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211 Cards in this Set

  • Front
  • Back
What are the three primary vesicles of the brain?

What five secondary vesicles do these three divide into?
1. Prosencephalon
2. Mesencephalon
3. Rhombencephalon

1. Telencephalon
2. Diencephalon- optic nerve and neural retina
3. Mesencephalon
4. Metencephalon- pons and cerebellum
5. Myelencephalon- medulla oblongata
Name the lumen and wall derivatives for each of the following primary vesicles of the brain:
Prosencephalon
Mesencephalon
Rhombencephalon
Prosencephalon: Lateral and third ventricles, cerebral hemispheres (cortex, insula, hippocampus, subcortical white matter, basal ganglia), diencephalon (thalamus, hypothalamus, epithalamus, subthalamus, optic vesicles)

Mesencephalon: Cerebral aqueduct, midbrain (colliculi, cerebral peduncles/crus cerebri)

Rhombencephalon: fourth ventricle, pons, cerebellum, medulla oblongata
What do neurons that fail to migrate during brain development become?
Basal ganglia along the lateral venetricles
What part of the brain is formed by invagination of the medial cortex into the lateral ventricle?
Hippocampal formation
From what is the choroid plexus formed?
Choroid plexus is formed from blood vessels that are pushed into the lateral ventricle.
Which basal ganglion follows the shape of the lateral ventricle?
Caudate nucleus
What four internal brain structures parallel the C-shape formed by the cerebral hemispheres?
1. Choroid plexus
2. Hippocampal formation/fornix
3. Caudate nucleus
4. Lateral ventricles
How is the insula formed?
The insula is formed by part of the telencephalon which grows slower and becomes buried within the lateral sulcus.
What are the five parts of the lateral ventricle?
1. Anterior horn (border is interventricular foramen)
2. Body
3. Atrium
4. Posterior horn
5. Inferior horn
Describe the pathway through which the hippocampus sends information.
Hippocampus-fornix-mamillary body-thalamus-cingulate gyrus-parahippocampal gyrus-hippocampus
Describe the location of the hippocampal formation in relation to the lateral ventricle.
The HF lies along the medial wall and floor of the inferior horn of the lateral ventricle.
What is the function of the hippocampus?

What happens when the hippocampus is bilaterally damaged?
The hippocampus is responsible for short-term memory.

Damage results in anterograde amnesia.
What white matter structures connect lobes/gyri on the same side of the brain?
Association fibers

Short: adjacent gyri
Long: distant regions (ie: arcuate fasciculus connects Wernicke's and Broca's areas)
What association fiber is deep to the cingulate gyrus?
Cingulum
What white matter structures connect corresponding areas on opposite sides of the brain?
Commissures
What are the long tracts that connect the cerebral cortex with the diencephalon, brain stem, or spinal cord? What do they communicate?
Projection fibers

Ascending: sensory
Descending: motor
What is the corona radiata made of?
Corona radiata is made of projection fibers.
Are basal nuclei made of gray matter or white matter?
Gray matter
What are the three recesses of the third ventricle?
1. Optic recess
2. Infundibular recess
3. Pineal recess
From what part of the neural tube do choroid plexus cells form?
Dorsal wall
Describe the major and minor routes through which CSF flows in the brain.
Major: Lateral ventricle-Interventricular foramen-3rd ventricle-Cerebral aqueduct-4th ventricle-lateral/median apertures-subarachnoid space

Minor: 4th ventricle-central canal of spinal cord
How many times daily does CSF turn over?
3
How does CSF return to the blood?
CSF returns to the blood from the subarachnoid space by flowing into arachnoid granulations, through which it diffuses, into the superior sagittal sinus.
Describe the two minor pathways by which CSF is reabsorbed into the blood.
1. Drainage may occur along cranial and spinal nerves through the cranial and interverebral foramina into lymphatics and veins.
2. Some CSF in the central canal may be reabsorbed through the ependymal lining into the capillaries.
Name the five major functions of the CSF.
1. Buoyancy of the brain
2. Cushion the brain and nerves during movement
3. Stability of chemical environment
4. Transport micronutrients and trace elements into th ebrain
5. Remove metabolic waste and excess neurotransmitters
How does a CT of and individual with hydrocephalus differ from the normal?
An individual with hydrocephalus has dilated ventricles and ill-defined brain structures.
Describe the difference between non-communicating hydrocephalus and communicating hydrocephalus.
Non-communicating: Obstruction within the ventricular system, ie: tumor in the 3rd ventricle, stenosis of aqueduct

