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A&P Chapter 12

STUDY
PLAY
What are examples of special senses?
What are the following examples of:

1. smell
2. taste
3. vision
4. hearing
5. balance
What are examples of general senses?
What are the following examples of:

1. somatic senses
2. visceral senses
What are examples of somatic senses?
What are the following examples of:

1. tactile sensations ( touch, pressure, vibration
2. thermal sensations ( warm and cold )
3. pain sensations
4. proprioceptive sensations ( joint and muscle position sense and movements of the limbs and head)
What information do visceral senses provide?
What provides information about conditions within internal organs?
What is Sensation?
What is the conscious or subconscious awareness of changes in the external or internal environment?
What conditions must be satisfied for a sensation to occur?
What do the following conditions allow to occur:

1. a stimulus, of change in the environment, capable of activating certain sensory neurons (may be in the form of light, heat, pressure, mechanical energy or chemical energy)
2. a sensory receptor, must convert the stimulus to an electrical signal, which ultimately produces one or more nerve impulses
3. the nerve impulses must be conducted along a neural pathway from the sensory receptor to the brain
4. a region of the brain must receive and integrate the nerve impulses into a sensation
What is Perception?
What is the conscious awareness and interpretation of sensations and is primarily a function of the cerebral cortex?
What is Adaptation?
What is a characteristic of most sensory receptors, is a decrease in the strength of a sensation during a prolonged stimulus?
What are the two types of sensory receptors?
\What are the two following receptors described as:

1. structural
2. functional
What is a Structural Receptor?
What type of sensory receptors are free nerve endings, which are bare dendrites that lack structural specializations at their ends?
What are examples of structural receptors?
What are the following examples of?

1. pain
2. temperature
3. tickle
4. itch
5. some touch sensations
What are encapsulated nerve endings?
What have their dendrites enclosed in a connective tissue capsule which are receptors of somatic and visceral sensations?
What are examples of encapsulated nerve endings?
What are the following examples of?

1. touch
2. pressure
3. vibrations
What are separate cells?
What are specialized that synapse with sensory neurons?

Hair cells of the inner ear
What are examples of mechanoreceptors?
What are the following examples of?

1. are sensitive to mechanical stimuli such as deformation, stretching or bending of cells
2. they provide sensations of touch, pressure, vibration, proprioception , hearing and equilibrium
3. they also monitor the stretching of blood vessels and internal organs
What are Thermoreceptors?
What detect changes in temperature?
What are Nociceptors?
What responds to painful stimuli resulting from physical or chemical damage to tissue?
What are Photoreceptors?
What detects light that strikes the retina of the eye?
What are Chemoreceptors?
What detect chemicals in the mouth ( taste ), nose ( smell ) and body fluids?
What are Osmoreceptors?
What detects the osmotic pressure of body fluids?
What are examples of somatic senses?
What are the following examples of?

1. skin
2. mucous membranes
3. muscles
4. tendons
5. joints

(These sensations arise from stimulation of sensory receptors.)
Where are the largest numbers of sensory receptors located?
The largest number of _________ are located in:

1. tip of the tongue
2. lips
3. fingertips
What are examples of tactile sensations?
What are the following examples of?

1. include touch, pressure, vibration, itch and tickle
2. they arise by activation of some of the same type of receptors
3. several types of encapsulated mechanoreceptors detect sensations of touch, pressure and vibration
4. free nerve endings detect other tactile sensations, such as itch, and tickle
What are examples of tactile receptors in the skin or subcutaneous layer?
What are the following examples of?

1. Meissner corpuscles
2. hair root plexuses
3. Merkel discs
4. Ruffini corpuscles
5. pacinian corpuscles
6. free nerve endings
What is Touch?
What is a sensation generally result from stimulation of tactile receptors in the skin or subcutaneous layer?
What are examples of touch receptors?
What are the following examples of?

1. Meissner corpuscle
2. hair root follicles
What are examples of Meissner corpuscle (corpuscles of touch)?
What are the following examples of?

1. are the touch receptors located in the dermal papillae of hairless skin
2. each corpuscle is an egg - shaped mass of dendrites enclosed by a capsule of connective tissue
3. they are abundant in the
a) finger tips
b) hands
c) eyelids
d) tip of the tongue
e) lips
f) nipples
g) sole
h) clitoris
i) tip of the penis
What are examples of hair root follicles?
What are the following examples of?

1. found in hairy skin, consists of free nerve endings wrapped around hair follicles
2. detect movements on the skin surface that disturb hairs
What are examples of slowly adapting touch receptors?
What are the following examples of?

1. Merkel discs
2. Ruffini corpuscles
What are examples of Merkel discs (tactile discs or type I cutaneous mechanoreceptors)?
What are the following examples of?

1. saucer - shaped, flattened free nerve endings that make contact with Merkel cells of stratum basale
2. these touch receptors are plentiful in finger tips, hands, lips and external genitalia
What are examples of Ruffini corpuscles or type II cutaneous mechanoreceptors?
What are the following examples of?

1. elongated encapsulated receptors located deep in the dermis, ligaments and tendons
2. present in the hands and abundant on the sole
3. they are most sensitive to stretching that occurs as digits or limbs are moved
What is Pressure?
What is a sustained sensation that is felt over a large area and occurs in deeper tissues?
What are examples of receptors that contribute to sensations of pressure?
What are the following examples of?

1. Meissner corpuscles
2. Merkel discs
3. pacinian corpuscles
What are examples of Pacinian or lamellated corpuscle?
What are the following examples of?

