Week 6 – Sensory Physiology Flashcards
What are the major types of sensory receptors?
a. Chemoreceptors – sense chemical changes (e.g. taste buds, olfaction, CO2, O2, etc.)
b. Mechanoreceptors –sense mechanical force (e.g. touch, pressure, sound, etc)
c. Thermoreceptors –sense heat and cold, etc.
d. Photoreceptors –sense light energy
e. Nociceptors (pain receptor) –sense tissue damage
What part of the Brain interprets Cutaneous sensation?
The Somatosensory cortex of the Parietal lobe in Brain
How do Rods & Cones differ from each other?
Rods:
- “Black & White” Dim vision
- Extreme sensitivity to light
- Blurry vision (Low acuity)
- Several Rods merge onto 1 bipolar cell
- Absorbs 1 wavelength of light well
Cones:
- Color vision
- Less sensitivity to light
- Sharp vision (Higher acuity)
- Every bipolar cell contains only 1 Cone
- Every Cone gains an absorption of a different wavelength of light
What are the 2 parts that facilitate/eases our sense of equilibrium (balance)?
- Vestibular apparatus:
o Part of the inner ear; has 2 Otolith organs
+ 3 Semicircular canals aka (Utricle + Saccule)
What are Skin Sensations ?
Recognized by sensory receptors of the skin; sensory receptor = dendritic nerve endings (i.e. dendrites of sensory neurons)
o touch and pressure (= mechanoreceptors)
o warmth and cold (= thermoreceptors)
Cold thermoreceptors -detect drops in temperature
more cold receptors than warm receptors
cold and cold-menthol receptors –also activated by chemical menthol
Warm thermoreceptors -detect increases in temperature
heat and capsaicin receptor –also activated by chemical capsaicin (from chili)
o Pain (= nociceptors -detect tissue damage)
Send input/info. to the Somatosensory cortex of the Parietal lobe
o larger areas of somatosensory cortex devoted to areas of body with higher density of sensory receptors
What is happening at the cellular level in a “color blind” individual (e.g., cones/rods) ?
When 1 or more Cone cells aren’t working, present, or recognize a different color than normal (American Academy of Opthalmology)
Cornea
The transparent and convex (curved outward) anterior portion of sclera; this transmits and reflects
light.
Iris
Colorful, pigmented muscle consisting of radially and circularly arranged muscle
with an opening (pupil) in the middle; iris is the muscle regulates the diameter of the
pupil and hence the amount of light entering the eye; controlled by the sympathetic and
parasympathetic division
Lens
Structure inside the eye that is attached to the ciliary muscle by suspensory ligaments and refracts (pulls in) light to focus light waves on the retina.
Ciliary muscles
Circular muscle that surrounds the lens to control lens shape. For distance vision, ciliary muscle relaxes and lens gets stretched thin. For near objects, the ciliary muscle contract and the elastic lens returns to a rounder shape
Retina
the inner layer of the eye that contains photoreceptor cells (rods and cones) and
other neural cells; this part of the eye is important in detection of light (photoreception )
and transmission of nerve impulses to the brain.
Fovea centralis
the center of the retina; this is a region where images are focused in bright light; lots of cones with one cone per ganglion cell, so it provides sharp central vision
Optic Disc (Blind spot)
this is a point slightly off-center in the retina which lacks photoreceptor cells; it represents a route for passage of blood vessels and optic nerve into
or out of the eye
How does the Cochlea accomplish the discrimination of sound pitch?
Discrimination: perception of pitch depends on where basilar membrane is displaced
low pitch: longer wave length, so waves travel further through the cochlea, peak displacement of basilar membrane closer to apex (top of spiral) of cochlea
high pitch: sound waves don’t travel as far through the cochlea, so peak displacement of basilar membrane closer to base of cochlea
What is Pitch?
Related to frequency of sound waves; measured in hertz (Hz, cycles per second)
