A + P Nervous System II Flashcards
brain and spinal cord are surrounded by…
meninges
3 layers of the meninges
dura mater
arachnoid mater
pia mater
dura mater
- functions
- visual characteristics in the brain
functions
-“tough” layer of the meninges
-forms structures that separate the cranial cavity into compartments
-protects the brain from displacement
visual
-in the brain the dura mater is sac-like
–provides a space for blood to return to the heart
two layers of the dura mater in the brain
endosteal layer (periosteal) miningeal layer
endosteal layer location
lies against the inside of the cranium
meningeal layer location
lies on top of the arachnoid mater (but separated by the subdural space
arachnoid mater
- separated from dura mater by…
- contains… and function of component
separated by... -subdural space contains -lymphatic fluid -acts to reduce friction between the two layers
pia mater
- contains…
- separated from arachnoid mater by…
- -composition
contains -blood vessels that supply the brain separated -subarachnoid space -consists of a web of collagen fibers filled with CSF
meningitis
bacterial (or viral) infection of the meninges covering the brain and spinal cord
effect of continued blood hemorrhaging in the subdural space following a head trauma
will put excessive pressure on the nervous tissue of the brain, which can cause permanent damage
blood-brain barrier physiology
capillaries of the brain are impermeable to water soluble compounds without the assistance of specific carriers (only lipid soluble substances can enter without carriers)
there is a separate transport system for glucose, large AAs, and glycine
-this system involves facilitated diffusion
all other tissues outside the CNS are exposed to all hormones and AAs from the blood, some of which are neurotransmitters
-if these were able to enter into the CNS the neurons would fire uncontrollably
the bulbous feet of the astrocytes wrapped around the capillaries regulate all of this
capillaries of the brain are impermeable to…
water soluble compounds without the assistance of specific carriers
what can enter the brain without carriers?
lipid soluble substances
separate transport system
- for what?
- what type of diffusion?
for what?
- glucose, large AAs, glycine
uses. .. - facilitated diffusion
what are tissues outside the CNS exposed to that tissues inside are not?
hormones and AAs from the blood, some of which are neurotransmitters
result if these neurotransmitters were allowed to enter into the CNS
neurons would fire uncontrollably
what regulates this process?
bulbous feet of the astrocytes
CSF
- produced in… by…
- similar to…
- -differences
produced in the ventricles of the brain by ependymal cells
similar to blood plasma
-contains less protein and has different ion concentration (more NaCl, H+, less Ca2+, K+)
CSF functions
supports and provides cushioning for the brain (brain essentially “floats” in CSF
transports nutrients, chemical messengers, and waste products
CSF circulates out of the ventricles into the central canal and…
-location
“bathes” the outside of the brain and spinal cord
-occurs within the subarachnoid space
journey of CSF after it leaves the subarachnoid space?
diffuses in a large cerebral vein (superior saggital sinus) to return to venous circulation
spinal cord composition
cervical enlargement from which are attached eight pairs of cervical spinal nerves
twelve pairs of throacic spinal nerves
lumbar enlargement from which are attached five pairs of lumbar spinal nerves
conus medullaris, the cone shaped end of the spinal cord
cause equina
-descends from the conus medullaris and gives rise to five pairs of sacral spinal nerves
single pair of coccygeal nerves
total number of spinal nerves
31
important internal features of the spinal cord
posterior median sulcus anterior medial fissure central canal dorsal root dorsal root ganglion ventral root grey matter white matter posterior grey horns anterior grey horns later grey horns
dorsal root
-type of neurons
sensory
what is the dorsal root ganglion
cell bodies of sensory neurons
ventral root
-type of neurons
motor
grey matter
- what is it?
