Sensory Physiology Quiz

Sensation

The process by which information about the environmental stimuli is received by a sensory receptor and then converted to action potentials that are sent to the brain

Perception

The brain receives and interprets the action potentials such that we are consiously aware of the sensation

What is an example of sensation?

A thermoreceptor will respond to a change in temperature at the skin surface and produce an action potential

What is an example of perception?

Information sent to the brain, which will receive and interpret the information as hot/cold

Exteroceptor

A sensory nerve ending that detects stimuli originating from outside the body

Interoceptor

A sensory nerve ending that detects stimuli originating from inside the body

Mechanoreceptor

A sensory receptor that responds to mechanical stimuli such as touch, pressure, vibration

Proprioceptors

A sensory receptor found in muscle, joint, and tendon tissue that detects changes in body position or movement

Thermoreceptors

A sensory receptor that responds to changes in temperature

Photoreceptors

A sensory receptor that detects light or changes in light, found only in the eyes

Chemoreceptor

A sensory receptor that responds to chemicals in solution

Nociceptors

A sensory receptor that responds to stimuli that is harmful to the body

Reflex Arc

A bodily response to some stimuli in a rapid, predictable pattern

What are the 3 components of a reflex arc?

A receptor, an integration center, and effector organ

Receptor

Respond to a particular type of sensory stimulus and then creates an action potential which is sent to the integration center

Integration Center

Interpret the incoming information and send out a motor response

Effector Organ

Performs the motor response

Motor Response

A muscle reaction triggered by a neural command

Intrinsic

A muscle contraction generated by local neural circuits independently of direct, conscious commands from the higher motor cortex

Spinal Reflex Arc

Very rapid movement of skeletal muscle tissue

Pupil

The open space at the center of the iris, the colored portion of the eye, that allows light to enter the eye and strike the retina

Why does the iris have two types of muscles?

They control the diameter of the pupil, therefore controlling how much light enters the eye

What happens when the dilator pupillae muscle of the iris contracts?

The pupil becomes wider

What happens when the sphincter pupillae muscle of the iris contracts?

The pupil becomes narrower

Consensual Reflex

The stimulus is applied to only one side of the body, but the response is observed on both sides of the body

Accommodation Reflex

Allows the eye to focus on objects at different distances

Lens

A strucutre inside the eye that helps to focus light directly on the retina by bending light as it enters the eye, allowing for clear vision

Pupil Accommodation

The size of the pupil changes according to distance of object requiring focus to adjust the amount of light entering the eye

Lens Accommodation

The lens can change shape to change the ability to refract light to focus it on the retina

Refract

To bend light

What happens when the lens is rounder / more it bulges?

The refractory power becomes stronger

What happens when the lens is flatter?

The refractoroy power weakens

Refractory Power

A measure of how strongly a lens, curved mirror, or surface bends light

Convergence

The process of both eyes moving/pointing inward to focus on an object depending on the distance of the object we look at

Patellar / Knee-Jerk Reflex

Occurs when the patellar tendon just below to patella when it is tapped by a reflex hammer

Jendrassik’s Maneuver

Alters the patellar reflex by forcing the individual to focus their attention somewhere else in the body, rather than thinking about the patellar reflex being performed on them

Achilles / Ankle-Jerk Reflex

When the Achilles tendon on the back of the ankle is tapped

Antagonistic Muscle

Usually have opposing action on a part of the body

What is the general rule with a muscle and its antagonist?

When the muscle contracts, the antagonist lengthens (and vice versa)

Palpate

Examine by touch

Ciliospinal Reflex

Mediated by the sympathetic nervous system (the “fight or flight” response) in response to pain

Plantar Reflex

Protects the sole of the foot when a painful stimulus is applied at the sole

Babinski’s Reflex

The big toe bends upward and the other toes fan out; normal in children under 1

Plantar Flexion

Toes can bend downward

Dorsiflexion

The big toe can point upward

Semicircular Canals

Three fluid-filled tubes in the inner ear that contribute to balance and equilibrium while moving

How do semicircular canals help contribute to balance and equilibrium while moving?

