Sensory Physiology: Receptors, Vision, and Chemical Senses

299 flashcards

What is sensory physiology: Detecting the environment and body position by converting stimuli into nerve signals.
What is sensory transduction: Conversion of stimulus energy into electrical signals.
What are the steps of sensory transduction: Stimulus changes receptor permeability ’ graded potential ’ action potential if threshold is reached.
What is a graded potential: A variable-size change in membrane potential caused by a stimulus.
What is an action potential: An all-or-nothing electrical signal once threshold is reached.
How is stronger stimulus intensity encoded: Higher action potential frequency and recruitment of more receptors.
What is photoreception: Detection of light.
What is chemoreception: Detection of chemicals, including smell and taste.
What is mechanoreception: Detection of physical deformation, touch, vibration, or movement.
What is thermoreception: Detection of temperature.
What is electroreception: Detection of electrical fields.
What is magnetoreception: Detection of magnetic fields.
What is baroreception: Detection of pressure.
Which animals use thermoreception to detect prey: Snakes, vampire bats, and mosquitoes.
Which animals use electroreception: Platypuses, sharks, crayfish, dolphins, and bees.
Which animals use magnetoreception: Birds, sea turtles, insects, mollusks, and some mammals.
Approximately what percentage of sensory receptors are in the eyes according to the lecture: About 70%.
What is the sclera: Tough outer fibrous layer protecting the eyeball.
What is the cornea: Transparent structure where light enters the eye.
What is the choroid: Blood vessel layer supplying oxygen and nutrients.
What is the iris: Colored portion of the eye.
What is the pupil: Opening regulating how much light enters the eye.
What is the retina: Layer containing light-sensitive cells.
What is the optic nerve: Carries visual signals toward the brain.
What is the lens: Focuses light.
What is the tapetum lucidum: Reflective layer that gives photoreceptors a second opportunity to detect light.
What is monocular vision: Vision with a single eye.
What is bi-ocular vision in these slides: Two eyes without coordinated vision.
What is binocular vision: Coordinated vision using both eyes.
Where is raptor visual acuity highest: Deep fovea, with dense receptors for distant objects.
What is a shallow fovea associated with in raptors: Higher resolution according to the lecture.
Why do raptors tilt their heads: To redirect their line of sight onto an object.
What is the nictitating membrane: Protective third eyelid moving sideways across the eye.
Why is the nictitating membrane useful: Cleans and protects the eye without fully blocking light.
What is the supraorbital ridge: Bony ridge above the eye that shades and protects it.
What does an ophthalmoscope examine: Optic disc, retina, macula, and choroid.
What does tonometry measure: Pressure inside the eye.
What is glaucoma associated with: Elevated eye pressure and optic nerve damage in the lecture's explanation.
What does fluorescein staining reveal: Damage or missing surface layer on the cornea.
What is an electroretinogram (ERG): A minimally invasive recording of the eye's electrical response to light.
What change in vision was observed in reproductive females in the lecture example: Greater visual sensitivity.
How do pit vipers detect infrared radiation: Heat-sensitive pit organs in the somatosensory system.
Do snakes literally see infrared light with their eyes: No; their pit organs detect heat.
What is Jacobson's organ associated with: Chemical sensing in snakes and lizards.
What is olfaction: Sense of smell; detection of airborne chemicals.
What is gustation: Sense of taste; detection of dissolved chemicals.
What are the five basic tastes: Sweet, salty, sour, bitter, and umami.
What type of olfactory neurons respond to odors in the lecture: Ciliated sensory neurons.
How many smell-related genes are listed for elephants, dogs, and humans: About 2,000; 1,000; and 400, respectively.
How many olfactory receptors are compared for dogs and humans: About 250 million in dogs versus 6 million in humans.
What is unusual about catfish taste buds: Many are outside the mouth, especially on barbels and lips.
What are catfish barbels used for: Chemical sensing and locating food.
