Chapter 16 Flashcards
Sensory Receptors
Respond to a stimulus, provide info about internal and external environments; each have a preferred stimulus; have a resting membrane potential
Receptive field
the distribution area of the endings of a sensory neuron (smaller = more precise)
Sensation
a stimulus we are consciously aware of (signals that reach the cerebral cortex)
Special Sense Receptors (5)
Olfaction (smell), gustation (taste), vision, audition (hearing), equilibrium
Exteroceptors
detect stimuli from external environment; skin and mucus membranes
Interoceptors
detect stimuli from internal organs; visceral sensory receptors monitoring internal environment
Proprioceptors
detect body and limb movements; somatosensory receptors of muscles, tendons, and joints
Chemoreceptors
detect chemicals dissolved in fluid (external and internal)
Thermoreceptors
detect changes in temperature (skin and hypothalamus)
Photoreceptors
detect change in light intensity, color, movement (retina)
Mechanoreceptors
detect distortion of cell membrane (touch, pressure, vibration, stretch)
Nociceptors
detect painful stimuli (somatic=surface damage and visceral=internal organ damage)
Unencapsulated tactile receptors
dendritic ends of sensory neurons with no protective cover
Encapsulated tactile receptors
neuron endings wrapped by connective tissue or covered by connective tissue and glial cells (neurolemmocytes)
Referred Pain
inaccurate localization of sensory signals
Vallate papillae
largest, fewest, contain most of the taste buds; located in a row of 10-12 along the posterior dorsal tongue surface
Accessory structures of the eye
six extrinsic eye muscles, eyebrows, eyelids, eyelashes, conjunctiva, lacrimal glands (caruncle and apparatus)
Sclera
white of the eye; dense irregular CT; provides shape, protects internal components; attachment site for extrinsic eye muscles
Cornea
anterior convex transparent “window”; inner layer of simple squamous epithelium, middle layer of collagen, outer layer of stratified squamous epithelium; no blood vessels; refracts light
Fibrous Tunic of the eye
Sclera and Cornea
Vascular tunic
Iris, Choroid, Ciliary body
Retina
Pigmented layer and natural layer
Choroid
extensive posterior region; many capillaries to nourish retina, many melanocytes to make melanin to absorb extraneous light
Ciliary body
ciliary muscles and processes; anterior to the choroid;
Iris
gives eye color, most anterior region of uvea, contains smooth muscle, melanocytes, vessels, neural structures; controls pupil diameter
Anterior chamber of eye
between cornea and iris
Posterior chamber of eye
Between the iris and the lens
Sphincter Pupillae muscles
concentrically circular fibers constrict pupil with parasympathetic nervous system activity
Dilator pupillae muscle
radially organized smooth muscle dilates pupil with sympathetic nervous system activity
Photoreceptors
contains rods and cones and the pigments that react to light
Optic Disc
Blind spot with no photoreceptors; where ganglion axons exit toward brain
Peripheral Retina
Contains primarily rods; functions most effectively in low light
Lens
changes shape to focus light on retina; shape is determined by ciliary muscle and suspensory ligaments
Auricle
funnel-shaped visible part of ear with elastic cartilage; protects ear entry-way and directs sound waves inward
External acoustic meatus
ear canal; extends to tympanic membrane;
Tympanic Membrane
Eardrum; funnel-shaped epithelial sheet separating external and middle ear; vibrates when sound waves hit it
Cochlea
houses membranous cochlear duct;
Vestibule
contains two saclike, membranous parts: utricle and saccule; interconnected and positioned at right angles
Semicircular Canal
contains membranous semicircular ducts
Macula
receptor for static equilibrium and linear acceleration; located in utricle and saccule of vestibule; composed of a layer of hair cells and supporting cells
Ampulla
contains crista ampullaris with hair cells and support cells; sterocilia and kinocilia of hair cells are embedded in gelatinous cupula;
Olfactory Hairs
