BIOL251 Sensory Physiology Lab Quiz 4

Two processes by which we can respond to stimuli and interpret it

sensation and perception

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 receiving and interpreting the action potentials such that we are consciously aware of the sensation

How are sensory receptors classified?

location and by what type of stimuli they respond to

Sensory receptors by location

exteroceptors and interoceptors

Sensory receptors by types of stimuli

mechanoreceptors, proprioceptors, thermoreceptors, photoreceptors, chemoreceptors, nociceptors

Mechanoreceptors

responds to mechanical stimuli such as touch, pressure, or vibration

Proprioceptors

found in muscles, tendons, and joint tissue. detects changes in body position or movement

Thermoreceptor

responds to change in temperature

Photoreceptor

found only in the eyes, detects light or changes in light

Chemoreceptor

responds to chemicals in solution

Nociceptor

responds to stimuli that is harmful to the body

Reflex arc

response to stimuli in a rapid, predictable pattern

3 components of a reflex arc

receptor, integration center, effector organ

Receptor

responds to a particular type of sensory stimulus and creates an action potential

Integration center

interprets incoming information from receptor and sends out a motor response

Effector organ

carries out the motor response

Intrinsic reflex arc

requires no experience or "learning" to be done by the body

Spinal reflex arc

rapid movement of skeletal muscle tissue (eg: touching. hot stove, receptors in skin send info about the temperature to the spinal cord, which sends a motor response to muscle tissue)

Eye reflexes

pupillary reflex and accommodation reflex

Pupillary reflex

the iris has two muscles that control the diameter of the pupil in response to light

Pupil

open space at the center of the iris

Iris

colored portion of the eye

Dilator pupillae muscle

causes the pupil to become wider

Sphincter pupillae muscle

causes the pupil to become narrower

Consensual reflex

stimulus is applied to only one side of the body but output is observed on both sides of the body (eg: light only shown to one eye but both pupils change diameter)

Accommodation reflex

response that allows the eye to focus on objects at different distances, involves the pupil and the lens

Lens

structure inside the eye that helps to focus light directly on the retina by bending light as it enters the eye

Three actions of the accommodation reflex

Pupil accommodation, lens accommodation, convergence

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 retina. the rounder the lens, the stronger the refractory power

Refractory power

determined by how scattered light rays are as they enter the eye (more scattered rays means object is close, lens must accommodate to bend more light)

Convergence

requires lateral and medial rectus muscles in eye, depends on distance of the object, eyes may need to point inwards to focus on the object

Tendon reflexes

any reflex arc that occurs when a tendon is tapped, causes a rapid contraction of the muscles associated with the tendon

3 types of tendon reflexes

patellar reflex, achilles reflex, antagonistic muscles

Patellar reflex (knee jerk)

tendon just below the knee cap is tapped with a reflex hammer

assesses L2-L4 vertebrae, diminished reflex can indicate peripheral neuropathy, lesions in sensory neurons that send info to spinal cord, etc.

Jendrassik's Maneuver

forcing the individual to focus attention elsewhere in the body, alters patellar reflex

Achilles reflex (ankle jerk)

tendon on the back of the ankle is tapped

assesses S1 nerve root, absence of reflex can indicate peripheral neuropathy or nerve root compression

Antagonistic muscle

a muscle that opposes the action of another. when one muscle contracts, the other lengthens

Importance of antagonist muscles in tendon reflexes

relaxation of the antagonistic muscle allows the muscle that contracts to do so strongly, smoothly, and in a coordinated pattern

Palpate

examine by touch

Ciliospinal reflex

response mediated by the sympathetic nervous system in response to pain (fight or flight)

Plantar reflex

protects the sole of the foot when painful stimuli is applied, most easily observable at the toes

Babinski's reflex

abnormal response in the foot for adults

indicates damage to the pyramidal tract fibers, a tract of nerve fibers that allow for voluntary movement

associated with amyotrophic lateral sclerosis (Lou Gehrig's disease), multiple sclerosis, stroke, and severe spinal cord injuries.