1. large oval structure, composed of multilayered connective tissue capsule that encloses a dendrite
2. they adapt rapidly
3. widely distributed in the body
a) in the dermis and subcutaneous layer
b) in the tissues that underlie mucous and serous membranes
c) around joints, tendons and muscles
d) in the periosteum
e) in the mammary glands
f) external genitalia
g) certain viscera, such as the pancreas and urinary bladder
What is Vibration?
What results from rapidly repetitive sensory signals from tactile receptors?
What are examples of Vibration receptors?
What are the following examples of?

1. Meissner corpuscles (detect lower - frequency vibrations)
2. pacinian corpuscles (detect higher - frequency vibrations)
What is an Itch sensation?
What sensation results from stimulation of free nerve endings, by certain chemicals, such as bradykinin, often because of a local inflammatory response?
What is a Tickle sensation?
What sensation typically arises only when someone else touches you, not when you touch yourself?
What type of endings do Thermoreceptors have?
What have free nerve endings?
What type of sensations do Thermoreceptors have?
What has the following distinct sensations:
1. coldness
2. warmth
What type of sensations do Nociceptors have?
What has the following distinct sensations:
1. the sensory receptors for pain sensations, found in every tissue of the body except the brain
2. they respond to several types of stimuli
What are the events that produce the sensation of pain?
What do the following events produce:
1. excessive stimulation of sensory receptors
2. excessive stretching of a structure
3. prolonged muscular contractions
4. inadequate blood flow to an organ
5. presence of certain chemical substances
What are the two types of pain?
What are the following examples of:

1. fast pain
2. slow pain
What are the characteristics of fast pain?
What are the following characteristic of?

1. occurs very rapidly, usually within 0.1 second after a stimulus is applied
2. this type of pain is also known as acute, sharp or pricking pain
3. not felt in the deeper tissues of the body
What are examples of fast pain?
What are the following examples of?

1. the pain felt from a needle puncture
2. knife cut to the skin
What are the characteristics of slow pain?
What are the following characteristic of?

1. begins a second or more after a stimulus is applied
2. it then gradually increases in intensity over a period of several seconds or minitues
3. it is referred to chronic, burning, aching or throbbing pain
4. occurs both in the skin and its deeper tissues or internal organs
What is an example of slow pain?
What is the following an example of?

The pain associated with a toothache
What are the characteristics of referred pain, a.k.a. visceral pain?
What are the following characteristic of?

1. when the it is felt in
2. just deep to the skin that overlies the stimulated organ
3. in a surface area far from the stimulated organ
Additional characteristics of referred pain:
The area of the referred pain is served by the same segment of the spinal cord
1. sensory neurons from the heart
2. the skin over the heart
3. the skin along the medial aspect of the left arm enter the spinal cord segments T1 to T5
What is an example of slow pain?
What is the following an example of?

Examples:
The pain of a heart attack typically is felt in the skin over the heart and along the left arm
What are the characteristics of proprioceptive sensations?
What are the following characteristic of?

1. where our head and limbs are located
2. how they are moving even if we are looking at them
3. so that we can walk, type or dress without using our eyes
4. allow us to estimate the weight of objects and determine the muscular effort necessary to perform a task
What is Kinesthesia?
What is the perception of body movements?
What are Proprioceptors?
What are the receptors for proprioceptive sensations?
Where are Proprioceptors located?
What is located in the following:

1. skeletal muscles ( muscle spindles )
2. in tendons ( tendon organs )
3. in and around synovial joints ( joint kinetic receptors )
in the inner ear ( hair cells )
Where do nerve impulses for conscious proprioception pass?
What passes along sensory tracts in the spinal cord and brain stem?

(Proprioceptive impulses also pass to the cerebellum, where they contribute to the cerebellum's role in coordinating skilled movements)
Where are nerve impulses for conscious proprioception relayed?
What is relayed to the primary somatosensory area (postcentral gyrus) in the parietal lobe of the cerebral cortex?
Olfaction - Sense of smell
The nose contains 10 - 100 million receptors used for _________________.
What area does the structure of the olfactory epithelium occupy?
What occupies the upper portion of the nasal cavity?
What does the structure of the olfactory epithelium consists of?
What consists of the three types of cells:

1. olfactory receptors
2. supporting cells
3. basal stem cells
What are olfactory receptors?
What are the first - order neurons of the olfactory pathway?
What are olfactory hairs?
What have several cilia projecting from a knob-shaped tip on each olfactory receptor, which respond to inhaled chemicals?
What are Odorants?
What are the chemicals that have an odor and can therefore stimulate the olfactory hairs?
Where do the axons of olfactory receptors extend from?
What extends from the olfactory epithelium to the olfactory bulb?
What are supporting cells?
What are columnar epithelial cells of the mucous membrane lining the nose?
What are the functions of the supporting cells?
What is the following an example of?

1. provide physical support
2. nourishment
3. electrical insulation for the olfactory receptors
4. help detoxify chemicals that come in contact with the olfactory epithelium
What are examples of Basal cells?
What is the following an example of?

1. stem cells located between the bases of the supporting cells
2. they continually undergo cell division to produce new olfactory receptors
What do olfactory glands produce?
What produce mucous that moistens the surface of the olfactory epithelium?
What are the functions of the olfactory glands?
What is the following an example of?

Serves as a solvent for inhaled odorants
How does stimulation of olfactory receptors occur?
What are the following characteristic steps of?

1. olfactory receptors react to odorant molecules by producing an electrical signal that triggers one or more nerve impulses
2. adaptation ( decreasing sensitivity ) to odors occurs rapidly
3. olfactory receptors adapt to about 50 % in the first second or so after stimulation and very slowly thereafter
What is the olfactory pathway?
What is on each side of the nose, about 40 bundles of slender, unmyelinated axons of olfactory receptors extend through about 20 holes in the cribriform plate of the ethmoid bone?
What are olfactory nerves?
What are the collection of the bundles of axons?
What are examples of olfactory bulbs?
What are the following examples of?

