Cceb 1 Flashcards by Rachael Kloosterman

What is the rate limiting step in cholesterol synthesis

HMG CoA reductase

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What stimulates HMG CoA to mevalonate?

Insulin

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What enzyme does statin, the ‘cholesterol lowering drug’ target?

Mevalonate

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What is pregnolone converted to in the sequence of steroid hormones?

Cholesterol - pregnalone - progesterone - cortisol, aldosterone, dehydroepiansrosterone (dhea) - androstenedione - testosterone - estradiol - estrogen

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What are the four ways to remove nitrogen?

Transamination - transfer of NH2 to another molecule
Deamination - in liver broken dowm
Ammonia formation - hydrogen is added to NH2 to form ammonia NH3
Urea formation - changes ammonia into non toxic urea excreted in urine

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Rate limiting enzyme in urea cycle?

Carbomoyl phosphate synthase

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In DNA synthesis, what pairs are joined with hydrogen to form two polynucleotide chains?

Adenine+ thymine
Guanine+ cytosine

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What are the characteristics of DNA synthesis?

Bidireccional (site of origin, out in both directions)
Semi conservative (one parent and one daughter strand)

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Which base pairs are for RNA and which for DNA?

Cytosine and guanine - DNA and RNA
Adenine and Thymine - DNA
Adenine and Uracil - RNA

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What protein is secreted by the notochord around day 18 of gestation?

Sonic hedgehog

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What week does the neural groove close?

Week 4

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What do the a) marginal and
b) mantle layer differenciate into?

A) White matter of spinal cord
B) Dorsal (alar) -> sensory neurons dorsal horn + ventral (basal plates) -> motor neurons ventral horn

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What does the tissue at the top of the neural tube become? And what do they give rise to?

Neural crest cells
- Dorsal root ganglion
- Adrenal medulla
- Melanocytes
- Enteric ganglia
- Schwann cells
- Sympathetic ganglia

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What do the posterior or dorsal columns tract carry?

Vibration, fine touch and joint position sense

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What are the two divisions of the dorsal columns and where do fibers from the lower limb and upper limb synapse in?

Medial gracilis (from the lower limb) and lateral cuneatus (from the upper limb)

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What are the four divisions of the anterolateral system and what do they carry?

Lateral spinothalamic (pain and temperature)
Ventral spinothalamic (crude touch and pressure)
Spinocerebellar (mediates autonomic responses to nociception)
Spinotectal tracts (eye movements response to tactile stimuli)

What do the descending tracts carry? Except for raphespinal tract?

Skeletal motor function, smooth muscles and secretory glands
Nociception modulation

1st, 2nd, 3rd and decussation of the
Dorsal columns?

1st mechanoreceptors
2nd nuclei gracilis and cuneatus
3rd medulla
Dorsal columns VPL nucleus of thalamus

1st, 2nd, 3rd and decussation of the
Anterolateral Spinothalamic tracts?

1st nociceptors
2nd lámina 1,2,5 in dorsal horn
3rd VPL nucleus of the thalamus
Decussation spinal cord

1st, 2nd, 3rd and decussation of the
Dorsal spinocerebellar

1st unconscious proprioception from ipsilateral lower limb
2nd Clarke’s nucleus in thoracic region
3rd cerebellum vía inferior cerebellar peduncle
Decussation does not cross

1st, 2nd, 3rd and decussation of the
Ventral spinocerebellar

1st unconscious proprioception from ipsilateral upper and lower limb
2nd lámina 7
3rd cerebellum vía superior peduncle
decussation first at the spinal cord then again in the pons ipsilateral

What are the four ascending tracts?

Dorsal column
Spinothalamic
Dorsal spinocerebellar
Ventral spinocerebellar

What are the 7 descending tracts and their 1st, 2nd order and decussation?

Rubrospinal: red nucleus, lam 5-8, midbrain

Tectospinal: tectum of midbrain, lam 6-8, midbrain

Lateral corticospinal: pre central gyrus, lám 4-9, medulla

Ventral corticospinal: pre central gyrus, lam 4-9, spinal cord at exit level

Reticulospinal: reticular formation, lam 8, various levels

Vestibulospinal: vestibular nuclei, lám 6-8, uncrossed

Raphespinal: raphe nucleus, lam 1,2,5, uncrossed

Function of the descending tracts?

Lateral corticospinal: voluntary control limbs

Ventral corticospinal: voluntary control of the head, neck and trunk

Rubrospinal: excited proximal flexors and inhibits extensors mainly upper limb

Reticulospinal: restricts and facilitates voluntary movements through a and y motor neurons

Tectospinal: coordinates head and eye turning in response to light via superior colliculus

Vestibulospinal: involved in postural reflexes- neck muscles, extensors of back and legs

Raphespinal: inhibits nociception by releasing serotonin and acts on the c fibers

What innervates the facet joints?

The facet joints of t1-2 are innervated by the medial branches of c8 and t1. This pattern continues in the lumbar spine. Of note the anatomy of the L5-S1 facet joint differs. It is innervated by the medial branch of L4 and the dorsal ramus of L5

What are the a&a of middle cerebral artery insufficiency?

Contralateral paralysis Aphasia (brocas damage aka broadmans 44+45) Sensory loss (ant internal capsule) Motor loss (post ant capsule)

What are the S&S of Wallenberg or lateral medullary vascular insufficiency?

Dysphagia Ataxia Horner's syndrome ispilateral Loss of pain and temp contralateral below the head

What are the S&S of medial medullary syndrome due to vertebral artery insufficiency/occlusion?

Contralateral spastic hemiplegia with loss of touch vibration and pressure

What are the s&s due to occlusion of the dorsal midbrain (aka Clauses syndrome)?

Ipsilateral cn3 palsy Contralateral ataxia and tremor

Weber aka medial midbrain syndrome (occlusion due to posterior cerebral artery branches) S&S

Contralateral spastic paralysis Ipsilateral CN 3 weakness (eye movements)

Distribution of blood supply of the brain

What are the 4 main thalamic nuclei

Vpl: neck and below Vpm: from head Lateral geniculate body: from Light (visual input) connects with superior colliculus Medial geniculate body: form Music auditory input connects with inferior colliculus

Basal ganglia nuclei

Caudate (+ putamen= corpus striatum) Lentiform (putamen, globus pallidus ext and int) Substantia nigra (pars compacta + reticulata)

3 functional psthways of cerebellum

Spinocerebellum ( balance of arms and legs) central aspect of posterior and anterior lobe Cerebrocerebellum ( info from cortex) lateral part of anterior and posterior lobe Vestibulocerebellum ( balance of trunk) in the floconodular lobe

3 nuclei of the cerebellum Medial to lateral

(Flowers Grow Every Day) Fastigial: spine Interposition Globose: proximal joints ex GH joint Emboliform: middle joints ex elbow Dentate: distal joints ex digital joints

What canNOT cross the BBB and what specialized regions have no BBB

Bacteria cannot, lipid soluble more freely than water soluble. Area postrema facilitates vomit response to toxins and the neurohypophysis and pineal gland for secreting hormones

Vertebral artery

CSF course

500 ml/ day produced by choroid plexus in lateral ventricles Into 3rd v to 4th v via aqueduct of sylvius Leaves via lateral foramina of lushka and median foramen of magendie Collects in cisterna Drains vía arachnoid granulations opening to the superior sagittal Sinus