PSL 310: Unit 2 Exam 2

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

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

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

what are two principle types of photoreceptor cells

- cone cells - rod cells

path of light through the human eye

- cornea - aqueous humor - lens - vitreous humor - retina

Cones are concentrated in a central, shallow pit within the macula lutea called the ____ ____:

- fovea - centralis

cells that provide lateral integration between neurons in the retina

- horizontal cells - amacrine cells

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

In the dark, cGMP-phosphodiesterase activity inside photoreceptor cells is ____, cyclic GMP concentration is ____, and the membrane is ____

- low - high - depolarized

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

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

Because of the shapes of their light-sensitive outer segments, the two types of photoreceptors are called ____ and ____

- rods - cones

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

order of cochlear chambers in the order they are affected by pressure waves entering the cochlea

- scala vestibuli - cochlear duct - scala tympani

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

types of sensory receptors

- skin pressure receptor - Proprioceptor - thermoreceptor

what senses are phasic

- tactile - olfaction - thermal

Afferent neurons convey information ____ the CNS, while efferent neurons convey information ____ the CNS

- towards - away

rod cells in the dark means RMP =

-40 mV

lens accommodation is employed to converge divergent light rays from objects further than

20 feet from the eye

Irregularity of the curvature of the lens or cornea of the eye causes a visual defect known as

Astigmatism

When pressure differences occur between the external auditory canal and the middle ear, yawning or swallowing opens the ____, allowing pressure to equilibrate

Eustachian tube

activation of ciliary muscle ____ receptors cause the lens to become more convex and increases its converging power

M3

Rapidly adapting mechanoreceptor, touch, and pressure

Meissner's corpuscle

Slowly adapting mechanoreceptor, touch, and pressure

Merkel's corpuscle

presbyopia results from

a decrease in converging power of the lens with age

Neurons that convey information from the tissues and organs of the body toward the CNS are classified as

afferent

what chamber of they eye is located between the iris and the cornea?

anterior

an increase of fluid pressure in _____ of the eye can lead to glaucoma

anterior chamber

filled with a clear fluid called aqueous humor

anterior chamber

Nociceptors are sensory receptors specialized to respond to

any stimulus that injures tissues

What eye condition results when the lens or cornea does not have a smoothly spherical surface?

astigmatism

most of the refraction of light occurs

at the corneal surface

the focal length is the distance

between the lens and the retina

what binds to cation channels on the inside of photoreceptor membranes, maintaining them in an open state?

cGMP

_____ refers to the clouding of the lens caused by lifelong accumulation of precipitated proteins

cataract

Over many years, unprotected exposure of the eyes to sunlight without wearing good sunglasses can contribute to a clouding of the lens called

cataracts

the reflex triad causes contraction of

ciliary muscle

Na+ channels are

closed in the light

Name the photoreceptor that is responsible for day and color vision

cone cell

what increases the refractive power of the lens?

contraction of the ciliary muscle

what type of lens are needed to see properly

converging

Which structure of the eye has the largest quantitative role in focusing light waves?

cornea

what is the greatest dioptric value

cornea

association: semicircular canals

crista ampularis

association: crista ampularis

cupula

in the light PDE

degrades cGMP to GMP

the reflex triad causes a decrease in the

diameter of the pupil

with hyperopia what objects can be seen clearly

distant

pain sensed in your arm is sent to the spinal cord through the

dorsal root ganglion

Neurons that carry information from the CNS toward the tissues and organs of the body are known as

efferent

if you are hyperopic you are

farsighted

with cone cells synapse with rods and cones in the retina and functions as

first order neurons in the visual pathway

Slowly adapting; may be nociceptor, thermoreceptor or mechanoreceptor

free neuron ending

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

Irreversible blindness can be caused by the condition _____, in which there is an increased pressure within the eye

glaucoma

When the flow of aqueous humor is blocked, and intraocular pressure increases, photoreceptors can be damaged. This condition is called

glaucoma

the refractive index of the cornea is

greater than that of air

analgesia association: NSAIDs

histamine

Inability to focus light rays from nearby objects on the retina is a characteristic of the condition

hyperopia

bleaching

inactivation of rhodopsin by bright light

the activation of pupillary a1 receptors

increases retinal illumination

what is responsible for sensing visceral stimuli

interoceptors

How is the fovea centralis histologically different from the rest of the retina?

it had fewer light-obstructing neurons

Photoreceptor cells are those that specifically respond to

light

rod cells are hyperpolarized in the

light

in dim light, rods are _____ cones

more active than

Individuals who have difficulty focusing on objects that are further away have a condition called

myopia/nearsightedness

people with hyperopia have difficulty focusing on

nearby objects

myopia is corrected with

negative diopters

rod cells in the dark mean there is a tonic response of

neurotransmitters onto bipolar neurons

A pain receptor which is stimulated by tissue damage is referred to as

nociceptor

in the inner ear the auditory organ is the

organ of corti

association: macula

otolith

rod cells in the dark mean cGMP levels are high in the

outer segment of the rod cell

in the inner ear the stapes interacts with the

oval window of the cochlea

Rapidly adapting mechanoreceptor, vibration, and deep pressure

pacinian corpuscle

ganglia are aggregations of nerve cell bodies in the

peripheral nervous system

ganglia are exclusively located in the

peripheral nervous system

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

During activation of visual neural pathways, ____ cells only undergo graded potentials; action potentials are first initiated in ____cells

photoreceptor and bipolar; ganglion

filled with a viscous, jellylike substance known as vitreous humor

posterior chamber

The need for reading glasses as people age is due to a condition called

presbyopia

The reduced ability to accommodate for near vision that commonly occurs with aging is called

presbyopia

analgesia association: aspirin

prostaglandins

Nociceptors from internal organs often activate interneurons linked to the somatosensory cortex that represents a superficial body part. This is known as ____ pain:

referred

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

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

Slowly adapting mechanoreceptor, skin stretch

ruffini corpuscle

ganglia contain

satellite cells

Pain, touch, pressure and thermoreception are all types of ____ senses

somatic

analgesia association: capsaicin

substance P

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

referred pain results from

the convergence of somatic and visceral pain pathways

Myopia is a condition caused by

the eyeball being too long relative to the focusing power on the lens

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

in the inner ear high frequency sound waves deform

the membrane near its base

True or false: the bleaching reaction of rhodopsin occurs when stepping from a dark place into a bright one

true

the reflex triad causes a convergence of

visual axes