NEURO Exam III

Most common risk factor for neurodegenerative diseases

Age

Physical symptoms of Parkinson's (3)

muscle rigidity, tremors, and postural instability

Markers of Parkinson's (2)

Loss of DA neurons in substantia nigra/nigrostriatal pathway (all; 50% loss for symptoms to begin) and aggregation of Lewy Bodies (not unique to Pk and not always present)

Lewy Bodies

Misfolded alpha-synuclein in presynaptic vesicules that create fibrils that aggregate

Selective Vulnerability (3 factors)

Branched axons, constant firing, and V-G Ca2+ channels make these neurons vulnerable to damage/death

Parkinson's malfunctioning proteins and functions

PINK (senses bad mitochondria) and PRKN (kills bad mitochondria)

Parkinson's Cycle

Oxidized DA damages lysosomes, which can't break down bad mitochondria, which causes oxidative stress and oxidizes DA

Treatments for PD (3)

L-DOPA increases DA signaling, deep brain stimulation (electrode in basal ganglia), injecting stem cells so they can differentiate into DA neurons

ALS alternative name

Lou Gehrig's disease

How long people with ALS live after diagnosis

3-5 yrs

ALS cause

prion-like degeneration of motoneurons in CNS

ALS symptom

muscles cannot be excited and waste away

Bulbar neurons

medullary neurons that help with chewing, speaking, and swallowing that degrade in ALS

Forms of ALS (2)

Upper and/or lower neuron degeneration

Upper neuron degeneration path and symptoms (2)

motor cortex and pyramidal path; muscle stiffness and spasms

Lower neuron degeneration and symptom

Thinning of ventral roots in the spinal cord leading to amyotrophic muscle wasting

Genes for ALS that cause aggregate proteins

SOD1 and TDP-43

Genes for ALS that cause defective RNA processing due to repeats

C9ORF72 and TDP-43

Loudness and measure

Amplitude; dB

Pitch and measure

Frequency; Hz

Timbre

Sound quality based on relative harmonic intensities

Pinna function

funnels sound into the ear canal in mammals

Tympanic membrane alternate name

eardrum

Ossicles (3) and function

Amplify sound; hammer (malleus), anvil (incus), and stirrup (stapes)

Oval window function

air movement transfers to fluid movement

Round window function

excess fluid from oval window goes into the round window/vestibular canal

Cochlea canals (3)

Scala vestibuli (top/entrance), scala media (middle), scala tympani (bottom)

Organ of Corti function and location

Scala media; converts sound into neural activity

Organ of Corti components (3)

Hair cells (receptors), basilar membrane (receives ripple from scala vest/tymp), tectoral membrane (on top)

Stereocilia and function

Hair cell bristles; connect basal and tectoral membranes. Open ion channels and depolarize hair cells

IHC function and row(s)

One row. Afferents: sound perception. Efferents: control IHC responsiveness

OHC function and row(s)

Three rows. Afferents: detect state of basilar membrane. Efferents: changes stiffness of basilar membrane for tuning

Basilar membrane stiffness organization

Narrow and stiff at the beginning for high pitches, wide and floppy at the end for low pitches

Cochlear nuclei

Brainstem nuclei where most auditory info crosses the midline

Binaural integration

Not all info crosses the midline, allowing for detection of relative intensity to determine location of sound

Superior olivary nuclei location and function

pons; first binaural analysis via integration from both ears

Inferior colliculi location and function

midbrain; processes auditory info

Medial geniculate nucleus location and function

thalamus; communicates between the inf. colliculi and the auditory cortex

Primary auditory cortex organization

Tonotopic; auditory neurons arranged from LOW to HIGH frequency

Deafness types (3)

Conduction deafness (middle ear problem), Sensorineural deafness (cochlea problem), Central deafness (brain problem)

Cochlear implant

Stimulates cochlea by replacing hairs; cures sensorineural deafness

dB scale type and when it is harmful (extended and 30 min)

log scale; 90 extended and 110 at 30 min

Tensor tympani and stapedius muscles function

Lock ossicles to dampen sound

Semicircular canals (3)

Fluid-filled canals for vestibular sense; pitch, roll, and yaw

Ampullae

Vestibular hair cells/stereocilia (extending into cupula) in semicircular canals

Vestibular nuclei and location

Brainstem nuclei that get info from CN VIII

Motion sickness causes (2)

