Neuroscience Flashcards

Question

What is the function of oligodendrocytes?

Answer 1

* function= myelinate axons in the **CNS** * there are lots of them in the white matter * each one extends its processes to wrap around parts of **several** axons * NB: diff to schwann cells which meylinate single axons in the PNS

Answer 2

* myelinate axons in the **PNS** * one wraps around **one axon**

Answer 3

* contains nerve fibres * composed of * axon * schwann cell * endoneurium * 1 or \> bundles/fasicles/nerve fibres * perineurium * epineurium

Answer 4

* astrocytes * oligodendrocytes * schwann cells

Answer 5

* support cells in ganglia

Answer 6

* immune cell * resembles macrophages (has phagocytic function) * constantly surveying CNS * changes rapidly in response to inflammatory or injury * upregulates cytokines and GFs * has a role in development and disease * prunes synapses

Answer 7

sensory ganglia * house the cell bodies of sensory neurons e.g. DRG autonomic ganglia * house the cell bodies of post ganglionic neurons * both bontain cell bodies of neurons outside the CNS and satelite cells (support cells)

Answer 8

* neurons are specialsed for signalling * morphologically distinct * actin, intermediate filaments, microtubules * electrically active * membrane contains Na, ATPase pumps, ion channels * rapid communication * long distance * specialised * high level of protein synthesis * metabolically limited * terminally differentiated * they don't divide with age

Answer 9

* actin * **dynamic** assembly/disassembly * allows shape changes and movement * e.g. spines and growth cones * intermediate filaments * in all processes * **permanent** * maintain the shape of the cell * changes in disease sates * microtubules * **dynamic** * composed of tubulin * **axon transport**

Answer 10

* parkinsons * movement disorder * depletion of DA in basal ganglia * schizophrenia * behavioural disorder * changes in DA rich areas in frontal cortex, basal ganglia and temporal lobe

Answer 11

No. A synapse can only be excitatory or inhibitory, not both!.

Answer 12

yes some neurotransmitters are excitatory (glutamate) and some are inhibitory (GABA) and some are both (dopamine/serotonin) it depends on what receptor is present.

Answer 13

* Upper part of the cranium= cranial vault * Lower part of the cranium= cranial floor

Answer 14

* Coronal suture * Frontal bone and parietal bones meet * Anteriorly * In the coronal plane * Sagittal suture * In sagittal plane * Where the 2 parietal bones unite * Lambdoid suture * Where the occipital and parietal bones unite * In coronal plane * Pterion suture * H shaped suture * Seen in lateral view * Frontal, parietal, temporal and sphenoid bone unite * Bones are particularly thin here * Deep to it is the middle meningeal artery * Dangerous area to get a fracture here!

Answer 15

* Vertical part * Forms the forrid * Horizontal part aka orbital plate * Supraorbital margins (top of the eye socket) there is a 90degree angle where the rest of the frontal bone projects backwards * Forms the roof of the orbit which is why its called the orbital plate

Answer 16

* Flat and rectangular * Moulded to the shape of the brain * Anteriorly unites with frontal bone at coronal suture * Both parietal bones meet at the sagittal suture

Answer 17

* Relatively flat and moulded to the shape of the brain * Has a prominent bulge posteriorly called the external occipital protuberance (EOP)

Answer 18

Squamous part * Similar to the parietal bone * Flat, moulded to brain contour * Unites superiorly with the parietal bone * 3 processes come off it * Anterior projection= zygomatic process of the temporal bone * Articulates with the cheek bone/zygoma * *Depressed fracture of the cheek bone refers to a fracture of the zygomatic arch and process* * Posterior projection= Mastoid process of the temporal bone * Full of air cells (bone that isn’t solid but filled with air) * Projects inferiorly downwards * Gives rise to muscles in the neck e.g. sternocleidomastoid * Its relatively superficial * Styloid process * Deeply placed * Muscles associated with midline structures e.g. the tongue, pharynx * Sharp spike/point Another part of the temporal bone=petrous bone * Only see it when the cranial vault has been removed * Wedge/pyramidal shaped * Forming part of the cranial floor

Answer 19

* Very little can be seen of it on the external aspect of the brain * Looks like a bat with outstretched wings * Has a body * depression in it (where the pituitary gland sits) * Pair of outstretched wings with a split/fissure in them called the superior orbital fissure * Splits the wings into a lesser part anteriorly and a larger part called the greater wing posteriorly * 2 legs hanging down called the Pterygoid plates * Involved with muscles of mastication

