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sensory receptor

A ______ is a specialized cell or cell process that monitors conditions in the body or the external environment.


The sensory information arriving at the CNS is called a ______

general senses

The term ______ refers to sensations of temperature, pain, touch, pressure, vibration, and proprioception (body position). ______ receptors are distributed throughout the body

smell (olfaction), taste (gustation), balance (equilibrium), hearing, and vision.

The special senses are ______

receptor specificity.

a touch receptor is very sensitive to pressure but relatively insensitive to chemical stimuli. This concept is called ______

free nerve endings

The simplest receptors are the dendrites of sensory neurons, called ______

receptive field

The area monitored by a single receptor cell is its______ (Figure 18.1). Whenever a sufficiently strong stimulus arrives in the ______, the CNS receives the information. The larger the ______, the poorer our ability to localize a stimulus.

labeled line

The connection between receptor and cortical neuron is called a ______. Each ______ carries information concerning a specific sensation (touch, pressure, vision, and so forth) from receptors in a specific part of the body.


Some sensory neurons, called ______receptors, are always active The photoreceptors of the eye and various receptors that monitor body position are examples of ______receptors.

phasic receptors

receptors normally inactive, become active with change in monitor stimulus. i.e. touch and pressure receptors in skin

phasic, tonic

Receptors that combine ______receptors and ______ coding convey extremely complicated sensory information; receptors that monitor the positions and movements of joints are in this category.


______ is the reduction of sensitivity with a constant stimulus

sensory adaptation

____ occurs when receptors or sensory neurons alter their levels of activity by responding strongly at first and then declining


fast adaption is characteristic of ____ receptors. Also called fast adapting receptions


slow adapting receptors are called ____receptors

central adaptation

a few seconds after exposure to a new smell the sensation fades. this is called ___

cerebral cortex

. Only about 1 percent of the information provided by afferent fibers reaches the _____and our conscious awareness.

Sensory Limitations

These are examples of _______:
1. Humans do not have receptors for every possible stimulus.
2. Our receptors have characteristic ranges of sensitivity.
3. A stimulus must be interpreted by the CNS. Our perception of a particular stimulus is an interpretation and not always a reality.


Senses: provide info re external environment


Senses: monitor body position


Senses: monitor conditions inside the body


respond to tissue damage, activated feeling of pain


respond to temperate changes


stimulated or inhibited by physical distortion contact or pressure


monitor chemical comp of body fluids and respond to specific molecules


___ are common receptors in superficial areas of skin, joint capsules, periostea of bones and around wall of blood vessels. Few are in deep visceral organs.


three types of ______ : (1) receptors sensitive to extremes of temperature, (2) receptors sensitive to mechanical damage, and (3) receptors sensitive to dissolved chemicals, such as those released by injured cells

fast pain

_____ is caused by deep cuts. This sensations reach the CNS quickly and often trigger somatic responses. Info also sent to primary sensory cortex. Central adaption may reduce pain perception

slow pain

_____ or burning and aching pain sensations begin later and persist longer then the other pain sensation. Slow pain sensations cause a generalized activation of the reticular formation and thalamus.


___ (receptors) are found in the dermis of the skin, skeletal muscles, liver, hypothalamus

cold, warm

3 to 4X more ___ receptors than ____ receptors


Temperature sensations are conducted along the same pathways that carry ______ sensations. They are sent to the reticular formation, thalamus, & primary sensory cortex


______ are sensitive to stimuli that stretch, compress, twist, or distort their plasmalemmae.

tactile receptors, baroreceptors, proprioceptors

There are three classes of mechanoreceptors______ , ______ , ______


______ receptors provide sensations of touch, pressure, and vibration


______ detect pressure changes in the walls of blood vessels and in portions of the digestive, reproductive, and urinary tracts


_______ monitor the positions of joints and muscles and are the most complex of the general sensory receptors.

Fine touch, pressure

_______ and _______ receptors provide detailed information about a source of stimulation, including its exact location, shape, size, texture, and movement

Crude touch pressure

_______ and _______ receptors provide poor localization and little additional information about the stimulus.

unencapsulated receptors, encapsulated receptors

six different types of tactile receptors in the skin. They can be subdivided into two groups:

free nerve endings, tactile disc, and root hair plexus

the unencapsulated receptors are:

tactile corpuscle, Ruffini corpuscle, and lamellated corpuscle

the encapsulated receptors are:


Free nerve endings are common in the _____ layer of the dermis

Merkel cell

Each _____ communicates with a sensory neuron across a vesicular synapse that involves an expanded nerve terminal known as a tactile disc

Merkel cells

In sensitive areas, the dendritic branches penetrate the epidermis and contact _______ in the stratum germinativum.


