The Body Senses, Olfaction, and Taste

Flashcards about body senses, tactile perception, mechanoreceptors, proprioception, nociceptors, thermoreception, olfaction, and gustation.

The Body Senses

Are grouped under the term TOUCH; one of the five senses.

Tactile Perception:

Perceiving Mechanical Stimulation of the Skin

Skin

The largest sensory organ typically covers a surface area between 1 and 2 meters for adults. Protects tissues against issues against injuries and helps regulation of body temperature.

Main types of skin:

Hairy skin and Glabrous (hairless)

Main layers of the skin

Epidermis and the dermis

Specialized endings of main mechanoreceptor types of mechanoreceptors

Merkel cells (SAI) and Meissner corpuscles (FAI)

Four main types of mechanoreceptors:

Slow-adapting type 1 (SAI small receptive field)

Slow-adapting type 1 (SAI small receptive field)

Perceiving pattern, texture, and shape

Four main types of mechanoreceptors:

Fast-adapting type 1 (FAI small receptive field)

Fast-adapting type 1 (FAI small receptive field)

Perceiving slips and maintaining grip control.

Four main types of mechanoreceptors:

Slow-adapting type II (SAII large receptive field)

Slow-adapting type II (SAII large receptive field)

Perceiving skin stretch and hand conformation

Four main types of mechanoreceptors:

Fast-adapting type II (FAII large receptive field)

Fast-adapting type II (FAII large receptive field)

Perceiving fine textures through transmitted vibration

Assessing spatial resolution/two-point threshold measure

Threshold smaller on fingertips and lips and larger on arms, legs and torso

Assessing patter perception/spatial event plot

SAI fibers provide rich representations of patterns, textures, and shapes

Perceiving pleasant touch

C- tactile mechanoreceptors (CT mechanoreceptors)

C- tactile mechanoreceptors (CT mechanoreceptors)

Are a type of free nerve endings only present in hairy skin; they respond to slow, gentle touch, sending signals to the insular cortex, an area of the brain involved in pleasure protection.

Proprioception

Perceiving Position and Movement of the Limbs

Three sensory organs provide information related to how the body and its parts are positioned

Muscle spindles, Golgi tendon organs, Joint receptors

Nociceptors

Sensory receptors that transduce the physical stimuli associated with damaging mechanical, thermal, or chemical events; are included among the free nerve endings in the epidermis and dermis.

Sensitization:

A mechanism that decreases the response threshold of nociceptors, so that even very low-level stimulation of an injury site can cause pain.

A-Delta Fibers

Myelinated nociceptors that transmit pain signals relatively rapidly, to produce a rapid response to potentially damaging mechanical stimuli and to excessive heat.

C Fibers

Unmyelinated axons of nociceptors that transmit pain signals relatively slow

Merkel cells:

Specialized endings of SAI mechanoreceptors, where transduction takes place.

Meissner corpuscles:

Specialized endings of FAI mechanoreceptors, where transduction takes
place.

Pacinian corpuscles:

Specialized endings of FAII mechanoreceptors, where transduction takes place.

Temperature

Alters your 2-point and absolute threshold

Masking

Masking can increase threshold

Inflammatory

Tissue damage; produces increase in # of white blood cells; bring biochemicals to fight infections

Nociceptive

Mostly free nerve endings; minor burns

Neuropathic

Strokes; extensive tissue damage; mild burns; spinal cord injury; damage to neurons; some damage will be irreversible; damage will often be chronic

Spinalthapmic

More pain; come thru dorsal root of the spinal cord

Medial lemniscus

More touch; come thru dorsal root of the spinal cord

Gate control theory of pain:

we have two physical pathways; you can take out one pathway and still have the other. Touch comes into the medial lemniscus; pain is coming in through the free nerve endings; unmyelinated; moving slow.

Thermoreception: Perceiving Temperature

63 degrees to 110 degrees

Cool fibers:

Kras end blub; seems to respond to changes in temp not touch; 17 to 40 degrees.

Warm fibers:

Ruffini; always near a joint; when move joint always reduces heat.

Dorsal Column (DC)- Medial Lemniscal Pathway (ML):

Nerve fibers carrying neural signals for tactile perception and proprioception.

Spinothalamic Pathway:

Nerve fibers carrying neural signals for nociception and thermoreception. (mostly c-fibers; pain and thermal)

Olfaction:

Perceiving Odors

Buck & Axel-

noble prize winner for SHAPE THEORY 1996

There are 2 olfactory systems-

Physically separate Olfactory epithelium (primary olfactory system) and VNO= vomeronasal organ (Jacobsons organ)

Odorants:

Molecules that olfactory receptors “recognize” and respond to by producing neural signals that the brain represents as perceptions of different odors. (must be volatile)

Anosmia:

Loss of the ability to perceive odors. (due to birth defect, accidents)

Cross-Adaptation:

In olfaction, reduced sensitivity to odorants that are chemically or perceptually similar to odorants to which the person has been continuously or repeatedly exposed.

Odotopic:

The spatial organization of odorant-specific activation patterns in the olfactory bulb of the brain.

Presbyosmia:

Age-related decline in the sense of smell.

Hyperosmia:

Overwhelming sensitivity to smell.

Hyposmia:

Decreased sense of smell.

Phantosmia:

Perceives smells that aren't actually present.

Dystosmia:

The quality of odor is distorted, or an unusual odor is perceived without an actual stimulus

Turbinate's:

Bony convolutions of tissue protruding into the nasal cavities, functioning to disperse air evenly throughout the nasal cavities.

Olfactory Receptor Neurons:

Neurons that transduce odorant molecules into neural signals.

Olfactory Epithelium:

A patch of tissue in the upper reaches of each nasal cavity; the epithelium contains ORNs and is covered by a layer of olfactory mucus.

Flehmens’ Response:

animal/humans curls back their upper lip, exposing their front teeth, inhales with the nostrils usually closed, and then often holds this position for several seconds. (Babies do this within 1 day of birth)

Ageusia

No taste

Hypogeusia:

Diminished taste

Hypergeusia:

Really taste everything

Presbygeusia:

Decline in hearing

Phantogeusia:

Phantom tastes

Dysgeusia:

Distorted sense of taste.

AGUST

Basic unit of taste

Sweet:

Calories, organic, carbs, carbon, hydrogen, oxygen

Salty:

Ocean

Bitter:

Toxic, dark green leafy vegetables, at least 30 different types of human bitter receptors

Sour:

Very hydrogen related

Umami:

Savory taste, combination of chemicals, maybe not an individual taste

Papilla:

The bumps on your tongue.

Circumvallate papilla:

All situated in a row at the back of the tongue.

Foliate papilla:

Located on the sides of the tongue near the back.

Fungiform papilla:

Located along the edges and top of the front two-thirds of the tongue.

Filiform papilla:

High proportion right around the middle of the tongue.

Receptor cells:

A type of taste receptor cells containing receptors that initiate transduction of sweet, umami, and bitter tastants.

Presynaptic cells:

A type of taste receptor cells in which the receptors take the form of ion channels, where transduction of salty and sour tastants is initiated.

Thalamus

The point to where TASTE GOES

Taste receptor cells.

Tastants are transduced into neural signals by these

The trigeminal sense:

Signals the presence of irritants in the mouth.

Across-fiber pattern modeling

This theory proposes that each cranial nerve fiber carries signals from multiple taste receptor types and that the cortical neurons receiving these signals are broadly tuned to respond to signals carrying information about multiple types of tastants