Lab 1 : Neural and Sensory Function Flashcards
Objectives
A) Investigate some properties of the special senses and somatic senses
2) Elicit some reflexes
3) Illustrate fine motor control
How do sensory cells respond to factors such as light, pressure, chemical nature?
-respond by creating electrical signals that are sent to the nervous system
Why is it important to have information on the internal and external environment
to maintain homeostasis
What are the special senses
vision, taste, smell, equilibrium, and hearing
What do the special senses depend on (think organ) and what do they contain
Depend on complex organs and contain a large number of INDIVIDUAL sensory receptor cells
Where are the sensory cells of somatic senses found
not concentrated in sensory organs (like special senses), but found widely distributed amounf the skin, muscles, joints
Do REFLEXES and FINE MUSCLE CONTROL depend on sensory cell information
Yes
What are the three aspects of Vision (like the tests ig)
1) Visual Acuity: refers to the degree of detail that the eye can distinguish
2) Astigmatism: the blurring or distortion of the visual image caused by a defective curvature of the refractive surfaces of the eyes
3) Colour Vision:Ability to see colour
What is used to determine visual acuity
A Snellen Chart:
Test works by…
1) Standing 6 meters away from the chart
2)Cover one eye and read the letters on the chart until they are hard to distinguish
3)The last line read without mistakes represents the APPROXIMATE VISUAL ACUITY OF THAT EYE
What does Myopia and hyperopia mean
Myopia:
-Nearsightedness
-ability to see objects near you, but objects far away appear blurry
-occurs when the shape of your eye causes light rays to bend incorrectly, focussing images INFRONT of your retina instead of on your retina
Hyperopia:
-Farsightedness
-ability to see objects far from you more clear than objects near you
-occurs when eyeball is too short or curvature of CORNEA is too little, making light to focus BEHIND the retina, instead of on
What is Astigmatism
-the blurring or distortion of the visual image caused by the defective curvature of the refractive surfaces of the eye
-causes some light rays to not be sharply foccused but spread
How to test for Astigmatism
-look at the chart from 3 meters (10ft) away
-if the lines (bars) are sharp and evenly dark: eyes are normal
-if the lines are unevenly thick and some darker than others, while other lines are blurred and light: astigmatism
What is colour blindness caused by
deficiency in the retina’s system (cones: sensory cells that do this) for converting RGB light into receptor potentials
What measures colour perception
Ichikawa Colour Vision Test:
-used to detect red-green heriditary deficiency
-plates that have different colours on it that make up different numbers
-held 30 inches away from subjecy
-plates 1-4 are for orientation
-plate 5 is where testing begins
-the subject must concentrate on the coloured plate and say the number that they immediately see (if more than one is seen, they say the most common one)
-plates 15-19 determine the type of colour blindness
RESULT INTERPRETATION:
if 8 of 10 (since plate 5-14 is tested) is right, normal vision
if 3 or more abnormal responses: continue plates 15-19 to see which type of colour deficiency is present
What is the most common type of colour blindness
-red green deficiency
What shape and where are the taste bud sensory cells found
Shape: Barrel-shaped groupings of sensory cells
Located: tongue, epithelial lining of the mouth
How to test for taste
1) Dry Tongue
2) Apply the mxture you are testing for on the tip, sides and back of tongue
3) Indicate where u taste the solution
Solutions tested for:
5% Sucrose: sweet
1% acetic acid: Sour
5% NaCl: Salt
0.5% quinine sulfate;bitter
Are taste buds for different things uniformly distributed (is each pf the four primary tastes sensed equally everywhere inside the mouth?)
YEP!
How to test Olfaction
-Pinch your nostrils and eat a peppermint candy, determine whether it tastes like peppermint
-unplug your nose and taste it now
Results:
when plugging your nose, the strength of the peppermint is less strong
-therefore, olfaction increases taste
What are the two ways that sensory cells can respond to prolonged stimulation
the two ways allow the cells to be classified as two different types of cells
1) Tonic Cells:
- aka slowly-adapting sensors
-produce a continous sequence of action potentials as long as stimulus is present
-therefore, APs are as long as stimulus
2) Phasic Cells:
-aka rapidly adapting receptors
-if a continous, constant strength stimulus present: AP’s sent to CNS by these cells have a decreasing frequency (ie think one sent every 5 seconds instead of one sent every second)
-sense stimuli that is not important to survival
Garlic test
-tests to see if holding a constant stimulus changes our perception of the smell
-after 30 seconds of holding it under nose, it cannot be smelt anymore
How is hearing detected?
-vibration of oval window in response to sound waves (air conduction)
AND
-sound waves transmitted through Skull bones (bone conduction)
What are the three types of hearing tests
1) Rinne’s Test:
-tests for hearing problems using bone conduction and air conduction
-do this test in quiet environment
2) Webers Test
-test for hearing problems as well EXCEPT this tests for hearing individually for both ears, allowing differences between hearing loss of the ears to be determined
-ie can see if earing loss in right ear is different from left
3) Auditory Acuity
-tests the ability to hear different frequencies
Rinne’s Test
Steps:
1) hit a tuning fork and place the butt of handle on the MASTOID PROCESS OF TEMPORAL BONE (behind ear)
2)once sound is no longer detected (through skull), move it to the ear hole (external auditory opening)
if no damage to middle ear…
-sound will reappear when held to ear opening (positive result)
-may be an indication of sensorineural hearing loss too
If listening through skull better than listening through ear opening…
-means result is negative
-conductive hearing loss (inner or middle ear damage that cause sound that travels through air to be impacted)
-can be stimulated by placing a cotton ball in ear and doing test again as this prevents air conduction from occuring
Air conduction vs bone conduction
Air conduction: when sound waves travel through air into ear opening
Bone conduction: when sound waves use skull bone to detect souns waves
Webers Test
-place tuning fork on midlline of skull
-test on both sides of head to test for both ears
when plugging an ear: it is louder in the ear that is plugged, meaning that external noise causes the noise pf the tuning fork to be percieved as quieter