______cells are sensitive to fine touch and pressure. They are tonically active and extremely sensitive and have narrow receptive fields. Free nerve endings are also associated with hair follicles.

root hair plexus

The free nerve endings of the _______ monitor distortions and movements across the body surface. When the hair is displaced, the movement of the follicle distorts the sensory dendrites and produces action potentials in the afferent fiber.

tactile corpuscles

Touch receptors located within dermal papillae adjacent to the basement membrane of the epidermis; also called Meissner's corpuscles.

tactile discs

Sensory nerve endings that contact special receptors called Merkel cells, located within the deeper layers of the epidermis; also called Merkel's discs.


Large, oval _____ corpuscles (also called Meissner's corpuscles) are found where tactile sensitivities are extremely well developed. They are especially common at the eyelids, lips, fingertips, nipples, and external genitalia.


______ corpuscles detect light touch, movement, and vibration; they adapt to stimulation within a second after contact.


_____ corpuscles, located in the dermis, are also sensitive to pressure and distortion of the skin, but they are tonically active and show little if any adaptation.

Lamellated corpuscles

_____ are considerably larger encapsulated receptors. layers shield the dendrite from virtually every source of stimulation other than direct pressure.


______ corpuscles respond to deep pressure but are most sensitive to pulsing or vibrating stimuli

lamellated, Ruffini

Although both _____corpuscles and ____ corpuscles respond to pressure, the ____ corpuscles adapt rapidly while the ____ corpuscles adapt quite slowly

lamellated corpuscles, Ruffini corpuscles

These receptors are scattered throughout the dermis, notably in the fingers, breasts, and external genitalia.


______ are stretch receptors that monitor changes in pressure.


a ______ consists of free nerve endings that branch within the elastic tissues in the wall of a hollow organ, a blood vessel, or the respiratory, digestive, or urinary tract


_____ monitor blood pressure in the walls of major vessels, including the carotid artery (at the carotid sinus) and the aorta (at the aortic sinus).


_________ in the lungs monitor the degree of lung expansion. This information is relayed to the respiratory rhythmicity center, which sets the pace of respiration.


________ in the urinary and digestive tracts trigger a variety of visceral reflexes, such as urination.


________ monitor the position of joints, the tension in tendons and ligaments, and the state of muscular contraction.


Generally, _____ do not adapt to constant stimulation. Muscle spindles are _______ that monitor the length of skeletal muscles

Golgi tendon organs

_______ monitor the tension in tendons during muscle contraction.


_______ are specialized neurons that can detect small changes in the concentration of specific chemicals or compounds.


In general, _______ respond only to water-soluble and lipid-soluble substances that are dissolved in the surrounding fluid.


____________ neurons are found within the carotid bodies, near the origin of the internal carotid arteries on each side of the neck, and in the aortic bodies between the major branches of the aortic arch.

carotid body

A group of receptors adjacent to the carotid sinus that are sensitive to changes in the carbon dioxide levels, pH, and oxygen concentrations of the arterial blood.

olfactory epithelium

A specialized neuroepithelium, the _________, which contains the bipolar olfactory receptors, supporting cells, and basal cells (stem cells).

olfactory receptors

Despite ongoing replacement, the total number of _________ declines with age, and the remaining receptors become less sensitive. As a result, elderly individuals have difficulty detecting odors in low concentrations.

receptors on tongue, ventral to dorsal

Filiform papillae, Fungiform papillae, Circumvallate papillae

gustatory cells

Each taste bud contains around 40 slender receptors, called _________

Taste buds monitors by 3 cranial nerves:

cranial nerves VII (facial), IX (glossopharyngeal), and X (vagus)


_________is a pleasant taste that is characteristic of beef broth and chicken broth.

the external ear, the middle ear, and the inner ear

The ear is divided into three anatomical regions: _________

ceruminous glands

_________ secrete a waxy material, help deny access to foreign objects or insects.

tympanic cavity

_________, contains the auditory ossicles

auditory tube

The_________serves to equalize the pressure in the middle ear cavity with external, atmospheric pressure.

malleus, the incus, and the stapes

he three auditory ossicles are the_________

tensor tympani

muscle that inserts on the handle of the malleus


muscle that inserts on the stapes


fluid of the inner ear

membranous labyrinth

Endolymph-filled tubes of the inner ear that enclose the receptors of the inner ear.


