Special Senses Flashcards
1
Q
- Stimuli
- Sensation
- 2 types of receptors
A
- Stimuli: Sensory information that our bodies are constantly exposed to
- Sensation: Our conscious awareness to these stimuli
2 classes;
- General senses receptors: temp, pain, touch, stretch & pressure
- Special senses receptors: gustation, olfaction, vision, equilibrium & auditory
2
Q
3 types of stimulus origin receptors
A
- Exteroceptors
- found in skin or mucous membranes (nasal, oral vagina, anal)- “external receptors”
- Interoceptors
- found in walls of viscera - detect stretching, oxygen depravation, temp & pressure
- Proprioceptors
- found in muscles, tendons & joints
- detect body and limb movement, muscle contraction and stretching and changes in capsule struct
3
Q
Modality of Stimulus (6)
A
- several classes of receptors based on stimulating agent
1. Chemoreceptors: detect specific molecules dissolved in fluid
2. Thermoreceptors: detect changes in temp
3. Photoreceptors: Detect changes in light intensity, colour & movement of light
4. Mechanoreceptors: detect physical deformation due to touch, pressure, vibration and stretch
5. Baroreceptors: detect pressure changes w/in body structures
6. Nociceptors: detect tissue damage and pain
4
Q
How does sensation occur?
A
- Sensory receptors respond to environmental stimuli
- Nerve impulses travel to cerebral cortex and sensation (conscious perception of stimuli) occurs
- sensory adaptation = decrease in stimulus response - can occur w/ repetitive stimuli (i.e. odour)
5
Q
Flow chart of sensation process
A
Stimulus -> sensory receptor -> nerve impulses along sensory fibre -> spinal cord -> brain
6
Q
Receptive fields
A
- Entire area through which the sensitive ends of a receptor cell are distributed
- Smaller the receptive field = more sensitive and precise receptor is to location & nature of stimulus
7
Q
Tactile Receptors
- what they are
- location
- 2 types
A
-Most numerous type of receptor
-are mechanoreceptors that react to touch, pressure and vibration stimuli
-located in dermis and subcutaneous layer
2 types;
1. Unencapsulated: endings not wrapped in CT or glial cells
2. Encapsulated: endings wrapped in CT or glial cells
8
Q
Types of Unencapsulated Tactile receptors (3)
A
- Free Nerve Ending: widespread in deep epidermis & papillary layer of dermis
- detect pressure, change in temp, pain, touch - Root hair plexus: surrounds hair follicles in reticular layer of dermis
- detect movement of hair - Tactile Disc: stratum basale of epidermis
- detect light touch, textures and shapes
9
Q
Types of Encapsulated tactile receptors (4)
A
- Krause Bulb: mucous membranes of oral, nasal, vagina and anal cavity
- detect light pressure and low-frequency vibration - Lamellated corpuscle: dermis, subcutaneous tissue, synovial membranes and some viscera
- detect deep pressure and high-frequency vibration - Ruffini Corpuscle: Dermis and subcutaneous layer
- detect continuous deep pressure and skin distortion
- Tactile corpuscle: Dermal papillae (esp. lips, palms, eyelids, nipples and genitals)
- detect fine, light touch and texture
10
Q
Clinically significant types of pain (2 types)
A
- Phantom pain: sensation associated w/ part of body that has been removed
- sensory cell bodies from limb remain alive as part of dorsal spinal root
- also called phantom limb syndrome
-Referred pain: occurs when impulses form certain viscera, such as heart or appendix, are perceived as originating in dermatome of skin instead of the organ
11
Q
Taste Receptors
- how many
- 5 main tastes
- 4 types of tongue papillae
A
- 4000 taste buds located primarily on tongue of adults
- 5 main types; sweet, sour, salty, bitter and umami (savoury)
- 80-90% of what we perceive as taste is actually due to sense of smell
- Are 4 types of tongue papillae: filiform, fungiform, vallate & foliate
12
Q
Olfaction
- what detects smell
- 3 layers of it
A
- sense of smell
- Paired olfactory organs w/in nasal cavity
- Olfactory epithelium has 3 layers;
1. Olfactory receptor cells
2. Supporting cells
3. Basal cells
13
Q
Smell receptors
- apical end
- olfactory pathways
A
- Depends on 10-20 million olfactory cells in roof of nasal cavity
- at apical end of olfactory receptor cells are free nerve endings called olfactory hairs (project through mucous lining)
- hairs contain receptors for airborne molecules - axons from bipolar neurons of nasal mucosa pass through foramina of cribriform plate and enter olfactory bulbs
- neurons w/in olfactory bulbs project axon bundles called olfactory tracts to the olfactory cortex of temporal lobe
14
Q
3 layers of Eye wall
A
- Fibrous tunic
- vascular tunic
- Retina
15
Q
Layers of eye wall; Fibrous tunic
-2 regions
A
- Composed of 2 regions;
1. Cornea: transparent, avascular; receives oxygen and nutrients from lacrimal fluid and aqueous humor
2. Sclera: makes up majority of fibrous tunic; considered white of eye- allows for the attachment of extrinsic eye muscles to eye
