CNS

Question 1

how does the vertebrate CNS develop?

Answer 1

NEURULATION: folding of neural plate, allowing for formation of neural tube which will run down back and create spinal cord (dorsal nerve cord)

Question 2

cephalization definition

Answer 2

bilateral symmetry

Question 3

describe the evolutionary pattern in formation of spinal cord

Answer 3

consolidation of PNS (only possible with cephalization) –> nerves
ventral nerve cord –> dorsal nerve cord –> spinal cord –> increasing role of forebrain

Question 4

three regions of brain neural tube

Answer 4

forebrain (procephalon), midbrain (mesencephalon), hindbrain (rhombocephalon)

Question 5

what does the forebrain develop into?

Answer 5

cerebrum and diencephalon

Question 6

what does the midbrain develop into?

Answer 6

midbrain remains as midbrain

Question 7

what does hindbrain develop into?

Answer 7

medulla oblongata, cerebellum and pons

Question 8

what are the methods of protection for CNS?

Answer 8

bony cage (skull, vertebrae), meninges, fluid between layers (CSF)

Question 9

what are the meninges layers?

Answer 9

dura mater, arachnoid mater, pia mater in that order

Question 10

how does arachnoid mater get its name?

Answer 10

cob-web like arrangement

Question 11

where is fluid stored in the brain?

Answer 11

4 ventricles. 1&2 = lateral ventricles; 3 & 4 carries into a hollow central canal inside spinal cord

Question 12

where does CSF originate?

Answer 12

3rd and 4th choroid plexus (inside the respective ventricles); they secrete 500mL CSF per day

Question 13

what is the composition of CSF?

Answer 13

water, ions, vitamins, nutrients

Question 14

what role does the choroid plexus play?

Answer 14

controls CSF composition

Question 15

what are the extracellular fluids of the CNS?

Answer 15

interstitial fluid (surrounds neurons and glial cells), plasma (within cerebral blood vessels), CSF (within ventricular system, bathes external surfaces of the brain, between meninges)

Question 16

compare CSF and plasma

Answer 16

lower [ion], [glucose], and pH; similar Na+; VERY LOW PROTEIN, NO BLOOD CELLS

Question 17

why would one perform a lumbar puncture?

Answer 17

to check protein and blood levels inside of CSF; suggests meningitis

Question 18

what cells make up the CSF? what are their function?

Answer 18

ependymal cells; creates barrier between compartments

Question 19

what is the role of CSF?

Answer 19

clean out metabolite and toxins; does this by being removed and replaced often (4x/day)

Question 20

what are the layers of brain involved in draining CSF?

Answer 20

subarachnoid space and dural sinus; CSF is absorbed into the venus dural sinus via arachnoid villi

Question 21

what is the circulatory path of CSF?

Answer 21

lateral ventricles –> 3rd ventricles –> 4th ventricle –> central canal of spinal cord OR FLUSHED –> subarchnoid space – (via arachnoid villi) –> superior sagittal sinus – venus return to the heart

Question 22

what are the special features of cerebral vasculature?

Answer 22

astrocyte foot processes - secrete paracrine factors that promote tight junctions, which allow for thin capillaries & prevent solute movement between cells

Question 23

what crosses the blood-brain barrier easily? what does not?

Answer 23

lipid-soluble molecules (ethanol) cross easily; hydrophilic substances (ions, AAs, peptides, proteins) need transport mechanisms to cross the blood-brain barrier

Question 24

how do drug-developers handle the blood-brain barrier?

Answer 24

make the drug the shape of their goal - ie if they want something to cross the blood barrier (like a drug to treat Parkinson’s disease), make it the shape of an amino acid. if they don’t want something to cross (like antihistamines), making it lipid-soluble

Question 25

what are the metabolic properties of neural tissue?

Answer 25

oxygen-dependent (cannot fall back on fermentation the way muscles can) - therefore O2 readily cosses blood brain barrier; glucose-dependent (brain uses 50% of body's glucose requirement lmao); highly vascular bc it's dependent on O2 and glucose

Question 26

what is hypoglycemia? what is the result of it?

Answer 26

low blood sugar; coma death

Question 27

what is the role of spinal cord?

Answer 27

path of info flow from brain to muscles/joints/glands/skin

Question 28

what are the divisions of the spinal cord? (from dorsal to ventral)

Answer 28

cervical, thoracic, lumbar, sacral

Question 29

what's the major/most important nerve coming from the spinal cord?

Answer 29

vagus nerve

Question 30

where do parasympathetic nerves arise?

Answer 30

cranial + sacral

Question 31

where do sympathetic nerves arise?

Answer 31

thoracic + lumbar

Question 32

what nerves are associated with the dorsal root ganglion?

Answer 32

incoming = afferent

Question 33

what nerves are associated with the ventral root ganglion?