Examples:
1. paired masses of gray matter located below the frontal lobes of the cerebrum
2. the olfactory nerves terminate in the olfactory bulbs in the brain
3. it has the axon terminals of olfactory receptors, the first - order neurons form synapses with the dendrites and cell bodies of second - order neurons in the olfactory pathway
What is an olfactory tract?
What are the extending neurons from the olfactory bulb?
Where are the primary olfactory areas located?
What are the following locations for?

1. in the temporal lobe of the cerebral cortex
2. some of the axons of the olfactory tract project to this area
3. conscious awareness of smell begins here
Where can other axons of the olfactory tract project to?
What are the following locations for?

1. limbic system
2. hypothalamus
Where are examples of primary olfactory area responses?
What are the following examples of?

1. sexual excitement upon smelling a certain perfume
2. nausea upon smelling a food that once made you violently ill

(These connections account for emotional and memory-evoked responses to odors)
What is Gustation also described as?
What is also known as your Sense of Taste?
Taste or gestation is much simpler than olfaction because only five primary tastes can be distinguished. What are these tastes?
What are the following examples of?

1. sour
2. sweet
3. bitter
4. salty
5. umami ( meaty or savory )
All other flavors are combinations of the five primary tastes, plus the accompanying olfactory and tactile ( touch ) sensations: What are examples?
What are the following examples of?

Examples:
1. chocolate
2. pepper
3. coffee
What are taste buds?
What have the receptors for taste sensation, located on the tongue?
10000
The young adult has nearly _______ taste buds.
What are some locations of taste buds?
Some ______ are also found:
1. on the roof of the mouth
2. pharynx ( throat )
3. epiglottis ( cartilage lid over the voice box )
What are examples of Papillae?
What are the following examples of?

1. are elevations of the tongue where taste buds are found
2. they provide a rough texture to the upper surface of the tongue
What do Vallate papillae form?
What form an inverted V shaped row at the back of the tongue?
What do Fungiform papillae form?
What are mushroom - shaped elevations scattered over the entire surface of the tongue?
Where are Filiform papillae located?
What also on the entire surface of the tongue, which contain touch receptors but no taste buds?
What do taste buds consist of?
What is an oval body consisting of three types of epithelial cells
1. supporting cells
2. gustatory receptor cells
3. basal cells
What are supporting cells?
What surround about 50 gustatory receptor cells?
What is a Gustatory hair?
What is single and long projects from each gustatory receptor cell?
What is a taste pore?
What is an opening in the taste bud where the gustatory hair project to the external surface?
What are examples of Basal cells?
What are the following examples of?

Examples:
1. are stem cells that produce supporting cells
2. which then develop into gustatory receptor cells
3. they have a life span of 10 days
What are gustatory receptor cells?
What are separate receptor cells?

They do not have an axon ( like olfactory receptors ) but rather synapse with the dendrites of the first - order sensory neurons of the gustatory pathway.
What are examples of Tastants?
What are the following examples of?

1. are the chemicals that stimulate gustatory receptor cells
2. once a tastant is dissolved in saliva, it can enter taste pores and make contact with the plasma membrane of the gustatory hairs
3. the result is an electrical signal that stimulates release of neurotransmitter molecules from the gustatory receptor cell
4. nerve impulses are triggered when these neurotransmitter molecules bind to their receptors on the dendrites of the first - order sensory neuron
5. the dendrites branch profusely and contact many gustatory receptors in several taste buds
6. individual gustatory receptor cells may respond to more than one of the primary tastes
7. complete adaptation ( loss of sensitivity ) to a specific taste can occur in 1 to 5 minutes of continuous stimulation
What are examples of a Gustatory pathway?
What are the following examples of?

1. three cranial nerves contain axons of first - order gustatory neurons that innervate the taste buds
2. the facial ( VII) nerve and glossopharyngeal ( IX ) nerve serve the tongue
3. the vagus ( X ) nerve serves the throat and epiglottis
4. from the taste buds, impulses propagate along these cranial nerves to the medulla oblongata
5. from the medulla, some axons carrying taste signals project to the limbic system and the hypothalamus and others project to the thalamus
6. taste signals from the thalamus project to the primary gustatory area
What is a Primary gustatory area?
What is located in the parietal lobe of cerebral cortex give rise to the conscious perception of taste?
TRUE
TRUE OR FALSE:

More than half of the sensory receptors in the human body are located in the eyes

A large part of the cerebral cortex is devoted processing visual information
What are examples of accessory structures of the eye?
What are the following examples of?

1. eyebrows
2. eyelashes
3. eyelids
4. extrinsic muscles that move the eyeballs
5. lacrimal ( tear - producing ) apparatus
What do eyebrows and eyelashes help protect the eyeballs from?
What help to protect the eyeballs from;

1. foreign objects
2. perspiration
3. direct rays of the sun
What are functions of the upper and lower eyelids?
What are the following examples of?

1. shade the eyes during sleep
2. protect the eyes from excessive light and foreign objects
3. spread lubricating secretions over the eyeballs ( by blinking )
What are the six extrinsic eye muscles cooperate to move each eyeball right, left, up, down and diagonally?
What are the following examples of?

1. superior rectus
2. inferior rectus
3. lateral rectus
4. medial rectus
5. superior oblique
6. inferior oblique
What do the neurons in the brain stem and cerebellum coordinate?
What coordinate and synchronize the movements of the eyes?
A lacrimal apparatus is a group of what?

