lecture 5 2401

visual acuity, is rated by comparison to a

"normal" standard. The standard vision rating of 20/20 is defined as the level of detail seen at a distance of 20 feet by a person with normal vision.

Activated muscle fibers use energy, so the greater the muscle tone, the higher the

"resting" rate of metabolism (all the chemical reactions occurring in the body). Increasing this rate is one of the significant effects of exercise in a weight-loss program. You lose weight when your daily energy use exceeds your daily

normal function requires

(1) substantial intracellular energy reserves, (2) a normal circulatory supply, (3) a normal blood oxygen level, and (4) a blood pH within normal limits. Anything that interferes with any of these factors will reduce the efficiency of muscle activity and cause premature muscle fatigue.

In the contraction phase

, tension increases to a peak. As the tension increases, calcium ions are binding to troponin, active sites on thin filaments are being exposed, and cross-bridge interactions are occurring. For this muscle fiber, the contraction phase ends roughly 15 msec after stimulation.

This state in which the pigments are fully receptive to stimulation is called the

. After 30 minutes or more in the dark, almost all visual pigments will have recovered from photobleaching. dark-adapted state

The auditory tube (also called the pharyngotympanic tube or the Eustachian tube)

.The auditory tube equalizes pressure on either side of the tympanic membrane.

The vestibular nuclei have four functions:

1. Integrating sensory information about balance and equilibrium that arrives from both sides of the head. 2.Relaying information from the vestibular complex to the cerebellum. 3.Relaying information from the vestibular complex to the cerebral cortex, providing a conscious sense of head position and movement. 4.Sending commands to motor nuclei in the brainstem and spinal cord.

The human olfactory system can discriminate between, or make subtle distinctions among,

2000-4000 chemical stimuli.

The relaxation phase lasts about

25 msec. During this period, the Ca2+ level is decreasing as calcium ions are pumped back into the SR, active sites are being covered by tropomyosin, and the number of active cross-bridges is declining as they detach. As a result, tension decreases to the resting level.

Aerobic metabolism normally provides

95 percent of the ATP demands of a resting cell. In this process, mitochondria absorb oxygen, ADP, phosphate ions, and organic substrates (such as pyruvate) from the surrounding cytoplasm.

is a motor neuron and all the muscle fibers that it controls. The size of a motor unit indicates how fine, or precise, a movement can be. Small motor units, with 4-6 muscle fibers, are found in the muscles of the eyes and fingers, where precise control is extremely important.

A motor unit

the myosin head must have what bound to it

ADP and Pi

to create powerstroke the myosin has to release

ADP and Pi

ADP + creatine phosphate -> During a contraction, each myosin head breaks down ATP, producing ADP and phosphate. The energy stored in creatine phosphate is then used to "recharge" ADP, converting it back to ATP through the reverse reaction:

ATP + creatine

sour

Acids taste

what is the function of tropomyosin

Blocks the binding sites in the actin when a muscle is relaxed so that the myosin heads cannot bind to them. This keeps the muscle relaxed

olfactory pathway, and inhibition at the intervening synapses can prevent the sensations from reaching the olfactory cortex. the olfactory receptors themselves adapt very little to an ongoing stimulus. Rather, central adaptation (provided by the innervation of the olfactory bulbs by other brain nuclei) ensures that you quickly lose awareness of a new smell but remain sensitive to others.

Considerable convergence takes place along the

refers to the ability of a muscle cell to shorten when it is stimulated.

Contractility

what is the function of the eustachian tube

Equalize pressure in the middle ear with the outside atmosphere

Equilibrium sensations inform us of the position of the head in space by monitoring

Equilibrium sensations inform us of the position of the head in space by monitoring gravity, linear acceleration, and rotation.

when the lights come on at first they seem almost unbearably bright, but over the next few minutes your sensitivity decreases as bleaching occurs.

Eventually, the rate of bleaching is balanced by the rate at which the visual pigments reassemble. This condition is the light-adapted state.

also known as responsiveness or irritability, is the ability to receive and respond to a stimulus. Muscle tissue responds to a chemical stimulus from a nerve cell with a change in membrane potential.

Excitability,

is stretching movement of a muscle, while elasticity is the ability of a muscle to recoil (spring back) to its resting length.

Extensibility

A single thin filament contains four main proteins:

F-actin, nebulin, tropomyosin, and troponin

what is the pathway of light in the eye

First, the light hits the cornea which allows it to enter through the pupil. The light then reaches the Aqueous humor which reflects the light. The light is then focused and travels through the Vitreous humor to reach the retina. Upon reaching the retina, it falls on the retinal receptors (rods and cones) which convert the light energy to nerve impulses. The nerve impulses travel through the optic nerve to the visual cortex.

Skeletal muscles called sphincters encircle the openings of the digestive and urinary tracts. These muscles give us voluntary control over swallowing, defecating, and urinating. (Involuntary sphincters have smooth muscle.)

Guarding Body Entrances and Exits.

(metric, measure), the muscle as a whole does not change length, and the tension produced never exceeds the load.