Communicating: Obstruction in the subarachnoid space, ie: tumor, unilateral brain shift, post-heorrhagic or post-infectious meningitis
Name a situation in which ventricular enlargement is not related to hydrocephalus.
Cerebral atrophy due to aging of Alzheimer's disease causes enlargement of the ventricles not related to hydrocephalus.
Describe the appearance, protein content, and glucose level or CSF with each of the following:

a. Bacterial meningitis
b. Viral meningitis
c. Tuberculosis meningitis
d.????
See slide
Describe four features of typical neuron morphology.
1. Large nucleus
2. Prominent nucleolus
3. Nissl granules
4. Processes
What special stain is used to identify myelin?
Luxol fast blue
What is the typical shape of a neuron in the cortex?
Pyramid/triangle
Where are Purkinje cells found?
Between the molecular and granular layers in the cerebellum
What is a stain that will highlight a neuronal soma and processes?
Golgi silver stain
How many synapses are in the human brain?
10^14
Describe red neuron.
Red neuron is the result of hypoxia. It is an ischemic change resulting in eosinophilia. It appears 8-24 hours after the ischemic insult. The nucleus breaks apart and disappears. The process is irreversible.

This process only occurs in a live person.
What happens when an axon is transected?
1. The portion of the axon distal to the injury, the axon undergoes Wallerian degeneration.
2. Central chromatolysis occurs: Dissolution of Nissl substance, movement of nucleus to periphery
3. Regeneration (occurs in PNS but not CNS)
What is distal axonopathy?
Distal axonopathy is a condition in which the distal end of an axon is destroyed as a result of some sort of toxin or metabolic insult.
What stain identifies neurofibrillary tangles (tau protein) in Alzheimer's?
Bielchowslky silver stain
Describe the nucleus of the oligodendroglial cell.

Name a pathology associated with this cell type.
Nucleus: small nucleus with perinuclear clearing

Pathology: Progressive Multifocal Leukoencephalopathy (papova virus)
Describe the pathology of multiple sclerosis.
The immune system mediates an attack on the white matter, causing demyelination.
Describe the nucleus of the astrocyte.

How do astrocytes respond to injury?
Nucleus: larger, more oval nucleus

Injury response: Astrogliosis- hypertrophy and proliferation
How are reactive astrocytes visualized?
Reactive astrocytes can be visualized with immunoperoxidase stain for GFAP.
What are gemistocytes?
Gemistocytes are very prominent reactive astrocytes.
Describe the appearance of macrophages in the brain.
Macrophages in the brain are often foamy from the phagocytosis of myelin.
When are microglial nodules present in the brain?
During a chronic inflammatory process
When are multinucleated giant microglial cells present?
In HIV encephalitis because of syncytia formation.

Can also form as a result of cell division problems.
What happens when the ventricular lining is disturbed?
Ependymal rosettes form adjacent to the ventricle, as the ependymal cells attempt to form a new ventricle
Describe cytotoxic edema.

Describe vasogenic edema.
Cytotoxic edema is an increase in intracellular water due to cell membrane damage. Usually in the cortex.

Vasogenic edema is an increase in extracellular water due to breakdown of the blood-brain barrier (due to tumor or abscess). Usually in the white matter.
Name two ways that macrophages get into the brain.
1. Differentiation of resident microglial cells
2. Damage to the BBB- monocyte entry and differentiation
Name the five general sensations.
1. Touch
2. Proprioception
3. Vibration
4. Pain
5. Temperature
Which spinal segments innervate the neck? Upper limb? Trunk? Lower limb?
Neck: C2-4
Upper limb: C4-8, T1
Trunk: T1-12
Lower limb: L1-S2
Perineum, genitalia, anus: S3-coccygeal
Where are the cell bodies located for the axons that innervate the dermatomes?
DRG
How are general sensory pathways organized?