What is a Pacinian corpuscle: A mechanoreceptor involved in sensing pressure and vibration.
What happens when a Pacinian corpuscle is deformed: Mechanically gated channels change permeability, creating depolarization.
Where is a Pacinian nerve ending myelinated: Myelinated outside the corpuscle, unmyelinated inside.
Where can touch-sensitive dendrites be found: Near skin surfaces and around hairs.
What is a hair cell: Mechanosensory receptor converting hair bundle movement to electrical signaling.
How many stereocilia are listed per hair cell: About 20-300.
What is a kinocilium: The single reference cilium on the hair cell in the lecture diagrams.
What happens when stereocilia bend toward the kinocilium: Channels open and neurotransmitter release increases.
What happens when stereocilia bend away from the kinocilium: Channels close and neurotransmitter release decreases or stops.
What happens to hair cells at rest: They release a low baseline amount of neurotransmitter.
What is the role of hair cells in the ear: Hearing and equilibrium.
What is the lateral line in fish: Mechanosensory system detecting low-frequency water displacement.
What can fish use the lateral line for: Prey detection, predator avoidance, social interactions, and locating objects.
What are trichobothria: Highly sensitive mechanosensory hairs on spider legs.
Why is electroreception common in aquatic animals: Water conducts electricity better than air.
How does a platypus locate prey underwater: Electroreception through its bill, alongside mechanoreception.
What can bees detect around flowers: Weak electric fields that may help with pollination.
What is acoustic impedance mismatch: A difference in how sound energy transfers between media, such as air and water.
What is the basic sound transmission pathway through the ear: Eardrum ’ ossicles ’ oval window ’ inner ear.
What is an auditory evoked potential: An electrical response recorded following sound stimulation.
How can hearing be measured besides evoked potentials: Behavioral or heart-rate responses and psychophysical experiments.
What does the cochlea encode: Sound frequency and intensity.
What is the vestibular apparatus: Inner-ear structures involved in balance and head movement detection.
What are the major vestibular structures listed: Saccule, utricle, and three semicircular canals.
What do the semicircular canals detect: Head rotational acceleration.
Why are the three semicircular canals oriented in different planes: To detect movement in different directions.
How does semicircular canal stimulation activate hair cells: Head movement shifts endolymph, bends cupula and hair cells, changing their electrical activity.
What is the cupula: Gelatinous structure displaced by endolymph movement in semicircular canals.
Why do aquatic mammals often have reduced external ears: To limit water entry, freezing, and heat loss.
What helps barn owls localize prey sounds: Facial ruff and asymmetrically placed ears.
What is the barn owl facial ruff: Feathers funneling high-frequency sounds toward the ears.
What do Eustachian tubes do: Equalize pressure across the eardrum.
What can happen with rapid pressure changes during diving: Eardrum injury or rupture.
What is ultrasound: Sound above about 20,000 Hz, the upper typical human hearing limit.
What is one hertz: One cycle per second.
What is the CNS: Brain and spinal cord.
What is the PNS: Nerves and ganglia outside the CNS.
What are the four major neurotransmitter categories in the slides: Acetylcholine, amino acids, biogenic amines, and neuropeptides.
What is acetylcholine (ACh): Neurotransmitter used in somatic, autonomic, and central pathways.
What is a cholinergic neuron: A neuron that releases acetylcholine.
What is the neuromuscular junction: Synapse between a somatic motor neuron and skeletal muscle.
What enzyme breaks down acetylcholine: Acetylcholinesterase (AChE).
What functions is acetylcholine associated with: Attention, memory, learning, sleep, movement, and visceral regulation.
What is the main inhibitory neurotransmitter in the brain: GABA.
What is the main excitatory neurotransmitter in the brain: Glutamate.
What is an excitatory amino-acid neurotransmitter in the spinal cord: Aspartate.
What is an inhibitory amino-acid neurotransmitter in the spinal cord: Glycine.
