Comprehensive Review of Senses and Neural Pathways

Flashcards covering key vocabulary and concepts related to sensory systems, neural pathways, and related diseases, perfect for exam preparation.

Retina

Part of the brain facing outward to receive light.

Nerve fibers from the retina

Gather at the optic disc (blind spot) and form the optic nerve

Photoreceptors

Rods and cones

Photoreceptors

Connect to bipolar cells, which then connect to ganglion cells.

Horizontal and amacrine cells

Help with communication between layers of cells in the retina.

Outer segment of rods and cones

Contains discs with light-sensitive pigments.

Inner segment of rods and cones

Holds the cell’s organelles.

Retinal Pigment Epithelium (RPE)

Layer of cells under rods and cones.

Functions of the Retinal Pigment Epithelium (RPE)

Removes old discs from photoreceptors, absorbs stray light, provides nutrients, prevents immune reactions, helps recycle retinal, and maintains stable ion levels.

Rods

Help us see in black and white in dim light.

Rhodopsin

Pigment in rods that absorbs green light best.

Bleaching reaction

Breaks into retinaldehyde and opsin when light hits rhodopsin.

11-cis form

In darkness, retinal is in this form.

All-trans

Changes to this form after light hits and separates from opsin.

Dark Adaptation

Process where rods make more pigments and adjust to improve vision in the dark.

Olfactory epithelium

Location of smell receptors

Olfactory Apparatus components:

Sensory neurons (bipolar), supporting cells, and basal stem cells

Olfactory Receptors

Neurons with a ciliated knob in the nasal cavity.

Proteins on cilia

Bind specific odors.

How Smell Works

Uses G-protein-coupled receptors

Olfactory bulb

Signals travel from sensory neurons to this structure first.

Glomerulus

Term for area where each receptor type connects to in the olfactory bulb.

Nearby cells

These release GABA to reduce noise and sharpen smell signals.

Frequency

How fast the wave vibrates (measured in Hz).

Loudness

How strong the wave is (measured in dB).

Pinna (auricle)

Collects sound.

Ossicles (3 tiny bones in the middle ear)

Malleus, incus, and stapes

Ossicles

Amplifies vibrations in the middle ear.

Oval window

Structure the stapes hits to send sound into the inner ear

Stapedius muscle

Helps protect the ear from loud sounds.

Perilymph

Fluid between the bony and membranous tubes in the inner ear.

Endolymph

Fluid inside the tubes of the inner ear (high in K⁺).

Sensory Hair Cells

Cells with tiny hair-like parts (stereocilia and kinocilium).

Utricle and Saccule

Detect straight-line motion (side-to-side and up-and-down).

Otoliths

Tiny crystals in the gel of the utricle and saccule that shift with movement.

Semicircular Canals

Detect rotation (spinning).

Inner Ear (Vestibular Apparatus)

Tells your brain about head position and movement.

Eyes

Help your brain understand your position by seeing the environment.

Joints, Muscles, Skin

Tell your brain what your body is doing (e.g., knee bend).

Vestibular nuclei

Clusters of neurons in the brainstem where signals meet.

Cerebellum

Brain's coordination center that gets signals from the vestibular system.

Oculomotor Center

Helps your eyes stay focused when you move your head.

Spinal Cord

Controls your body's posture and movements to keep you upright.

Vestibular nystagmus

Repetitive, jerky eye movement caused by fluid in the semicircular canals keeping moving after you stop spinning.

Vertigo

False sense of spinning.

Meniere’s Disease

A disorder that causes rotational vertigo, tinnitus, and sometimes vestibular nystagmus.

Oval window

Vibrations start here and move into the perilymph in the scala vestibuli.

Vestibular membrane

Membrane through which vibrations cross into the cochlear duct.

Basilar membrane

Membrane through which vibrations continue into the perilymph of the scala tympani.

Round window

Vibrations exit the cochlea here to help release pressure.

Lateral Inhibition

Stronger touch stimulates certain receptors more than nearby ones.

Interoceptors

Respond to chemicals inside the body.

Exteroceptors

Respond to chemicals outside the body (taste and smell).

Taste buds

Receptors for taste.

Papillae

Bumps on the tongue with taste buds.

Fungiform Papillae:

Front of the tongue, signal via the facial nerve

Circumvallate Papillae:

Back of the tongue, signal via the glossopharyngeal nerve

Foliate Papillae:

Sides of the tongue, signal via the glossopharyngeal nerve

Primary gustatory cortex

Located at the insula

Somatosensory cortex

Located at the parietal lobe

Prefrontal cortex

for flavor evaluation

Labeled line theory

Each taste cell responds to one type of taste

Phasic Receptors (Fast-Adapting)

Respond quickly when a stimulus starts, then stop responding if it continues.

Tonic Receptors (Slow-Adapting)

Keep firing steadily as long as the stimulus is present, do not adapt quickly.

Generator Potential

A graded, local change in voltage in response to a stimulus.

Phasic receptor

Pacinian corpuscles are examples of this receptor type

Exteroceptors

Respond to stimuli from outside the body; includes cutaneous receptors and special senses

Interoceptors

Respond to internal stimuli; found in organs; include mechanoreceptors and chemoreceptors; monitor blood pressure, pH, and oxygen concentrations

Cutaneous Receptors

Skin sensory receptors

Ruffini corpuscles

Detect skin stretch

Meissner’s corpuscles

Sense movement across skin

Merkel’s disks

Detect indentation/pressure

Pacinian corpuscles

Sense deep pressure

Cold Receptors

Activated by cool temps (8–28°C), inhibited by warmth

Warm Receptors

Activated by warmth, inhibited by cold

Hot (Painful Heat) Receptors

Detect dangerous heat (above 43°C)

Pain Receptors (Nociceptors)

Detect pain from damage or irritation

Acute itch

Triggered by histamine, treatable with antihistamines

Emotional Response to Pain

happens when pain signals go from the thalamus to the anterior cingulate gyrus, part of the limbic system, which handles emotions.

Referred Pain:

Sometimes, pain from internal organs (viscera) is confused as pain in a different body part.

Receptive Fields:

The area of skin that affects a specific sensory neuron when touched

Two-Point Touch Threshold:

Tests how close two points can be on the skin before you feel them as one touch instead of two

Long-Term Potentiation (LTP)

A long-lasting increase in synaptic strength following high-frequency stimulation

AMPA Receptors

Mediate fast excitatory postsynaptic potentials (EPSPs) via Na⁺ influx

NMDA Receptors

Require both ligand (glutamate) and membrane depolarization to remove Mg²⁺ block

Synaptic Plasticity

Includes both LTP and long-term depression (LTD).

Hippocampus

Converts short-term memory to long-term; affected in Alzheimer’s

Amygdala

Emotional memory.

Prefrontal Cortex

Working memory and decision making

Thalamus

Relay station for sensory and motor signals

Hypothalamus:

Regulates hormones and emotions.

Epithalamus:

Contains the pineal gland (melatonin production).

Substantia Nigra:

Dopamine production; degeneration → Parkinson’s.

Reticular Activating System (RAS)

Network in brainstem that projects to thalamus and cortex.

Medullary rhythmicity center

Controls basic rhythm of breathing

Pneumotaxic and apneustic centers (pons)

Modify breathing rhythm

Cerebellum:

Coordinates respiratory muscles and posture

Reticular Activating System (RAS):

Regulates consciousness, wakefulness, and attention.

Varicosities:

Swelling along autonomic axons where NTs are released.

Agonists vs. Antagonists:

Drugs/toxins that either activate or block receptors.