How can lesions of these pathways be localized?
3 neuron chain:

Neuron 1: in PNS in DRG (may synapse with neuron 2 at the same spinal cord level or further up)

Neuron 2: in CNS- spinal cord or brain stem, axons decussate

Neuron 3: in sensory nucleus of thalamus

Lesions below the decussation cause ipsilateral loss of sensation, while lesions above the decussation cause contralteral loss of sensation.
What type of sensations does the dorsal column-medial lemniscus pathway carry?
1. Discriminative touch
2. Vibration
3. Proprioception
What type of sensations does the spinothalamic tract carry?
1. Pain (fast and slow)
2. Temperature
3. Crude touch
Where does neuron 1 of the DC-ML travel for C1-T5? For T6-S2?
Where do these neurons terminate?
C1-T5: Fasciculus cuneatus
T6-S2: Fasciculus gracilis

C1-T5: Nucleus cuneatus
T6-S2: Nucleus gracilis
Where do axons travel in the DC-ML pathway before and after decussation?
Before: Dorsal columns
After: Medial lemniscus
Where do signals from the DC-ML pathway terminate?
Post-central gyrus and paracentral lobule
Where do neurons 2 and 3 of the DC-ML pathway synapse?
VPL nucleus of the thalamus
Of the fasciculus gracilis and the fasciculus cuneatus, which runs more medially in the spinal cord?
Fasciculus gracilis
From what three locations does the multimodal association cortex accept information?
1. Visual association cortex
2. General sensory association cortex
3. Auditory association cortex
What happens when the parietal lobe is damaged?

On which side does this happen more frequently?
Hemineglect- loss of awareness of the contralateral side of the body

Right-sided brain damage/ left-sided hemineglect
Name the results of lesions in the DC-ML pathway.
1. Loss of propriocepton- ataxia, loss of balance, + Romberg sign
2. Loss of discriminative touch, 2-point discrimination, tactile localization
3. Loss of sense of vibration
4. Abnormal sensation- paresthesia, dysthesia (tingling, numbness, tightness)
5. Astereognosis, agraphtesthesia
6. Hemineglect
Where are the cell bodies for neuron 1 in the spinothalamic tract located?
DRG
Where is the STT located?
The STT is found after the second neurons in the STT pathway decussate.
Where are the cell bodies of neuron 3 in the STT located?
VPL nucleus of the thalamus
Where are the cell bodies of neuron 2 in the STT located?
Dorsal horn of the spinal cord at the level of the entering spinal nerve
How can the dorsal, lateral, and ventral funiculi be distinguished?
The dorsal funiculus is from the dorsal midline to the exit of the dorsal root. The lateral funiculus is located between the exit locations of the dorsal and ventral roots. The ventral funiculus is located between the ventral midline and exit of the ventral roots.
Where in the spinal cord does axon crossing occur?
Through the white commissure on an oblique trajectory, over 1-2 spinal cord segments
List the result of lesions in the STT.
1. Loss of pain sensation/analgesia, reduced sensation, hypalgesia
2. Loss of temparature sensation
3. Abnormal sensation (spontaneous shooting pain, burning sensation)

Sensory loss will be ipsilateral for a lesion below the decussation and contralateral for a lesion above the decussation.
Which spinal cord segments send signals up the fasciculus gracilis? Fasciculus cuneatus?
Gracilis: sacral, lumbar, thoracic
Cuneatus: thoracic, cervical
Describe 3 striking things about the arrangement of the primary sensory cortex.
1. Body parts are disproportionately represented
2. Body part representation is upside down
3. There is no overlap in blood supply between the regions
What is the only branch of the trigeminal nerve that has motor fibers?
V3- Mandibular branch
What sensations are received by the spinal nucleus?
Pain, temperature, crude touch
What sensations are received by the main/pontine nucleus?
Discriminative touch, vibration, proprioception
What sensations are received by the mesencephalic nucleus?
Proprioceptive reflexes
From which nuclei does the trigeminothalamic tract arise?

