Somatic nervous system quiz

Quiz Sadness

photoreceptors (rods and cones)

change membrane potential when stimulated by light energy

rods

very sensitive, contain photosensitive pigment rhodopsin, not sensing

cons

require brighter light to produce signal

Opsins

three cone photopigments of each eye each sensitive to a particular wavelength of light

optic disc

innermost layer of retina

blind spots

no photoreceptors at the very back of eye where the optic nerve begins

fovea

exact center of retina where no supporting cells and blood vessels are located

visual acuity

sharpness of vision

spinal nerves

typically contain different afferent axons from sensory receptors in skin mixed with efferent axons

dorsal root

contains only axons of sensory neurons

ventral root

contains only axons of motor neurons

diencephalon

region beneath cerebrum (hypothalamus and thalamus)

thalamus

collection of several nuclei, important relay between cerebrum and rest of nervous system

hypothalamus

has both somatic and autonomic functions

anterior nucleus

relay between hypothalamus and emotion and memory producing limbic system

medial nucleus

relay for info from limbic system and basal ganglia to cerebral cortex (memory creation during learning and determines alertness)

lateral nucleus

special and somatic sense info relayed to appropriate sensory cortex of cerebrum

somatosensory stimuli

travel below the neck via spinal cord, ex dorsal column system, spinothalamic tract

Somatosensory stimuli

travel the head and neck via cranial nerves, ex trigeminal system

dorsal column system

responsible for touch sensations and proprioception

fasciculus gracilis

contains axons from legs and lower body

fasciculus cuneatus

upper body and arms

medial lemniscus

second neuron in system projects from nuclei ascends brain stem as a bundle

Spinothalamic tract

responsible for pain and temperature sensations (dorsal root ———> dorsal horns)

trigeminal pathway

three successive neurons

sensory reception

occurs in periphery, signal sent to CNS

regions in CNS play a role in somatic processes

diencephalon, spinal cord and brain stem, cerebral cortex and subcortical structures

Axons from terminal ganglia

project to one of three locations (spinal trigeminal nucleus of medulla, chief sensory nucleus in pons, mesencephalic nuclei in midbrain)

sound localization occurs here

synapses with neurons in cochlear nuclei of superior medulla

interaural time difference

difference in arrival times of sounds to one ear compared to other

interaural intensity difference

difference in loudness of sounds to one ear compared to other

axons from inferior colliculus project to two locations

thalamus and superior colliculus

Thalamus (medial geniculate nucleus)

recieves info and projects it to auditory cortex in temporal lobe

superior colliculus

receives input from visual and somatosensory as well as ears, initiates stimulation of muscles that turn head and neck toward auditory stimulus

visual information

is segregated between left and right sides of visual fields

left field of view of each eye

processed on the right side of brain

right field of view of each eye

processed on the left side of brain

decussate

meaning to cross or intersect each other to form an x

optic tract

axons extending from optic chiasm

lateral geniculate nucleus of thalamus

axons from this nucleus project to visual cortex of cerebrum

suprachiasmatic nucleus of hypothalamus

only small number of of rgc axons project here,

cortical processing

stimuli ype identified based on location of original receptor cell

sensory processing cortex involves three distinct areas

primary sensory, association area, multimodal integration area

motor areas

primary motor cortex, motor association areas, frontal eye field

Sensory areas and related association areas

primary somatosensory cortex, sensory association area, wernicke’s area

prefrontal cortex

broca’s area

general interpretation area

primary visual cortex, visual association area, primary auditory cortex, auditory association

Visual Pathway example

1. projecting from retinae through thalamus to primary visual cortex in occipital lobe (recognize basic shapes, build on the image)

2. visual association cortex (adding color and motion info)

3. visual processing relayed to temporal or parietal lobe

ventral stream

relays to temporal lobe structures (interacts with non-visual cortex to incorporate visual stimuli into memories)

dorsal stream

relays information to parietal lobe (influences frontal lobe activity)