In an isometric contraction

tension increases and the skeletal muscle's length changes. Lifting an object off a desk, walking, and running involve _________. This is when tension increases and the skeletal muscles length changes

In an isotonic contraction

what forms a tubular network around each myofibril, fitting over it like lacy shirtsleeves. The SR is similar to the smooth endoplasmic reticulum of other cells.

In skeletal muscle fibers, a membrane complex called the sarcoplasmic reticulum (SR)

when a photoreceptor releases an inhibitory neurotransmitter how does it affect the bipolar neuron

In the dark, a photoreceptor (rod/cone) cell will release glutamate, which inhibits (hyperpolarizes) the ON bipolar cells and excites (depolarizes) the OFF bipolar cells. it produces an ISPS so we cannot see

what happens to photoreceptors in the dark

In the dark, the photoreceptors maximally release glutamate and these bipolar cells are maximally hyperpolarized.

what is sound

It consists of waves of pressure conducted through a medium such as air or water. In air, each pressure wave consists of a region where the air molecules are crowded together and an adjacent zone where they are farther apart

Muscle contractions use energy, and whenever energy is used in the body, some of it is converted to heat. The heat released by working muscles keeps body temperature in the range needed for normal functioning.

Maintaining Body Temperature.

Tension in our skeletal muscles maintains body posture—for example, holding your head still when you read a book or balancing your body weight above your feet when you walk. Without constant muscular activity, we could neither sit upright nor stand.

Maintaining Posture and Body Position.

occurs when all motor units in the muscle contract in a state of complete tetanus. Such powerful contractions do not last long, however, because the individual muscle fibers soon use up their available energy reserves.

Peak tension

How does the pupil constrict

Pupil constriction is controlled by the iris sphincter muscle. The iris sphincter muscle encircles the pupil like a cord that reduces the size of the pupil when it contracts

how does the pupil dialate

Pupil dilation is controlled by the iris dilator muscle. The dilator muscle consists of fibers that are oriented radially, and connect the exterior of the iris with the interior. When the dilator muscle contracts, it pulls the interior of the iris outward, thus increasing the size of the pupil

We can subdivide the bony labyrinth into the vestibule, the semicircular canals, and the cochlea The vestibule (consists of a pair of membranous sacs: the saccule (and the utricle. what is the function of this sac

Receptors in these sacs provide equilibrium sensations. The three semicircular canals enclose three slender semicircular ducts.

is an inherited disease characterized by progressive retinal degeneration.

Retinitis pigmentosa (RP) As the visual receptors gradually deteriorate, blindness eventually results. The mutations that are responsible change the structure of the photoreceptors—specifically, the visual pigments of the membrane discs. We do not know how the altered pigments lead to the destruction of photoreceptors.

what is the pigment in the outer segment of the cone and rod

Rods express one type of visual pigment, rhodopsin, whereas cones express different types of cone opsins for detecting light with different wavelengths

The Shape of the Lens. The rounder the lens, the more refraction occurs.

So, a very round lens has a shorter focal distance than a flatter one

When our diet contains too few proteins or calories, the contractile proteins in skeletal muscles are broken down, and their amino acids released into the circulation. The liver can use some of these amino acids to synthesize glucose, and others can be broken down to provide energy

Storing Nutrients.

Layers of skeletal muscle make up the abdominal wall and the pelvic floor cavity. These muscles support the weight of our visceral organs and shield our internal tissues from injury.

Supporting Soft Tissues.

what is the function of ganglion cells

Synapse with bipolar cells and transmit APs to the brain via axons in optic nerve.

_______ In a resting sarcomere, the __________is a lighter region on either side of the M line. _______ contains thick filaments, but no thin filaments.

The H Band.

is in the center of the A band. Proteins of the _____ connect the central portion of each thick filament to neighboring thick filaments. These dark-staining proteins help stabilize the positions of the thick filaments.

The M line

________consist of proteins called actinins, which interconnect thin filaments of adjacent sarcomeres. At both ends of the sarcomere, thin filaments extend from the ___________toward the M line and into the zone of overlap.

The Z lines

_____________ is a dark region where thin filaments are located between the thick filaments. Here three thick filaments surround each thin filament, and six thin filaments surround each thick filament.

The Zone of Overlap. i

What happens when you inhale through your nose?

The air swirls within your nasal cavity. This turbulence brings airborne substances, including water-soluble and lipid-soluble substances called odorants, to your olfactory organs

The cornea is covered by

The cornea is covered by a very delicate squamous corneal epithelium, five to seven cells thick, that is continuous with the bulbar conjunctiva.

external, middle and internal ear

The ear is divided into three anatomical regions:

1) filiform (filum, thread) papillae, (2) fungiform (fungus, mushroom) papillae, (3) vallate papillae, and (4) foliate papillae.

