Special Senses: Receptors, Ex: 22 General Sensation
muscle spindles
receptors sensitive to change in length of the muscle and the rate of that change. proprioceptors mechanoreceptors (stretch)
olfactory nerves
The first pair of cranial nerves; they carry sensory signals from the olfactory bulbs to the brain.
Types of papillae on tongue
filiform, fungiform, foliate, circumvallate
gustatory hairs
fine hairs that extend from the taste receptors into taste pores, thereby connecting taste pores to taste receptors
foliate papillae
located on side walls of tongue (not in humans) #A
olfactory epithelium contains
(pseudostratified) olfactory receptors, supporting cells, basal cells
olfactory hairs (cilia)
-dendrites of receptor -site of transduction
Muscle spindles
A type of simple encapsulated receptor. Location types: Fusiform (spindle shaped) propriceptors Stimulation types: Mechanoreceptors (muscle stretch) Found within skeletal muscles, particularly those of the extremities.
Joint kinesthetic receptors
A type of simple encapsulated receptor. Location types: Proprioceptors that monitor stretch in the articular capsules the enclose synovial joints. Stimulation type: Mechanoreceptors and nociceptors. Found in joint capsules and synovlia joints.
Golgi tendon organs
A type of simple encapsulated receptor. Location types: Proprioceptors. Stimulation type: Mechanoreceptors (tendon stretch) Located in tendons, close to the skeletal muscle insertion
Receptor
Any structure that is specialized to detect a stimulus. Some are simple nerve endings, like dendrites, others are sense organs; nerve endings combined with connective, epithelial, or muscular tissues that enhance or moderate the response to a stimulus.
Free nerve endings of sensory neurons
Body Location: Most body tissue, most dense in connective tissue, dermis, joint capsules, and epithelia They are exteroceptors, proprioceptors, and interceptors. Thermoreceptors mechanoreceptors nociceptors
olfactory supporting cells
Columnar epithelial cells; provide nourishment, protection, and electrical insulation for receptors, detoxify chemicals that contact the olfactory hairs
anatomy of a taste bud
Each gourd-shaped taste bud consists of three major cell typesSupporting cells - insulate the receptor Basal cells - dynamic stem cells Gustatory cells - taste cel
Meissner's corpuscles
Encapsulated. Location types: exteroceptors Stimulation types: Mechanoreceptors (light pressure, discriminative touch, vibration of low frequency). Found in the dermal papillae of hairless skin, particularly nipples, external genitalia, fingertips, soles of feet, eyelids
krause's end bulbs
Encapsulated. Location types: exteroceptors Stimulation types: Mechanoreceptors (probably modified Meissner's corpuscles). Found in the connective tissue of mucosae (mouth, conjuctive of eye) and of hairless skin near body openings (lips).
Ruffini's corpuscles
Encapsulated. Location types: exteroceptors and proprioceptors. Stimulation types: Mechanoreceptors (deep pressure and stretch); slowly adapting. Deep in dermis, hypodermis, and joint capsules.
Pacinian corpuscles
Encapsulated. Location types: exteroceptors, interoceptors, and some proprioceptors. Stimulation types: Mechanoreceptors (deep pressure, stretch, vibration of high frequency); rapidly adapting. Found in subcutaneous tissue of the skin; periostea, mesentery tendons, ligaments, joint capsules, most abundant on fingers, soles of feet, external genitalia, and nipples.
cribriform plate of ethmoid bone with olfactory foramina
H
joint capsule receptors
Located in capsules that enclose joints Monitor pressure, tension, and movement
taste buds
Most of the 10,000 or so taste buds are found on the tongueTaste buds are found in papillae of the tongue mucosaPapillae come in three types: filiform, fungiform, and circumvallateFungiform and circumvallate papillae contain taste buds
Simple Receptors
Most receptors are simple in structure and include encapsulated and unencapsulated varieties. Example: Sensory neurons
fungiform papillae
Mushroom-like protuberances often containing taste buds and located on the sides and tip of the tongue. #D
hair folicle receptor
Nerve receptors that detect hair movement, wraps around each hair bulb. Exteroceptors Mechanoreceptors (light pressure, slowly adapting)
olfactory pathway to brain
Olfactory receptor cells synapse with mitral cellsGlomerular mitral cells process odor signalsMitral cells send impulses to:The olfactory cortex The hypothalamus, amygdala, and limbic system
Photoreceptors
Respond to changes in light, found in the eye
Chemoreceptors
Respond to chemical changes, including odors, tastes, and composition of body fluid.