cilia projecting from receptor cell dendrite that house chemoreceptors for a specific odorant
Olfactory Bulbs
Ends of olfactory tracts located under the brain’s frontal lobes; where olfactory nerve fiber synapse with mitral cells and tufted cells
Olfactory Tracts
axon bundles of mitral and tufted cells on inferior frontal lobe surface; project directly to primary olfactory cortex, hypothalamus, amygdala and other regions
Taste Buds
onion-shaped organs housing taste receptors; made of gustatory cells, supporting cells, and basal cells
Gustatory Cells
neuroepithelial chemoreceptive cells of taste buds; detect tastants and live 7-9 days
Filiform Papillae
short and spiked; no taste buds; help manipulate food; anterior two-thirds of tongue surface
Fungiform Papillae
mushroom-shaped; each contains a few taste buds; located on tip and sides of tongue
Foliate Papillae
Leaflike ridges; not well developed; house a few taste buds in early childhood; located on posterior lateral tongue
Rods
longer and narrower; more numerous; highly sensitive and activated by dim light; many rods converge on fewer bipolar cells which converge on fewer ganglion cells (sensitivity to dim light but a blury image)
Cones
concentrated at fovea centralis; activated by high intensity light, allows color vision; cones have a one-to-one relationship with bipolar cells and ganglion cells (sharp image but only in bright light)
Eyebrows
located along supraorbital ridge; aid in nonverbal communication and prevent sweat from dripping into eyes
Eyelashes
extend from margins of eyelids; prevent objects coming into contact with eye; initiate blink reflex
Conjunctiva
transparent lining of eye and lid surfaces; specialized stratified columnar epithelium
Lacrimal Apparatus Functions
produces, collects, drains fluid; lubricates, cleanses and moistens eye, reduces eyelid friction, defends against microbes, oxygenates and nourishes cornea;
Lacrimal Apparatus
Lacrimal gland to lacrimal puncta to lacrimal canaliculus to lacrimal sac to nasolacrimal duct to nasal cavity
Ciliary Muscles
bands of smooth muscle connected to lens; contraction loosens suspensory ligaments, altering lens shape
Pupil
opening in center of iris connecting the two chambers
Aqueous Humor
transparent watery fluid in anterior cavity; continuously produced by ciliary processes; nourishes and oxygenates lens and inner cornea
Somatic Sensory Receptors
tactile receptors of skin and mucous membranes; proprioceptors of joints, muscles, and tendons
Visceral Sensory Receptors
found in walls of internal organs, they monitor stretch, chemical environment, temperature, pain
Free Nerve Ending
terminal ends of sensory neuron dendrites; Simplest tactile receptors, Reside close to skin surface and in mucous membranes, Mainly for pain and temperature but also light touch and pressure
Root Hair Plexuses
wrap around hair follicle, detect hair displacement,
Tactile Discs
flattened endings of sensory neurons extending to tactile cells
End Bulbs
are ensheathed in connective tissue; Located in dermis and mucus membranes; Detect pressure and low-frequency vibration
Lamellated Corpuscles
wrapped in neurolemmocytes and concentric layers of connective tissue; Located deep in dermis, hypodermis, some organ walls; Detect deep pressure, course touch, high-frequency vibration
Bulbous Corpscles
wrapped in CT; Within dermis and subcutaneous layer; Detect deep pressure and skin distortion
Tactile Corpscles
intertwined endings wrapped in modified neurolemmocytes, covered in connective tissue; Discriminative light touch—allow recognition of texture, shape
Basal Cells
replace olfactory receptor cells every 40 to 60 days; replacement and sensitivity decline with age
Vitreous Humor
Transparent gelatinous fluid in posterior cavity; Helps eye maintain shape; Supports retina—keeps it flush against back of eye
Lamina Propria
Areolar connective tissue layer internal to olfactory epithelium; Houses blood vessels, nerves, and olfactory glands
Taste Pore
Path to tongue surface
Gustation Pathway
Gustatory cells through facial and glossopharyngeal nerves and synapse in the medulla oblongata