain from the spinal cord they aim for | medulla oblongata |
external landmark for a level frontal shot | tip of the nose |
external landmark for a level side shot is at the base of the | ear lobe |
functions of the medulla oblongata | sensory relay, relay to the thalamus, cardiac center, vaomotor center, repiratory center, coughing, sneezing, salivation, swallowing gagging, and vomiting |
the medulla serves a s acardia center by regulating? | heart's rate and strength of its contraction |
the medulla swerves a the vasomotor center by controlling the contration and relaxation of | smooth muscle in the walls of the smallest arteries (arterioles) to alter vessel diameter and bp |
the medulla acts ads the respiratory center and is also influenced by the ? | pons |