click below
click below
Normal Size Small Size show me how
Exam 2 Concepts
Fundamentals of Neurobiology
Question | Answer |
---|---|
focal lengths of the cornea and lens | the cornea only has one single focal length while the lens curvature can change leading to different focal lengths |
how do we focus on an object | iris constricts/expands that makes the pupil constricts/expands that covers/opens the lens blocking away diverging light to focus on an object |
difference between the extracellular matrix fibers of the sclera and cornea | cornea fibers are orderly so light can pass through while sclera fibers are dense and clustered together for strength |
rods and cones density | cones densest in fovea (only has cones) and rods densest in peripheral retina on sides of macula (also use a little cones) |
what do rods respond to | absence of light |
phototransduction in the dark | cGMP levels goes up, Na+ channels (ligand-gated like, no action potential) open, opens voltage gated Ca+2 channel, initiating neurotransmitter release. |
phototransduction in the light | cGMP levels go down, Na+ channels (ligand-gated like) close, hyperpolarization, Ca+2 channels stay closed, no neurotransmitter release |
something in the right nasal hemifield gets processed | in the left temporal retina |
something in the right temporal hemifield get processed | in the right nasal retina |
something in the left nasal hemifield gets processed | in the right temporal retina |
something in the left temporal hemifield gets processed | in the left nasal retina |
something in the nasal retina will go to which layers of the LGN | 1 4 6 |
something in the temporal retina will go to which layers of the LGN | 2 3 5 |
m type retina ganglion cells go to which layer of the LGN | 1 and 2 |
p type retina ganglion cells go to which layer of the LGN | 3 4 5 6 |
something in the right temporal hemifield will follow which optic nerve | right |
something in the right nasal hemifield will follow which optic nerve | left |
something in the left temporal hemifield will follow which optic nerve | left |
something in the left nasal hemifield will follow which optic nerve | right |
does something in the right temporal hemifield decussate at the optic chiasm | yes |
does something in the right nasal temporal hemifield decussate at the optic chiasm | no |
does something in the left temporal hemifield decussate at the optic chiasm | yes |
does something in the left nasal hemifield decussate at the optic chiasm | no |
does something in temporal hemifields decussate at the optic chiasm | yes |
does something in nasal hemifields decussate at the optic chiasm | no |
does something in nasal retina decussate at the optic chiasm | yes |
does something in the temporal retina decussate at the optic chiasm | no |
which optic tract does something in the right hemifield follow | left |
which optic tract does something in the left hemifield follow | right |
in layer 4 of the primary visual cortex which cells detect movement | alpha |
in layer 4 of the primary visual cortex which cells detect color | beta |
auditory pathway | sounds waves to tympanic membrane, ossicles move, oval window membrane moves, fluid in cochlea moves, response in sensory neurons starts, signal transferred to brain stem, then to thalamus in MGN, to primary auditory cortex in temporal lobe |
cochlea function | when fluid is pushed from oval window, the wave properties of sound are conserved in the wave properties of the fluid that causes the basilar membrane to bend in response |
basilar membrane structures and functions | membrane is wider at apex where it is most flexible and narrow at the base where it is most stiff. higher frequencies with higher energies are needed to displace the stiff base of the membrane |
pitch and volume | pitch is depends on the region of the basilar membrane activated that activated the corresponding receptor (one receptor per region), and volume depends on the number of hair cells activated and the firing rate of each hair cell |
transduction of sound by cilia | when basilar membrane moves, whole complex moves either towards or away from tectorial membrane, depending on the direction of the movement, the cell will hyperpolarize/depolarize via K+ mechanical gated channel that will cause no/release of NT |
action potential for sound | specifc neurons arranged into bands in auditory cortex are hardwired to specific set of hair cells |
location of sound below 3 kHz | based on MSO cells that are only activated with coincident innervation from the right and left cochlear nucleus and the cells are arranged at systematic distances from the nucleus and the length of the axons determines which MSO is activated. |
location of sound above 3 kHZ | activation of cochlear nucleus of one side will excite the ipsalateral LSO and activate the contralateral MNTB that will inhibit the LSO on the contralateral side |