What nucleus does this tract end in?
Spinal nucleus and main/pontine nucleus

Ventral posterior medial (VPM) nucleus of the thalamus
Describe the course of the spinal tract of V.
The spinal tract of V enters mid-pons from the trigeminal sensory root and descends to the spinal nucleus in the medulla oblongata. It is not concerned with any conscious appreciation of pain and temperature.
Where do axons from the trigeminal pathway decussate?
Close to the medulla, in the brainstem, after passing through the spinal/pontine/mesencephalic nuclei, while traveling toward the contralateral VPM.
What path does neuron 3 in the trigeminal pathway follow?
It exits the VPM of the thalamus and travels up through the posterior limb of the internal capsule to the primary sensory cortex.
What is the result of a lesion in the posterior limb of the internal capsule or the TTT at or above the upper pons?
Hemianesthesia- loss of feeling on the contralateral side of the body, including the face. All sensory pathways run through the internal capsule, and because of the proximity of the TTT and DC-ML/STT pathways, any lesion affecting TTT is likely to affect the other two as well.
From where do the VPM and VPL receive sensation from?
VPM: contralateral face
VPL: contralateral body
What is the result of a lesion on the spinal tract of V?
Loss of pain and temperature sensation on the ipsilateral half of the face
Which cranial nerves are involved in the blink reflex?
Trigeminal: sensory
Facial: motor
Describe the path of the jaw jerk reflex.
Muscles of mastication send sensory signals up through nerve V to the mesencephalic nucleus of V. A signal then travels through the motor nucleus of V to the bilateral muscles of mastication.
Which cranial nerves provide special sensory innervation to the tongue?
Posterior third of tongue: IX
Anterior two-thirds of tongue: VII (chorda tympani)
What percent of childhood cancers are represented by CNS neoplasms?
20-25%
Where are most brain tumors located in adults? Children?
In adults, 70% of brain tumors are located above the tentorium. In children, 70% are located below the tentorium.
From what cell type are the most common brain tumors derived?
Astrocytes
Why do craniopharyngiomas often recurr?
Grossly, craniopharyngiomas look like they have smooth borders, but histologically it can be seen that they have many infiltrative fingers that may be left behind.
What is the common way for primary brain tumors to metastasize?

Less common?
Common: through CSF

Less common: outside CSF due to surgery
What type of tumor grows as a well-circumscribed nodule on a nerve root?