The human tongue has four types of lingual papillae

the iris contains

The iris contains blood vessels, pigment cells (melanocytes), and two layers of smooth muscle fibers called pupillary muscles. When these muscles contract, they change the diameter of the pupil, the central opening of the iris. There are two groups of pupillary muscles: dilator pupillae and sphincter pupillae The autonomic nervous system controls both muscle groups.

lense fibers are

These highly specialized cells have lost their nuclei and other organelles. They are long and slender and are filled with transparent proteins called crystallins. These proteins give the lens both its clarity and its focusing power.

what are cross bridges

These projections, or myosin heads, that are found on the thick filaments formed from the binding of actin with myosin. The formation shows muscle shortening caused by the movement of the contractile protein. The cross-bridge muscular contraction cycle is identified in all muscle types, including cardiac, smooth, and skeletal muscles

tympanic membrane (tympanon, drum), or eardrum.

This thin, semitransparent sheet separates the external ear from the middle ear.

surfaces are continuous with the sarcolemma and extend deep into the sarcoplasm. They are filled with extracellular fluid and form passageways through the muscle fiber, like a network of tunnels through a mountain. As extensions of the sarcolemma, T tubules share the same special property of being able to propagate an electrical impulse. As a result, electrical impulses generated by the sarcolemma also travel along the T tubules into the cell interior. These impulses, called action potentials, trigger muscle fiber contraction.

Transverse tubules, or T tubules, are narrow tubes whose

We rely more on__________ than on any other special sense

Vision

The recovery period

When a muscle fiber contracts, conditions in the sarcoplasm change. Energy reserves are consumed, heat is released, and, if the contraction was at a maximum level, oxygen is less available and lactate is generated. In the recovery period, the conditions in muscle fibers are returned to a normal, pre-exertion level. After a period of moderate activity, muscle fibers may need several hours to recover. After sustained activity at a higher level, complete recovery can take a week.

When sound waves cause the tympanic membrane to vibrate, the ossicles conduct

When sound waves cause the tympanic membrane to vibrate, the ossicles conduct the vibrations to the internal ear.

when light hits one of the photoreceptors it causes bleaching of the pigment

When the rod photopigments are exposed to light they undergo a process called bleaching. It is called bleaching because the photopigment color actually become almost transparent. In the dark when they regenerate and regain their pigmentation again.

ceruminous glands—integumentary glands along the external acoustic meatus—secrete

a waxy material called cerumen (or earwax) that helps keep out foreign objects or small insects.

The pigmented layer of the retina does what

absorbs light that passes through the neural layer, preventing light from bouncing (reflecting) back through the neural layer and producing visual "echoes." The pigment cells also have important biochemical interactions with the retina's photoreceptors.

The olfactory pathway begins with .

afferent fibers leaving the olfactory epithelium that collect into 20 or more bundles. These bundles penetrate the cribriform plate of the ethmoid bone to reach the olfactory bulbs of the cerebrum, where the first synapse occurs. Efferent fibers from nuclei elsewhere in the brain also innervate neurons of the olfactory bulbs. Axons leaving the olfactory bulb travel along the olfactory tract to the olfactory cortex of the cerebral hemispheres, the hypothalamus, and portions of the limbic system

The middle ear, or tympanic cavity, is an

air-filled chamber separated from the external acoustic meatus by the tympanic membrane

A sarcomere works most efficiently within

an optimal range of lengths. When the resting sarcomere length is within this range, the maximum number of cross-bridges can form, and the maximum amount of tension is produced. If the resting sarcomere length falls outside the range—if the sarcomere is stretched and lengthened, or compressed and shortened—it cannot produce as much tension when stimulated. An increase in sarcomere length reduces the tension produced by reducing the zone of overlap and, hence, the number of potential cross-bridges.

Glycolysis is the

anaerobic breakdown of glucose to pyruvate in the cytosol of a cell. It is an anaerobic process because it does not require oxygen. Glycolysis provides a net gain of 2 ATP molecules and generates 2 pyruvate molecules from each glucose molecule.

Aqueous humor is a fluid that circulates within the

anterior cavity. It passes from the posterior chamber to the anterior chamber through the pupil It also freely diffuses through the posterior cavity and across the surface of the retina. Its composition resembles that of cerebrospinal fluid.

The eye's intra-ocular pressure can be measured in the

anterior chamber, where the fluid pushes against the inner surface of the cornea. Intra-ocular pressure is usually checked by applanation tonometry whereby a small, flat disk is placed on the anesthetized cornea to measure the tension. Normal intraocular pressure ranges from 12 to 21 mm Hg.

Filiform papillae are found in the

anterior two-thirds of the tongue running parallel to the midline groove. They do not contain taste buds, but they do provide an abrasive coat that creates friction to help move food around the mouth. Fungiform papillae are scattered around the tongue with concentration along the tip and sides. Each small fungiform papilla contains about 5 taste buds.

the lacrimal glands contain

antibacterial enzyme lysozyme and antibodies that attack pathogens before they enter the body.

Additional refraction takes place when the light passes from the

aqueous humor in the anterior chamber into the relatively dense lens. The lens provides the extra refraction needed to focus the light rays from an object toward a focal point—a specific point of intersection on the retina.

