Brain and Spinal Cord Flashcards
What are meninges?
layers of tissue that protect the spinal cord
Three layers of meninges
- dura mater
-epidural space (blood vessels and fat) - arachnoid mater
-subarachnoid space (filled with CSF) - pia matter
menegitis
inflammation of meninges
what does the white matter of the spinal cord contain?
ascending tracts (sensory info toward brain)
descending tracts (outgoing motor info from brain)
what does a dorsal root contain?
axons of sensory afferent neurons
what does a ventral root contain?
axons of motor efferent neurons
What does a dorsal root ganglion contain?
cell bodies of sensory neurons
what does a spinal nerve contain?
space where dorsal and ventral roots join
what are dermatomes?
area of skin that provides sensory input via the dorsal roots of one pair of spinal nerves (help diagnosis damage of specific vertebrae)
what causes shingles?
caused by a virus that attacks dorsal roots which produces a painful rash and blisters on skin whose distribution corresponds to that of the affected sensory nerves
what is a reflex?
rapid automatic responses to specific stimuli
what is a relfex arc
the wiring of a single reflex
steps of a simple neural reflex
- stimulus activates a receptor
- sensory neuron stimulated
- info processing in CNS
- activation of motor neuron
- response of peripheral effector
What are the four ways a reflex can be classified?
- development
- response
- processing site
- complexity of circuit
develpmental classification
inate relfex- born with
acquired reflex- learned
response classification
somatic- skeletal muscle
visceral- action of smooth muscle, cardial muscle, or glands
complexity of circuit classification
monosynaptic- one synapse
polysynaptic- multiple synapse
processing site classification
spinal reflex- precessed in spinal cord
cranial reflex- processed in brain
describe the reflex arc of a monosynaptic stretch reflex
- muscle spindle stretched
- stimulus travels via afferent neurons to spinal cord
- synapse with efferent motor neuron which tells muscle to contract
describe the relfex arc of a polysynaptic withdrawal reflex
interneurons control more than one muscle group, responses could involve stiumulation of some muscle and inhibition of others
what information is provided by testing different spinal reflexes?
info about status of corresponding spinal segments
what is the babinski reflex?
when stimulated an adult will point toes, baby will flare their feet.
what is a neural tube?
a hollow cylinder that is the start of the CNS during embryonic development
How many primary brain vesicles are there?
- forebrain (prosencephalon)
- midbrain (mesencephalon)
- hindbrain (rhombencephalon)
at what point do the secondary brain vesicles develop?
after 5 weeks of development
How many vesicles are there once the secondary brain vesicles develop?
cerebrum, cerebellum, diencephalon (thalamus and hypothalamus) brain stem (mesencaphalon… midbrain… pons, medulla oblongata)
What does the hollow part of the tube develop into?
The CNS
What are ventricles?
cerebrospinal fluid filled chambers of the brain
List the ventricles
- lateral ventricles (I and II), drained by interventricular foramen into…
- third ventricle, drained by cerebral aqueducts into…
- fourth ventrical, becomes continuous with central canal of spinal cord
Three cranial meninges
- dura mater
- arachnoid mater
- pia mater
what are the functions of CSF and how is it formed?
surrounds all exposed surfaces of CNS, cushions delicate neural structures, transpots nutrients chemical messengers and waste products. Formed by choroid plexus- specialized ependymal cells and capillaries that secrete CSF and remove waste
Function of the Medulla oblongata
cardiac centers regulate heart beat, respiratory rhythmicity center sets pace of breathing. Als o regulates autonomic functions
Function of the pons
controls smooth transition between inhalation and exhalations
function of the midbrain
processes visual and auditory data and then generates startle relfex
what is decussation and where does it come occur?
crossing over of most descending tracts that occurs in medulla oblongata
What is the main function fo the cerebellum
controls and coordinates the contraction of skeletal muscles
What are the major regions of the diencephalon?
Thalamus and Hypothalamus
Primary function of the thalamus
relay center for sensory and motor pathways
primary function of the hypothalamus
involuntary control center of the body
What is the limbic system known as?
emotional brain
Functions of the amaygdala
links emotions with memories
functions of the hippocampus
involved in learning
What is the gray matter of the cerebrum called?
cerebral cortex
What part of the cortex is know as the primary sensory cortex?
parietal lobe (postcentral gyrus)
what part of the cortex is know as the primary motor cortex?
frontal lobe (precentral gyrus)
what is the function of the prefrontal cortex?
performs abstract intellectual functions
In the cerebral cortex, where are the auditory, olfactory, motor speach, and visual areas?