Plantar flexion

toes curl downward, normal response to reflex

Dorsiflexion

big toe points upward, indicative of Babinski

Labyrinthine reflexes

the inner ear plays a role in hearing and in equilibrium,

Types of labyrinthine reflexes

nystagmus, proprioception and spatial orientation

Nystagmus

reflexive movement of the eyes controlled by semicircular canals

Semicircular canals

three fluid-filled tubes in the inner ear that contribute to balance and movement by aiding in visual fixation on objects

Anterior semicircular canal

stimulated by forward and backward head movement (eg: backflip)

Posterior semicircular canal

stimulated by movement causing the head to tilt to the side (eg: cartwheel)

Lateral semicircular canal

stimulated by movement where the head spins or moves side to side (eg: spinning in a circle)

2 phases of nystagmus

fast phase and slow phase

Slow phase of nystagmus

first phase of nystagmus, eyes will slowly move in one direction as to maintain fixation on a moving target

Fast phase of nystagmus

eyes rapidly move or twitch in opposite direction

How is nystagmus named?

direction of fast phase

Rotary nystagmus

observed during movement when the fluid in the semicircular canal moves, stimulating receptors in the inner ear

difficult to observe

post-rotary nystagmus

eyes continue to move reflexively after movement

fast and slow phase opposite of rotary

Spatial orientation

the ability to maintain the body's position and posture in relation to our surroundings, allows us to move around objects rather than bump into them, allows us to move our own body parts

How does the brain carry out spatial orientation?

Inner ear, proprioceptors, photoreceptors

Inner Ear (spatial orientation)

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

Proprioceptors (spatial orientation)

monitors information such as joint position and stretch, joint angles, tendon tension, and muscle stretch. allows the brain to produce smooth, coordinated body movements without needing to visually monitor the movement.

Photoreceptors (spatial orientation)

receptors in the eyes provide visual information to the brain, allows brain to understand how body parts are positioned relative to one another

Five senses

sight, hearing, touch, taste, smell

Reflexes of touch

Tactile sensibility, adaptation to touch

Tactile sensibility

Ability to perceive touch through mechanoreceptors.

The smaller the receptive area the more sensitive the skin will be to touch because it provides specific information about what mechanoreceptor has been stimulated in the skin

Two point threshold

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

Adaptation to touch

The number of sensory impulses transmitted by sensory receptors can change with both intensity of the stimulus and the length of time the stimulus is applied.

Sensory adaptation

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)

Hearing reflexes

Weber Test and Rinne Test

Tuning fork tests

used to distinguish between conduction deafness and nerve deafness

Conduction deafness

hearing loss caused by damage to structures from the tympanic membrane to the auditory ossicles (malleus, incus, and stapes)

Nerve deafness

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

Weber test results for no hearing loss

No lateralization

Weber test results in conductive hearing loss

lateralization to poorer ear

Weber test results for nerve deafness

lateralization to better

Rinne test result for no hearing loss

sound perceived longer by air conduction

Rinne test results in conductive hearing loss

bone conduction >/= air conduction

Rinne test results in nerve deafness

air conduction > bone conduction

Reflexes for vision

near point, blind spot, visual acuity, test for colorblindness

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

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

Presbyopia

lens becomes less flexible and the accommodation becomes less effective, causes loss of near focusing ability

Blind spot

no photoreceptors here because this is the location where the optic nerve and blood vessels enter and leave the ey

Optic disc

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. The overall idea here is that for a "normal" eye (i.e., an eye with normal vision), letters of different sizes should be seen clearly at different distances. Larger letters should be seen at longer distances, and smaller letters should be seen at shorter distances.

Visual acuity formula

V=d/D

d= distance at which the patient can read letters

D= the distance to which a normal eye can read the letters

Myopia

caused by the eyeball being misshapen such that light cannot be correctly focused on the retina

an see objects up close, while objects farther away are blurry or unclear (nearsightedness)

Hyperopia

also an issue caused by the shape of the eyeball and light not being focused directly on the retina. but here, individuals can see objects far away clearly while nearby objects are blurry or unfocused. (farsightedness)

Young-Helmholtz theory of Color Vision

Different cones respond to different wavelengths of light. There are red cones, blue cones, and green cones. The combination of stimulation of the 3 different types of cones allows us to differentiate around 1 million colors

Cone

photoreceptor in the eye

Colorblindness

abnormality that is transferred genetically, resulting from a lack of a particular gene on the X chromosome. Being a recessive trait, an individual with XY chromosomes has a higher likelihood of the trait if the recessive trait is present on the X chromosome.

Most common color blindness

red-green color blindness

Red-green color blindness

person lacks either the red or the green cones in the retina. If an individual lacks the red cones, the red wavelengths of light will stimulate primarily green cones and they will perceive red as green. If the green cones are missing, the individual will perceive only red colors when viewing green wavelengths of light

Ishihara test

collections of differently colored dots arranged on a plate. People with color vision can see numbers formed by the differently colored dots, while those who are colorblind can see the dots but cannot recognize a number

Five categories of taste

salty, sour, sweet, umami, bitter

Sweet

elicited by sugars, saccharin, alcohols and some amino acids

Salty

elicited by metal ions

Sour

elicited by acids releasing their hydrogen ions in solution