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To get a sense of the
importance of size in microscopy, see
the following on Cell Size & Scale:
http://learn.genetics.utah.edu/content/begin/cells/scale/
(Just drag the bar right to increase, and
left to decrease, the magnification.
Note, also, the scale that appears in the upper left hand corner!)
Looking: Light passes through the lens of the eye, and the vitreous humour, hits the retina, which stimulates rods (B/W) & cones (color) to send images are sent along the optic nerve . . .
Seeing: The brain actually processes the information, based upon prior knowledge, and assigns meaning to the images received.
When we LOOK, light hitting the Retina at the back of the eye sends a message along the
Optic Nerve also known as the 2nd Cranial Nerve (N II) passes through the
Optic Chiasm, by which the Sensory Data crosses over from Right to Left, and vice versa, then along the
Optic Tract to the
Lateral Geniculate Nucleus of the Thalamus (Diencephalon) to the
Primary Visual Cortex of the Occipital Lobe.
The Sensory Data is then PROCESSED, allowing us to SEE!
I have noticed many of my students over the years giving me drawings made while looking under the microscope that in no way resemble the actual tissues observed under the microscope.
These drwings almost always either have no labels, or the labels are so ill-conceived as to be of little value.
The usual response from students when I point these things out is "That's what I saw."
Given our definition of seeing above, it is clear that far from seeing, these students were only looking.
Had the students actually been seeing the specimen, not only would their drawing have been more accurate, but all of the visible eukaryotic cellular structures would have been properly labeled (The structures that follow depend upon the specimen being observed: cell wall and/or cell membrane, cytoplasm, nuclear membrane, nucleus, nucleolus, flagellum, cilia).
NOTE: Even though students may understand that they are looking at cells, it is VERY common to get drawings that fail to have cell membrane boundaries, and which focus only on the nuclei, which are usually mislabeled as cells, and usually just drawn as a bunch of dots.
After completing this tutorial, you should be able to focus your prior knowledge about cells and tissues upon what you are looking at, and you will most likely then be seeing it for the first time.
Your drawings will not only be more accurate representations of the specimens, but they will also contain more accurate labels. Am unlabeled drawing is little more than random scribbles on a piece of paper. Labels indicate that you actually were seeing the cells.
Before we continue w/ looking and seeing, we need to emphasize the issue with an analogy:: Listening vs. Hearing. There is another page at the end of the following tutorial that compares microscope photos (photomicrographs) with the drawings that you should be able to make from them.
One of the best ways to appreciate the difference between Looking and Seeing is to step back and compare Listening vs. Hearing.
The best way to truly understand the difference is to listen to a piece of music twice: the first time without preparation, and the second time using the new knowledge you are about to receive, which will help your brain to interpret the music differently!
Listening: Compressed waves of air (sound waves) hit the typanic membrane (ear drum), the vibration is amplified through the auditory ossicles (the bones of the inner ear), and the vibrations cause compressions in the fluid within the cochlea, causing the hair cells to and images are sent along the vestibulocochlear nerve . . .
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| Good Vibrations . . . | Better Vibrations . . . |
Hearing: The brain actually processes the information, based upon prior knowledge, and assigns meaning to the sounds received.
When we LISTEN, compression waves in the Cochlear Fluid stimulates Hair Cells sends a message along the
The Cochlear Branch joins the Vestibulocochlear Nerve, also known as the the Eigth Cranial Nerve (N VIII) travels through the
Vestibular and Cochlear Nuclei of the Pons and the Medulla Oblongata, and then travel through the
Medial Geniculate Nucleus of the Thalamus to the
Auditory Cortex of the Temporal Lobe.
The Sensory Data is then PROCESSED, allowing us to HEAR!
The basic elements of music:
Melody = the succession of notes played one after another (the horizontal aspect of the music)
Harmony = the sound when two or more notes are played simultaneously (the vertical aspect of the music)
Rhythm = the number of beat per measure (4/4, 3/4, 6/8, etc.), as well as the pattern of beats used in the measure (4 equal beats, 1 beat then 2 faster beats then 2 beats like the first)
Tempo = the speed at which the music moves (i.e., the time a certain beat in the music is held), from adagio (very slow) to allegro (very fast)
Timbre = the specific sound of the instrument, from the wooden sound of a clarinet to the brassy sound of a trombone
Dynamic Level = the volume of the music, from pianissimo ( pp = very soft) to fortissimmo (ff = very loud): ppp . . . pp . . . p . . . mp . . . mf . . . f . . . ff . . . fff
Try to identify any patterns in the music as you listen.
Try to identify the number of beats in the music (Most Rock & Roll is built on 4 beats -- it is in 4/4 time, hence the "boom, thwack, boom, thwack" alternation of bass drum on the 1st and third beats, and snare/symbols on the 2nd and fourth beats, "one, two, three, four." Most Jazz, on the other hand, emphasizes the 2nd and fourth beats in4/4 time, "one, two, three, four."); this leads to frustration when performing in front of audiences unaccustomed to Jazz, as such an audience will clap on one and three, while the band will emphasize two and four!
Listen for any changes in dynamic level, tempo, or timbre.
Click HERE to hear a MIDI file of the 3rd Movement, a Minuet, from Schubert's Piano Sonata # 18 in G major, "Fantasia," D. 894, Opus 78 |
Franz Peter Schubert |
Now that you have listened to the minuet, click on the link below to learn about the FORM of a Minuet. After learning the FORM you need to listen to the music ONE MORE TIME! The difference this time is that, having armed yourself with knowledge about musical form, you will actually HEAR the music for the first time!!!