Olfactory sensory neurons are

are highly modified nerve cells. The exposed tip of each sensory neuron forms a prominent dendritic bulb that projects beyond the epithelial surface. The dendritic bulb is a base for up to 20 cilia-shaped dendrites that extend into the surrounding mucus. These dendrites lie parallel to the epithelial surface, exposing their considerable surface area to odorants.

The foliate papillae are found

as a series of folds along the lateral margins with taste buds embedded in their surfaces.

The processing of visual stimuli from cones is different

because of their lack of convergence. In the fovea centralis, the ratio of cones to ganglion cells is 1:1. The ganglion cells that monitor cones, called P cells

when a light hits rhodopsin it becomes

becomes trans and unbinds from dopsin

what does ACH do at the sarcolemma

binds to the nicotinic receptors and opens sodium channels

Rods and cones synapse with about 6 million neurons called

bipolar cells

A comparable network of amacrine (AM-ah-krin) cells occurs where

bipolar cells synapse with ganglion cells. Horizontal and amacrine cells can facilitate or inhibit communication between photoreceptors and ganglion cells, altering the sensitivity of the retina. These cells play an important role in the eye's adjustment to dim or brightly lit environments.

Rhodopsin is broken apart into retinal and opsin through a process called

bleaching.. Before recombining with opsin, the retinal must be enzymatically converted back to its original shape. This conversion requires energy in the form of ATP and it takes time. Then rhodopsin is regenerated by being recombined with opsin. Bleaching and regeneration is a cyclical process.

Damage to the cornea may cause

blindness even though the functional components of the eye—including the photoreceptors—are perfectly normal. The cornea has a very restricted ability to repair itself. For this reason, corneal injuries must be treated immediately to prevent serious vision losses.

The cornea has no

blood vessels. Its superficial epithelial cells obtain oxygen and nutrients by diffusion from the tears that flow across their free surfaces. The cornea also has numerous free nerve endings, making it the most sensitive portion of the eye.

This resting tension in a skeletal muscle is

called muscle tone.

Olfactory stimulation is the only type of sensory information that reaches the

cerebral cortex directly

what structures change lens shape

ciliary body

The bulk of the ciliary body consists of the

ciliary muscle, a ring of smooth muscle that projects into the interior of the eye.

The epithelium covering this muscle has numerous folds called

ciliary processes. The ciliary zonule (suspensory ligament) is the ring of fibers that attaches the lens to the ciliary processes.

Visual inputs to the suprachiasmatic nucleus of the hypothalamus affect the function of other brainstem nuclei. The suprachiasmatic nucleus and the pineal gland of the epithalamus receive visual information and use it to establish a

circadian

Accommodation is the automatic adjustment of the eye to give us

clear vision. During accommodation, the lens becomes rounder to focus the image of a nearby object on the retina. The lens becomes flatter to focus the image of a distant object on the retina.

the outer surface of the sarcolemma is attached to

collagen fibers of the tendon or aponeurosis of the skeletal muscle.

The external ear—the visible portion of the ear—

collects and directs sound waves toward the middle ear, a chamber located within the petrous part of the temporal bone.

Persons who are unable to distinguish certain colors have a form of

color blindness

The epithelium covering the inner surfaces of the eyelids and the outer surface of the eyeball is called the

conjunctiva

what is the function of bipolar cells

connect photoreceptors to ganglion cells

palpebral conjunctiva covers the

covers the inner surface of the eyelids

The gustatory pathway starts with taste buds, which are innervated by

cranial nerves VII (facial), IX (glossopharyngeal), and X (vagus). The facial nerve innervates all the taste buds located on the anterior two-thirds of the tongue, from the tip to the line of vallate papillae. The glossopharyngeal nerve innervates the vallate papillae and the posterior one-third of the tongue. The vagus nerve innervates taste buds scattered on the surface of the epiglottis.

The sensory afferent fibers are carried by

cranial nerves synapse in the solitary nucleus of the medulla oblongata. The axons of the postsynaptic neurons then enter the medial lemniscus. There, the neurons join axons that carry somatic sensory information on touch, pressure, and proprioception. After another synapse in the thalamus, the information is sent to the appropriate portions of the gustatory cortex of the insula.

ATP + creatine -> The primary function of ATP is to transfer energy from one location to another rather than to store it long term.

creatine phosphate

The walls of the bony labyrinth consist of

dense bone that separates the perilymph of the cochlear chambers from the air-filled middle ear. Collagen fibers connect the bony margins of the opening known as the oval window to the base of the stapes.

Hearing enables us to

detect and interpret sound waves. Both of these senses are provided by the internal ear, a receptor complex located in the temporal bone of the skull.

in a chemical sense whether its taste or olfactory in order for the odorant to stimulate a receptor it has to

dissolve in aqueous solution

The tension produced by an individual muscle fiber

does vary, however, for other reasons. Tension production is greatest when a muscle is stimulated at its optimal length. A couple of factors are important:

Neurons and skeletal muscle fibers, however, have

electrically excitable membranes.