Which biogenic amines are catecholamines in these slides: Norepinephrine, epinephrine, and dopamine.
What do norepinephrine and epinephrine influence in the CNS: Mood, dreaming, wakefulness, and alertness.
What is an adrenergic neuron: A neuron releasing norepinephrine or epinephrine.
What is dopamine involved in: Reward, motivation, memory, attention, emotion, and motor control.
What is a dopaminergic neuron: A neuron releasing dopamine.
What is serotonin also called: 5-HT.
What is serotonin associated with: Mood, sleep, eating, digestion, alertness, and temperature regulation.
What amino acid is the precursor to serotonin: Tryptophan.
What does histamine do in the brain: Contributes to alertness and hypothalamic signaling.
What does histamine do when released by mast cells and basophils: Vasodilation and increased vascular permeability.
What enzyme breaks down biogenic amines: Monoamine oxidase (MAO).
What is the expected effect of an MAO inhibitor: Reduced breakdown and increased persistence of biogenic amines.
What is substance P: Neuropeptide involved in pain transmission; also linked to vasodilation and nausea.
What are enkephalins: Natural opioid peptides that inhibit pain signaling, especially in the spinal cord.
What are endorphins: Natural opioid peptides that reduce pain perception and may produce euphoria.
How can endorphins reduce pain signaling: Presynaptic inhibition of substance P transmission.
Why can the same neurotransmitter have opposite effects on different tissues: Different receptor types on target tissues.
What are the six major brain divisions listed: Cerebrum, diencephalon, midbrain, cerebellum, pons, and medulla oblongata.
What does the frontal lobe do: Memory, behavior, personality, and voluntary movement.
What does the parietal lobe do: Somatic sensory perception.
What does the temporal lobe do: Auditory and olfactory perception.
What does the occipital lobe do: Visual perception.
What does the insula do: Visceral perception.
What is the limbic system: Interconnected brain structures involved in emotion, motivation, arousal, and autonomic/endocrine responses.
What does the cingulate gyrus do: Decision-related processing, planning, shifting thoughts, and unpleasantness of pain.
What does the amygdala do: Recognizes emotional signals and threats, including facial expressions.
What does the hippocampus do: Spatial memory and consolidation of memories into long-term storage.
What are the three major parts of the diencephalon: Epithalamus, thalamus, and hypothalamus.
What gland is in the epithalamus: Pineal gland.
What hormone from the pineal gland is associated with sleep timing: Melatonin.
What is the thalamus: Major gateway and filter for sensory information reaching the cerebral cortex.
Which sense is the main exception to thalamic sensory relay: Olfaction (smell).
What can the thalamus do to sensory input: Filter, amplify, or tone down signals.
What is the hypothalamus: Main visceral control center for homeostasis.
What does the hypothalamus regulate: Temperature, hunger, thirst, sleep-wake cycles, autonomic activity, and endocrine function.
What are the main functions of the midbrain: Visual and auditory reflexes and motor control.
Where is the substantia nigra: Midbrain.
What does the cerebellum do: Maintains posture and balance and refines skilled coordinated movements.
What does the pons regulate: Respiration, bladder control, facial sensation/expression, posture, and eye control.
What are the three vital centers in the medulla oblongata: Cardiac, respiratory, and vasomotor centers.
What does the vasomotor center control: Blood vessel diameter and therefore vascular resistance and pressure.
What is vasoconstriction: Narrowing blood vessels, generally increasing resistance and blood pressure.
What is vasodilation: Widening blood vessels, generally decreasing resistance.
Why can opioids suppress breathing: They act on opioid receptors in respiratory control circuits.
What are the two major divisions of the PNS in the lecture: Somatic nervous system and autonomic nervous system.
What does the somatic nervous system control: Skeletal muscle, usually voluntary movement.
How many motor neurons connect CNS to skeletal muscle in the somatic system: One.
What neurotransmitter does a somatic motor neuron release: Acetylcholine.