Auditory and olfactory- temporal lobe
motor speech- left cerebral hemisphere
visual- occipital
what is the function of the association areas of the cerebral cortex?
interpret incoming data or coordinate a motor response
what does hemispheric lateralization mean?
functional differences between the left and right hemispheres
what information does an EEG give?
electrical activity of the brain
What stimuli do each of the following general sensory receptors sense: nociceptors, thermoreceptors, mechanoreceptors, and chemoreceptors
nociceptors- pain
thermoreceptors- temperature
mechanoreceptors- stimuli that distort their plasma membranes
chemoreceptors- water-soluble and lipid-soluble substances that are dissolved in the body fluids
what is hydrocephalus?
water on the brain- CSF builds up and forces cranial bones to enlarge
what is amyotrophic lateral sclerosis?
progressive degenerative disorder that affects motor neurons. Causes atrophy of associated skeletal muscles.
Spinothalamic pathway
- from receptor to synapse in spinal cord
- crosses spinal cord and reaches thalamus
- from thalamus to primary sensory cortex
carry crude touch, pressure, pain, and temperature sensations
posterior column pathway
ends at primary sensory cortex, carries sensation of highly localized fine touch
spinocerebellar pathway
carries propriceptive information about postiion of skeletal muscles, joints, and tendons to cerebellum
How many neurons does it take in the somatic and autonomic nervous system to reach effector?
A- 2
S-1
What are the effectors in the somatic and autonomic systems and are they consciously or subconsciously controled
A- glands, cardiac, smooth (unconscious)
S- skeletal muscle )conscious)
Do all organs have dual innervation?
No- blood vessels are only controlled by the sympathetic divison
Two efferent divisons of the autonomic NS
Sympathetic and Parasympathetic
Where are the sympathetic autonomic ganglia?
close to the spinal cord
where are the parasympathetic autonimic ganglia
near target organ
What neurotransmitters are release by preganlgionic and postganglionic neurons in the sympathetic nervous system
Pre- ACh
Post- NE and E
What neurons are released by preglanglionic and postganglionic neurons in the parasympathetic NS
pre- ACh
Post- ACh
Receptors that are stimulated by ACh are____; whereas receptors that are stimulated by NE and E are____
Cholinergic; adrenergic
Nicotinic receptors
chemicallly gated ion channels; ACh always excited the poastynaptic cell with these receptors
Muscarinic receptors
stimulation activates a G protein which activates or inactivates enzymes within the cell
Heart rate
S- increase
P- decrease
Lungs diameter
s- dialate
p- constrict
GI and Urinary Tract sphincters
S- constrict
P- dialate
Which two receptors initiate important autonimic reflexes?
Baroreceptors (change in pressure)
Chemoreceptors (change in pH)
What are the 5 special senses
olfaction, gustation, equilibrium, hearing, vision
Neurogenesis
complete turnover (olfactor receptors every month)
Olfactory pathway
- collct into 20 or more bundles
- pass through olfactory foramina in cribriform plate of ethmoid
- reach olfactory bulbs of cerebrum where first synapse occurs
- axons leaving olfactory bulb traveling along olfactory tract to reach cerebral cortex
Where are taste receptors located
tongue and soft palate pharynx and epiglotis
What are the epithelial projections on your tongue called that taste buds are associated with?
papillae
What are filiform papillae?
contain tactile receptors but no taste buds
Gustatory pathway
- three cranial nerves contain axons of sensroy neurons from taste buds
- these cranial nerves synapse with part of the medulla oblongata then on the thalamus and then cerbral cortex
function of auditory tube
permits equalization of pressure on either side of tympanic membrane
what structures in the inner ear contain receptors for the sense of equilibrium and sense of hearing
Semicircular canals and vestibule- equilibrium
cochlea- hearing
what is the fluid called within the bony labyrinth
perilymph
fluid in membranous labryinth
endolymph
oval window
where cochlear begins
round window
cochlea ends
sense of equilibrium
state of balance information about position and movement of head
two parts of the vestibule
utricle and saccule
pathway for equilibrium sensation
- vestibular receptors of semicircular canals, utricle, and saccule to
- vestibular branch of vestibulocochlear nere to
- medulla/ pons junction to
- cerebellum and cerebral cortex
describe the auditory pathway
sound waves stimulates the tympanic membrave-auditory ossicles-oval window-fluid in cochlea-basilar membrane-cochlear branch of vestibulocochlear nerve-medulla-thalmus-cerebral cortex
