Chapter 18: General and Special Senses Flashcards
What is a sensory receptor?
A specialized cell that sends sensations to CNS
what are the 2 sensory receptors? describe them
tonic: always sending signals to the CNS
phasic: becomes active only with changes in the conditions they monitor
What are the five types of receptors? state what they are used to detect
- ) Chemoreceptors:
- smell
- taste - ) Nociceptors:
- Cell damage (mechanical, electrical, thermal) - ) Thermoreceptors
- thermal - ) Mechanoreceptors:
- hearing
- stretching
- body position - ) Photoreceptors
- light
What is the receptive field?
area monitored by a single receptor cell
What is receptor specificity?
each receptor responds to a specific stimulus
Example: photoreceptor will not respond to a chemical stimulus
What is sensation?
The sensory information arriving at the CNS
What is perception?
Conscious awareness of sensation
- All nerve impulses are identical (just action potentials)
- Brain interprets impulses
- “Feeling” that occurs when sensory impulses are interpreted
When does sensory adaptation occur?
what does it result in?
- Occurs when sensory receptors are subjected to continuous stimulation
- Results in a reduction of sensitivity
- At some point along the pathway, impulses are conducted at a decreased rate
What are the two types of sensory adaption?
peripheral adaptation:
when sensory receptors decrease their level of activity
central adaptation:
Sensory neurons are still active
CNS causes reduced perception
describe sensory limitations
Sensory information from receptors is incomplete.
-Do not have receptors for every stimulus
-Other animals can detect things we cannot:
(Infrared, ultraviolet, ultrasonic, magnetism, etc.)
Receptors have limited ranges
Stimulation requires a neural event that is interpreted
Compare General and Specialized senses
General senses:
-Do NOT have specialized receptor cells or sensory organs
Special senses:
- Can have specialized receptor cells separate from the sensory neuron
- Structurally more complex
- Receptors localized in sense organs
What are the three major general senses groups? briefly describe
Exteroceptors -Relay info about external environment Proprioceptors -Depict body position in space Interoceptors -Monitor the internal environment
describe nociceptors
Sense tissue damage perceived as pain free nerve endings with large receptive field -found everywhere except brain -Provide a protective function -do not adapt well
What are the three types of pain? (just names)
fast pain
slow pain
referred pain
describe fast pain
Prickling pain
Quick; inducing a reflex usually; end when stimulus ends
describe slow pain
Burning
Begin later; persist longer; ache
describe referred pain
- Visceral pain that feels like it is coming from a more superficial region
- Due to superficial structures being innervated by the same spinal nerves as the damaged viscera
- “Brain-freeze”
describe thermoreceptors
-involve heat & cold
(no difference in structure between the two)
-Free nerve endings in skin
-Quick to adapt
-Felt as pain
(if temp goes above 45 C or if temp goes below 10 C)
which receptor type is sensitive to mechanical forces that cause tissues to be deformed?
Mechanoreceptors
What are the three types of mechanoreceptors? state what they sense
Tactile -touch, pressure & vibration Baroreceptors -pressure changes in walls of vessels, etc Proprioceptors -position of joints & muscles
There are 6 types of tactile receptors in two categories. What are the two categories?
unencapsulated
encapsulated
what are the three unencapsulated tactile receptors?
describe them
- ) Free nerve endings
- in papillary of dermis
- general touch - ) Root hair
- monitor distortions & movement across body surface - ) Tactile disc
- expanded nerve terminal that synapses with Merkel cell
- sensitive to fine touch
what are the three encapsulated tactile receptors?
describe them
- ) Tactile (Meissner’s) corpuscles
- found where tactile sensitivities are very well developed - ) Lamellated (Pacinian) corpuscle
- respond to deep pressure - ) Ruffini corpuscle
- in dermis
- detect pressure with little adaptation
describe Baroreceptors
-Stretch Receptors
-Monitor changes in pressure
-Detect stretching of tissue walls
-Regulates autonomic activities
examples:
digestive tract
bladder
carotid sinus
lung
colon
major arteries
describe proprioceptors
- Monitor position of joints, tension in tendons, state of muscle contraction
- No adaptation to stimulus
name and describe the two types of proprioceptors
Muscle spindle: monitor length of muscle
Golgi tendon organ: monitor tension in a tendon during contraction
Chemoreceptors respond to _________________ and monitor___________________________________
substances dissolved in surrounding fluids;
chemical composition of body fluids (ie: sensitive to pH, pCO2 changes)
Where are Chemoreceptors found?
inside CNS; medulla
aortic bodies
carotid bodies
What is Olfaction?
sense of smell
describe the Olfactory organ (3)
- Located within the nasal cavity on either side of nasal septum
- Covers the cribiform plate of ethmoid
- Made up of olfactory epithelium
the Olfactory Epithelium consists of what? (3)
Olfactory receptors -chemoreceptors Supporting cells -surround the receptors Basal cells -stem cells that grow new cells
The olfactory cells are covered in excretions from_________
olfactory glands
describe the olfactory receptors (3)
- Highly modified bipolar neurons
- Have cilia that extend into mucus secreted by olfactory glands
- Odorous particles dissolve into mucus and cause depolarization
describe the olfactory pathway (6)
- impulses travel along axons of receptor cells
- Pass through openings in cribiform plate
- Go to olfactory bulb and cranial nerve I
- Unique in that the impulse does NOT go through the thalamus
- Travel along tracts to limbic system (smells can trigger strong emotion_
- Interpreted as smell in temporal lobe & base of frontal
How many primary smells do we have?
50
Refer to slide 26 for last information regarding Olfaction
What sense is Gustation?
Taste
chemoreceptors in gustation structures are called what?
taste buds