What happens when a somatic motor neuron fires at the NMJ: Skeletal muscle contracts.
What does the autonomic nervous system control: Cardiac muscle, smooth muscle, and glands, mostly involuntarily.
How many neurons are in a typical autonomic motor pathway: Two: preganglionic and postganglionic.
What is a preganglionic neuron: Autonomic neuron from the CNS to a peripheral ganglion.
What is a postganglionic neuron: Autonomic neuron from a ganglion to an effector.
What is a ganglion: Cluster of neuron cell bodies in the PNS.
What is a nerve: Bundle of axons in the PNS.
What are the two divisions of the ANS: Parasympathetic and sympathetic.
What is parasympathetic activity nicknamed: Rest and digest.
What is sympathetic activity nicknamed: Fight or flight.
Where does the parasympathetic division originate: Craniosacral regions.
Where does the sympathetic division originate: Thoracolumbar regions.
Where are parasympathetic ganglia typically located: Near or within target organs.
Where are sympathetic ganglia typically located: Near the CNS/spinal cord.
What is the typical parasympathetic fiber arrangement: Long preganglionic and short postganglionic fibers.
What is the typical sympathetic fiber arrangement: Short preganglionic and long postganglionic fibers.
What neurotransmitter is released by autonomic preganglionic neurons: Acetylcholine.
What neurotransmitter is typically released by parasympathetic postganglionic neurons: Acetylcholine.
What neurotransmitter is typically released by sympathetic postganglionic neurons: Norepinephrine (with exceptions).
What type of receptor receives ACh at autonomic ganglia: Nicotinic cholinergic receptor.
What type of receptor usually receives ACh on parasympathetic target organs: Muscarinic cholinergic receptor.
What type of receptor usually receives NE on sympathetic target organs: Adrenergic alpha or beta receptor.
How does parasympathetic activity affect heart rate: Decreases it.
How does sympathetic activity affect heart rate: Increases it.
How does parasympathetic activity affect bronchioles: Constricts them.
How does sympathetic activity affect bronchioles: Dilates them.
How does parasympathetic activity affect pupils: Constricts pupils for close focus.
How does sympathetic activity affect pupils: Dilates pupils for distant focus.
How does parasympathetic activity affect saliva: Increases salivation.
How does sympathetic activity affect the mouth: Often causes dry mouth.
How does parasympathetic activity affect digestion: Increases GI motility and secretions.
How does sympathetic activity affect digestion: Decreases GI motility and secretions.
What tissue in bronchioles responds directly to ANS signaling: Smooth muscle.
What tissue in blood vessel walls responds directly to ANS signaling: Vascular smooth muscle.
What do alpha adrenergic receptors generally cause in blood vessels in the slides: Vasoconstriction.
What do beta adrenergic receptors generally cause in blood vessels in the slides: Vasodilation.
How does vessel radius affect resistance: Larger radius lowers resistance; smaller radius raises resistance.
How does vasoconstriction affect blood pressure and local flow in the slides: Typically raises pressure and decreases local flow.
How does vasodilation affect blood pressure and local flow in the slides: Typically lowers resistance/pressure and increases local flow.
Does the ANS directly innervate skeletal muscle fibers: No; somatic motor neurons control skeletal muscle contraction.
How does sympathetic activity help supply skeletal muscle during emergencies: Can dilate blood vessels supplying skeletal muscles, increasing blood flow.
How does parasympathetic activity affect erectile tissue: Promotes vasodilation and engorgement.
How does sympathetic activity affect reproductive ducts: Causes smooth muscle contraction and fluid ejection.
Which ANS division is described as more convergent: Parasympathetic, producing focused responses.
Which ANS division is described as more divergent: Sympathetic, producing widespread simultaneous responses.
Why can sympathetic responses affect multiple organs at once: Divergent neural pathways branch to multiple targets.
Why is the parasympathetic response usually more localized: Ganglia lie near targets, producing more focused signaling.
If a student is startled, which ANS division becomes dominant: Sympathetic.