Is it benign or malignant?
Schwannoma

Benign, but causes compression of nerve and spinal cord
Where do metastases into the brain often settle?
Between the gray and white matter because this is often where vascular beds end
What is the most common type of brain tumor?
Malignant astrocytoma
When patients present to the hospital with brain tumors, how many fall into each of the following categories?
Metastatic brain tumors
Extracerebral primary brain tumors
Intracerebral primary brain tumors
Metastatic brain tumors: 20%
Extracerebral primary brain tumors: 20%
Intracerebral primary brain tumors: 60%
Where in the CNS are germline tumors most frequently found?
The pineal region
What types of tumors are most likely to be present in the brain ventricles?
Ependymomas, choroid plexus papillomas
What is the most common childhood brain tumor?
Medullablastoma
From which meningeal layer is a meningioma derived?
Arachnoid, although it will later infiltrate into the dura
What are the four classifications of gliomas?
Astrocytomas (15%)
Glioblastoma multiforme (30%)
Oligodendroglioma (5%)
Ependymoma (5%)
Describe the grading system of astrocytic neoplasms.
Grade I: Juvenile pilocytic astrocytoma, optic nerve glioma- well-circumscribed, good prognosis
Grade II: Astrocytoma- infiltrative, no mitotic figures, not cured surgically but long survival
Grade III: Anaplastic astrocytoma- Histologically malignant with mitotic figures, 3-5 year survival
Grade IV: Glioblastoma multiforme- High grade malignant tumor with mitotic figures, endothelial proliferation, and/or necrosis, 9-18 mo. survival
What causes endothelial proliferation in glioblastoma multiforme?
Increased production of VEGF
Describe the histological appearance of a grade I pilocytic astrocytoma.
Not very cellular, biphasic (some eosinophilic portions, some clear portions), Rosenthal fibers (red inclusions)
Describe the histological appearance of a grade II astrocytoma.
Increased cellularity, fibrillary background, nuclear pleomorphism, absence of mitotic figures
Describe the histological appearance of a grade III astrocytoma.
Increased cellularity, nuclear pleomorphism, mitotic figures, fibrillary processes
Describe the gross appearance of a grade IV glioblastoma.
Very variable (multiforme), may cross corpus callosum
Describe the histological appearance of a grade IV glioblastoma.
Hypercellular, nuclear pleomorphism, fibrillary background, proliferating blood vessels (glomeruloid), necrosis with surrounding palisading
Describe the histological appearance of an oligodendroglioma.
Small round nucleus, halo (like oligodendroglial cells), hypercellular, uniformity of cell type, anastamosing blood vessels
Describe the histological appearance of an ependymoma.
Ependymal rosettes within tumor
In which two groups of patients is the incidence of primary CNS lymphoma increased?
AIDS patients
Transplant patients (immunosuppressed)
Name three reasons that CNS lymphoma is difficult to treat.
1. High grade
2. Location in brain lends itself to difficult symptomatology
3. Traditional lymphoma treatments are difficult to get into the brain and may have worse side effects in the brain
What two types of brain tumors may become necrotic?
1. Metastatic secondary tumors
2. Glioblastoma multiforme
What are the five cancers that most commonly metastasize to the brain?
1. Lung
2. Breast
3. Colon
4. Kidney
5. Melanoma
Describe three major presentations with metastatic cancer to the brain.
1. Intracerebral mass with focal neurological signs
2. Encephalopathy with no focal neurological signs
3. Cranial nerve palsies
Briefly describe the two ways that glioblastoma multiforme occurs.
1. Patients initially present with astrocytoma which progresses to glioblastoma multiforme. These patients often have a p53 mutation.
2. Direct presentation with glioblastoma multiforme. Associated with EGF-R amplification.
Describe the histological appearance of meningiomas.
Whorls, calcifications, hypercellular
Why are meningiomas more common in women?
The cells have estrogen receptors that increase growth rate.
Describe the histological appearance of schwannomas.
They have Antoni A and Antoni B areas, which are hypercellular with palisading, and loose and mixoid, respectively.
Compare and contrast Schwannomas and neurofibromas.
Both are benign tumors of Schwann cells. Schwannomas compress the adjacent nerve but can be surgically excised. Consider NFII if bilateral. Neurofibromas expand the nerve of origin and cannot be surgically excised without sacrifice of the nerve. Consider NFI. Rare malignant progression.
Name the two most common intraventricular tumors.
1. Ependymoma
2. Choroid plexus papilloma
Name the two most common pituitary region tumors.
1. Adenoma
2. Craniopharyngioma
Name the three most common pineal region tumors.
1. Germ cell
2. Pinealoma
3. Astrocytoma
What is the most common meningeal tumor?
Meningioma
Name the three most common intracerebral tumors.
1. Astrocytoma
2. Glioblastoma
3. Oligodendroglioma
Name the three most common cerebellar tumors.
1. Juvenile pilocytic astrocytoma
2. Medulloblastoma
3. Hemangioblastoma
Name the two most common intramedullary spinal tumors.

