Chapter 13: The Brain Flashcards
the typical brain has a volume of
1200 mL
the average male brain IS __ % larger than the female brain
10
the brain is visible by the __ week of development
4th
what are the four major brain regions?
- cerebrum
- cerebellum
- diencephalon
- brainstem
the left and right side of the brain are divided into
cerebral hemispheres
the left and right hemispheres are divided by
deep fissures
the surface of the cerebrum has folds called ___ and grooves called __. Function?
gyri; sulci; increase surface area
the cerebral cortex has a superficial layer of
gray matter
what are the 3 major functions of the cerebral cortex?
- conscious thought
- memory storage and processing
- sensory processing
- control of skeletal muscles
the cerebellum is partially hidden by the
cerebral hemispheres
what is the second largest brain structure?
cerebellum
the cerebellum makes up __% of the brain’s volume and houses __% of its neurons
10% and 50%
what is the main function of the cerebellum?
coordinate motor commands from the cerebral cortex
the dienchephalon is made of two parts:
the thalamus and the hypothalamus
role of the thalamus
sensory relay and processing
role of the hypothalamus
emotions, autonomic function, hormone production
the brainstem is made of three parts:
midbrain, pons, medulla oblongata
the midbrain controls nuclei that : (3)
- process visual / auditory information
- control reflexes triggered by them
- helps maintain consciousness
the pons connects the __ to the __
cerebellum; brainstem
function of the pons (2)
- tracts and relay centers
2. somatic and visceral motor control
function of medulla oblongata (2)
- relays sensory information through brainstem and to the thalamus
- regulates many autonomic functions
what are ventricles?
chambers formed during development
ventricles are filled with __ and lined with __
CSF; ependymal cells
lateral ventricles
one in each cerebral hemisphere
interventricular foramen
connect lateral ventricles to third ventricle
third ventricle
located in the dienchephalon
cerebral aqueduct
slender canal in midbrain that connects third to fourth ventricle
fourth ventricle
upper part of medulla oblongata that narrow to become the central canal of the spinal cord
corpus callosum
thick tract of white matter that interconnects the cerebral hemispheres
what 4 things protect the brain?
- cranial bones
- cerebrospinal fluid
- blood brain barrier
- cranial meninges
the cranial meninges are continuous with the __
spinal meninges
3 layers of cranial meninges?
- dura
- arachnoid mater
- pia matter
2 layers of dura mater
- periosteal layer(outer)
2. meningeal layer
arachnoid mater consists of (3)
arachnoid membrane, arachnoid trabeculae and subarachnoid space
which arachnoid mater is closest to the dura mater?
arachnoid membrane
arachnoid trabeculae
fibrous strands through subarachnoid space; connects to the pia mater
subarachnoid space
between arachnoid membrane and pia mater
pia mater is bound to the brain by __
astrocyte processes that extend into evry fold
astrocyte processes are accompanied by branches of __ as they penetrate the __ of the brain
cerebral blood vessels; surface
what are the 3 functions of the CSF?
- support weight of brain
- cushion brain / spinal cord from physical trauma
- transport nutrients, chemical messengers, wastes
CSF is produced and maintained by the
choroid plexus
what makes up the choroid plexus?
ependymal cells with tight junctions and capillaries
there is a choroid plexus in each __
ventricle
materials diffuse between CSF and __ of CNS
interstitial fluid
CSF circulates from __ through ___ to __
choroid plexus; ventricles; central canal of spinal cord
CSF is absorbed into venous circulation at
arachnoid granulations
what are arachnoid granulations?
fingerlike extensions of arachnoid membrane that penetrate meningeal layer of dura mater
all communication between brain and spinal cord travels in ascending and descending tracts through
medulla oblongata
the medulla oblongata coordinates __ and __
complex autonomic reflexes and visceral functions
the medulla oblongata contains __ centers for vital functions
autonomic
the medulla oblongata contains __ along sensory and motor pathways
relay stations
the medulla oblongata contains __ associated with 5 cranial nerves
nuclei
the medulla oblongata contains __ that contain tracts of motor fibers from cerebral cortex
pyramids
some pyramid fibers cross to opposite side of medulla, this is called
decussation
the pons links the cerebellum with the
midbrain, dienchephalon, cerebrum, medulla oblongata, spinal cord
what are the 4 groups of structures in the pons?