Between the bony and membranous labyrinths flows perilymph while the membranous labyrinth contains

endolymph Perilymph closely resembles cerebrospinal fluid. In contrast, endolymph has electrolyte concentrations that differ from those of typical body fluids.

Portions of the endolymphatic duct secrete

endolymph continuously, and excess fluid returns to the general circulation at the endolymphatic sac. There the capillaries absorb endolymph removed by a combination of active transport and vesicular transport.

Thyroid hormones elevate the rate of

energy consumption in resting and active skeletal muscles

when the myofibrils shorten or contract, the

entire cell shortens and pulls on the tendon. Scattered among the myofibrils are mitochondria and granules of glycogen, the storage form of glucose. Mitochondrial activity and glucose breakdown by glycolysis provide energy in the form of ATP for short-duration, maximum-intensity muscular contractions

receptors of the vestibular complex provide you with

equilibrium sensations. In both the semicircular ducts and the vestibule, these receptors are hair cells. The hair cells of the semicircular ducts convey information about rotational movements of the head. The hair cells in the saccule and the utricle of the vestibule convey information about your position with respect to gravity, and tell you if you are accelerating or decelerating.

In neurons and skeletal muscle fibers, the depolarization and repolarization

events produce an electrical impulse, or action potential, that is propagated along their plasma membranes. Unlike the plasma membranes of most cells, excitable membranes contain voltage-gated ion channels that are activated and inactivated by changes in the membrane potential. These electrical channels become activated when the membranes of neurons and skeletal muscle fibers first depolarize from the resting potential to a threshold potential (from −70 to −60 mV for neurons and from −85 to −55 mV for skeletal muscle fibers). Upon reaching the threshold potential, voltage-gated sodium ion channels open and there is a rapid influx of positively charged sodium ions into the cell.

scleral venous sinus (canal of Schlemm), a passageway that

extends completely around the eye at the level of the corneoscleral junction. Collecting channels then deliver the aqueous humor to veins in the sclera.

the cillary body does what

extends posteriorly to the level of the ora serrata (Ō-ra ser-RAH-tuh; serrated mouth), the serrated anterior edge of the neural layer of the retina (see Figure 17-5c).

sounds coming from the side or front are collected and channeled into the

external acoustic meatus.

The accessory structures of the eye include the

eyelids and the superficial epithelium of the eye, as well as the structures involved with the production, secretion, and removal of tears.

when an object is 20 ft or more away the lens becomes more ( nearsighted can see what's close to you but its blurry when its far away)

flat

The combination of taste and smell is what provides the

flavor, or distinctive quality of a particular food or drink.

The distance between the center of the lens and its focal point is the

focal distance of the lens.

What is the function of the lens

focus the visual image on the photoreceptors.

why are there so many nuclei in a skeletal muscle

for protein synthesis

The active shortening of myofibrils is responsible

for skeletal muscle fiber contraction.

optic disc, a circular region just medial to the

fovea centralis. The optic disc is the origin of the optic nerve (II). From this point, the axons turn, penetrate the wall of the eye, and proceed toward the diencephalon

These cells in turn synapse within the layer of the 1 million neurons called

ganglion cells, which lie adjacent to the posterior cavity.

The palpebral fissure is the

gap that separates the free margins of the upper and lower eyelids. The two eyelids are connected, however, at the medial angle (medial canthus) and the lateral angle (lateral canthus)

Olfactory reception begins with the binding of an odorant to a G protein-coupled receptor in the plasma membrane of an olfactory dendrite. This creates a depolarization called a

generator potential

for a muscle to relax you must

get rid of calcium break the cross bridge the troponin-tropomyosin complex prevents the myosin heads from binding to the active sites on the actin microfilaments

what is the most important factor in producing muscle relaxation

getting calcium back into the sarcoplasmic reticulum

___________________ or taste, provides information about the foods and liquids we eat and drink.

gustation

The receptors of the cochlear duct provide a sense of

hearing that enables us to detect the quietest whisper, yet remain functional in a noisy room. The receptors responsible for auditory sensations are hair cells similar to those of the vestibular complex.

What is the function of the vitreous body

helps stabilize the shape of the eye

where would the vitreous body be found

in the posterior cavity function- hold retina up

A muscle producing almost maximum tension during rapid cycles of contraction and relaxation is in

incomplete tetanus

Conjunctivitis, or pinkeye, is an

inflammation of the conjunctiva. The most obvious sign, redness, is due to the dilation of blood vessels deep to the conjunctival epithelium. This condition may be caused by pathogenic infection or by physical, allergic, or chemical irritation of the conjunctival surface.

A tropomyosin molecule

is a double-stranded protein that covers seven active sites. It is bound to one molecule of troponin midway along its length.