Give examples
What are the following examples of?

1. glands
2. ducts
3. canals
4. sac
What are lacrimal glands?
What are right and left, about the size and shape of an almond, secrete lacrimal fluid or tear?
What are lacrimal ducts?
What convey the lacrimal fluid onto the surface of the upper eyelid?
What are lacrimal canals?
What carry the fluid over the surface of the eyeball toward the nose?
What is the nasolacrimal duct?
What allows the tears to drain into the nasal cavity?
A tear is a watery solution containing what?

Give examples
What are the following examples of?

1. salts
2. some mucous
3. bacteria - killing enzyme called lysozyme
What is the function of tear?
_________ is designed to clean, lubricate and moisten the portion of the eyeball exposed to the air to prevent it from drying?
How are tears cleared away?
Normally tears are cleared away by evaporation or by passing into the nasal cavity as fast as they are produced.
What is Crying?
What is the only human expression for emotions, both happiness and sadness?
2.5 cm ( 1 inch )
The adult eyeball measures about _________ in diameter?
What three layers is the eyeball divided into?
What are the following examples of?

1. fibrous tunic
2. vascular tunic
3. retina
What is fibrous tunic?
What is the outer coat of the eyeball, consists of an anterior cornea and a posterior sclera?
What are features of the cornea?
What are the following features characteristic of?

1. a transparent fibrous coat that covers the colored iris
2. it is curved to help focus light rays onto the retina
What are features of the sclera?
What are the following features characteristic of?

1. the ' white ' of the eye
2. a coat of dense connective tissue that covers all of entire eyeball except the cornea
3. it gives shape to the eyeball, makes it more rigid and protects its inner parts
What are features of conjunctiva?
What are the following features characteristic of?

1. an epithelial layer covers the sclera but not the cornea
2. lines the inner surface of the eyelids
What are features of Vascular tunic?

(The middle layer of the eyeball)
What are the following features characteristic of?

1. choroid
2. ciliary body
3. iris
What are features of the choroid?
What are the following features characteristic of?

1. a thin membrane that lines most of the internal surface of the sclera
2. it contains many blood vessels that help nourish the retina
3. it also contains melanocytes that produce the pigment melanin, which causes this layer to appear dark brown in color
What are features of melanin in the choroid?
What are the following features characteristic of?

1. absorbs stray light rays, which prevents reflection and scattering of light within the eyeball
2. as a result, the image cast on the retina by the cornea and lens remains sharp and clear
What does the ciliary body, at the front of the eye, consist of?
What are the following features characteristic of?

1. ciliary processes ( folds on the inner surface of the ciliary body )
2. ciliary muscle ( a smooth muscle that alters the shape of the lens for viewing objects up close or at a distance )
What is aqueous humor?
What is a fluid secreted by the capillaries in the ciliary processes?
What are features of the Lens?
What are the following features characteristic of?

1. a transparent structure that focuses light rays onto the retina
2. it is constructed of many layers of elastic protein fibers
What are the zonular fibers?
What attach the lens to the ciliary muscle and hold the lens in position?
What are features of the Iris?
What are the following features characteristic of?

1. the colored part of the eyeball
2. it includes both circular and radial smooth muscle fibers
3. the smooth muscle of the iris regulates the amount of light passing through the lens
What is the Pupil?
What is the hole in the center of the iris, through which light enters the eyeball?
Parasympathetic division
When the eye is stimulated by bright light, the ______________ of the autonomic nervous system ( ANS ) causes contraction of the circular muscle of the iris, which decreases the size of the pupil ( constriction )
Sympathetic division
When the eye must adjust to dim light, the _____________ of the ANS causes the radial muscles to contract, which increases the size of the pupil ( dilation )
What are features of the Retina?
What are the following features characteristic of?

1. the third and inner coat of the eyeball
2. lines the posterior three - quarters of the eyeball
3. it is the beginning of the visual pathway
4. it has two layers, the neural layer and the pigmented layer
What is the neural layer?
What is a multilayered outgrowth of the brain?
What are the three distinct layers of retinal neurons?
What are the following features characteristic of?

1. photoreceptor layer
2. bipolar cell layer
3. ganglion cell layer
Distinct layers of retinal neurons
These are separated by two zones, outer and inner synaptic layers, where synaptic contacts are made

(Light passes through the ganglion and bipolar cell layers and both synaptic layers before it reaches the photoreceptor layer.)
What are features of the pigmented layer of the retina?
What are the following features characteristic of?

1. a sheet of melanin containing epithelial cells located between the choroid and the neural part of the brain
2. the melanin helps to absorb stray light rays
What are Photoreceptors?
What are specialized cells that begin the process by which light rays are ultimately converted to nerve impulses.
What are the two types of photoreceptors?
What are the following types of:

1. rods
2. cones
What are Rods?
What allow us to see shades of gray in dim light, such as moonlight?
What are Cones?
What are stimulated by brighter light. Giving rise to high acute, color vision?
What are the three types of cones are present in the retina?
What are the following:

1. blue cones, which are sensitive to blue light
2. green cones which are sensitive to green light
3. red cones which are sensitive to red light
What is color vision?
What results from the stimulation of various combinations of these three types of cones?
What is macula lutea?
What is the yellow spot in the exact center of the retina?
What are features of the fovea centralis?
What are the following features characteristic of?

1. a small depression in the center of the macula lutea
2. it is the highest area of visual acuity
What is visual acuity or resolution?
What is the sharpness of vision, because of its high concentration of cones?
Where are rods absent from?
What are absent from the fovea centralis and macula lutea?
Where are rods present in a higher number?
What increase in numbers toward the periphery of the retina?
What are features of visual acuity or resolution?
What are the following features characteristic of?

