Neuro chap 8, 11-14 study guide

5 tastes

salt, sour, sweet, bitter, umami

chemistry of each taste

salt - electrolytes

sour - acidic

sweet - saccharides

bitter - K or Mg

umami - acidic

fungiform papillae

front of tongue, have taste buds

foliate papilllae

sides of tongue, have taste buds

vallate papillae

large at back of tongue, have taste buds

taste buds basic definition

cluster of taste receptors in papillae

life span of taste receptor cells

2 weeks

receptor potential

appropriate chemical activates taste receptor, depolarizes

responses of cells to various tastes

selective or broad

transduction of taste salt

salt - Na enters and opens Ca, leads to release serotonin

transduction of taste sour

H ions open acid channel and blocks K channels, releases serotonin

transduction of taste sweet, bitter, umami

GPCRs, second messenger IP3 releases Ca which opens ATP channels

cranial nerves related to taste

facial nerve 7 (anterior tongue), glossopharyngeal nerve 9 (posterior of tongue), vagus nerve 10 (epiglottis and pharynx)

taste pathway

medulla gustatory nucleus (MGN), ventral posterior medial (VPM) nucleus in thalamus, gustatory cortex (thalamus)

ageusia

loss of taste

labeled line hypothesis

separate paths for each taste quality

population coding

info combined and compared to determine taste

olfactory epithelium cell types

olfactory receptor cells, basal cells, supporting cells (mucus)

olfactory receptor cells lifespan

4-8 weeks

anosmia

no smell

olfactory path

mucus, receptor cells, olfactory bulb and cribiform plates, olfactory nerve, olfactory cortex

olfactory transduction

1. captured by mucus binds to gcr and activates

2. activates adenylyl cyclase which stimulates production of cAMP (second messenger, cation channel)

3. cAMP opens Na and Ca channels - causes depolarization (EPSP)

4. Ca closes Cl channels

5. Cl leaves (unusual), membrane depolarization (EPSP), combo generates AP

unique about olfactory cortex anatomy

bypasses thalamus

2 types of skin

hairy and glabrous

mechanoreceptors stimuli

pressure, stretch, touch, vibraiton

mechanoreceptor types

merkels discs, hair follicle receptors, meissner’s corpuscules, pacinian corpuscule, ruffini endings

merkels discs/meissner’s corpuscules

upper layer, light touch and pressure

pacinian corpuscles

deep layer vibration

ruffini endings

sustained pressure, mechanosensitive channels allow Na and Ca to depolarize

2 point discrimination

more mechanoreceptors in fingers, receptor types w small receptive fields, more brain tissue for fingers, neural mechanisms for high res discriminations

primary afferent axons

Aalpha, Abeta, Adelta, C fibers

A alpha fibers

giant, fastest, proprioceptors for skel muscle

A beta fibers

big, fast, non painful touch

A delta fibers

medium, pain/temp, immediate localized pain

C fibers

teensy, slowest, temp/pain/itch, delayed and diffused

spine segments

cervical - neck and arms

thoracic - chest

lumbar - legs

sacral - back of legs and genitals

shingles

type of herpes when all neurons of a single dorsal root become infected

spinal cord organization

dorsal horn, ventral horn, intermediate zone, and white matter

dorsal horns

sensory

ventral horn

motor

intermediate zone

interneurons

second order sensory neurons

in cord and receive input from dorsal root

dorsal column medial lemniscal pathway

non painful touch, decussates in medulla, dorsal column nuclei in medulla, thalamus (VP nucleus), primary somatosensory cortex

trigeminal pathway

touch from face, head, oral cavity

primary somatosensory cortex

parietal lobe behind central sulcus, primary bc receives dense inputs from VP nucleus of thalamus, neurons very sensitive

cortical somatotopy, homunculus

map of which sections of cortex are dedicated to certain body parts sensation

cortical map plasticity

cortex can expand into unused areas due to loss/training

agnosia

cant recognize objects

neglect syndrome

part of body completely suppressed

nociceptors

pain receptors

nociception

sensory process to provide signals that trigger pain

different types of nociceptors

all cation channels, chemical - acid, thermo - TRP, mechanical - pressure

hyperalgesia

more sensitive to pain after injury, inflammation, sensitize nociceptors, central sensitization in cord

referred pain

from internal organs but feels like from skin

spinothalamic pathway

painful touch, decussated immediately in cord

function of periaqueductal grey

center for analgesia (pain relief)

various endogenous opiods/ opiod receptors/ endorphins

morphine, heroin, codeine

related to producing opiods - enkephalin, edorphin, dynorphin

neurons for temperature

thermoreceptors, TRPs, menthol = cold, calpaicin = hot

smooth muscles

involuntary digestive tract, arteries, peristalsis

striated muscle

skeletal and cardiac

skeletal muscle

voluntary

cardiac muscle

involuntary

muscle fibers

individual muscle cell, multinucleated

somatic motor system

peripheral NS, voluntary, control skel muscle

low motor neurons

spinal cord directly command muscle contractions

upper motor neurons

motor cortex or brainstem and synapse onto lower motor neurons

ventral root

axons of motor neurons

motor unit

one alpha motor neuron and the fibers it innervates

motor neuron pool

all motor units for a single muscle

ways NS controls the force of muscle contractions

1. Varying firing rate (twitch summation)

2. Recruiting additional synergistic motor units (more small motor units = more fine control)

3. size principle – small neurons excited more easily

3 major sources of info to alpha motor nueron

Dorsal root ganglion cells – sensory input from muscle spindles

upper motor neurons – initiation and control of voluntary

interneurons – largest input

3 types of motor neurons

slow – slowly fatiguing red fiber smallest

fast – FF largest (fast fatiguing white) or FR medium (fatigue resistant white)

lateral line organs purpose

detect pressure changes and evolved to balance, aquatic animals and amphibians

vestibulo-ocular reflex

keep eyes pointed, sense head rotation

otolith organs

gravity and tilts

semicircular canals

rotation