Answer 20

* anterior cranial fossa * formed by horizontal plates of frontal bones and lesser wings of sphenoid * also has ethmoid bone that has the cribiform plate in it * middle cranial fossa * formed by greater wings of sphenoid anteriorly and petrous part of temporal bone posteriorly * posterior cranial fossa * formed by the occipital bones

Answer 21

* olfactory nerve fibres

Answer 22

* (its in the body of the sphenoid) * the pituitary gland

Answer 23

* optic nerve * opthalamic artery

Answer 24

* nerves to extra-ocular muslces * branches of the trigemnial nerve

Answer 25

* maxillary nerve

Answer 26

* Mandibular nerve

Answer 27

* middle meningeal artery

Answer 28

* (Hole in the petruos part of the temporal bone) * (‘In the step itself’) * Facial nerve * vestibulocochlear nerve

Answer 29

* (Irregularly shaped) * (In the split between petrus part of the temporal bone and occipital bone) * CNs IX,X,XI * internal jugular vein

Answer 30

* (In the occipital bone) * (Seen better when the skull is turned upside down on the bottom outside surface of the skull) * Holds the hypoglossal nerve

Answer 31

the brain stem

Answer 32

* Falx cerebri * Sickle shaped * Lies in the sagittal plane/in midline * Projects beneath the sagittal suture * Lodges between the right and left hemispheres but doesn’t go all of the way through * Tentorium cerebelli * Mostly Horizontal orientated (its tented) * Crescent shaped * Separates cerebral hemispheres above from cerebellum below * It’s a roof over the posterior cranial fossa * Falx cerebelli * Tiny * Seperates the cerebelli hemispheres * From behind * Diaphragm sellae * Roofs over the pit of the sphenoid where the pituitary sits

Answer 33

* Endothelial lines space containing venous blood where the outer and inner layer of dura has split * Collects venous blood from the brain (cerebral veins), diploe veins (drain spongy/middle table/component of skull bones), Emissary veins (from the scalp outside the skull through the outer plate of compact bone), Superior cerebral veins

Answer 34

* **superior sagittal sinus** * Extends from the falx cerebri anteriorly sticking up from the cribiform plate to posterior where it attaches to the internal aspect of the external occipital protubrence * Collects blood form the brain and some from the scalp * **Inferior sagittal sinus** * In the inferior aspect of the falx cerebri * **Straight sinus** * Where the inferior sagittal sinus gets to the point where the falx cerebri and the tentorium cerebelli and it mixes with the great cerebral vein to become straight * **Confluence of sinuses** * The superior sagittal sinus and straight sinus meet at the internal aspect of the EOP * **transverse sinus** * **sigmoid sinus** * At the edge of the middle cranial fossa (petrous part of the temporal bone) the transverse sinus then moves out in an S shaped bend =sigmoid sinus * then out the jugular foramen to now be called the **internal jugular vein** * **Cavernous sinus** * Pair of them * Sits on the lateral aspect of the body of the sphenoid * Receive blood from the cerebral, ophthalmic and emissory viens of the face * Structures that are heading for the superior orbital fissure lie underneath/through its lateral wall

Answer 35

* There are many small meningeal arteries! * The middle meningeal artery is the largest and the most important * It’s a branch of the maxillary artery * external carotid artery--\> superficial temporal artery (goes to the temple) and the posterior auricular artery and the maxillary artery * middle meningeal artery enters the skull through the foramen spinosum then splits into an anterior and posterior branch that grooves the internal surface * anterior division runs directly to the pterion * middle meningeal artery lies in the extra-dural space often tears during trauma--\> bleeds quickly--\>blood pulses!--\>extradural haemorrhageà intracranial P rises quickly

Answer 36

* Commonly during a fall--\>tearing occurs where the cerebral veins enter the superior sagittal sinus--\>venous bleed into the subdural space--\>blood oozes! --\>clot can calcify and not be detected--\> no symptoms (and can be find later)--\>calcified clot can become an epileptic focus * cerebral veins draining into the superior sagittal sinus

Answer 37

Site of action * General anaesthetics act on the brain cortex (hence depresses cortical processing of pain, loss of consciousness) * Local anesthetics act on peripheral nerves (therefore they regulate pain pathways) Mechanism of action * General anaesthetics * lipid theory * anaesthesia is caused by volume expansion of membrane lipids and can be reveresed by pressure * receptor interaction theory * inhibition of excitatory receptors and enhancement of inhibitory receptors * Local anaesthetics * act on Na transmembrane channels * hydrophobic theory * fast * non use dependent (does NOT depend on firing of nerves) * non charged form of drug binds to channel * hydrophilic theory * slow * use dependent * non charged form crosses the membrane then reforms charged form and can bind when the channel opens * Examples * General anaesthetics * desflurane, sevofulrane, isoflurane * propofol, thiopentone * Local anaesthetics * procaine, lignocaine, bupivicaine, roprivicaine * tetrodotoxin, saxitoxin