1. from photoreceptors, information flows through the outer synaptic layer to the bipolar cells of the bipolar cell layer
2. from bipolar cells through the inner synaptic layer to the ganglion cells of the ganglion cell layer
3. between 6 and 600 rods synapse with a single bipolar cell in the outer synaptic layer
4. a cone usually synapses with just one bipolar cell
What are features of the optic disc ( blind spot )?
What are the following features characteristic of?

1. a small area of the retina posteriorly where the axons of the ganglion cells extend
2. because the optic disc contains no rods or cones, we cannot see an image that strikes the blind spot
What is the optic nerve?
What is the extension of the axons of the ganglion cells?
What are the features of the interior of the eyeball?
What are the following features characteristic of?

The lens divides the __________ into two cavities
1. anterior cavity
2. vitreous chamber
What does the anterior cavity lie?
What lies anterior to the lens?
What are features of the aqueous humor?
What are the following features characteristic of?

1. a watery fluid, similar to cerebrospinal fluid, fills the anterior cavity
2. secreted into the anterior cavity by the blood capillaries of the ciliary processes of the ciliary body
3. normally it is completely replaced about every 90 minutes
What are functions of the aqueous humor?
What are the following functions for:

1. helps to maintain the shape of the eye
2. nourishes the lens and cornea ( neither of which has blood vessels )
What is the Scleral venous sinus ( canal of Schlemn )?
What is an opening where the sclera and cornea meet, in which the aqueous humor drains and reenters the blood?
What are features of the vitreous chamber?
What are the following features characteristic of?

1. lies behind the lens
2. it is the second and larger cavity of the eyeball
What are features of the vitreous body?
What are the following features characteristic of?

1. clear, jellylike substance in the vitreous chamber
2. it is formed during embryonic life and is not replaced thereafter
3. it helps prevent the eyeball from collapsing and holds the retina flush against the choroid
What are features of intraocular pressure?
What are the following features characteristic of?

1. the pressure of the eye, produced mainly by the aqueous humor with a smaller contribution from the vitreous body
2. normal intraocular pressure ( about 16 mm Hg ) is maintained by a balance between production and drainage of the aqueous humor
What are functions of intraocular pressure?
What are the following functions for:

1. it maintains the shape of the eyeball
2. keeps the retina smoothly pressed against the choroid so the retina is well nourished and forms clear images
Image formation and Binocular vision.
The eye is like a camera, its optical elements focus an image of some object on a light-sensitive "film", the retina, while ensuring the correct amount of light makes the proper "exposure".
What are the three processes of how the eye forms clear images of objects on the retina?
What do the following processes represent:

1. the refraction or bending of light by the lens and cornea
2. the changes in shape of the lens
3. constriction or narrowing of the pupil
Refraction of light rays.
When light rays traveling through a transparent substance (such as air) pass into a second transparent substance with a different density (such as water) they bend at the junction between the two substances.
What is Refraction?
What is the bending of the light rays?

(About 75 % of the total ______ of light occurs at the cornea)
What are features of Accommodation?
What are the following features characteristic of?
:
1. the lens of the eye is convex on both its anterior and posterior surfaces
2. its ability to refract light increases as its curvature becomes greater
3. when the eye is focusing on a closer object, the lens becomes more convex and refracts the light rays more
What is Accommodation?
What is the increase in the curvature of the lens?
What happens when you are viewing distant objects?
The ciliary muscle of the ciliary body is relaxed and the lens is fairly flat because it is stretched in all directions by taut zonular fibers, when you are doing what?
What happens when you view a close object?
The ciliary muscle contract, which pulls the ciliary process and choroids forward toward the lens, when you are doing what?
The action releases tension on the lens doing what to the eye?
What is allowing it, the eye, to become rounder (more convex) which increases its focusing power and causes greater convergence of the light rays?
What is emmetropic eye?
What is called when the normal eye, can sufficiently refract light rays from an object ( 20 feet ) away so that a clear image is focused on the retina?
What is Myopia
What are the following features characteristic of?

1. nearsightedness
2. occurs when the eyeball is too long relative to the focusing power of the cornea and lens
3. myopic individuals can see nearby objects clearly, but not distant objects
What are the features of Hyperopia (hypermetropia)?
What are the following features characteristic of?

1. farsightedness
2. the eyeball length is short relative to the focusing power of the cornea and lens
3. hyperoptic individuals can see distant objects clearly, but not nearby objects
What is Astigmatism?
What is another refraction abnormality in which either the cornea or the lens has an irregular curvature ?
What is Presbyopia?
What occurs with aging, the lens loses some of the elasticity so its ability to accommodate decreases and at about age 40, people who have not previously worn glasses begin to require them for close vision, such as reading?
What are features of Constriction of the pupil?
What are the following features characteristic of?

1. is a narrowing of the diameter of the hole through which light enters the eye due to contraction of the circular muscles of the iris
2. this autonomic reflex occurs simultaneously with accommodation
3. prevent light rays from entering the eye through the periphery of the lens
4. light rays entering at the periphery of the lens would not be brought to focus on the retina and would result in blurred vision
5. the pupil also constricts in bright light to limit the amount of light that strikes the retina
What is Binocular vision?
What is a characteristic when both eyes focus on only one set of objects?
What is Convergence?
What is the name for the automatic movement of the two eyeballs toward the midline, which is caused by the coordinated action of the extrinsic eye muscles ?