Equilibrium

is the state of physical balance. We'll explore the structures within the internal ear that enable us to maintain this balance.

the peak tension developed is less than the load, and the muscle elongates due to the contraction of another muscle or the pull of gravity.

isotonic eccentric contraction

in the muscle cycle of contraction when taking about the cross bridge when ATP binds with the myosin head what does it do

it breaks the cross bridge it also hydrolyses ATPase and the ATP becomes ADP and Pi

what does the depolarization of t tubules do

it opens calcium channels T tubules and SER constitute a signal-transducing apparatus that converts depolarizations of the plasma membrane into a spike of cytoplasmic Ca2+ to trigger contraction (Fig. 39.14). An action potential moving through a T tubule triggers the release of Ca2+ from SER into the cytoplasm

what id there was no achetychloinerase in the synapse

it wouldnt break down the ach in the synapse and the muscle wouldnt be able to relax

Blinking sweeps the tears across the ocular surface. Tears accumulate at the medial angle of eye in an area known as the

lacrimal lake, or "lake of tears." The lacrimal lake covers the lacrimal caruncle, which bulges anteriorly. The lacrimal puncta (singular, punctum), two small pores, drain the lacrimal lake. They empty into the lacrimal canaliculi, small canals that in turn lead to the lacrimal sac, which nestles within the lacrimal sulcus of the orbit

The eyelashes are associated with unusually

large sebaceous glands. Along the inner margin of the lid are small, modified sebaceous glands called tarsal glands. They secrete a lipid-rich substance that helps keep the eyelids from sticking together.

in the ear is you increase the sound level what does that do to the origin of corti

large virbration in the ear

When anaerobic metabolism is the primary method of ATP generation, muscle fibers become

less efficient at capturing energy.

Certain smells can trigger profound emotional and behavioral responses, as well as memories, due to the fact that olfactory information is also distributed to the `

limbic system and hypothalamus.

The surface of the tongue has numerous variously shaped epithelial projections called

lingual papillae

where in the eye are cones found

macula

The incus (incus, anvil), the middle ossicle, attaches the

malleus to the stapes the inner ossicle. The edges of the base of the stapes are bound to the edges of the oval window, an opening in the temporal bone that surrounds the internal ear.

The three auditory ossicles are the

malleus, the incus, and the stapes

Cerumen also slows the growth of

microorganisms and so reduces the chances of infection. In addition, the canal is lined with many small, outwardly projecting hairs. These hairs trap debris and also provide increased tactile sensitivity through their root hair plexuses.

A constant flow of tears keeps conjunctival surfaces

moist and clean. Tears reduce friction, remove debris, prevent bacterial infection, and provide nutrients and oxygen to portions of the conjunctival epithelium. The lacrimal apparatus produces, distributes, and removes tears. The lacrimal apparatus of each eye consists of (1) a lacrimal gland with associated ducts, (2) paired lacrimal canaliculi, (3) a lacrimal sac, and (4) a nasolacrimal duct

What is the sliding filament theory

muscle contraction occurs through the relative sliding of two sets of filaments (actin and myosin). This sliding is produced by cyclic interactions of sidepieces from the myosin filament (cross-bridges) with specific sites on the actin filament.

Gravity may assist opposing

muscle groups in quickly returning a muscle to its resting length after a contraction

Under resting conditions, however, the troponin-tropomyosin complex prevents

myosin binding. Strands of tropomyosin cover the active sites on G-actin and prevent actin-myosin interaction.

where is ATpase located?

myosin head (this is an enzyme that hydrolyzes ATP)

These olfactory organs, which are located in the

nasal cavity

The middle ear communicates both with the

nasopharynx (the superior portion of the pharynx), through the auditory tube, and with the mastoid air cells, through a number of small connections .

A network of horizontal cells extends across the

neural layer of the retina at the level of the synapses between photoreceptors and bipolar cells.

As a result, the problem first becomes apparent at night, when the dim light proves insufficient to activate the rods. This condition, known as

night blindness, or nyctalopia, can be treated by eating a diet rich in vitamin A. The body can convert the carotene pigments in many vegetables to vitamin A. Carrots are a particularly good source of carotene, leading to the old adage that carrots are good for your

The sclera, or "white of the eye," covers most of the

ocular surface. The sclera consists of a dense fibrous connective tissue containing both collagen and elastic fibers. This layer is thickest over the posterior surface of the eye, near the exit of the optic nerve. The sclera is thinnest over the anterior surface. The six extrinsic eye muscles insert on the sclera, blending their collagen fibers with those of the fibrous layer.

Typically, a ganglion cell responds differently to stimuli that arrive in the center

of its receptive field than to stimuli that arrive at the edges (Figure 17-19). Some ganglion cells, called on-center neurons

the sense of smell is called

olfaction

The olfactory epithelium contains the

olfactory sensory neurons, supporting cells, and regenerative basal epithelial cells This epithelium covers the inferior surface of the cribriform plate, the superior portion of the perpendicular plate, and the superior nasal conchae of the ethmoid.

Light is refracted, or bent, when it passes from

one medium to another medium with a different density. You can see this effect if you stick a pencil into a glass of water. Notice that the shaft of the pencil appears to bend sharply at the air-water interface.