If someone is quietly digesting lunch, which ANS division is most active: Parasympathetic.
If a drug blocks muscarinic receptors, which ANS target signaling is reduced: Parasympathetic ACh signaling at many target organs.
If NE binds vascular alpha receptors, what happens: Blood vessels constrict.
If NE binds vascular beta receptors, what happens in the slide model: Blood vessels dilate.
If a brain injury disrupts balance and refined movements, which region is likely affected: Cerebellum.
If visual perception is impaired, which cerebral lobe is relevant: Occipital lobe.
If smell bypasses the main thalamic relay, which sense is involved: Olfaction.
If hair bundles bend toward the kinocilium, what happens to transmitter release: It increases.
If an action potential threshold is not reached, what happens: No action potential is generated.
What is autocrine signaling: A cell releases a signal that acts on itself.
What is paracrine signaling: Local chemical signaling to nearby cells.
What are the two long-distance control systems: Endocrine and nervous systems.
How does endocrine signaling travel: Hormones travel through the bloodstream.
How does nervous system signaling travel: Electrical signals travel along axons; neurotransmitters signal target cells.
Endocrine vs nervous system response speed: Endocrine is slower and longer-lasting; nervous is faster and brief.
Which cells respond to a hormone: Only cells with the appropriate hormone receptor.
What makes up the CNS: Brain and spinal cord.
What makes up the PNS: Nerves and ganglia outside the CNS.
What are the two PNS motor divisions: Somatic and autonomic nervous systems.
What does a sensory neuron do: Carries incoming information from receptors toward the CNS.
What does an interneuron do: Integrates and processes information within the CNS.
What does a motor neuron do: Carries outgoing commands toward effector tissues.
Which functional neuron type is most abundant: Interneurons.
What is the basic neural information pathway: Stimulus ’ receptor ’ sensory neuron ’ interneuron ’ motor neuron ’ effector.
What do dendrites do: Receive incoming information.
What does the cell body do: Integrates information and contains the nucleus.
What does the axon do: Conducts outgoing electrical signals.
What does an axon terminal do: Releases neurotransmitters.
What are nodes of Ranvier: Gaps between myelin segments on an axon.
What is the resting membrane potential in the slides: -70 mV.
What does resting membrane potential describe: The electrical charge difference across the membrane at rest.
What is electrochemical disequilibrium: An electrical and chemical imbalance across a membrane.
What is an ion equilibrium potential: Membrane voltage where an ion has no net electrochemical movement.
What is a graded potential: A local change in membrane voltage that varies in size.
What does decremental mean: The signal becomes smaller as it spreads.
What is an action potential: A rapid all-or-none change in membrane voltage that propagates without fading.
What does all-or-none mean: An action potential occurs fully once threshold is reached.
What is the threshold in the lecture: -55 mV.
Where do action potentials typically begin: At the axon hillock or initial segment.
What are the four action potential phases listed: Threshold, depolarization, repolarization, hyperpolarization.
What ion channels open at threshold: Voltage-gated Na+ channels; K+ channels open more slowly.
What causes depolarization: Na+ enters the neuron, making the inside more positive.
What is the approximate action potential peak: +30 mV.
What happens to Na+ channels near the peak: They inactivate.
What causes repolarization: K+ leaves through voltage-gated K+ channels.
What causes hyperpolarization: K+ channels close slowly, so extra K+ leaves.
What restores the resting voltage after hyperpolarization: K+ channels close and resting ion permeability predominates.
What is the absolute refractory period: A period when another action potential cannot be initiated.
What is the relative refractory period: A period when a stronger-than-normal stimulus is needed.
Why are action potentials non-decremental: They regenerate along the axon rather than fading.
Can graded potentials summate: Yes, they can add together.
Can action potentials summate in amplitude: No, each action potential has a fixed amplitude.
What is temporal summation: Repeated inputs close together in time add up.
What is spatial summation: Inputs from different locations add together.
