Central Nervous System Part II Flashcards
List the 3, paired gray matter structures of the diencephalon. What is enclosed by these structures?
Thalamus
Hypothalamus
Epithalamus
How are the 2 halves of the thalamus connected?
Interthalamic adhesion
What is the main function of the thalamus?
Act as a relay station for information coming into the cortex
What types of impulses are being relayed to the thalamus?
Impulses from the hypothalamus for regulating emotion and visceral function
Impulses from the cerebellum and basal nuclei to help direct motor cortices
Impulses for memory and sensory integration that are projected to specific association cortices
What is the function of the mamillary bodies? The infundibulum?
Mammillary Bodies - paired, pea-like anterior nuclei that act as olfactory relay stations
Infundibulum - the stalk of hypothalamic tissue that connects to the pituitary gland
What is the main function of the hypothalamus? List some ways the hypothalamus can achieve this function. Recall the specifics given in class about the role of the hormone ADH and the role of the suprachiasmatic nucleus.
The hypothalamus is the body’s main visceral control and regulation center – it is vital for maintaining homeostasis
How the hypothalamus maintains homeostasis:
It controls the autonomic nervous system
Ex: blood pressure, rate + force of heartbeat, digestive tract motility, pupil size
It initiates physical responses to emotions
As part of the limbic system – it perceives pleasure, fear, rage, biological rhythms, and sex drive
List some symptoms of hypothalamic disorder.
Severe body wasting
Obesity
Sleep disturbances
Dehydration
Emotional imbalances
What is the role of the pineal gland?
The pineal gland extends from the posterior border and secretes melatonin
List the 3 regions of the midbrain.
Midbrain
Pons
Medulla Oblongata
What are the cerebral peduncles?
Two ventral bulges that contain pyramidal motor tracts and form the little pillars that hold up the cerebrum
What 2 things are connected by the cerebral aqueduct? What is contained within the cerebral aqueduct?
Cerebral Aqueduct - channel that runs through the midbrain and connects the 3rd and 4th ventricles
What cranial nerves originate from the midbrain? What is the function of these cranial nerves?
Define corpora quadrigemia and it’s 2 component parts. What reflexes are maintained here?
Corpora Quadrigemina -paired dorsal protrusions
Superior Colliculi - visual reflex centers that coordinate head + eye movements for visual tracking
Inferior Colliculi - auditory reflex centers that coordinate things like the startle reflex
What is the substantia nigra? How is it linked to Parkinson’s Disease?
Substantia Nigra - band-like, contains a high amount of melanin – a precursor to dopamine; functionally linked to the basal nuclei
Degeneration of substantia nigra is the cause of Parkinson’s Disease
What is 1 function of the red nucleus?
Red Nucleus - part of the reticular formation; lies deep to the substantia nigra; acts as a relay nuclei for some descending motor pathways causing limb flexion
What cranial nerves originate in the pons? What is the function of these cranial nerves?
The pons is the origin point of cranial nerves V (trigeminal), VI (abducens), and VII (facial) …
The 4th ventricle separates the ___________ and ______________. It is continuous with the ____________________.
pons, cerebellum …
What is the choroid plexus? Where is it located? What does it produce?
Choroid plexus - a capillary-rich membrane that forms cerebral spinal fluid (CSF)
Located in the medulla oblongata
What primitive life functions are maintained by the medulla?
Cardiovascular Centers:
Cardiac Center: adjusts force and rate of heart contraction
Vasomotor Center: adjusts blood vessel diameter for regulation of blood pressure
Respiratory Centers:
Generate basic respiratory rhythm
Control the rate and depth of breathing
What is the function of the cerebellum?
Processes inputs from the cerebral cortex, brain stem, and sensory receptors to provide the precise timing and coordinated patterns needed for the many movements of daily living
Also plays a major role in balance
Cerebellar hemispheres are connected by the ______________.
Vermis
What are the 3 lobes of the cerebellum? What is the arbor vitae?
Anterior
Posterior
Flocculonodular
Arbor Vitae - a thin cortex of gray matter with a deeper, distinctive treelike pattern of white matter
Be generally familiar the cerebellar homunculi – which portions of the body are controlled by the medial and lateral portions?
Describe the process of how the cerebellum fine tunes motor activity. I am especially interested in you understanding the communications between the cerebral cortex and the cerebellum.
It receives impulses from the cerebral cortex of the intent to initiate voluntary muscle contraction
It receives signals from proprioceptors throughout the body as well as visual and equilibrium pathways – these continuously inform the cerebellum of the body’s position and momentum
It calculates the best way to smoothly and effectively coordinate muscle contractions
It sends a “blueprint” of coordinated movement to the cerebral motor cortex and brain stem nuclei
What would a cerebellar impairment look like? I gave quite a few examples in class!