Answer 33

outgoing = efferent

Question 34

what's happening in the white matter?

Answer 34

mostly travel - this is travel of information to the brain AFTER integration of information; all about speed, so highly myelinated

Question 35

what's happening in the grey matter? what types of nuclei are found in the grey matter?

Answer 35

synapses and integration of information; no myelin obviously; sensory and motor nuclei

Question 36

what is happening in dorsal horn?

Answer 36

incoming somatic sensory nuclei (touch, pressure, pain); visceral sensory nuclei

Question 37

what is happening in ventral horn?

Answer 37

somatic motor nuclei synapses

Question 38

what is the brain stem? what nerves originate from it?

Answer 38

structures from mid and hindbrain; organised like spinal cord; most cranial nerves originate from brain stem - sensory and motor information for head and neck; vagus nerve(?);

Question 39

what is the reticular formation? where would you find its nuclei?

Answer 39

diffuse network of neurons involving processes such as arousal/sleep, muscle tone, coordination of breathing, blood pressure, etc; find nuclei of it in the brain stem

Question 40

what is happening in the lateral horn?

Answer 40

autonomic efferent nuclei

Question 41

what are the ascending tracts?

Answer 41

``` dorsal columns (sacral/lumbar + thoracic/cervical) which respond to touch/pressure/pain; spinocerebellar tracts which responds to proprioception = posture + coordination; spinothalmic which respond to pain+temp ```

Question 42

what are the descending tracts?

Answer 42

lateral+ventromedial corticospinal tracts = voluntary movement

Question 43

what is the path of a reflex?

Answer 43

stimulus --> sensory neurons --> interneurons --> command to muscles or gland --> response; spinal reflex initiates response without input from brain

Question 44

where do cranial nerves originate from? what do they do?

Answer 44

brainstem; carry sensory and motor info for head/neck; cranial nerve X = vagus

Question 45

what are the different brain stem structures? what are their functions?

Answer 45

midbrain = coordination of eye movement, visual and auditory senses; pons = relay station between cerebrum and cerebellum incl. regulating breathing; medulla = control of involuntary functions = BP, breathing, swallowing, vomiting + ascending somatosensory tracts + descending corticospinal tracts + site of crossing over for more neurons

Question 46

what are the different functions of the medulla?

Answer 46

grey matter: control of involuntary functions (breathing, swallowing, vomiting) white matter: asecnding somatosensory tracts + descending corticospinal tracts + site of crossing over (decussation) for most neurons in the corticospinal tract

Question 47

cerebellum function?

Answer 47

2nd largest structure of brain (after cerebrum), coordinates movement

Question 48

location of diencephalon? what are the different parts of it?

Answer 48

between brain stem and cerebrum; includes thamalamus, pineal gland, hypothalamus, and "pituitary gland"

Question 49

thalamus function?

Answer 49

relays and integrates information from the lower parts of the CNS, ears, eyes, motor info from cerebellum

Question 50

hypothalamus function?

Answer 50

tiny region of the brain but major centre for homeostasis; hunger, satiety, thirst, influences autonomic response, endocrine systems, regulates pituitary gland

Question 51

pinal gland

Answer 51

secretes melatonin; involved in regulation of circadian rhythms

Question 52

cereberum function?

Answer 52

largest region of brain; site of higher brain function

Question 53

four regions of cerebrum?

Answer 53

frontal, temporal, parietal, occipital

Question 54

what are the grooves called in cerebrum? what are the "raised" areas called?

Answer 54

sulcus = grooves, gyrus = raised

Question 55

what are the different regions of grey matter in cerebrum?

Answer 55

basal ganglia, limbic system, ceberal cortex

Question 56

role of basal ganglia?

Answer 56

coordinates movement

Question 57

role of limbic system?

Answer 57

coordinates fear/emotion with higher cognitive functoins

Question 58

what are the different functional areas of the cerebral cortex?

Answer 58

sensory areas (sensory input translation into perception), motor areas (control skeletal muscles), association areas (integrate information of sensory and motor areas)

Question 59

where is primary motor area?

Answer 59

right next to central sulcus (aka precentral gyrus), it contains cell bodies of primary ascending motor neurons

Question 60

where is the primary somatosensory cortex?

Answer 60

on ridges posterior to central sulcus = postcentral gyrus; terminals of ascending sensory pathways from skin, muscoskeletal system, viscera, info about touch/pressure/pain/temp/body postition

Question 61

where are the special senses located?

Answer 61

each have their own devoted area + assocation area eg primary vision cortex and visual association area are in occipital lobe

Question 62

what would a lot of fibres in the motor cortex mean?

Answer 62

fine movements, eg by hands/lips/tongue

Question 63

what would a lot of fibres in the somatosensory cortex mean?

Answer 63

sensitive area eg lips/hands