Between the bony and membranous labyrinths flows the _________, a liquid whose properties closely resemble those of cerebrospinal fluid.

vestibule the semicircular canals, and the cochlea

The bony labyrinth can be subdivided into the (3)_________

utricle, saccule

Receptors in the _________and ____provide sensations of gravity and linear acceleration. Those in the semicircular canals are stimulated by rotation of the head.

oval window

Opening in the bony labyrinth where the stapes attaches to the membranous wall of the scala vestibuli.

hair cells

The sensory receptors of the inner ear are called _________

vestibular complex

It consists of the semicircular canals, the utricle, and the saccule.

oval maculae

The hair cells of the utricle and saccule are clustered in the _________


when an elevator starts its downward plunge, we are immediately aware of it because the _________no longer push so forcefully against the surface of the receptor cells.

The two vestibular nuclei

1. integrate the sensory information concerning balance and equilibrium arriving from each side of the head;
2. relay information from the vestibular apparatus to the cerebellum;cerebral cortex
4. send commands to motor nuclei in the brain stem and spinal cord.


The oval window is at the base of the _________duct


the round window is at the base of the _________duct.

organ of Corti

The hair cells of the cochlear duct are found in the _________

tectorial membrane

Gelatinous membrane suspended over the hair cells of the organ of Corti.


Movement of the stapes sets up pressure waves in the _________. These waves distort the cochlear duct and the organ of Corti, stimulating the hair cells.


Before reaching the cerebral cortex and our conscious awareness, ascending auditory sensations synapse in the _________

accessory structures

The _________ of the eye include the eyelids, the superficial epithelium of the eye, and the structures associated with the production, secretion, and removal of tears.

lacrimal caruncle

the _________ (Figure 18.19a) produce the thick secretions that contribute to the gritty deposits occasionally found after a good night's sleep.


The epithelium covering the inner surface of the eyelids and the outer surface of the eye is called the _________

lacrimal apparatus

The _________ produces, distributes, and removes tears.

(1) a lacrimal gland, (2) superior and inferior lacrimal canaliculi, (3) a lacrimal sac, and (4) a nasolacrimal duct

The lacrimal apparatus of each eye consists of (4) _________

lacrimal gland

Tear gland on the dorsolateral surface of the eye.

nasolacrimal duct

Passageway that transports tears from the nasolacrimal sac to the nasal cavity.

lacrimal puncta

the superior and inferior _________ drain the lacrimal lake

fibrous tunic

outer layer of the eye

vascular tunic

middle layer of the eye

neural tunic

inner layer of the eye

vitreous chamber

The large posterior cavity of the eye is called the _________

aqueous humor

The 2 part anterior cavity of the eye is called the

sclera and the cornea

The fibrous tunic, the outermost layer of the eye, consists of the (2) _________

The functions of this layer include (1) providing a route for blood vessels and lymphatics (2) regulating the amount of light entering the eye, (3) secreting and reabsorbing the aqueous humor (4) controlling the shape of the lens,

functions of the vascular tunic

ciliary body

A thickened region of the choroid that encircles the lens of the eye; it includes the ciliary muscle and the ciliary processes that support the suspensory ligaments of the lens.

ora serrata

The anterior edge of the neural retina.

pigmented layer

The neural tunic outer layer _________

neural layer

The neural tunic inner layer _________

macula lutea

area w no rods

bipolar cells

rods and cones synapse with ____

ganglion cells

_________ are the only cells in the retina that generate action potentials to the brain.

optic disc

it is commonly called the blind spot


The transparent body lying behind the iris and pupil and in front of the vitreous humor.


tension in the suspensory ligaments flattens the lens. In this position the eye is focused for _________vision.

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