Mechanoreceptors
Respond to physical deformation of tissue (ie. vibration, touch, pressure, stretch, tension). They include the organs of hearing and balance.
Nociceptors
Respond to sensations of pain from tissue damage to to trauma (cuts, blows), ischemia (poor blood flow), or excessive stimulation to agents such as heat and chemicals
Exteroceptors
Respond to stimuli arising outside the body Receptors in the skin for touch, pressure, pain, and temperature Most special sense organs.
Exteroceptors
Respond to stimuli arising outside the body. Sensitive to touch, pressure, pain, and temperature. Includes the special sense organs (eyes, ears, nose)
Interoceptors
Respond to stimuli arising within the body. Sensitive to chemical changes, stretch, and temperature changes inside the body (bladder pressure, nausea, internal pain, etc)
Thermoreceptors
Respond to temperature changes
Proprioceptors
Sensory neurons that monitor position and movement of body parts. Respond to degree of stretch of the organs they occupy. Monitor how much organs containing these receptors are stretched. Include muscles, tendons, and joint capsules. They can determine how much force is being applied to your limbs allowing you to pick something up without crushing it or dropping it.
Proprioceptors
Sensory receptors found in muscle, tendons, joints, ligaments and connective tissue covering bones that detect their degree of stretch, body movements and position.
Unencapsulated Receptors
Simple receptors with free dendritic nerve endings. Examples: Merkel discs, Root hair plexuses, and Itch Receptors
Encapsulated Receptors
Simple receptors. Consist of one or more fiber terminals of sensory neurons enclosed in a connective tissue capsule. Virtually all are mechanoreceptors. Examples: Meissner's corpuscles, Pacinian corpuscles, Ruffini's corpuscles, Muscle spindles, Golgi tendon organs, Joint kinesthetic receptors
Complex Receptors
Special sense organs like the eye, ear, and nose.
sensory receptors
Specialized cells unique to each sense organ that respond to a particular form of sensory stimulation.
Five basic qualities of taste
Sweet - sugars, saccharin, alcohol, and some amino acids Salt - metal ions Sour - hydrogen ions Bitter - alkaloids such as quinine and nicotine Umami - elicited by the amino acid glutama
other influencers on taste
Taste is 80% smellThermoreceptors, mechanoreceptors, nociceptors also influence tastesTemperature and texture enhance or detract from taste
sense of smell
The organ of smell is the olfactory epithelium, which covers the superior nasal concha Olfactory receptor cells are bipolar neurons with radiating olfactory ciliaOlfactory receptors are surrounded and cushioned by supporting cellsBasal cells lie at the base of the epithelia
Transduction
The process of converting outside stimuli, such as light, into neural activity relayed to the CNS. Sensation (awareness of the stimuli) and perception (conscious interpretation of the stimulus) occur in the brain.
taste trasnduction
The stimulus energy of taste is converted into a nerve impulse by:Na+ influx in salty tastesH+ in sour tastes (by directly entering the cell, by opening cation channels, or by blockade of K+channels)Gustducin in sweet and bitter taste
Olfactory glands (Bowman's glands)
These are mucus glands found in the lamina propria (connective tissue) that moisten olfactory epithelium and dissolve odor molecules. #B
filiform papillae
Threadlike elevations that cover most of the tongue. no taste buds
Root hair plexuses
Unencapsulated. Location types: exteroceptors Stimulation types: Mechanoreceptors (hair deflection); rapidly adapting. Found in and surrounding hair follicles.
Modified free dendritic endings: Merkel discs
Unencapsulated. Location types: exteroceptors Stimulation types: Mechanoreceptors (light pressure); slowly adapting. Found in the basal layer of epidermis of skin
Free dendritic nerve endings of sensory neurons
Unencapsulated. Location types: exteroceptors, interoceptors, and proprioceptors. Stimulation types: Nociceptors (pain), thermorecptors (heat and cold), possible mechanoreceptors (pressure). Found in most body tissues; most dense in connective tissues (ligaments, tendons, dermis, joint capsules, periostea) and epithelia (epidermis, cornea, mucosae, and glands)
olfactory tracts
a bundle of axons connecting the cells of the olfactory bulb to several target regions in the brain.