The auricle protects the

opening of the canal and provides directional sensitivity. Sounds coming from behind the head are blocked by the auricle,

axons from the entire population of ganglion cells converge on the

optic disc, penetrate the wall of the eye, and proceed toward the diencephalon as the optic nerve (II). The two optic nerves, one from each eye, reach the diencephalon after a partial crossover at the optic chiasm

bulbar conjunctiva covers the

or ocular conjunctiva, covers the anterior surface of the eye

The fibrous layer, the

outermost layer of the eyeball, consists of the whitish sclera (SKLER-uh) and the transparent cornea. The fibrous layer (1) supports and protects the eye, (2) serves as an attachment site for the extrinsic eye muscles, and (3) contains structures that assist in focusing.

The amount of oxygen required to restore normal, pre-exertion conditions is called the

oxygen debt, or excess postexercise oxygen consumption (EPOC).

in light what 3 neurons do we see

photoreceptors ganglion cells, and bipolar cells. They all transmit and process signals

The fornix of the eye is a

pocket created where the palpebral conjunctiva becomes continuous with the bulbar conjunctiva.

The hair cells of the utricle and saccule provide

position and linear movement sensations,

Vallate papillae appear as an inverted "V" near

posterior margin of the tongue. There are up to 12 vallate papillae, and each contains as many as 100 taste buds.

Similarly, in a skeletal muscle fiber, the amount of tension generated during a contraction depends on the number of

power strokes performed by cross-bridges in each of the myofibrils. filaments within these sarcomeres. When the muscle fiber is stimulated to contract, only myosin heads in The number of cross-bridges that can form, in turn, depends on the amount of overlap between thick filaments and thin the zones of overlap can bind to active sites and produce tension.

In general, skeletal muscle contractions pull on tendons to move our bones. Skeletal muscle actions range from simple motions, such as extending the arm or breathing, to the highly coordinated movements of swimming or piano playing.

producing movement

When we are exposed to very loud noises, two small muscles in the middle ear

protect the tympanic membrane and ossicles from violent movements:

Myofibrils consist of bundles of

protein filaments called myofilaments.

Excitable membranes permit

rapid communication between different parts of a cell.

The smooth but steady increase in muscular tension produced by increasing the number of active motor units is

recruitment.

what are the colored cones

red blue green

When a higher stimulation frequency eliminates the

relaxation phase

What does creatine phosphate do?

replenishes ATP

Tension production depends on the fiber's

resting length at the time of stimulation, which determines the amount of overlap between thick and thin filaments. It also depends on the frequency of stimulation, which affects the internal concentration of calcium ions and thus the amount bound to troponin.

The contraction of opposing muscles, those that perform opposite actions, can

return a muscle to its resting length more quickly than elastic forces can. Consider the muscles of the arm that flex or extend the elbow.

what does opsin bind to in the dark

rhodopsin

Visual pigments are derivatives of the compound

rhodopsin or visual purple, the visual pigment found in rods rhodopsin consists of a protein, opsin, bound to the pigment retinal which is synthesized from vitamin A. All rods contain the same form of opsin. Cones contain the same retinal pigment that rods do, but the retinal is attached to different forms of opsin.

The hair cells of the semicircular ducts are active during a

rotational movement, but are quiet when the body is motionless. T

when an object is 20ft away or closer the lens becomes more (farsighted can see easily what is far away but struggle when its close to you)

round

Myofibrils are anchored to the inner surface of the

sarcolemma at each end of a skeletal muscle fiber. .

thin and thick myofilaments are organized into repeating functional units called

sarcomeres. Sarcomeres are the smallest functional units of the muscle fiber. Interactions between the thick and thin filaments within sarcomeres are responsible for muscle contraction.

unami

savory

what monitors rotational movement

semicircular canals

neural layer of the retina contains

several layers of cells. The inner layers of the retina contain supporting cells and neurons that do preliminary processing and integration of visual information. The outermost part, closest to the pigmented layer of the retina, contains the photoreceptors, the cells that detect light.

The tensor tympani is a

short ribbon of muscle originating on the petrous part of the temporal bone and the auditory tube, and inserting on the "handle" of the malleus. When the tensor tympani contracts, it pulls the malleus medially, stiffening the tympanic membrane.

The eyelids, or palpebrae, are a continuation of the

skin. Their continual blinking keeps the surface of the eye lubricated. They also act like windshield wipers, removing dust and debris. The eyelids can also close firmly to protect the delicate surface of the eye.

salt

sodium

Structures of the middle ear collect

sound waves and transmit them to an appropriate portion of the internal ear, which contains the sensory organs for both hearing and equilibrium.