- ascending, descending, transverse tracts
- nuclei controlling respiration
- sensory and motor nuclei of cranial nerves
- nuclei/tracts that process/relay information sent to/from cerebellum
the reticular formation contains __ regulating __ and spans from __ to __
nuclei/centres; vital autonomic functions; medulla oblongata to midbrain
the cerebellum is the automatic ___
processing centre
the cerebellum monitors __ sensations (5)
proprioceptive, visual, tactile, balance, auditory
the cerebellum has 2 primary functions
- adjusting postural muscles by modifying activities of brainstem centers
- programming / fine-tuning movements controlled at conscious / subconscious levels
- refines leraned movements
- compares motor commands with proprioceptive information, makes adjustments as needed
what is the most complex / integrative part of the brainstem?
midbrain
the midbrain can direct complex motor patterns at __ level
subconscious
__ influences level of activity in entire nervous system
midbrain
what is the corpora quadrigemina?
two pairs of sensory nuclei
what are the two pairs of sensory nuclei in the corpora quadrigemina?
- superior colliculus
2. inferior colliculus
the superior colliculus receives __ input from medulla oblongata and pons
visual
the superior colliculus controls reflex movements of the __, __ and __ in response to __ stimuli
eyes, head and neck; visual
the inferior colliculus receives __ input from medulla oblongata and pons
auditory
the inferior colliculus controls reflex movements of __, __ and __ in response to __ stimulus
head, neck and trunk; auditory
reticular activating system (RAS) is a specialized part of the __
reticular formation
function of RAS
stimulation increases alertness and attentiveness
damage to the RAS causes
unconsciousness
the red nucleus receives information from the __ and __
cerebrum and cerebellum
the red nucleus sends __ motor commands for __ position and __
subconscious; upper limb; muscle tone
what are the 3 parts of the diencephalon?
- epithalamus
- thalamus
- hypothalamus
the epithalamus is contains the
pineal gland
the pineal gland is an __ structure and secretes __
endocrine; melatonin
the pineal gland is located in the
posterior epithalamus
melatonin regulates
day-night cycles and reproductive functions
the thalamus __ sensory information, Passing on __
filters; only a small portion
the final relay for ascending sensory information is projected to __ from thalamus
cerebral cortex
each thalamic region is connected to specific areas in the
cortex
the hypothalamus conatins important __ and __ centers
control and integrative
the hypothalamus may be stimulated by (3)
- sensory information from cerebrum, brainstem, spinal cord
- changes in composition of CSF and interstitial fluid
- chemicals in circulating blood (lacks blood brain barrier)
__ connects the hypothalamus to the pituitary gland
infundibulum
what is the limbic system?
functional grouping of tracts and nuclei along border of cerebrum and diencephalon
4 functions of the limbic system
- establishing emotional states
- linking conscious, intellectual functions of cerebral cortex with unconscious and autonomic functions of brainstem
- facilitating memory storage / retrieval
- affecting motivation
what are the diencephalon components of the limbic system?
thalamus and hypothalamus
what part of thalamus contributes to the limbic system?
anterior thalamic nuclei from mammillary body to cingulate gyrus
which part os the hypothalamus contributes to the limbic system?
hypothalamic nuclei, mammillary body
what is the role of the hypothalamus in the limbic system?
emotions ( rage, fear, pain, sexual arousal, pleasure) and produce general alertness / excitement / or lethargy / sleep via stimulation of reticular formation
what are the 2 nuclei cerebral components of the limbic system?
- amygdaloid body
2. hippocampus
___ is the interface between limbic system, sensory system, and cerebrum
amygdaloid body
___ plays a role in regulating heart rate , fight or flight, and linking emotions and memories
amygdaloid body
what is the role of the hippocampus in the limbic system?
learning, especially storage and retrieval of longterm memories
the basal nuclei of the cerebrum adjust and refine __
ongoing voluntary movements
basal nuclei of the cerebrum are masses of ___ within each cerebral hemisphere, deep to the ___
grey matter; floor of lateral ventricles
basal nuclei have __ control over skeletal muscle tone
subconscious
basal nuclei of the cerebrum help coordinate __
learned movement patterns
basal nuclei of cerebrum do not __ movements, but provide __
initiate; general pattern/rhythm
basal nuclei can have __ control or __ modification of movement
direct / indirect
direct control over movement by cerebral basal nuclei stimulates
motor nuclei in the brainstem
example of direct control by basal nuclei
control of cycles of arm/thigh while walking
indirect modification of movement by basal nuclei sends output to __ after synapsing in the __
cerebral cortex; thalamus
example of indirect modification of meovemnt
subconsciously adjust muscle tone as you begin a voluntary movement
what are the 5 lobes of the cerebrum?
