Unit 4 Special Senses Flashcards
1
Q
general senses
A
Temperature Pressure Fine touch Pain (nociceptors) Proprioceptors of muscles and joints
2
Q
special senses
A
Smell Sight Equilibrium Taste Hearing
3
Q
vision
A
dominant sense
70% of body’s sensory receptors are in the eye
Half of cerebral cortex is involved in visual processing
4
Q
eye structure
A
- wall with 3 layers
- internal cavities
- lens
5
Q
fibrous layer (wall)
A
outermost layer; dense avascular connective tissue
sclera
cornea
6
Q
sclera
A
- opaque posterior region
- Protects and shapes eyeball
- Anchors extrinsic eye muscles
- Posteriorly, continuous with dura mater (where optic nerve exits)
7
Q
cornea
A
- Transparent anterior 1/6th of fibrous layer
- Forms clear window that lets light enter and bends light as it enters
- Epithelium covers both surfaces
a. Outer layer protects from abrasions
b. Inner layer, corneal endothelium, contains sodium pumps that help maintain clarity of cornea - Numerous pain receptors contribute to blinking and tearing reflexes
8
Q
vascular layer
A
middle pigmented layer, aka uvea
- choroid region
- ciliary body
- iris
9
Q
choroid region
A
- Posterior portion of uvea
- Supplies blood to all layers
- Brown pigment absorbs light to prevent light scattering (causes visual confusion)
10
Q
ciliary body
A
- Anteriorly, choroid becomes ciliary body
- Thickened ring of tissue surrounding lens
- Consists of smooth muscle bundles, ciliary muscles, that contort shape of lens
- Capillaries of ciliary processes secrete fluid for anterior segment
- Ciliary zone (suspensory ligament) extends from ciliary processes to lens (holds position)
11
Q
iris
A
- Colored part of eye, lies between cornea and lens, continuous with ciliary body
- Pupil: central opening that regulates amount of light entering eye
- Changes in emotional state: pupils dilate when subject matter is appealing or requires problem solving skills
12
Q
pupil
A
- Close vision, bright light, cause sphincter papillae (circular muscles) to contact and pupils to constrict; parasympathetic control
- Distant vision, dim light cause dilator papillae (radial muscles) to contract and pupils to dilate; sympathetic control
13
Q
retina (inner layer)
A
originates as an out pocketing of brain contains: Millions of photoreceptor cells that transduce light energy Neurons Glial cells
14
Q
outer pigmented layer of retina
A
- single-cell-thick lining next to choroid, extends anteriorly, covering ciliary body and iris
- Absorbs light and prevents its scattering
- Phagocytes photoreceptor cell fragments
- Stores vitamin A
15
Q
inner neural layer
A
- transparent layer that runs anteriorly to margin of ciliary body; anterior end has serrated edges called ora serrata
- composed of neurons: photoreceptors, bipolar cells, ganglion cells
a. Signals spread from photoreceptors to bipolar cells to ganglion cells
b. Ganglion cell axons exit eye as optic nerve - Optic disc
- Has quarter-billion photoreceptors called rods and cones