DCML pathway | information ascends through dorsal column on ipsilateral side, synapse in medulla, decussate and ascends via medial lemniscus to thalamus, synpase in VP thalamus, projects to cortex |
ST pathway | information goes through ventral horn and crosses grey bridge and ascends spinothalamic tract, synapse at VP thalamus, projects to cortex, |
organization of motor neurons | upper spinal cord has motor neurons that control upper extremities and etc. muscles that are axial have neurons located medially in spinal cord. muscles that are farther away from spinal cord have neurons lateral in spinal cord |
spinal cord circuit reflex with 1a sensory fiber | does not go to brain. sensory fiber coming from muscle spindle fiber synapses with alpha motor neuron in ventral horn and innervates muscle causes contraction which is monosynaptic and monitors muscle length |
spinal cord circuid reflex with 1b sensory fiber | goes to brain. proprioception from golgi tendon organ via 1b sensory afferent to activate interneuron which inhibits alpha motor neurons causing relaxation of muscle that monitors and maintains muscle force |
flexion reflex pathway | based on sensory receptor within muscle and requires polysynaptic: activation of ipsalateral flexor, inhibition of ipsalateral extensor, inhibition of contralateral flexor, activation of contralateral extensor |
spinal motor programs | circuit for coordinated control of walking resides within spinal cord, brain intiates movement but does not control the individual movements |
nature of spinal cord interneurons | laterally interneurons contact ipsalateral motor neurons within single or few adjoining segments giving exacting control. medial interneurons have long axons and connect to many segments on ipsa and contra sides, non-exact control |
descending projection from primary motor cortex | neurons travel from layer 4 through internal capsule and cerbral peduncle through pons where they become less organized and re-coalesce on ventral surface of medulla where they beomc pyramidical neurons |
lateral corticospinal pathway | originate from parts of the motor cortex that represent the limbs, decussate and enter lateral column and terminate on lateral cells groups in ventral and intermediate spinal gray matter |
venral corticospinal pathway | originate from parts of the motor cortex that areas involved in posture and terminate in medial parts of ventral horn and intermediate zone. do not decussate |
hypophyseal portal system | hypothalamus delivers hypophysiotropic factors to anterior pituitary via secondary plexus. the hypophyseal portal vein connects the anterior pituitary with the median eminence. the primary plexus darins interstitial space of the median eminence |
SON vs PVN | SON makes most of both OT and ADH but makes more OT and PVN makes more ADH than OT. OT(SON) > ADH (SON)>ADH(PVN)>OT(PVN) |
the affects of a hormone depend on | the receptor, the receptor location, the number of receptors, the amount of the hormone, and the binding profile of the receptors |
posterior pituitary hormones production and secretion (AVP,ADH, OT) | synthesized in SON and PVN and transported to posterior pituitary in neurosecretory vesicles. secretion erquires activation of sensory receptors that generates CNS signaling to SON and PVN. neural pathways can be excitatory (Ach) or inhibitory (NE) |
let down reflex | suckling of areola and nipple activates nerve ending that activates ST pathway to hypothalamus that releases OT that travells to receptors on myoepithelial cells around alveoli of mammary glands that cause contraction of cells |
expression of milk | contraction of myoepithelial cells compress underling alveolae that pressurizes fluid within alveolae and pushes it through lactiferous duct |
production vs expression of milk | milk produced in alveolar secretory cells that are controlled by PRL not OT. OT is only needed for excretion |
uterine myometrial contraction | OT receptor number and sensitive increase during terminal stages of labor. progesterone starts labor then as labor progresses, progesterone levels go down, estrogen levels go up and so do OT levels |
roles of AVP | regulation of blood pressure (control of smooth muscle contraction) and regulation of osmolarity (movement of water and solutes across DCT of medullary nephron and increase absorption of water and Na+) |
direct method of regulation of blood pressure | blood pressure low activates JGA releases renin which activates the angiotensin that activates angiotensin II that causes vasoconstriciton of arterial smooth mucles that increases BP |
indirect method of regulation of blood pressure | BP low activates JGA releases renin activates angiotensin activates angiotensin II activates aldosteron mechanism increases Na+ absorption activates osmoreceptors increase AVP levels excretes hypertonic urine and increase water absorption and BP goes up |