Central Nervous System Part II

Question 1

List the 3, paired gray matter structures of the diencephalon. What is enclosed by these structures?

Answer 1

Thalamus

Hypothalamus

Epithalamus

Question 2

How are the 2 halves of the thalamus connected?

Answer 2

Interthalamic adhesion

Question 3

What is the main function of the thalamus?

Answer 3

Act as a relay station for information coming into the cortex

Question 4

What types of impulses are being relayed to the thalamus?

Answer 4

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

Question 5

What is the function of the mamillary bodies? The infundibulum?

Answer 5

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

Question 6

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.

Answer 6

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

Question 7

List some symptoms of hypothalamic disorder.

Answer 7

Severe body wasting

Obesity

Sleep disturbances

Dehydration

Emotional imbalances

Question 8

What is the role of the pineal gland?

Answer 8

The pineal gland extends from the posterior border and secretes melatonin

Question 9

List the 3 regions of the midbrain.

Answer 9

Midbrain

Pons

Medulla Oblongata

Question 10

What are the cerebral peduncles?

Answer 10

Two ventral bulges that contain pyramidal motor tracts and form the little pillars that hold up the cerebrum

Question 11

What 2 things are connected by the cerebral aqueduct? What is contained within the cerebral aqueduct?

Answer 11

Cerebral Aqueduct - channel that runs through the midbrain and connects the 3rd and 4th ventricles

Question 12

What cranial nerves originate from the midbrain? What is the function of these cranial nerves?

Question 13

Define corpora quadrigemia and it’s 2 component parts. What reflexes are maintained here?

Answer 13

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

Question 14

What is the substantia nigra? How is it linked to Parkinson’s Disease?

Answer 14

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

Question 15

What is 1 function of the red nucleus?

Answer 15

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

Question 16

What cranial nerves originate in the pons? What is the function of these cranial nerves?

Answer 16

The pons is the origin point of cranial nerves V (trigeminal), VI (abducens), and VII (facial) …

Question 17

The 4th ventricle separates the ___________ and ______________. It is continuous with the ____________________.

Answer 17

pons, cerebellum …

Question 18

What is the choroid plexus? Where is it located? What does it produce?

Answer 18

Choroid plexus - a capillary-rich membrane that forms cerebral spinal fluid (CSF)

Located in the medulla oblongata

Question 19

What primitive life functions are maintained by the medulla?

Answer 19

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

Question 20

What is the function of the cerebellum?

Answer 20

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

Question 21

Cerebellar hemispheres are connected by the ______________.

Answer 21

Vermis

Question 22

What are the 3 lobes of the cerebellum? What is the arbor vitae?

Answer 22

Anterior
Posterior
Flocculonodular

Arbor Vitae - a thin cortex of gray matter with a deeper, distinctive treelike pattern of white matter

Question 23

Be generally familiar the cerebellar homunculi – which portions of the body are controlled by the medial and lateral portions?

Question 24

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.

Answer 24

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

Question 25

What would a cerebellar impairment look like? I gave quite a few examples in class!

Answer 25

Result in loss of muscle tone and clumsy, uncertain movements

Question 26

What is the limbic system? What is it’s primary function?

Answer 26

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 ...

Question 27

Where are the structures of the limbic system located?

Answer 27

Rhinecephalon

Question 28

What is the fornix? The amygdaloid body? The cingulate gyrus?

Answer 28

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

Question 29

Generally, explain the strong connection between memories and smells. Generally, explain the connection between high blood pressure and stress/strong emotions.

Question 30

Generally, what is the reticular formation? What does it govern? Where are some places that have its extensive connections?

Answer 30

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

Question 31

Name the 3 columns of the reticular formation that run through the brain stem.

Answer 31

Raphe Nuclei Medial (Large Cell) Group of Nuclei Lateral (Small Cell) Group of Nuclei

Question 32

What is the RAS? What are its functions? What is a potential outcome of damage to the RAS?

Answer 32

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)

Question 33

Which cerebral hemisphere houses the language centers? What happens in the analogous centers in the right hemisphere?