- organization
cell bodies of neurons
organized in functional groups know as somatic and visceral nuclei
white matter
myelinated axons of neurons
posterior grey horns
-composition
contain sensory nuclei
anterior grey horns
-composition
contain motor nuclei
lateral grey horns
-function
contral smooth muscle, cardiac muscle and glands
ventricles of the brain
four ventricles
-lateral ventricles: one in each cerebral hemisphere
3rd ventricle: in the diencephalon
4th ventricle: in the pons and medulla
ventricular communication
3rd ventricle attached to the lateral ventricles by the interventricular foramen and the 4th ventricle by way of the cerebral aquaduct
4th ventricle attaches to the central canal of the spinal cord
makeup of the rest of the brain
cerebrum (telencephalon)
thalamus and hypothalamus (diencephalon)
midbrain (mesencephalon), pons, medulla oblongata (all make up the brain stem)
cerebellum
the cerebrum
- visual characterisics
- three areas divided structurally
visual -largest major region of the brain -divided into two cerebral hemispheres areas -cerebral cortex -limbic system -basal ganglia
cerebral cortex
- visual characteristics
- functions
visual -superficial surface -marked by gyri, sulci, fissures functions -voluntary muscle movement -sensory functions -intellect and thoughts -some memories
limbic system
- location
- main structures
location -group of structures located on the medial aspect of each cerebral hemisphere and diencephalon main structures -hypothalamus -anterior portion of the thalamus
limbic system functions
emotional states and related behavioral drives
links conscious intellectual function of the cerebral cortex and the unconscious autonomic functions of the brain stem
contains long-term memory storage and retrieval
parts of the limbic system
amygdala hippocampus parahippocampal gyrus cingulate gyrus fornix hypothalamus thalamus
amygdala
-function
involved in signaling the cortex of motivationally significant stimuli such as those related to reward and fear in addition to social functions such as mating
hippocampus
-required for…
the formation of long-term memories and implicated in maintenance of cognitive maps for navigation
parahippocampal gyrus
-function
plays a role in the formation of spatial memory
cingulate gyrus
-functions
autonomic functions
- regulating HR
- blood pressure
- cognitive processing
- attentional processing
fornix
-function
carries signals from the hippocampus to the mammillary bodies and septal nuclei
hypothalamus
- functions
- affects and regulates
regulates the autonomic nervous system via hormone production and release affects and regulates -BP -HR -hunger -thirst -sexual arousal -sleep/wake cycle alcohol affects this
thalamus
-function
the “relay station” to the cerebral cortex
basal ganglia
- composition
- connected with…
- functions
composition
-group of nuclei situated at the base of the cerebrum
connected with
-cerebral cortex and thalamus
functions
-voluntary motor control
-procedural learning for routine behaviors (habits)
-eye movements
-varied cognitive and emotional functions
cerebral cortex
- function
- anatomical divisions
function -most of the actual information processing that occurs anatomical divisions -frontal lobe -parietal lobes -temporal lobes -occipital lobe
cerebral cortex functional divisions
- divided by what?
- functional divisions
divided by the central sulcus functional divisions -primary motor cortex -premotor cortex -prefrontal cortex -Broca's area -primary somatic sensory cortex -\_\_\_\_\_\_\_\_ -visual association area -gustatory cortex -primary auditory cortex -auditory association area
primary motor cortex
-function
origin site of impulses of voluntary movement to skeletal muscles
premotor cortex
-function
coordinates learned movements
prefrontal cortex
- location
- function
conscious intellect
location
-found in both hemispheres
function
-coordinates information from all association areas of the cortex
-functions in predicting the future consequences of events, contains feelings of frustrations, tension, and anxiety
Broca’s area
-location
-functions
special condition
location -found in left hemisphere function -controls speech -regulates patterns of breathing and vocalization for speech can understand but cannot speak
visual association area
-location
occipital lobe
gustatory cortex
function
-location
receives taste sensations (parietal lobe)
primary auditory cortex
- function
- location
receives hearing sensations (temporal lobe)
auditory association area (Wernicke’s Area)
- location
- special condition
temporal and parietal lobes
can speak but cannot comprehend
olfactory cortex
- function
- location
receives sense of smell
temporal lobe
cortical connections
each area on a single hemispheric cortex is interconnected by white matter (axons) beneath the cerebral cortex
each hemisphere is interconnected by the corpus callosum and the Anterior Commisure
some white matter (medulla) also interconnects the cortex with the diencephalon, brain stem, cerebellum, and spinal cord
primary somatic sensory cortex
- function
- location
receives sensory information from touch, pressure, pain, and temperature receptors (parietal lobe)
occipital lobe
- function
- location
receives visual information (occipital lobe)
cerebellum
- primary functions
- -general function
- -specific function
modulate movement
- makes rapid adjustments in muscle tone and position for balance and equilibrium
- programs and fine-tunes voluntary and involuntary movements initiated by signals sent from the cerebrum and brain stem
cerebral processing centers
- function
- left brain
- right brain
control complex motor activities and perform analytical functions
left brain
-contains the general interpretative center involving language and mathematical calculations, speech center, and writing
right brain
-responsible for the spatial visualization and analysis
-responsible for analysis by touch (many musicians and artists are left handed)
thalamus
-functions
- receives all sensory information (except olfaction)
- filters this info, relaying a small amount of info to the primary cortex and the rest to the basal ganglia or brain stem
- coordinates voluntary and involuntary motor commands
hypothalamus
-overall function
maintenance of homeostasis
hypothalamus
-specific functions
controls the pituitary gland (nervous system link to the endocrine system)
controls emotions and some senses/feelings (anger, pleasure, etc.)
