physio 3200 online exam 4

Sensory System

A specialized part of the nervous system responsible for detecting external and internal stimuli converting them into electrical signals (transduction) and processing this information to create perception.

Stimulus

Energy or a chemical that impinges upon and activates a sensory receptor.

Sensation

Conscious awareness of a stimulus.

Perception

Understanding the meaning of a sensation.

Sensory Receptors

Specialized nerve endings or cells that convert physical or chemical stimuli to generate graded potentials called receptor potentials which can initiate action potentials that travel into the central nervous system.

Mechanoreceptors

Sensory receptors that respond to mechanical stimuli including touch blood pressure on skin joints muscle inner ear etc.

Photoreceptors

Receptors in the eye that detect ranges of light wavelengths.

Thermoreceptors

Sensory receptors that detect temperature changes.

Chemoreceptors

Sensory receptors that respond to chemicals and sense smell and taste.

Nociceptors

Sensory receptors that detect the sense of pain activated by heat mechanical or other painful stimuli.

Sensory Transduction

The process by which sensory receptors transform electrical or chemical stimuli into graded potentials.

Receptor Potential

A graded potential generated by ion flux across a specialized receptor membrane when specific ion channels open or close.

Receptor Adaptation

The reduced receptor sensitivity that lowers action potential frequency in an afferent neuron despite continuous stimuli.

Rapidly Adapting Receptors (Phasic Receptors)

Receptors that respond to changes in stimulation relating their action potential frequency to the rate of change in stimulus application/intensity.

Slowly Adapting Receptors (Tonic Receptors)

Receptors that respond to sustained stimuli referring to a decrease in action potential frequency despite a lack of change in stimulus strength.

Coding

The conversion of stimulus into action potentials that conveys sensory information to the central nervous system.

Sensory Unit

Includes the location of sensory receptors the axon processes reaching peripherally and centrally from the cell body and the terminals in the CNS.

Receptive Field

The area of the body where stimulation leads to activity in a particular afferent neuron.

Stimulus Modality

Another term for stimulus type such as temperature sound pressure light pain taste etc.

Labelled Lines

Distinct anatomical pathways carrying modality-specific action potentials to the central nervous system.

Sensory Acuity

The precision or clarity with which the nervous system can discern one stimulus from an adjacent one.

Convergence

Input from different or multiple afferent neurons projecting onto the same interneuron.

Divergence

The splitting of a single afferent neuron to synapse onto many downstream interneurons.

Lateral Inhibition

A mechanism that enables the localization of a stimulus site by strongly inhibiting information from afferent neurons at the edge of a stimulus compared to the center enhancing contrast.

Specific Ascending Pathways

Neural pathways that transmit information about a single particular sensory modality to specific sensory areas of the cerebral cortex.

Nonspecific Ascending Pathways (Polymodal)

Neural pathways that receive input from primary afferents that detect more than one modality.

Cortical Association Areas

Regions of the cerebral cortex that integrate relayed input from sensory stimuli leading to sensation and perception and serve higher functions like memory or emotion.

Phantom Limb Phenomenon

A phenomenon occurring when a limb lost through injury or amputation is still felt as present because sensory neural circuits in the CNS remain active without peripheral input.

Analgesia

The selective suppression of pain without effects on consciousness or other sensations.

Somatic Receptors

Receptors distributed across skin hair follicles muscles bones tendons and joints that initiate somatic sensation.

Stretch-Activated Ion Channels

Ion channels that open their pores in response to mechanical deformation of the plasma membrane allowing sodium influx.

Meissner's Corpuscle

A rapidly adapting mechanoreceptor responsible for sensing touch and pressure.

Merkel's Corpuscle

A slowly adapting mechanoreceptor responsible for sensing touch and pressure.

Free Neuron Ending

Slowly adapting small-diameter structures with little or no myelination including nociceptors itch receptors thermoreceptors and mechanoreceptors.