Answer 33

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

Question 34

What is aphasia? Compare/contrast Broca’s and Wernicke’s Aphasias.

Answer 34

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

Question 35

What is memory? Define declarative, procedural, motor, and emotional memory.

Answer 35

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)

Question 36

Differentiate short term and long-term memory. What factors affect the transfer of information from STM to LTM?

Answer 36

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

Question 37

What is memory consolidation? What portions of the brain are involved in the memory consolidation process?

Answer 37

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

Question 38

Damage to what structure of the brain causes amnesia? Differentiate anterograde and retrograde amnesia.

Answer 38

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

Question 39

What is an EEG? What is it measuring? What are EEGs used to diagnose?

Answer 39

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

Question 40

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!

Answer 40

Consciousness involves: Perception of sensation Voluntary initiation and control of movement Capabilities associated with higher mental processing – memory, logic, judgment ...

Question 41

Differentiate between fainting, coma, and brain death.

Answer 41

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

Question 42

Define sleep. How is sleep different than coma?

Answer 42

Sleep - a state of partial unconsciousness from which a person can be aroused by stimulation

Question 43

What are the 2 major types of sleep?

Answer 43

Non-rapid eye movement (NREM) sleep Rapid-eye movement (REM) sleep

Question 44

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.

Answer 44

slow-wave Frequency of waves declines, but amplitude increases EEG, heart rate, respiratory rate, blood pressure, and GI motility change NREM

Question 45

What physiological changes are expected during REM sleep? What kinds of these does the brain accomplish during REM sleep?

Answer 45

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

Question 46

Review the typical pattern of a full sleep session on slide 34.

Question 47

What are orexins? Destruction of orexins may cause _________.

Answer 47

Orexins – peptides that help the cortex to wake up Narcolespy

Question 48

Define/differentiate narcolepsy, cataplexy, and insomnia.

Answer 48

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

Question 49

List the 3 meninges in order from superficial to deep. What are the functions of the meninges?

Answer 49

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

Question 50

What are the two layers of the dura mater? Which of these layers extends into the spinal cord?

Answer 50

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

Question 51

__________________ exist in separations between the 2 layers of the dura mater. What is the functions of these?

Answer 51

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

Question 52

Name 1 structure formed by extension of the dura mater into the cranial cavity.

Answer 52

In several places, the dura mater extends inwards to form flat partitions that subdivide the cranial cavity (ex: falx cerebri)

Question 53

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?

Answer 53

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

Question 54

What is a subdural or a subarachnoid hematoma? What would cause them?

Question 55

What is meningitis? Encephalitis? How is meningitis diagnosed? Anatomically, where would CSF typically be collected in the lumbar puncture?

Answer 55

Meningitis - inflammation of the meninges Meningitis is typically diagnosed by observing microbes in a sample of CSF – the sample is obtained via lumbar puncture

Question 56

Where is CSF formed? What is its function?

Answer 56

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

Question 57

What type of glial cell helps to circulate CSF?

Answer 57

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

Question 58

How much CSF does the typical adult have? How often is it replaced?

Answer 58

Normal adult CSF volume is ~150 mL; it is replaced every 8 hours

Question 59

Define and understand hydrocephaly.

Answer 59

Hydrocephaly - a clinical condition caused by CSF being produced faster than it is drained – it builds up in the ventricles

Question 60

Why is a stable environment crucially important to the brain?

Answer 60

The blood brain barrier helps to maintain a stable environment for the brain – chemical variations could lead to uncontrollable neuron firings

Question 61

How is this stable environment achieved?

Answer 61

Exceptionally impermeable tight junctions between capillary endothelial cells are its major component

Question 62

What types of substances can pass through the blood brain barrier? What types cannot?

Answer 62

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

Question 63

What type of glial cell reinforces capillaries to form the blood brain barrier?

Answer 63

...

Question 64

What portions of the brain are not covered by the blood brain barrier? What is the physiological importance of this?

Answer 64

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...