Name the three most common extramedullary spinal tumors.
Intra:
1. Ependymoma
2. Astrocytoma

Extra:
1. Schwannoma
2. Meningioma
3. Neurofibroma
What does the intracranial dura become as it enters the orbit?
Periorbita (periosteum), which gives off orbital septum, and optic sheath
What is the function of orbital fat?
The orbital fat functions as a socket to hold the eyeball in place and allow it to rotate easily.
List the five layers of the eyelid.
1. Skin- very thin
2. Subcutaneous layer- little fat
3. Muscular layer- orbicularis oculi and levator pelpebrae superioris
4. Tarsofascial layer- orbital septum, superior tarsal muscle
5. Palpebral conjunctiva
What structure is infected to create a stye?
Sebacious gland
What structure is is infected to create a chalazion?
Tarsal gland
Which direction does the eyeball move around the vertical axis for abduction and adduction? Elevation and depression (around horizontal axis)?
Abduction: lateral
Adduction: medial

Elevation: superior
Depression: inferior
Define intorsion and extorsion.
Intorsion is the rotation of the eyeball medially around an axis straight back through the pupil. Extorsion is the reverse.
How many extraocular muscles are there? Name them and the direction the eyeball moves with contraction.
Seven

1. Levator palpebrae superioris
2. Superior rectus- elevation and adduction
3. Inferior rectus- depression and adduction
4. Medial rectus- adduction
5. Lateral rectus- abduction
6. Superior oblique- depression and abduction
7. Inferior oblique- elevation and abduction
Which two extraocular muscles work together to look downwards?
Superior oblique and inferior rectus
Is there a difference between anatomical function and clinical testing of extraocular muscles and cranial nerves?
Yes, and be able to answer questions about this.
See UCD website for eye simulator.
.
Which cranial nerves innervate the extraocular muscles?
Trochlear- superior oblique
Abducent- lateral rectus
Oculomotor- all others
Where do sympathetic nerve components originate?
Parasympathetic?
T1-L2

Brainstem and S2-4
Where do sympathetics innervating the head originate?

Where do they synapse?

With what structure do the post-ganglionic axons travel?
T1-4

Superior cervical ganglion

Internal carotid artery
What part of the brain is the master controller of the autonomic nervous system?
Hypothalamus
Describe the basic outline of the regulation of the ANS.
Neocortex provides sensory information, which is transmitted to the septal nuclei, amygdala, and hippocampus. This information is integrated in the hypothalamus and neocortex, then transmitted back out as ANS responses, such as behavior and homeostasis.
What are the four pathways from the hypothalamus to the ANS centers?
1. Medial forebrain bundle (MFB)
2. Dorsal longitudinal fasciculus (DLF)
3. Mammillotegmental tract (MTegT)
4. Hypothalamo-spinal tract (HST)
What is Horner's syndrome?
Horner's syndrome is the result of a peripheral lesion, usually in the superior cervical ganglia. It is manifested as ptosis (loss of tarsal contraction), miosis (pupil constriction), and facial anhydrosis.
Where do central lesions affecting the face occur?
Above T1 or in the brain stem
Where are the parasympathetic preganglionic cell bodies related to the head and neck located?
Subnuclei of cranial nerves III, VII, IX, X
Where are the post-ganglionic cell bodies associated with cranial nerves III, VII, and IX located?

Cranial nerve X?
In identifiable ganglia close to the target tissue.

In the target tissue
How do parasympathetic axons get to their targets?
By hitchhiking on blood vessels or other nerves (ie: trigeminal)
What does the vagus nerve innervate in the head and neck?
Nothing!
What head and neck problems might occur if there is a lesion very high up on the vagus?
Difficulty speaking and swallowing due to damage of the recurrent laryngeal nerve
Where are preganglionic parasympathetic cell bodies of the oculomotor nerve located?

Post-ganglionic?
In the Edinger-Westphal nucleus in the midbrain.

Ciliary ganglion
What is the function of the parasympathetic fibers traveling in the short ciliary nerves?
Constriction of the sphincter muscles of the pupil and accomodation by ciliary muscles of the eye
What signs of oculomotor damage might one see?
1. Mydriasis (dilated pupil)
2. Loss of light reflex
3. Loss of accommodation
4. Loss of ability to move eye in a medial direction
5. Ptosis due to loss of innervation to levator palpebrae
Describe the pathway of the parasympathetic component of the facial nerve.
Cell bodies in superior salivatory nucleus, axons form nervous intermedius, travel with chorda tympani, join lingual nerve V3, synapse in submandibular ganglia, innervate sublingual and submandibular glands.