regulates body temperature
controls sleep and circadian cycles
-pineal gland
receives olfactory information
relays info to the autonomic centers in the pons and medulla oblongata
midbrain
-functions
- processes visual and auditory responses and generates involuntary motor responses, such as reflexes to sudden visual and auditory stimuli
- produces dopamine which affects consciousness, motivation, and alertness
pons
-functions
- connects the cerebellum with the midbrain
- serves as a relay point between the diencephalon, cerebrum, and spinal cord
- helps with involuntary control of respiration
medulla oblongata
-functions
- connects the cerebellum with the midbrain
- serves as a relay point between the diencephalon, cerebrum, and spinal cord
- helps with involuntary control of respiration
medulla oblongata
-functions
- a relay point between the diencephalon, cerebrum, and spinal cord
- contains major control centers for regulation of cardiovascular activity respiration and digestion
cerebellum
- primary functions
- -general function
- -specific function
modulates movement
- makes rapid adjustments in muscle tone and position for balance and equilibrium
- programs and fine-tunes voluntary and involuntary movements initiated by signals sent from the cerebrum and brain stem
cranial nerves
- #
- where do they emerge
12 pairs of nerves emerge directly from the brain
-1st and 12th emergy from the cerebrum and the others emerge from various aspects of the brain stem
cranial nerves
-where do they receive input?
- from the special senses, such as vision, hearing, smell, and tasts
- can receive sensory information from the face and send motor impulses to facial muscles
memory
- types
- where are memories stored
types -fact or skill -short- and long term storage -cerebral cortex: familiar sounds, faces, tastes, and smells -cerebrum and hippocampus: short-and long-term declarative memory -cerebellum: procedural memory -within the synapses themselves
PNS composition
all nervous material outside of the brain and spinal cord
- sensory receptors
- nerves and ganglia
- efferent motor endings
mechanoreceptors
detect mechanical forces such as touch, pressure, vibrations, stretch, and itch
thermoreceptors
detect temperature changes
photoreceptors
detect light energy
chemoreceptors
detect chemicals in solution such as smell, taste, and changes in blood chemistry
sensory receptors classified according to location
exteroceptors
interoceptors
proprioceptors
exteroceptors
sensitive to stimuli outside the body (located at or near the body surface)
includes receptors of the skin and special sense organs
interoceptors
sensitive to stimuli arising within the body (within the internal visceral organs and within blood vessels)
sensory receptors
-function
specialized structures that respond to stimuli or changes in the environment by sending impulses along afferent neurons to the CNS
sensory receptors classifications
- how?
- classifications
classified according to the type of stimulus they detect classifications -mechanoreceptors thermoreceptors photoreceptors chemoreceptors nociceptors
nociceptors
detect damaging stimuli that result in pain
proprioceptors
sensitive to internal stimuli in skeletal muscles, tendons, joints, ligaments, and connective tissue covering bones and muscles
sensory receptors classified according to structural complexity
simple receptors
complex receptors
simple receptors
-what are they?
location
modified nerve endings of sensory neurons
location
-skin, mucous membranes, muscles, and connective tissue
complex receptors
-what are they?
special senses of vision, hearing, smell, and taste
nerve basic structure
parallel bundles of myelinated or unmyelinated axons endoneurium fascicles perineurium epineurium
endoneurium function
encloses each axon
fascicles
-what is it?
bundle of axons
perineurium function
covers a fascicle
epineurium function
covers groups of fascicles and an artery/vein
nerves classification
motor nerves consisting of motor neurons only (efferent)
sensory nerves consisting of sensory neurons only (afferent)
mixed nerves consisting of sensory and motor neurons
another way of classifying nerves
somatic
visceral
ganglia
-what are they?
collections of neuron cell bodies associated with sensory neurons (afferent - dorsal root), and motor neurons (efferent - ventral root)
five components of reflex activity
arrival of stimulus and activation of receptor activation of sensory neuron information processing in CNS activation of motor neuron response by effector (muscle or gland)
involuntary reflexes
- what are they?
- location types
reflex patterns that are inherited rather than learned, having evolved as involuntary survival mechanisms
types
-ipsilateral
-contralateral
reflex types
stretch reflex
flexion (withdrawal) reflex
reciprocal inhibition
crossed-extension reflex
stretch reflex purpose
-controlled by
maintain healthy muscle tone by quickly shortening a muscle if it is stretched too far or too fast
controlled by…
-muscle spindles
flexion (withdrawal) reflex
- how is it initiated
- what happens?
initiated by a painful stimulus
one or more muscles (usually flexor muscles) will quickly contract to remove the limb from harm
reciprocal inhibition
-what is it?
during a reflex action, the antagonistic muscles are inhibited to permit the appropriate movement
crossed-extension reflex
- function
- what happens?
important in maintaining balance during reflex movements
when the flexors contract on one side of the body, the extensors contract on the other side of the body
conditioned reflexes
-what are they?
voluntary actions initiated in the brain may become reflex actions through continued association of a particular stimulus with a certain result
stages of a reflex
arrival of stimulus and activation of receptor activation of sensory neuron information processing activation of motor neuron response of peripheral effector