Aides in visual fixation on moving objects

Nystagmus

A reflextive movement when the inner ear is stimulated caused by semicircular canals

Anterior Semicircular Canal

Stimulated by forward and backward head movements (ex. flips)

Posterior Semicircular Canal

Stimulated by movement causing the head to tilt to the side (ex. cartwheels)

Lateral Semicircular Canal

Stimulated by movement where the head spins or moves side-side (ex. spinning)

Fast Phase Nystagmus

Rapid movement when the eyes move during nystagmus

Slow Phase Nystagmus

Slow movement when the eyes move during nystagmus

What designated the fast phase?

The direction of nystagmus

Rotary Nystagmus

Observed during movement when the fluid in the semicircular canal moves/flows, stimulating receptors in the inner ear

Post-Rotary Nystagmus

The eyes continue to move reflexively after movement has stopped

What are the opposite phases of rotary nystagmus?

The fast phase and slow phase of post-rotary nystagmus

Spatial Orientation

The ability to maintain the body’s position and posture in relation to our surroundings

The Inner Ear

Receptors here respond to changes in head position during linear acceleration and rotational movement

How is a mechanoreceptor stimulated?

The physical deformation of the receptor

What happens when the receptive area is smaller?

The more sensitive the skin will be to touch

Two-Point Threshold

The smallest distance at which two points of contact can be felt

Sensory Adaptation

If a stimulus is applied for a prolonged period without change, the rate of receptor discharge will slow, and conscious awareness of the stimulus will decline or is lost (until some stimulus change occurs)

Conduction Deafness

Results from damage to structures from the tympanic membrane to the auditory ossicles

What happens when the auditory ossicles (malleus, incus, stapes) are damaged?

Prevents transmission of sound to the inner ear

Nerve / Sensorineural Deafness

Occurs when the auditory nerve or brain is damaged such at action potentials relating to sound are either not produced by the auditory nerve or cannot be interpreted by the brain

If the condition is no hear loss, what are the Weber & Rinne test results?

There is no lateralization, and sound is perceived longer by air conduction

If the condition is conduction deafness, what are the Weber & Rinne test results?

There is lateralization to the poorer ear, and sound is perceived as long or longer by bone conduction

If the condition is nerve / sensorineural deafness, what are the Weber & Rinne rest results?

There is lateralization to the better ear, and sound is perceived longer by air conduction

Near Point

The closest point at which an object can be placed from the face and still form a focused image within the eye’s accommodation range

What is the near point test used for?

To demonstrate the elasticity of the lens and its ability to accommodate when viewing an object up close

What happens to the lens as we age?

The lens becomes less flexible and the accommodation becomes less effective

Presbyopia

A loss of near focusing ability

Optic Disc (Blind Spot)

An area at the back of the eye on the retina where there are no photoreceptors for visual reception

Visual Acuity

The sharpness of vision, involving the ability to discern letters or numbers at a given distance according to a fixed standard

Snellen Test

Uses a chart with letters of different sizes to show letters of different sizes should be seen clearly at different distances

How is a person’s visual acuity stated?

V = d / D; d = distance at which the patient can read the letters in a particular row, D = the distance at which a normal eye can read the letters in the same row

Myopia / Nearsightedness

Can see objects up close, while objects farther away are blurry or unclear (light cannot be correctly focused on the retina)

Hyperopia / Farsightedness

Can see objects far away clearly while nearby objects are blurry or unfocused (the shape of the eyeball and light not being focused directly on the retina)

Young-Helmholtz Theory of Color Vision

The theory of trichromatic color vision

Cone

A type of photoreceptor in the eye that allows for color vision; different ones respond to different wavelengths of light (red, blue, green)

What causes color blindness?

A lack of a particular gene on the X chromosome

Who is more likely to be colorblind?

An individual with XY chromosomes if the recessive trait is present on the X chromosome

Red-Green Color Blindness

The person lacks either the red or the green cones in the retina

Ishihara Test

The test for colorblindess consisting of different colored dots arranged on a plate