Answer 38

* generally safe * proportional to blood level * CVS effects * myocardial depression * depression of vasomotor centre * hypotension (except cocaine) * CNS effects * excitation * tremor * convulsion * resp arrest * not proportional to blood level * hyersensitivity/allergic rxns

Answer 39

* OTC * lozenges * sports gels * professional use only * eye drops for procedures * injections (lignocaine) for dysrhythmias

Answer 40

inhaled (to maintain you under) * desflurane * sevoflurane * isoflurane IV (to get you under quickly) * propofol * thiopentone Inhaled and IV are both LIQUIDS and they both AVOID 1ST PASS METABOLISM

Answer 41

resp * impiared ventilation * depressed resp centre * obstruction of airways (retention of secretions bc of mucocillary escalator is inhibited) cvs * decreased vasomotor centre function * depressed contractility * peripheral vasodilation * cardiac arrhythmias * inadequate response to fall in BP or CO

Answer 42

* spina bifida * ancephaly

Answer 43

* rostral end of neural tube starts to swell * forms 3 distinct vesicles * prosencephalon (forebrain) * mesencephalon (midbrain) * rhombencephalon (hindbrain) * prosencephalon splits into * telencephalon * diencephalon * Rhombencelphalon splits into 7 segments the rest is spinal cord * Rhombencephalon splits into * metencephalon (pons) * myeloencephalon (medulla)

Answer 44

* cortex * basal ganglia * hippocampus

Answer 45

* thalamus * hypothalamus

Answer 46

* neuroepithelium covers the neural tube * it adds layers to generate the cortex * all new neurons are born at the ventricular surface which contains stem cells

Answer 47

* cells attached to both surface * they are stem cells and can produce neurons * they act as railway tracks

Answer 48

* reelin mutation (one of the guide molecules to guide neurons across the layers) * Lissencephaly (DCX mutation)

Answer 49

fragile X syndrome

Answer 50

* signalling molecules set up gradients that define topography * floor plate induces ventral horn motor neurons * interneurons appear just dorsal to motor neurons * axonal growth initially via pioneer axons * axon is towed by growth cone * growth is steered up the chemical gradient * refinement/pruning of synaptic connections

Answer 51

* if you temporarily cover 1 eye shortly after birth in a kitten, 6 months later the eye is blind * everything is normal in the retina, the blindness is cortical and permament * the cortex is dominated by the eye that was open * closure at 6 weeks has no effect. therefore as long as you have the first 6 weeks of vision, closing the eye has no effect * therefore there is a critical period * BUT if both eyes are closed there is no ocular dominance column disruption therefore there is no competition for cortical space therefore they arent blind * the critical period for humans is 10 years!! Therefore if you interput vision during this period impairment can occur

Answer 52

* Meissner encode rate of force * Merkel encode grip force * Pacinian encode vibrations * Ruffini encode hand posture

Answer 53

* A deta type * with large myelinated axons * with cell bodies in the DRG * note its a single long axon from the periphery to the CNS. i.e. big toe axon has to travel a long distance

Answer 54

* the size of the receptor field determines whether you can detect the number of stimuli applied * Left hand side graph * big activation of b even though it is touching all 3 receptive fields, the brain detects there is only 1 point of contact * right hand side graph * a and c repond strongly because you have put the blue point right in the middle of its field. b has a weak amount of firing because its on its very edge of its receptive field. therefore the brain thinks there are 2 points of contact being applied

Answer 55

FALSE C1 only has a motor output

Answer 56

* 3 neuron sequence to reach the somatosensory cortex * **decussation in the caudal medulla**

Answer 57

* transmits pain, temp and touch * as it enters the spinal cord it immediately forms a connection with interneurons * crosses at the level of the spinal cord then ascends * note: motor neurons are ventral in the spinal cord. sensory neurons are dorsal

Answer 58

* axons that innervate Distal muscles are lateral * axons that innervate proximal muscles are more medial

Answer 59

* motor pool= all the motor neurons in the spinal cord that innervates a particular muscle. * motor unit= all the muscles that one motor neuron controls/innervates

Answer 60

* specialised sensory receptorsin the belly of a muscle * they detect changes in length of the muscle * sensory fibres= group I and II afferent axons wrap around muscles and have a surrounding CT sheath * muscle spindles lie in parallel with the muscle