Result in loss of muscle tone and clumsy, uncertain movements
What is the limbic system? What is it’s primary function?
The limbic system interacts with the prefrontal lobes – allows us to react emotionally to things we consciously understand to be happening and makes us consciously aware of the emotional richness of life …
Where are the structures of the limbic system located?
Rhinecephalon
What is the fornix? The amygdaloid body? The cingulate gyrus?
Fornix - fiber tract that links limbic system regions
Amygdaloid Body - recognizes angry or fearful facial expressions, assesses danger, and elicits fear responses
Cingulate Gyrus - plays a role in expressing emotions via gestures and resolving mental conflict
Generally, explain the strong connection between memories and smells. Generally, explain the connection between high blood pressure and stress/strong emotions.
Generally, what is the reticular formation? What does it govern? Where are some places that have
its extensive connections?
Extends through the central core of the brain stem
Consists of loosely clustered neurons in otherwise white matter
The reticular formation has far-flung axonal connections with the hypothalamus, thalamus, cerebral cortex, cerebellum, and spinal cord
These extensive connections allow the reticular formation to govern brain arousal
Name the 3 columns of the reticular formation that run through the brain stem.
Raphe Nuclei
Medial (Large Cell) Group of Nuclei
Lateral (Small Cell) Group of Nuclei
What is the RAS? What are its functions? What is a potential outcome of damage to the RAS?
RAS - Reticular Activating System
Sends continuous impulses to the cerebral cortex to keep it conscious and alert
Filters out repetitive, familiar, or weak stimuli – 99% of stimuli is not relayed to consciousness
The RAS is inhibited by the sleep centers, alcohol, and drugs
Severe injury to the RAS can result in permanent unconsciousness (coma)
Which cerebral hemisphere houses the language centers? What happens in the analogous centers in the right hemisphere?
Language implementation involves practically all the association cortex of the left hemisphere
The corresponding areas in the right hemisphere are involved with the nonverbal components of language – tone of voice, gestures
What is aphasia? Compare/contrast Broca’s and Wernicke’s Aphasias.
Aphasia - loss of language abilities
Broca’s Area: involved with speech production
Lesions to Broca’s Area can result in understanding of language, but inability to speak
Wernicke’s Area: involved with understanding spoken language and written words
Lesions to Wernicke’s Area can result in ability to speak, but the spoken words are often nonsense
What is memory? Define declarative, procedural, motor, and emotional memory.
Memory - the storage and retrieval of information
Declarative: memory of facts (names, faces, words, dates)
Procedural: memory of skills (playing the piano)
Motor: memory of motor skills (riding a bike)
Emotional: memory of experiences linked to an emotion (heart pounding before a performance)
Differentiate short term and long-term memory. What factors affect the transfer of information from STM to LTM?
Short Term Memory (STM, working memory) - temporary holding of information – limited to 7 or 8 pieces of information (ex: phone number)
Long Term Memory (LTM) - seemingly limitless capacity but does decline with age and the information can be forgotten
Emotional State: best if alert, surprised, motivated, or aroused
Rehearsal: repetition and practice
Association: tying new information with old memories
Automatic Memory: subconscious information stored in LTM
What is memory consolidation? What portions of the brain are involved in the memory consolidation process?
Memory Consolidation - involves fitting new facts into categories already stored in the cerebral cortex
Consolidation of memories involves in the hippocampus, temporal cortical areas, thalamus, and prefrontal cortex
Damage to what structure of the brain causes amnesia? Differentiate anterograde and retrograde amnesia.
Damage to the hippocampus or the surrounding temporal lobe structures can result in only slight memory loss
Anterograde Amnesia: consolidated memories are not lost, but no new inputs are associated with the old ones
Person lives only in the here and now
Cannot recall a conversation held 5 minutes ago
Retrograde Amnesia: loss of memories formed in the distant past
What is an EEG? What is it measuring? What are EEGs used to diagnose?
Electroencephalogram (EEG) records the electrical activity that accompanies brain function
Used for diagnosing epilepsy and sleep disorders
Helps to localize lesions, tumors, infarcts, infections, and abscesses
Used in research and to definitively determine brain death
What does “consciousness” involve? What are some things that you would assess to see if a patient is “conscious”? I gave examples of a test battery in class!
Consciousness involves:
Perception of sensation
Voluntary initiation and control of movement
Capabilities associated with higher mental processing – memory, logic, judgment
…
Differentiate between fainting, coma, and brain death.
Fainting (Syncope): brief loss of consciousness
Most often due to the inadequate cerebral blood flow caused by low blood pressure or acute ischemia
Coma: significant unresponsiveness to sensory stimuli for an extended time period
NOT the same as deep sleep – Oxygen consumption is lowered
Brain Death: irreversible coma
There are often ethical and legal issues surrounding whether a person is dead or alive
Define sleep. How is sleep different than coma?