Pacinian Corpuscle

A rapidly adapting mechanoreceptor responsible for sensing vibration and deep pressure.

Ruffini Corpuscle

A slowly adapting mechanoreceptor responsible for sensing skin stretch.

Muscle-Spindle Stretch Receptors

Mechanoreceptors in skeletal muscles responding to the absolute magnitude of muscle stretch and the rate at which the stretch occurs monitoring muscle length.

Golgi Tendon Organs

Mechanoreceptors located in fibrous tendons near the muscle-tendon junction that monitor muscle tension.

TRP Ion Channels

Transient Receptor Potential channels in the axon terminal membrane that open at various overlapping temperature ranges to cause depolarization via sodium and calcium influx.

Substance P / Glutamate

Neurotransmitters released from primary afferent pain fibers in the dorsal horn of the spinal cord during pain stimulation.

Referred Pain

The sensation of pain experienced at a somatic site other than the injured or diseased visceral tissue due to convergence onto the same ascending interneuron.

Hyperalgesia

An increased sensitivity to painful stimuli that can last for hours after the original stimulus is gone.

Anterolateral Pathway (Spinothalamic Pathway)

A sensory pathway that processes pain and temperature whose second neuron immediately crosses to the opposite side of the spinal cord and ascends to the thalamus.

Dorsal Column Pathway

A sensory pathway processing fine touch proprioception vibration and two-point discrimination that ascends on the same side of the spinal cord and crosses over in the brainstem.

Motor Unit

A motor neuron and all the skeletal muscle fibers it innervates.

Motor Neuron Pool

All the motor neurons in the central nervous system that affect a single specific skeletal muscle.

Motor Program

The pattern or sequence of neural activity required to properly perform a desired movement created by middle-level structures.

Proprioception

Afferent information about the position of the body and its parts in space.

Intrafusal Muscle Fibers

The modified skeletal muscle fibers within a muscle spindle apparatus wrapped by afferent stretch receptors.

Extrafusal Muscle Fibers

The primary skeletal muscle fibers that form the bulk of the muscle and generate its mechanical force and movement.

Alpha Motor Neurons

Large motor neurons that activate extrafusal muscle fibers to induce muscle contraction and force.

Gamma Motor Neurons

Smaller motor neurons that activate intrafusal muscle fibers to maintain tension in the muscle spindle and prevent slackening.

Alpha-Gamma Coactivation

The simultaneous firing of both alpha and gamma motor neurons during voluntary muscle shortening to maintain muscle spindle sensory feedback.

Stretch Reflex

A monosynaptic reflex wherein afferent fibers from a stretched muscle spindle synapse directly and excitatorily on alpha motor neurons of the same muscle t

what structure is involved in the sense of balance and spatial orientation?

Semicircular canals

cochlea

structure in the inner ear that is responsible for converting sound vibrations into neural signals

olfactory epithelium

structure that contains the sensory receptors for smell

olfactory bulb

neural structure in the forebrain that receives smell information from the nose and begins processing our sense of smell

Eustachian tube

a narrow, 35-millimeter-long canal that connects your middle ear to the back of your throat

Ossicles

three incredibly small bones located in the middle ear: the malleus, incus, and stapes. They are collectively known as the auditory ossicles

tympanic membrane

a thin, cone-shaped layer of tissue that separates the outer ear from the middle ear. It plays a crucial role in the hearing process by vibrating when struck by sound waves and transmitting these signals to the tiny bones in the middle ear

what best describes a monosynaptic reflex?

It involves a direct connection between a sensory neuron and a motor neuron.

Where is the primary motor cortex found?

between the somatosensory cortex and premotor area of the cerebrum

what is the pattern of neurotransmitter activity is most consistent with the awake state?

high orexins, histamine, and norepinephrine; low GABA

general reflex arc are listed in the order information typically flows through them following a stimulus

receptor, afferent pathway, integrating center, efferent pathway, effecto