Can spatial summation increase or decrease voltage: Yes, excitatory and inhibitory inputs can combine.
Do graded potentials have refractory periods: No.
Do action potentials have refractory periods: Yes, absolute and relative.
What triggers graded potentials according to the lecture: Signals such as neurotransmitters and hormones.
What triggers an action potential: Membrane voltage reaching threshold.
Where are graded potentials common: Dendrites and cell body.
How do action potentials normally travel: One way along the axon toward terminals.
What three factors affect conduction speed: Axon diameter, temperature, and myelination.
How does larger axon diameter affect speed: Larger axons conduct faster.
How does myelination affect speed: Myelination increases conduction speed.
What is saltatory conduction: Action potentials regenerate at nodes of Ranvier in myelinated axons.
How does temperature affect conduction: Temperature changes ion-channel kinetics and conduction speed.
What is a synapse: A junction where a neuron communicates with another cell.
What is the synaptic cleft: The gap between presynaptic and postsynaptic cells.
What happens when a presynaptic action potential arrives: Neurotransmitter is released into the synaptic cleft.
What is an ionotropic response: Neurotransmitter directly opens an ion channel receptor.
What is a metabotropic response: Receptor activation triggers intracellular second-messenger signaling.
Which is more direct: ionotropic or metabotropic: Ionotropic.
What is a second messenger: An intracellular molecule that relays a receptor's signal.
What happens if ligand-gated Na+ channels open: Na+ enters, usually causing depolarization.
What happens if K+ channels open: K+ typically exits, tending to hyperpolarize the cell.
What happens if Cl- channels open: Cl- conductance usually inhibits firing by hyperpolarizing or stabilizing voltage.
What is an excitatory postsynaptic potential (EPSP): A graded change that makes firing more likely.
What is an inhibitory postsynaptic potential (IPSP): A graded change that makes firing less likely.
What are the two main ways to stop synaptic signaling: Stop presynaptic impulses and clear neurotransmitter from the cleft.
What are the three ways neurotransmitter is cleared: Diffusion, enzymatic degradation, and reuptake.
What is neurotransmitter reuptake: Transport of released neurotransmitter back into the presynaptic cell.
What is enzymatic degradation of neurotransmitter: Enzymes break transmitters into inactive fragments.
What is an agonist: A molecule that activates a receptor and produces a response.
What is an antagonist: A molecule that binds a receptor and blocks activation.
What drug class does the lecture give as tranquilizers: Benzodiazepines.
What benzodiazepines are named in the slides: Valium (diazepam) and Xanax (alprazolam).
How many glial cell types are listed: Six: two in the PNS and four in the CNS.
Which glial cells myelinate PNS axons: Schwann cells.
Which glial cells protect ganglia in the PNS: Satellite cells.
Which glial cells myelinate CNS axons: Oligodendrocytes.
What is the role of astrocytes: Help maintain the blood-brain barrier.
What is the role of microglia: Phagocytic immune defense in the CNS.
What is the role of ependymal cells: Line CNS fluid cavities and help produce/circulate CSF.
What is cerebrospinal fluid (CSF): Fluid associated with CNS ventricles and central canal.
Which glial cells respond to CNS infection or damage: Microglia.
A neuron reaches -55 mV. What happens next: Voltage-gated Na+ channels open and depolarization begins.
A neuron is losing K+ rapidly. Which AP phase: Repolarization, or hyperpolarization if below resting voltage.
Repeated stimuli from one synapse add up. What is this: Temporal summation.
Inputs from several synapses add up. What is this: Spatial summation.
A drug blocks a receptor without activating it. What is it: An antagonist.
A neurotransmitter opens a channel directly. What response: Ionotropic.
A receptor activates an intracellular signaling cascade. What response: Metabotropic.
Damage to CNS myelin-producing cells affects which glia: Oligodendrocytes.
Damage to PNS myelin-producing cells affects which glia: Schwann cells