Sleep - a state of partial unconsciousness from which a person can be aroused by stimulation
What are the 2 major types of sleep?
Non-rapid eye movement (NREM) sleep
Rapid-eye movement (REM) sleep
Stages 3 and 4 of NREM sleep are _____ _____ sleep. How do EEG waves change in these stages? These 2 stages are presumed to be _________ sleep.
slow-wave
Frequency of waves declines, but amplitude increases
EEG, heart rate, respiratory rate, blood pressure, and GI motility change
NREM
What physiological changes are expected during REM sleep? What kinds of these does the brain accomplish during REM sleep?
Temporary paralysis, except for rapid eye movements
Oxygen consumption, heart rate, and breathing increase – can be greater than during waking hours
Most dreaming occurs during REM sleep
Review the typical pattern of a full sleep session on slide 34.
What are orexins? Destruction of orexins may cause _________.
Orexins – peptides that help the cortex to wake up
Narcolespy
Define/differentiate narcolepsy, cataplexy, and insomnia.
Narcolepsy: neurological disorder characterized by extreme daytime sleepiness and sudden attacks of sleep
Cataplexy: sudden, abrupt loss of muscle tone while a person is awake – often follows strong emotion or laughter
Insomnia: chronic inability to obtain the amount or quality of sleep needed to adequately function
Most adults need 7-8 hours of sleep/night
List the 3 meninges in order from superficial to deep. What are the functions of the meninges?
Dura Mater
Arachnoid Mater
Pia Mater
Cover and protect the CNS
Protect blood vessels, enclose venous sinuses
Contain cerebrospinal fluid (CSF)
Form partitions in the skull
What are the two layers of the dura mater? Which of these layers extends into the spinal cord?
Periosteal Layer - attaches to the inner surface of the skull – only found in the brain, not the spinal cord
Meningeal Layer - true external covering of the brain – extends into the vertebral canal as the spinal dura mater
__________________ exist in separations between the 2 layers of the dura mater. What is the functions of these?
Two layers are mostly fused – separate in certain areas to form dural venous sinuses
Sinuses collect venous blood from the brain and empty into the jugular veins of the neck
Name 1 structure formed by extension of the dura mater into the cranial cavity.
In several places, the dura mater extends inwards to form flat partitions that subdivide the cranial cavity (ex: falx cerebri)
Be ready to localize the subdural and subarachnoid spaces in a picture. Which of these spaces is
wider?
What is the function of arachnoid granulations?
Separated from the dura mater by the thin subdural space
Subarachnoid Space: wider space that contains CSF and the largest blood vessels of the brain
Arachnoid granulations protrude through the dura mater into the superior sagittal sinus – they permit reabsorption of CSF back into venous blood
What is a subdural or a subarachnoid hematoma? What would cause them?
What is meningitis? Encephalitis? How is meningitis diagnosed? Anatomically, where would CSF typically be collected in the lumbar puncture?
Meningitis - inflammation of the meninges
Meningitis is typically diagnosed by observing microbes in a sample of CSF – the sample is obtained via lumbar puncture
Where is CSF formed? What is its function?
CSF is found in and around the brain and spinal cord – it forms a liquid, constant volume cushion
Functions:
Gives buoyancy to the CNS structures – reduces the weight of the brain by 97%
Protects the CNS from blows and other traumas
Nourishes the brain and carries chemical signals
What type of glial cell helps to circulate CSF?
CSF is filtered from the plexus at a constant rate
Ependymal cells use ion pumps to control the composition of CSF and to help cleanse CSF by removing waste
Cilia of the ependymal cells help to keep CSF in motio
How much CSF does the typical adult have? How often is it replaced?
Normal adult CSF volume is ~150 mL; it is replaced every 8 hours
Define and understand hydrocephaly.
Hydrocephaly - a clinical condition caused by CSF being produced faster than it is drained – it builds up in the ventricles
Why is a stable environment crucially important to the brain?
The blood brain barrier helps to maintain a stable environment for the brain – chemical variations could lead to uncontrollable neuron firings
How is this stable environment achieved?
Exceptionally impermeable tight junctions between capillary endothelial cells are its major component
What types of substances can pass through the blood brain barrier? What types cannot?
Simple Diffusion: allows lipid-soluble substances and blood gases to pass freely through cell membrane
Specific Transport Mechanisms: facilitated diffusion moves substances that are important to the brain (glucose, amino acids, and specific ions) but denies entry to metabolic wastes, proteins, toxins, and drugs
What type of glial cell reinforces capillaries to form the blood brain barrier?
…
What portions of the brain are not covered by the blood brain barrier? What is the physiological importance of this?
The blood brain barrier is absent in some areas – such as the vomiting center and the hypothalamus
Full access to neural tissue is necessary in these areas to monitor chemical composition and temperature of blood…