frontal, parietal, temporal, occipital, insula
the central sulcus separates
frontal from parietal lobe
the precentral gyrus contains __ and controls __
primary motor cortex; voluntary movements
the postcentral gyrus contains __ and controls __
primary somatosensory cortex; conscious awareness of somatosensory information
each hemisphere receives sensory information from and sends commands to ___ side of the body
opposite
crossing over occurs in the __ and __
brainstem and spinal cord
the boundaries of the cerebral hemispheres are well-defined (t/f)
false
the cerebral cortex is divided into 6 functional categories:
- motor cortex
- sensory cortex
- visual cortex
- auditory cortex
- olfactory cortex
- gustatory cortex
each sensory and motor region connected to nearby __
association area
an association area is a region that
interprets incoming data or coordinates motor response
the primary motor cortex directs __ movement by controlling motor neurons in the ___
volunatary; brainstem / spinal cord
which cortex is responsible for coordinating learned movements?
premotor cortex
the premotor cortex has which association area?
somatic motor
the primary somatosensory cortex receives sensory information from
receptors of touch, pain, pressure, vibration, temperature
the somatosensory association area monitors activity in ___ cortex and recognizes __
primary somatosensory; different sensations
the gustatory cortex is located in the
insula
function of the auditory association area
recognizes different sounds (such as speech/tones)
the primary visual cortex receives visual information from
lateral geniculate bodies
function of the visual association area
monitors activity and patterns in visual cortex and interprets the information
what are the 5 functions of integrative centers?
- receive information from association areas
- direct motor activities
- perform analytical functions
- in lobes / cortical areas of both cerebral hemispheres
- language areas typically associated with left hemisphere
the Broca’s areas is the ___ area
motor speech
which area regulates breathing / vocalization patterns for normal speech
Broca’s area
if the Broca’s area is damaged, can ___ but cannot __
make sounds, but not words
the ___ cortex integrates information from sensory association areas and performs intellectual functions
prefrontal
the frontal eye field controls___
learned eye movements
example of function performed by frontal eye field
scanning lines of text
which area is associated with language comprehension?
Wernicke’s area
the wernicke’s area receives information from ___ association areas
somatosensory
which area plays a key role in personality by linking sensory information to visual and auditory memories
Wernicke’s area
what is hemispheric lateralization?
regional specialization of each hemisphere
the left hemisphere contains the specialized __ areas
language, math
the premotor cortex for hand movements is larger on the ___ side of the hand you write with
opposite
the right cerebral hemisphere analyzes ___ information and relates ___ to it
sensory; body
interpretive centers for identifying familiar objects by touch, smell, sight, taste is located in the ___ cerebral hemisphere
right
interior of cerebral hemispheres mostly consists of ___ matter
white
white matter is grouped based on __
function
____ connect areas in the same cerebral hemisphere
association fibers
____ connect the two cerebral hemispheres
commissural fibers
what is the most important band of commissural fibers?
the corpus callosum
the corpus callosum allows for ___ between through the two hemispheres
communication / coordination
what is the anterior commissure?
smaller tract connecting the 2 hemispheres
the anterior commissure becomes more important if
the corpus callosum is damaged
what is the function of projection fibers?
link cerebral cortex to diencephalon, brainstem, cerebellum, and spinal cord
all projection fibers pass through the ___
diencephalon
neural function depends on __ events
electrical
electrical activity of all the neurons in the brain generates __ measurable by ___ placed on the scalp
an electrical field; electrodes
what is an EEG?
electroencephalogram that tracks electrical patterns “brain waves”
alpha waves occur__ and disappear
in healthy awake adults who close their eyes; during sleep or with specific concentration
beta wave have ___ frequency than alpha waves
higher
beta waves appear in people who are
concentrating, under stress or tension
theta waves appear transiently in __
normal sleep in adults
theta waves are usually seen in
children and intensely frustrated adults
delta waves have ___ amplitudes and __ frequency
large; low
delta waves are found normally in ___
sleep in all ages
delta waves in infants is a sign of
incomplete cortical development
delta waves in an awake adult is a sign of
tumor, vascular block, inflammation damaged part of the brain
how many pairs of cranial nerves are there ?
12
CN I
olfactory nerve
CN II
optic nerve
CN III
oculomotor nerve
CN IV
trochclear nerve
CN V
trigeminal nerve
CN VI
Abducens nerve
CN VII
facial nerve
CN VIII
vestibulocochlear nerve
CN IX
glossopharyngeal nerve
CN X
vagus nerve
CN XI
accessory nerve
CN XII
hypoglossal nerve
sensory receptors
specialized cells / processes that alert CNS about conditions in / out of your body
general senses
temperature, pain, touch, pressure, vibration, position
where are general sense receptors found in the body?
scattered throughout
sensory pathways begin at __ and end ___
begin at peripheral receptors and end in CNS
sensations
information carried by a sensory pathway
perception
conscious awareness of a sensation
receptive field
area monitored by a single receptor cell
the larger the receptor field, the ___ able to localize stimulus
less likely
what are free nerve endings?
tips of dendrites of sensory neurons
what is the simplest form of receptor?
free nerve endings
describe the receptor specificity in free nerve endings
respond to many stimuli, so not much
example of free nerve endings
pain receptors stimulated by chemicals, pressure, temperature, or trauma
nociceptors are ___ receptors
pain
nociceptors are free nerve endings with __ receptive fields and __ sensitivity
large; broad
what 2 types of axons carry pain information?