Disconnect between vestibular and visual stimuli or unnatural passive movement

Utricle and Saccule and function

Membranes (not fluids) with hair cells that detect linear acceleration

Microvilli location and function

Taste cells; increase surface area

Individual taste bud sensitivity

Sensitive to one type only, but every part of the tongue has every type of taste bud

Papillae

Bumps on the tongue with taste receptors (increase surface area)

Ion channel taste senses

Salty (Na+ and other cations and maybe anions) and sour (H+)

Sour channel receptor

OTOP1 (pH-based)

Class A vs C GPCRs

A = regular, C = heterodimerize

Bitter receptor and class

T2R (A)

Umami receptors (2 types)

T1R1 and T1R3 (C); mGluR (MSG GPCR)

Sweet receptors (1 type)

T1R2 and T1R3 (C)

Is tasting based on # of papillae?

NO

Bitter receptors uniqueness

Broad; many receptors, same flavor

Taste receptors location

All over the body

Taste brain route (2)

Thalamus to gustary cortex

Cranial nerves for taste (3)

VII, IX, X

Anosmia

Odor blindness

Olfactory Epithelium

sheet at top of nasal cavity with olfactory receptor cells that sense airborne particles with cilia

Is the olfactory epithelium topographically organized?

No in humans but yes in mice

Cilia and gene relationship

One cilia = one gene for one scent reception type

Olfactory bulb components

Glomeruli (arbor collecting ONE type of scent) and mitrial cells (connect to glomeruli)

How often olfactory cilia are replaced

every 30-90 days

How olfactory sensory cells know which glomeruli to attach to

Receptor proteins bind to specific glomeruli

Only sense that doesn't pass through the thalamus

smell

Olfactory pathway (4.5 steps)

receptors to glomeruli to mitrial cells to (amygdala to hippocampus) or (prepyriform cortex)

Olfactory receptors in mice vs humans

1000+ vs 400

Vomeronasal organ (VNO), what receptors are used, and who uses them

Receptor cells detecting pheromones using V1R and V2R GPCRs in rodents

Trace Amine-Associated Receptors (TAAR), location, and who uses them

Pheromone detectors in epithelium and used by animals including humans

Do you know the diagram of the ear and eye?

You should

Myopia

Eye is too long, so convergence happens too short. Causes nearsightedness.

Optic cell types in order from top to bottom of retina (6)

[optic nerve], ganglion, amacrine, bipolar, horizontal, rods/cones, [pigmented epithelium]

Visual pathway steps (13)

Light to cornea to pupil to lens to epithelium to photoreceptors to bipolar cells to ganglion cells to optic nerve to optic chiasm to optic tract to lateral geniculate nucleus in thalamus to visual cortex

How light changes through the eye

Inverted and upside-down when hitting the retina

Retina

Receptive surface with photoreceptors

Cornea

Outer layer of the eye and primary refractor

Lens

Fine-tuner for refraction

Lens movement and what happens with age

Ciliary muscles, which become weaker with age and can focus the lens less

Photoreceptor types

Rods (low light) and cones (color)

Horizontal and amacrine cells functions (2)

Local processing and inhibitory reactions

Rods, cones, and bipolar cells potential uniqueness

Graded potentials, not APs.

What cells send APs for vision

Ganglion cells

Rhodopsin

Membrane of GPCRs that respond to light

Rods glutamate relationship

Rods reduce glutamate in the dark and photoreceptor activation STOPS glutamate flow

Pupil

Where light enters the eye

Optic disc and what it causes

Where blood vessles and gangli on cells leave the retina - blindspot because no photoreceptors

Fovea

Center of retina/vision and has the highest number of cones

Rod and cone structure (3 parts)

Body to mitochondria/golgi to membrane with discs of GPCRs

Optic chiasm

Where parts of the optic nerves cross the midline (right visual field goes to left brain and vice versa NOT based on eye but on side)

Lateral Geniculate Nucleus (LGN)

Part of the thalamus that combines visual fields into a complex visual field via hierarchy.

Complex visual fields

Based on hierarchy of processing, cells detect lines and movements by stacking info

Rhodopsin activation

11-cis retinal from vitamin A transformed to all-trans retinal via photon, activating the GPCR and preventing depolarization

Fovea features (3)

Cones only (and smaller), no other cell types (no ganglia), more cortex for this area

Brightness distinction factors (3)

Iris radius, photopic an scotopic sensitivity levels, and visual fields via bipolar cells

On-center bipolar cells

Inhibited by glutamate via mGluR6. Thus activated by light.