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what is responsible for sensing visceral stimuli
interoceptors
pain sensed in your arm is sent to the spinal cord through the
dorsal root ganglion
what senses are phasic
- tactile
- olfaction
- thermal
in a simple reflex arc terminal knobs of afferent neurons synapse with
the cell body and dendrites of an interneuron in the posterior horn of the spinal cord
analgesia association: capsaicin
substance P
analgesia association: NSAIDs
Decreasing prostaglandin
analgesia association: aspirin
prostaglandins
an increase of fluid pressure in _____ of the eye can lead to glaucoma
anterior chamber
what is the greatest dioptric value
cornea
the activation of pupillary a1 receptors
increases retinal illumination
the refractive index of the cornea is
greater than that of air
the focal length is the distance
between the lens and the retina
most of the refraction of light occurs
at the corneal surface
activation of ciliary muscle ____ receptors cause the lens to become more convex and increases its converging power
M3
lens accommodation is employed to converge divergent light rays from objects further than
20 feet from the eye
the reflex triad causes a decrease in the
diameter of the pupil
the reflex triad causes a convergence of
visual axes
the reflex triad causes contraction of
ciliary muscle
rod cells in the dark mean cGMP levels are high in the
outer segment of the rod cell
rod cells in the dark mean there is a tonic response of
neurotransmitters onto bipolar neurons
rod cells in the dark means RMP =
-40 mV
in the inner ear the auditory organ is the
organ of corti
in the inner ear high frequency sound waves deform
the membrane near its base
in the inner ear the stapes interacts with the
oval window of the cochlea
presbyopia results from
a decrease in converging power of the lens with age
association: semicircular canals
crista ampularis
association: crista ampularis
cupula
association: macula
otolith
ganglia are exclusively located in the
peripheral nervous system
ganglia are aggregations of nerve cell bodies in the
peripheral nervous system
ganglia contain
satellite cells
with hyperopia what objects can be seen clearly
distant
if you are hyperopic you are
farsighted
what type of lens are needed to see properly
converging
in the light PDE
degrades cGMP to GMP
rod cells are hyperpolarized in the
light
Na+ channels are
closed in the light
myopia is corrected with
negative diopters
Neurons that carry information from the CNS toward the tissues and organs of the body are known as
efferent
A pain receptor which is stimulated by tissue damage is referred to as
nociceptor
Patients who have lost a body part by accident or amputation sometimes experience sensory perception in that part as though it weren't there. This phenomenon is called
phantom limb
Pain, touch, pressure and thermoreception are all types of ____ senses
somatic
Neurons that convey information from the tissues and organs of the body toward the CNS are classified as
afferent
Nociceptors are sensory receptors specialized to respond to
any stimulus that injures tissues
Rapidly adapting mechanoreceptor, touch, and pressure
Meissner's corpuscle
Slowly adapting mechanoreceptor, touch, and pressure
Merkel's corpuscle
Slowly adapting; may be nociceptor, thermoreceptor or mechanoreceptor
free neuron ending
Rapidly adapting mechanoreceptor, vibration, and deep pressure
pacinian corpuscle
Slowly adapting mechanoreceptor, skin stretch
ruffini corpuscle
Features of rapidly adapting receptors
- Receptor potentials do not persist for the duration of the time that a stimulus is applied
- They fire bursts of action potentials, when a stimulus is applied and again when it is removed
types of sensory receptors
- skin pressure receptor
- Proprioceptor
- thermoreceptor
Afferent neurons convey information ____ the CNS, while efferent neurons convey information ____ the CNS
- towards
- away
The sensation felt along the medial aspect of the left arm during a heart attack, which in reality occurs due to the stimulation of visceral pain pathways, is an example of
referred pain
referred pain results from
the convergence of somatic and visceral pain pathways
In general, mechanoreceptors are highly specialized neuron endings that are linked to networks of ____ fibers within a capsule that is often filled with fluid. These networks transmit the mechanical tension in the fluid-filled capsule to ____ channels in the neuron endings and activate them
- collagen/protein
- ion
path of light through the human eye
- cornea
- aqueous humor
- lens
- vitreous humor
- retina
How is the fovea centralis histologically different from the rest of the retina?
it had fewer light-obstructing neurons
Nociceptors from internal organs often activate interneurons linked to the somatosensory cortex that represents a superficial body part. This is known as ____ pain:
referred
filled with a viscous, jellylike substance known as vitreous humor
posterior chamber
filled with a clear fluid called aqueous humor
anterior chamber
Cones are concentrated in a central, shallow pit within the macula lutea called the ____ ____:
- fovea
- centralis
A ray of light passes from the air through a curved lens. In which option will the refraction result in a focused image?
the focal point is on the retina
what chamber of they eye is located between the iris and the cornea?
anterior
what increases the refractive power of the lens?
contraction of the ciliary muscle
Which two options are characteristics of slowly adapting receptors?