The nearer the object, the greater the ___________ needed to maintain binocular vision.
What is Photopigment ( visual pigment )?
What is a substance that can absorb light and undergo a change in structure ?
What is Rhodopsin?
What is the photopigment in rod and it has the two combinations:

1. opsin ( a protein )
2. retinal ( a derivative of vitamin A )
What are rods?
What usually are nonfunctional in daylight?

After going from bright sunlight into a dark room, it takes about 40 minutes before the _____ function maximally.
What are cones?
What function in bright light and provide color vision ?
TRUE
TRUE OR FALSE?

Photopigments in cones also contain retinal
What are types of proteins are found in cones?
There are three different opsin proteins one in each of the three types of cones?

The cone photopigments reform much more quickly than the rod photopigments .
What causes Night blindness?
What is when prolonged vitamin A deficiency resulting below - normal amount of rhodopsin?
What causes Colorblindness?
What is when an individual with an absence or deficiency of one of the three types of cones from the retina cannot distinguish some colors from others .
What is red - green color blindness?
What is the most common type, either red cones or green cones are missing, thus the person cannot distinguish between red and green ?
What are the features of the visual pathway ?
What are the following features characteristic of?

1. after stimulation by light, the rods and cones trigger electrical signals in bipolar cells 2. bipolar cells transmit both excitatory and inhibitory signals to ganglion cells
3. the ganglion cells become depolarized and generate nerve impulses
4. the axons of the ganglion cells exit the eyeball as the optic nerve
5. they extend posteriorly to the optic chiasma ( cross over )
6. in the opeic chiasma, about half of the axons from each eye cross to the opposite side of the brain
7. after passing to the optic chiasma, the axons now part of the optic tract, terminate in the thalamus
8. here they synapse with neurons whose axons project to the primary visual areas in the occipital lobe of the cerebral cortex
9. because of the crossing at the optic chiasma, the right side of the brain receives signals from both eyes for interpretation of visual sensation from the left side of an object
10. the left side of the brain receives signals from both the eyes for interpretation of visual sensations from the right side of the object
What are the features of hearing and equilibrium
What are the following features characteristic of?

1. the ear is a marvelously sensitive structure
2. its sensory receptors can convert sound vibrations into electric signals 1000 times faster than photoreceptors can respond to light
3. besides receptors for sound waves, the ear also contains receptors for equilibrium ( balance )
What are the structures of the ear ?
(The ear is divided into three main regions)
What are the following features characteristic of?

1. external ear ( which collects sound waves and channels them inward )
2. middle ear ( which conveys sound vibrations to the oval window )
3. internal ear ( which houses the receptors for hearing and equilibrium )
What are the features of the external ( outer ) ear?
What collects the sound waves and passes them inward ?

It consists of
1. auricle
2. external auditory canal
3. ceruminous glands
4. ear drum
What are the features of the Auricle?
What are the following features characteristic of?

1. a skin - covered flap of elastic cartilage shaped like a flared end of a trumpet
2. plays a small role in collecting sound waves and directing them toward external auditory canal
What are the features of the external auditory canal?
What are the following features characteristic of?

1. a curved tube that extends from the auricle and directs sound waves toward the ear drum
2. the canal contains a few hairs and ceruminous glands
What are Ceruminous glands?
What secrete ear wax, the cerumen .

The hairs and cerumen help prevent foreign objects from entering the ear.
What are the features of the eardrum (tympanic membrane)?
What are the following features characteristic of?

1. a thin, semitransparent partition between the external auditory canal and the middle ear
2. sound waves cause the eardrum to vibrate
What is a Perforated eardrum?
What is the tearing of the tympanic membrane , due to trauma or infection?
What is the Middle ear?
What is a small, air - filled cavity between the eardrum and inner ear?
What is the Auditory tube?
What is commonly known as eustachian tube connects the middle ear with the upper part of the throat?

When the ______________ is open, air pressure can equalize on both sides of the eardrum.
What are the Auditory ossicles?
What are the three tiny bones :

1. malleus
2. incus
3. stapes
What are the two tiny skeletal muscles control the amount of movement of these bones to prevent damage by excessive loud noise ?
What are the following:

1. tensor tympani
2. stapedius
What is the Oval window?
What is a small opening in the thin bony partition between the middle and internal ear, where the stapes fits?
What are the two parts of the Internal (inner) ear?
What is divided into

1. outer bony labyrinth
2. inner membranous labyrinth
What is the Bony labyrinth?
What is a series of cavities in the temporal bone that includes

1. cochlea
2. vestibule
3. semicircular canals
What are the structures of the Cochlea ?
What are the following features characteristic of?

Examples
1. sense organ for hearing
2. is a bony spiral canal resembles a snail's shell
3. divided into three channels
What are the structures of the Vestibule?
What are the following features characteristic of?

Examples
1. the oval - shaped middle part of the bony labyrinth 2. it consists of two sacs, utricle and saccule
What are the three Semicircular canals?
1. anterior
2. posterior
3. lateral
What are the Vestibule and semicircular canals?
What are the sense organs for equilibrium and balance?
What is Perilymph?
What is the fluid fills the bony labyrinth?
What is the Vestibule?
What is the oval - shaped middle part of the bony labyrinth?
What is the Membranous labyrinth?
What contains a series of sacs and tubes with the same general shape as the bony labyrinth?
What is Endolymph?
What is the fluid fills the membranous labyrinth?
What are the parts of the membranous labyrinth?
1. utricle
2. saccule
3. cochlear duct
4. semicircular duct
Utricle
is a little bag
Saccule
is a little sac
What are Semicircular ducts?
What are inside the semicircular canals, which connect with the utricle of the vestibule?
What is the Cochlear duct?
What is a continuation of the membranous labyrinth into cochlea?
What is the Scala vestibuli?
What is the channel above the cochlear duct, which ends at the oval window?
What is the Scala tympani?
What is the channel below the cochlear duct?
What is the Round window?
What is the membrane-covered opening directly below the oval window?
TRUE
TRUE OR FALSE?