Answer 61

* sensory receptor organ * detects changes in muscle tension/the amount of force that is being applied to the muscle * sensory nerve enters and interdigitates with the CT of muscle tendons * the golgi tendon lies in series with the muscle

Answer 62

* aka tendon jerk reflex/deep tendon reflex * the most simple reflex * you can do it anywhere there is a tendon * giving a tap to the tendon gives the muscle a bit of a stretch--\> activates stretch receptors/muscle spindle is lengthened--\> neuronal activity enters spinal cord--\> excitatory synapse at the end of the afferent fibre--\> synapses with and excites motor neuron--\> increaes rate of AP--\> muscle contracts * the spindle also activates an inhibitory interneuron which inhibits the antagonist motor neuron * NB muscle spindles are the only sensory organ that synapses directly with motor neurons * muscle spindles are low threshold and therefore dont need a lot of change in activity to actiavte them

Answer 63

* supraorbital margin * formed by the frontal bone * can see the supraorbital notch * infrorbital margin * zygomatic bone * maxilla * roof of orbit * frontal bone * lesser wing of sphenoid * floor * maxilla * zygomatic * palatine * lateral wall * zygomatic * greater wing of sphenoid * medial wall * maxilla * lacrimal bone (*most commonly fractured)*** * ethmoid *(most commonly fractured)* * body of sphenoid

Answer 64

* forms 5/6th of the eyeball * forms part of the outer coat of the eyeball * maintains the shape of the globe * offers R to internal and external forces * provides attachment for the EOMs * made of collagen organised into whirls therefore quite strong

Answer 65

* anterior 1/6th of the eye * forms part of the outer coat of the eye * refracting component * avascular and transparent * has 5 layers * its collagen fibrils are uniform in diam and run parallel to each other in lamellae. each lamellae lie at angles to each other therefore it is transparent

Answer 66

* its the junction between the iris and the cornea * its where the aqueous humour drains out of the eye * key structures in there * cornea * trabecular meshwork * canal of schlemm * ciliary body

Answer 67

* its made up of the iris, choroid and ciliary body * lies between the sclera and the cornea * its the middle coat of the eye ball * function= provides nutrition to the eyeball

Answer 68

* formation of aqueous humour (ciliary epithelium) * tethers lens (ciliary processes) * accomodation (ciliary muscle)

Answer 69

* its the substance made form the ciliary epithelium of the ciliary body * its important for maintaining the health of the lens and cornea * it creats the IOP * it passes through the pupil and drains via the anterior chambre angle into the venous supply

Answer 70

* it involves * ciliary muscle * innernated by parasymp NS * important for focussing * circular muscle * zonules(ligaments) that attach between the ciliary porcesses and the lens * when the ciliary muscle contracts, the lens becomes fat, this takes the P off the zonules therefore you can see up close objects * when the ciliary muscle relaxes the lens becomes taught and thin, this increases the P on the zonules and contracts them therefore you can see far away objects

Answer 71

* the loss of accomodation that occurs with age * caused by a reduction in the flexibility of the lens capsule and zonules * note: the nerves are still ok!

Answer 72

* sphincter pupillae * constricts the pupil * innervated by parasymp * has circular fibres so when it contracts it constricts the pupil * dilator pupillae * dilates the pupil * innervated by symp * has radial fibres so when it contracts it pulls the pupil open and dilates it

Answer 73

* underneath the retina * its the 3 layers of blood vessels * supplies nutrients to the retina

Answer 74

* optic nerve/optic disc * formed by the axons of the ganglion cells as they exit the retina to pass visual info to higher cortical areas * fovea/foveola=small dot in the macular * avascular * high density of cones * no rods * macular=surrounds the fovea * posterior pole * orra serrata= edge of the retina and the ciliary body

Answer 75

* band of dense CT that goes across the optic nerve from one side of the retina to the other * sieve hole that transmits nerve fibres

Answer 76

to the orbit * tributaries of the ophthalmic artery which is a branch of the internal carotid artery * central retinal artery (its the one you see when you look via an ophthalamscope) * ciliary arteries * long posterior ciliary artery * short posterior ciliary artery * anterior ciliary artery to the retina * dual blood supply * central retinal artery * supplies the inner retina * posterior ciliary artery * supplies the outer retina (photoreceptors)

Answer 77

* orbicularis oculi * depresses the upper lid (eyelid closes) * innervated by CNVII * levator palpebrae superiorsis * elevates upper lid (eyelid opens) * innervated by CNIII

Neuroscience Flashcards

(104 cards)