- myelinated A type
2. unmyelinated C type
myelinated A type axons carry __ pain
fast
in myelinated A type axons, pain quickly reaches ____ for conscious awareness, triggering ___ reflexes
primary somatsensory cortex; somatic
with type A pain, you can usually
locate the stimulus
unmyelinated C type pain is ___ pain
slow (burning, aching)
C type pain results in
general activation of reticular formation and thalamus
with C type pain you are able to
tell youre in pain, but cant pinpoint past a general area
thermoreceptors are free nerve endings in the __, __, ___, and ___
dermis, skeletal muscles, liver, hypothalamus
cold receptors are 3-4 times more ___ than warm receptors
numerous
what are the differences beteen cold and warm receptors?
none
chemoreceptors respond to ___ and ___ substances dissolved in ___ such as ___
water and lipid soluble; body fluids (interstitial fluids, blood, CSF)
mechanoreceptors respond to
physical distortion of their PM
what are the 3 types of mechanoreceptors?
- proprioceptors
- baroreceptors
- tactile receptors
proprioceptors monitor
position of joints/muscles
what is the most complex type of general sensory receptor?
proprioceptor
example of a proprioceptor
muscle spindle
baroreceptors detect
pressure changes in BV, digestive, respiratory, and urinary tracts
tactile receptors provide sensations of
touch, pressure, and vibration
tactile receptors include
fine and crude touch/pressure receptors
receptors are categorized by nature of
their response to stimulation
tonic receptors are ___ adapting, always __
slow; active
in tonic receptors, action potential reflects
level of stimulation
phasic receptors are __ adapting and nomally
fast; inactive
phasic receptors become active for a short time when
a change occurs in what they are monitoring
adaption
reduction in sensitivity with constant stimulus
what are the 2 types of adaption?
- peripheral
2. central
peripheral adaption occurs when ___ changes: first responds ___, then activity ___
level of receptor activity; strongly, the activity declines
peripheral adaption is especially characteristic to ___ receptors
phasic
example of peripheral adaption
temperature is not noticed until it changes
central adaptation occurs along ____ and involves
sensory pathways in CNS; inhibition of nuclei along sensory pathway
example of central adaption
new smell stops after it is initially detected, but neurons still send signals
tactile sensory receptors are ___ responding to ___
mechanoreceptors ; touch, pressure, vibration
there is a great diversity of tactile sensory receptors in
the skin
6 types of tactile receptors in the skin
- free nerve endings
- root hair plexus
- tactile discs
- tactile corpuscles
- lamellar corpuscles
- bulbous corpuscles
what is the most common tactile receptor in the skin?
free nerve ending
free nerve endings are ___ specific and respond to __
not; touch, pressure, pain, temperature
root hair plexus monitors __
distortion/movement of hair follicle
displacement of hair distorts ___ and generates
sensory dendrites; action potentials
root hair plexus adapt __
rapidly
tactile discs monitor
fine touch and pressure
tactile discs have extremely ___ tonic receptors
sensitive
tactile discs have ___ receptive fields
very small
tactile corpuscles detect
fine touch, pressure, low frequency vbration
tactile corpuscles adapt within __
1 second
tactile corpuscles are abundant in
eyelids, lips, fingertips
lamellar corpuscles are sensitive to
deep pressure
lamellar corpuscles are ___ adapting and most sensitive to ___
fast; pulsing or high-frequency vibration
lamellar corpuscles have ___ receptors
large
lamellar corpuscles are abundant in
fingers, fasciae, joint capsules, some viscera (mesenteries, pancreas, urethra, and bladder)
bulbous corpuscles are sensitive to
pressure and distortion of deep dermis
tension of dermis stimulates
dendrite
tonic receptors have __ adaption
little
somatotopy
functional map of primary somatosensory cortex
sensory hommunculus
somatotope showing the relative size of cortex devoted to any specific body area
motor homunculus
functional map of primary motor cortex
proportions reflect number of ___and degree of ___ in body region
motor units; fine motor control