- They maintain a persistent or slowly decaying receptor potential
- Action potentials continue to be generated for the duration of a stimulus
The reduced ability to accommodate for near vision that commonly occurs with aging is called
presbyopia
When light waves diverging from a point on an object pass from air into the curved surface of the cornea and lens of the eye, they are refracted inward, converging back into a point on the
retina
Individuals who have difficulty focusing on objects that are further away have a condition called
myopia/nearsightedness
As the distance between the eye and a viewed object increases, the object is kept in focus because the ciliary muscle ____ and the lens ____
- relaxes
- flattens
The need for reading glasses as people age is due to a condition called
presbyopia
What eye condition results when the lens or cornea does not have a smoothly spherical surface?
astigmatism
Which structure of the eye has the largest quantitative role in focusing light waves?
cornea
Inability to focus light rays from nearby objects on the retina is a characteristic of the condition
hyperopia
hyperopia or farsightedness occurs when the eyeball is too _____ or the lens isn't round enough, causing light rays to reach the cornea before they are in _____
- short
- focus
people with hyperopia have difficulty focusing on
nearby objects
Irregularity of the curvature of the lens or cornea of the eye causes a visual defect known as
Astigmatism
order of the structures beginning with the front of the retina on the far left to the optic nerve fibers on the far right side
- horizontal cells
- bipolar cells
- photoreceptor cells
- amacrine cells
- ganglion cells
- choroid
what are two principle types of photoreceptor cells
- cone cells
- rod cells
Photoreceptor cells are those that specifically respond to
light
in dim light, rods are _____ cones
more active than
Myopia is a condition caused by
the eyeball being too long relative to the focusing power on the lens
what binds to cation channels on the inside of photoreceptor membranes, maintaining them in an open state?
cGMP
In light adaptation, the eye is at first extremely sensitive to light as ____ are overwhelmingly activated, and the visual image is too bright and has poor contrast. However the ____ is soon inactivated (sometimes said to be "bleached") as a retinal dissociates from it
- rods
- rhodopsin
The back later of the retina, closest to the choroid, is composed of the ____ (rods and cones), while the front layer, consists of the ____ cells, whose axons become the optic nerve
- photoreceptor
- bipolar
Because of the shapes of their light-sensitive outer segments, the two types of photoreceptors are called ____ and ____
- rods
- cones
When light strikes the retina and initiates action potentials that travel to the visual cortex, the first cell type that undergoes an action potential is a ____ cell
ganglion
Name the photoreceptor that is responsible for day and color vision
cone cell
with cone cells synapse with rods and cones in the retina and functions as
first order neurons in the visual pathway
Over many years, unprotected exposure of the eyes to sunlight without wearing good sunglasses can contribute to a clouding of the lens called
cataracts
In the dark, cGMP-phosphodiesterase activity inside photoreceptor cells is ____, cyclic GMP concentration is ____, and the membrane is ____
- low
- high
- depolarized
True or false: the bleaching reaction of rhodopsin occurs when stepping from a dark place into a bright one
true
bleaching
inactivation of rhodopsin by bright light
Irreversible blindness can be caused by the condition _____, in which there is an increased pressure within the eye
glaucoma
cells that provide lateral integration between neurons in the retina
- horizontal cells
- amacrine cells
During activation of visual neural pathways, ____ cells only undergo graded potentials; action potentials are first initiated in ____cells
photoreceptor and bipolar; ganglion
When pressure differences occur between the external auditory canal and the middle ear, yawning or swallowing opens the ____, allowing pressure to equilibrate
Eustachian tube
_____ refers to the clouding of the lens caused by lifelong accumulation of precipitated proteins
cataract
order of cochlear chambers in the order they are affected by pressure waves entering the cochlea
- scala vestibuli
- cochlear duct
- scala tympani
When the flow of aqueous humor is blocked, and intraocular pressure increases, photoreceptors can be damaged. This condition is called
glaucoma
The fluid filling the cochlear duct is different from that of most extracellular fluid in that it has a high concentration of
potassium