Free (naked) dendritic endings
an unspecialized, afferent nerve fiber sending its signal to a sensory neuron. Afferent in this case means bringing information from the body's periphery toward the brain. They function as cutaneous nociceptors and are essentially used by vertebrates to detect pain. They are the most common type of nerve ending, and are most frequently found in the skin. They mostly resemble the fine roots of a plant. any type of adapting
testing tactile localization
brain's ability to determine which portion of the skin has been touched. areas:
Chemical Senses
chemical senses - gustation (taste) and olfaction (smell) •Their chemoreceptors respond to chemicals in aqueous solution-Taste - to substances dissolved in saliva-Smell - to substances dissolved in fluids of the nasal membranes
sensory adaptation
diminished sensitivity as a consequence of constant stimulation
Ruffin's Corpuscles Type 2 cutaneous (bulbous) mechanoreceptors
deep in dermis, hypodermis, and joint capsules DEEP CONTINUOUS PRESSURE exteroceptors, Proprioceptors, mechanoreceptors (deep pressure, stretching, slowly adapting or non adapting
lamellar corpuscle
deep pressure receptor
Phenomenon of referred pain
elbow in ice water yields pain from ulna nerve radiating to hand.
taste nerves
facial (2/3 of tongue), glossopharyngeal (posterior 1/3 of tongue), vagus (Pharynx)
circumvallate papillae
large papillae with taste buds (V formation on the posterior surface of tongue) #B
Olfactory epithelium location
lining the roof the the nasal cavity
olfactory stem cells
located near the basal surface of the epithelium, they divide to form new olfactory sensory neurons
negative afterimage effect and adaptation
negative afterimage that is caused by adaptation of the photoreceptors in the retina.
taste pore
opening that exposes taste cell microvilli (gustatory hairs) to oral cavity
referred pain
pain that is felt in a location other than where the pain originates.
basal epithelial cells
precursor cells that divide to replace the gustatory epithelial cells
sense organs
receptors are large and complex (eyes, nose, ears...)
punctate distribution
refers to the unequal distribution sensory receptors on the body
Thermoreceptors
respond to changes in temperature
Chemoreceptors
respond to chemicals e.g., smell, taste, changes in blood chemistry
Pacinian corpuscles
respond to deep pressure and vibration exteroceptors, Proprioceptors, interoceptors mechanoreceptors (deep pressure, stretch, vibration high frequency, rapidly adapting)
Photoreceptors
respond to light energy (retina)
Interoceptors
respond to stimuli arising in internal viscera and blood vessels (include stretch receptors, chemoreceptors, and others)
Mechanoreceptors
respond to touch, pressure, vibration, stretch, and itch
general senses
sensory receptors activated by touch, pressure, pain, heat, cold, stretch vibration, changes in body position.
Nociceptors
sensory receptors that enable the perception of pain in response to potentially harmful stimuli
olfactory sense neurons
specialized receptor cells that are bipolar neurons with nonmotile olfactory cilia.
intrafusal cells
specialized slender skeletal muscle cells
Merkel disk receptors
superficial cutaneous mechanoreceptors for light pressure; light pressure; slowly adapting exteroceptors
two factors influence taste appreciation of food
texture, thermo
tactile localization
the brain's ability to determine which portion of the skin has been touched. The receptive field has a corresponding "touch" field in the body's primary somatosensory cortex. . Smaller the receptive field the greater the brains ability to detect location of stimulus
olfactory bulb
the first brain structure to pick up smell information from the nose
olfactory adaptation
the temporary, normal inability to distinguish a particular odor after a prolonged exposure to that airborne compound.
gustatory receptor cells
the working cell of the taste bud Lifespan: 10 days have gustatory hairs the extend through the taste pore to contact food particles
location of taste buds
tongue, soft palate, cheeks, epiglottis, pharynx
Meissner's corpuscles Type 1 cutaneous mechanoreceptors
touch receptors in the papillary layer of the dermis (eyelids, nipples, soles of feet, genitals, fingertips) Exteroceptors mechanoreceptors (light touch, vibration, rapidly adapting)
Four qualities of cutaneous sensations
touch, heat, cold, & pain. They are non-uniformly distributed throughout the body (hands have more touch receptors than arm, etc). Distribution based on the importance of the area and the need for those receptors.
two-point threshold test
used to determine a crude map of density of tactile receptors in various regions of the skin.
special senses
vision, hearing, equilibrium, smell, taste.
Golgi tendon organs
works with kinesthetic senses; specialized nerve endings attached to tendon (attaches muscles and bones) and sense movement