Greater petrosal nerve travels from nervous intermedius to synapse in the pterygopalatine ganglia and continue on the to the lacrimal and nasal glands.
What pathology occurs with facial nerve parasympathetic lesions?

Somatomotor?
Dry eye, dry mouth

Bell's palsy
Describe the pathway of the parasympathetic components of the glossopharyngeal nerve.
Cell bodies in inferior salivatory nucleus, axons travel via the lesser petrosal nerve to synapse in the otic ganglia. Post-synaptic fibers travel with V3 to the parotid gland.
What pathology occurs with glossopharyngeal lesions?
No parasympathetic deficit
Loss of taste in posterior 3rd of tongue
Unilateral loss of gag reflex
Unilateral weakness swallowing

Damage usually associated with damage to X and XI as well.
Describe the synthesis of ACh.

What substance is limiting?
Starting as phosphatidyl ethanolamine. Methylated by SAM to phosphatidyl choline. Choline is bound to acetyl CoA by choline acetyltransferase (CAT) to make ACh, which is then packaged into synaptic vesicles.

Choline is limiting, and so ACh must be recycled.
What is hemicholinium?
Hemicholinium is a high affinity choline uptake inhibitor. Its presence results in the depeletion of choline stores.
What does black widow venom do?

Botulinum toxin?
Causes rapid and massiv ACh release, overstimulating post-synaptic receptors.

Prevents ACh release, causing paralysis.
What enzyme breaks down ACh? Which amino acid is the active residue?
AChE- serine is active residue
What four substances inhibit AChE action?
1. Physostigmine
2. Sarin
3. Selenophosphates
4. Diisopropylfluorophosphate
What two conditions may be slightly alleviated by AChE inhibition?
Alzheimer's and myasthenia gravis
Describe nicotinic receptors.
Nicotinic receptors are chemically gated sodium channels, which have open, closed, and desensitized (phosphorylated) configurations. They are fast action and excitatory receptors.
Agonist: nicotine
Antagonist: curare
Describe the subunit composition of muscle nicotinic receptors.

...some CNS receptors.

How many alpha subunit variants are there?

Beta?
2 alpha, one beta, gamma, delta

All alpha-7

Nine

Four
Variations in what molecule appears to affect predisposition for nicotine addiction?
Nicotinic receptors
Describe muscarinic receptors.
Muscarinic receptors are coupled to G proteins and affect expression of second messengers. They have a relatively slow reaction.
Agonist: muscarine
Antagonist: atropine
How many subtypes of muscarinic receptors are there?
Five
What are the seven events in cholinergic synapses that can be pharmacologically regulated?
1. ACh synthesis
2. ACh transport into synaptic vesicles
3. ACh release from presynaptic neurons
4. Post-synaptic receptor modulation
5. Feedback by presynaptic muscarinic receptor
6. AChE inhibition
7. Choline uptake inhibition
Briefly describe the action of botulinum toxin.
After ingestion, it is transported to to peripheral cholinergic receptors, via the vasculature, where it binds presynaptic nerve cells at the myoneuronal junction, where it is internalized and converted to a Zn endopeptidase, destroying the exocytosis apparatus and preventing the release of ACh.
Briefly describe the action of tetanus toxin.
Tetanus toxin undergoes retrograde transport to the spinal cord and brainstem and blocks inhibitory neurotransmitters, like glycine and GABA.
What is the general function of the hypothalamus?
Site of communication between body and brain- convert brain signals to hormones, and vice versa
Describe the difference in the composition of the anterior and posterior pituitary.
The anterior pituitary is glandular tissue, while the posterior pituitary is neural tissue.
What is the difference between a normal neuron and a neuroendocrine neuron?
Neuroendocrine neurons release their contents in close proximity to a capillary, rather than another neuron.
Describe the pathway by which a signal is transmitted from the hypothalamus to the body.
The hypothalamus releases neurohormones into the hypothalamic portal system to be transmitted to the anterior pituitary, which will release hormones into the venous blood.
How is homeostasis maintained?
End organ products communicate to the hypothalamus that signals are being produced at adequate levels... feedback inhibition.
What two neuroendocrine hormones are produced in the posterior pituitary?
Vasopressin (ADH)
Oxytocin
What are the three medial to lateral regions of the hypothalamus?
Periventricular, medial (most nuclei), lateral
Name the four common features of hypothalamic nuclei.
1. Densely connected with one another
2. Inputs integrate sensory and endocrine cues
3. Outputs regulate autonomic and endocrine fn
4. Responsible for homeostasis and motivated social behaviors
What are the four anterior to posterior regions of the hypothalamus?
Preoptic, anterior, middle, posterior
What is the preoptic region of the hypothalamus involved in?