Both the scala vestibule and scala tympani are part of the bony labyrinth of the cochlea and are filled with perilymph.
What is the Vestibular membrane?
What lies between the cochlear duct and scala vestibule?
What is the Basilar membrane?
What lies between the cochlear duct and scala tympani?
What are features of the Spiral organ (organ of Corti)?
What rests on the basilar membrane, is the organ of hearing and it consists of

1. supporting cells
2. hair cells
What are the features of Hair cells?
What are the following features characteristic of?

1. the receptors for auditory sensations
2. they have long processes at their free ends and they extend into the endolymph of the cochlear duct
3. they form synapses with sensory and motor neurons in the cochlear branch of the VIII nerve
(vestibulocochlear nerve)
What is Tectorial membrane?
What is a flexible, gelatinous membrane covers the hair cells?
The events involved in stimulation of hair cells by sound waves:
What are the following features characteristic of?

1. the auricle directs sound waves into the external auditory canal
2. sound waves striking the eardrum cause it to vibrate
a) the distance and speed of its movement depend on the intensity and frequency of the sound waves
b) more intense ( louder ) sounds produce larger vibrations
c) the eardrum vibrates slowly in response to low - frequency ( low - pitched ) sounds and rapidly in response to high - frequency ( high - pitched ) sounds
3. the central area of the eardrum connects to the malleus, which also starts to vibrate
a) the vibration is transmitted from the malleus to the incus and then to the stapes
4. as the stapes moves back and forth, it pushes the oval window in and out
5. the movement of the oval window sets up fluid pressure waves in the perilymph of the cochlea
a) as the oval window bulges inward, it pushes on the perilymph of the scala vestibule
6. the fluid pressure waves are transmitted from the scala vestibule to the scala tympani and eventually to the membrane covering the round window
a) this causes it to bulge outward into the middle ear 7. as the pressure waves deform the walls of the scala vestibule and scala tympani, they also push the vestibular membrane back and forth, creating pressure waves in the endolymph inside the cochlear duct
8. the pressure waves in the endolymph cause the basilar membrane to vibrate, which moves the hair cells of the spiral organ against the tectorial membrane
a) bending of these hairs stimulate the hair cells to release neurotransmitter molecules at synapses with sensory neurons, that are part of the vestibulocochlear ( VIII ) nerve
b) then, the sensory neurons generate nerve impulses that conduct along the vestibulocochlear ( VIII ) nerve
What are Otoacoustic emissions?
What are the following features characteristic of?

1. when the cochlea has the surprising ability to produce sounds
2. these sounds arise from vibrations of the hair cells themselves, caused in part by signals from motor neurons that synapse with the hair cells
What are features of the Auditory pathway?
What are the following features characteristic of?

1. sensory neurons in the cochlear branch of each vestibulocochlear ( VIII ) nerve terminate in the medulla oblongata on the same side of the brain
2. from the medulla, axons ascend to the midbrain, then to the thalamus and finally to the primary auditory area in the temporal lobe
3. because many auditory axons cross the opposite side, the right and left primary auditory areas receive nerve impulses from both ears
What are features of the Vestibular apparatus?
What are collectively the receptor organs for equilibrium which include :
1. saccule
2. utricle
3. membranous semicircular ducts
Two types of equilibrium ( balance )?
What are the following features characteristic of?

1. static equilibrium
2. dynamic equilibrium
What are features of Static equilibrium?
What are the following features characteristic of?

1. refers to the maintenance of the position of the body ( mainly the head ) relative to the force of gravity 2. body movements that stimulate the receptors for static equilibrium include tilting the head and linear acceleration or deceleration , such as when the body is being moved in an elevator or in a car that is speeding up or slowing down
3. the walls of both the utricle and saccule contain a small thickened region called macula
4. the two maculae which are perpendicular to one another, are the receptors for static equilibrium
5. the maculae provide sensory information and help maintain appropriate posture and balance
6. the maculae also contribute to some aspects of dynamic equilibrium by detecting linear acceleration and deceleration
Macula consists of what two types of cells?
What are the following features characteristic of?

1. hair cells ( sensory receptors )
2. supporting cells
What is the Otolithic membrane?
What is a thick, jelly like substance in which the hairs of the hair cells protrude?
What are Otoliths?
What are a layer of dense calcium carbonate crystals, extends over the entire surface of the otolithic membrane ?
vestibulocochlear nerve
If you tilt your head forward, gravity pulls the membrane ( and the otoliths ) so it slides over the hair cells in the direction of the tilt.

This stimulates the hair cells and triggers nerve impulses that conduct along the vestibular branch of what nerve?
What are features of the Dynamic equilibrium?
What are the following features characteristic of?

1. the maintenance of the body position ( mainly the head ) in response to rotational accelearation or deceleration
2. the three membranous semicircular ducts lie at right angles to one another in three planes
3. the positioning permits detection of rotational acceleration or deceleration
What is the Ampulla?
What is the dilated portion of each duct?
What is the Crista?
What is a small elevation in the ampulla, and contains a group of:

1. hair cells
2. supporting cells
What is the Copula?
What is a mass of gelatinous material covering the crista ?

When the head moves, the attached membranous semicircular ducts and the hair cells move with it .