Developmentally, what is it part of?
Male sexuality, parental behavior

Telencephalon
What is the periventricular region of the hypothalamus involved in?
Thirst
What is the superchiasmatic nucleus of the hypothalamus involved in?
Circadian rhythm
What is the anterior nucleus of the hypothalamus involved in?
Aggressive behavior, heat loss center
What is the paraventricular nucleus of the hypothalamus involved in?
Chronic stress and cortisol release, parasympathetic activation
What are the ventromedial nucleus and arcuate nucleus of the hypothalamus involved in?
Satiety and hunger

VMH also involved in female sexuality
What happens if the arcuate nucleus has a lesion?
Decrease in body weight- hunger is reduced
What happens if the ventromedial nucleus has a lesion?
Increase in body weight- satiety is reduced
What is the function of the posterior nucleus of the hypothalamus?
Body temperature- heat gain center
What is the function of nasal mucus?
Nasal mucus houses the cilia of the olfactory receptors and dissolves airborne molecules.
How are olfactory cilia and glomeruli organized?
Cilia for the same scent are dispersed randomly in the nasal epithelium, but there is a single glomerulus for each scent, which organizes sensory input.
Is olfaction ipsilateral or contralateral?
Ipsilateral
Where does the olfactory tract terminate?
Amygdala
Puriform (primary olfactory) cortex
Entorhinal area
From where do olfactory neurons arise?
Nasal epithelium
What is anosmia?

What causes it?
Lack of sense of smell

Trauma, age
What do humans lack that allows animals to detect non-volatile scents?
Vomeronasal organ
What structure forms the uncus?
Amygdala
From where does the amygdala receive signals?

What sort of response does it create?
Hippocampus, hypothalamus, septum, sensory cortex, prefrontal cortex, brainstem, thalamus

Emotional
What does the corticomedial amygdala do?
Receives olfactory input, connects to hypothalamus
What does the basolateral amygdala do?
Emotional component of memory, connected to hippocampus, autonomic responses to memory, fear
What structures communicate through the stria terminalis?
Amygdala to hypothalamus
Describe Kluver-Bucy syndrome.
It includes visual agnosia, increased oral tendencies, decreased emotional response, hypersexuality, and hypermetamorphosis. It is a result of bilateral amygdala damage.
What is the role of the amygdala in anxiety?
Under stressful conditions, the prefrontal cortex slows down making decisions and the amygdala takes over. In a person with anxiety, there may be hypersensitivity to emotional cues where the amygdala takes over.
What are the three parts of the hippocampal formation?

Describe the arrangement of these components.
1. Dentate gyrus
2. Ammon's horn/hippocampus proper (c1-4)
3. Subiculum

It is a highly folded structure resembling a seahorse.
What is the hippocamus involved in?
Learning and memory
What is the primary source of input to the hippocampus?

Output?
Input: Entorhinal cortex (information enters through subiculum)

Output: Hypothalamus (via fornix) and temporal/frontal lobes
What is the Papez circuit?
The Papez circuit is important for the establishment of long-term memory. The hippocampus connects to the mammillary bodies via the fornix, and a circuit is made to the cingulate cortex and back to the hippocampus via the anterior nucleus.
Where is the septum located?
Between the two lateral ventricles
What is the function of the septum?
It has large cholinergic neurons which extend throughout the brain and are important for arousal and attention.
What is the function of the nucleus accumbens?
It is involved in reward. Many drugs and natural rewards increase dopamine in the nucleus accumbens.