Bending of the hairs cause electrical signals in the hair cells In turn, these signals trigger nerve impulses in sensory neurons that part of the vestibular branch of the vestibulocochlear nerve .
What are the features of the Equilibrium pathways ?
What are the following features characteristic of?

1. most of the vestibular branch axons of the vestibulocochlear ( VIII ) nerve enter the brain stem
2. and extend to the medulla or the cerebellum, where they synapse with the next neurons in the equilibrium pathways
3. from the medulla, some axons conduct nerve impulses along the cranial nerves that control eye movements and head and neck movements
4. other axons from a spinal cord tract that conveys impulses for regulation of muscle tone in response to head movements
5. various pathways among medulla, cerebellum and cerebrum enable the cerebellum to play a key role in maintaining equilibrium
6. the cerebellum continuously receives sensory information from the utricle and saccule
7. in response, the cerebellum makes adjustments to the signals going from the motor cortex to specific skeletal muscles to maintain equilibrium
What are the features of Cataract?
What are the following features characteristic of?

1. a common cause of blindness is a loss of transparency of the lens
2. the lens become cloudy ( less transparent ) due to changes in the structure of the lens proteins
3. it often occurs
a) with aging
b) but may also be caused by injury
c) excessive exposure to ultraviolet rays
d) certain medications ( such as long - term use of steroids )
e) or complications of other diseases ( for example, diabetes )
f) people who smoke also have increased risk of developing cataracts
g) sight can be usually restored by surgical removal of the old lens and implantation of an artificial one
What are the features of Glaucoma?
What are the following features characteristic of?

1. is the most common cause of blindness
2. due to a buildup of aqueous humor within the anterior cavity causes an abnormally high intraocular pressure
3. persistent pressure results in
a) a progression from mild visual impairment to irreversible destruction of retina
b) damage to the optic nerve
c) blindness
What is the definition of Deafness?
What is a significant or total hearing loss?
What is Sensorineural deafness?
What is caused by either impairment of hair cells in the cochlea or damage of the cochlear branch of the vestibulocochlear nerve?


This type of deafness may be caused by:
1. atherosclerosis which reduces blood supply to the ears
2. repeated exposure to loud noise, which destroys hair cells of the spiral organ
3. certain drugs such as aspirin and streptomycin
What is Conduction deafness?
What is caused by impairment of the outer and middle ear mechanisms for transmitting sounds to the cochlea?

It may be caused by:
1. otosclerosis, the depletion new bone around the oval window
2. impacted cerumen
3. injury to the eardrum
4. aging, which often results in thickening of the eardrum
5. stiffening of the joints of the auditory ossicles
What is Meniere's disease?
What results from an increased amount of endolymph that enlarges the membranous labyrinth ?

Symptoms are
1. fluctuating hearing loss ( caused by distortion of the basilar membrane of the cochlea )
2. roaring tinnitus ( ringing )
3. almost total destruction of hearing may occur over a period of years
What is Vertigo?
What is ( a sensation of spinning or whirling ) characteristic of Meniere's disease?
What is Otitis media?
What is an acute infection of the middle ear caused primarily by bacteria and associated with infections of the nose and throat ?

Symptoms include:
1. pain
2. malaise ( discomfort or uneasiness )
3. fever
Middle ear infections and damage:
Reddening and outward bulging of the eardrum, which may rupture unless prompt treatment is received ( this may involve draining pus from the middle ear ) .

Bacteria from the nasopharynx passing into the auditory tube is the primary cause of all middle ear infections .

Children are more susceptible than adults to middle ear infections because their auditory tubes are almost horizontal, which decreases drainage
What is Age-related macular disease (AMD)?
What is the degeneration of the macula lutea of the retina in persons 50 years of age and older ?
What is Anosmia?
What is total lack of the sense of smell?
What is a Cochlear implant?
What is a device that translates sound s into electrical signals , that can be interpreted by the brain, useful for people with deafness caused by damage to hair cells in the cochlea?
What are the features of Conjunctivitis (pinkeye) ?
What are the following features characteristic of?

1. an inflammation of the conjunctiva, caused by bacteria such as pneumocci, staphylococci or Hemophilus influenza
2. it is very contagious and more common in children 3. may also be caused by irritants, such as dust, smoke or pollutants in the air
What are Detached retinais?
What is the detachment of the neural portion of the retina from the pigment epithelium due to trauma, disease, or age - related degeneration ?
What is LASIK ( laser - assisted in - situ keratomileusis )?
What is a surgery with a laser to correct the curvature of the cornea for conditions such as nearsightedness, farsightedness and astigmatism ?
What is Nystagmus?
What is a rapid involuntary movement of the eyeballs, possibly caused by a disease of the central nervous system, associated with conditions that cause vertigo ?
Otalgia
What is an earache?
What is a Retinoblastoma?
What is a tumor arising from immature retinal cells, it accounts 2% of child - blood cancers?
What is a Scotoma?
What is an area of reduced or lost vision in the visual field?
What is Strabismus?
What is an imbalance in the extrinsic eye muscles that causes a misalignment of one eye so that its line of vision is not parallel with that of the other eye ( cross - eyes ) the condition produces squint?
What is Tinnitus?
What is a ringing, roaring or clicking in the ears?
What is Trachoma?
What is a serious form of conjunctivitis and the greatest single cause of blindness in the world ?

1. it is caused by the bacterium Chlamydia trachomatis
2. the disease produces an excessive growth of subconjunctival tissue and invasion of blood vessels into the cornea, which progresses until the entire cornea is opaque, causing blindness
What is Vertigo?
What is a sensation of spinning or movement in which the world seems to revolve or the person seems to revolve in space?