The latent period begins at

stimulation and lasts about 2 msec. During this period, the action potential sweeps across the sarcolemma, and the SR releases calcium ions. The muscle fiber does not produce tension during the latent period, because the contraction cycle has yet to begin.

glycolysis is important only because it provides the

substrates for aerobic metabolism in the mitochondria. Yet, because it can proceed without oxygen, glycolysis becomes an important source of energy when energy demands are at a maximum and the available supply of oxygen limits how quickly the mitochondria can produce ATP.

sweet

sugars

Gustatory (GUS-ta-tor-ē) epithelial cells or taste receptors are found in taste buds that are distributed over the

superior surface of the tongue and adjacent portions of the pharynx and larynx. These receptors are stimulated by dissolved food molecules. This stimulation leads to action potentials that are sent to the gustatory cortex for interpretation.

what are the major tastes

sweet, sour, salty, bitter, umami

the level of stimulation from the olfactory receptors plays a major role in

taste perception

When a contraction ends, some of the energy initially "spent" in stretching the

tendons and distorting intracellular organelles is recovered as they recoil or rebound to their original dimensions. This elasticity gradually helps return the muscle fibers in the muscle to their optimal resting length.

The eye is often compared to a camera. To provide useful information, the lens of the eye, like a camera lens, must focus

the arriving image. To say that an image is "in focus" means that the light rays arriving from an object strike the sensitive surface of the retina (or the semiconductor device that records light electronically in digital cameras) in precise order so as to form a miniature image of the object. If the rays are not perfectly focused, the image is blurry. Focusing normally occurs in two steps, as light passes first through the cornea and then the lens. To focus the light on the retina, the lens must change shape, or undergo accommodation.

why cant we see in the dark

the cones lose their ability to respond to light

The border between the sclera and the cornea is called

the corneoscleral junction, or corneal limbus. Deep to the delicate corneal epithelium, the cornea consists primarily of a dense matrix containing multiple layers of collagen fibers, organized so as not to interfere with the passage of light.

The ear is divided into three anatomical regions:

the external ear, the middle ear, and the internal ear

The Distance of the Object from the Lens. The closer an object is to the lens,

the greater the focal distance

he vascular layer, or uvea is a pigmented region that includes

the iris, ciliary body, and choroid It contains numerous blood vessels, lymphatic vessels, and the intrinsic (smooth) muscles of the eye. This middle layer (1) provides a route for blood vessels and lymphatics that supply the tissues of the eye; (2) regulates the amount of light that enters the eye; (3) secretes and reabsorbs the aqueous humor that circulates within the chambers of the eye; and (4) controls the shape of the lens, an essential part of the focusing process.

when light enters the eye what structure of the eye produces teh most refraction

the lens

the nasolacrimal duct passes through the

the nasolacrimal duct passes through the nasolacrimal canal, formed by the lacrimal bone and the maxilla. This duct delivers tears to the nasal cavity on that side. The duct empties into the inferior meatus, a narrow passageway inferior and lateral to the inferior nasal concha.

The olfactory organs are made up of two layers:

the olfactory epithelium and the lamina propria

An abnormal blind spot, or scotoma may appear in the field of vision at positions other than at

the optic disc. A scotoma is permanent and may result from compression of the optic nerve, damage to photoreceptors, or central damage along the visual pathway.

What is recruitment?

the process in which multiple motor units work together in a single contraction to increase force

in response to dim light, sympathetic activation causes

the pupils to dilate.

surrounds the sarcoplasm or cytoplasm of the muscle fiber. Like the plasma membranes of other body cells, the sarcolemma has a characteristic membrane potential. In a skeletal muscle fiber, a sudden change in the membrane potential is the first step that leads to a contraction

the sarcolemma or plasma membrane of a muscle fiber,

Receptors within the cochlear duct provide

the sense of hearing. The duct is sandwiched between a pair of perilymph-filled chambers. The entire complex spirals around a central bony hub, much like a snail shell.

At the medial angle of eye, the lacrimal caruncle a mass of soft tissue, contains glands producing

the thick secretions that contribute to the gritty deposits that sometimes appear after a good night's sleep.

what happens during muscle relation

there is no active mechanism for returning shortened muscle fibers to their resting length. After a contraction, a muscle returns to its original length through a combination of elastic forces, opposing muscle contractions, and gravity.

Titin helps keep the

thick and thin filaments in proper alignment and aids in restoring resting sarcomere length after contraction. It also helps the muscle fiber resist extreme stretching that would otherwise disrupt the contraction mechanism.

The I band is a region of the sarcomere that contains

thin filaments but no thick filaments. It extends from the A band of one sarcomere to the A band of the next sarcomere Z lines bisect the I bands and mark the boundary between adjacent sarcomeres.

Myofibrils contain two types of myofilaments

thin filaments composed primarily of actin, and thick filaments composed primarily of myosin. myofibrils contain titin, elastic myofilaments associated with the thick filaments.

The inner layer, or retina, is the deepest of the three layers of the eye. It consists of a

thin lining called the pigmented layer, and a thicker, covering called the neural layer. The pigmented layer contains pigment cells that support the functions of the photoreceptors, which are located in the neural layer of the retina.

The malleus (malleus, hammer) attaches at

three points to the interior surface of the tympanic membrane.

in response to bright light, parasympathetic activation causes the pupils

to constrict

we can relate the tension produced by the entire muscle fiber

to the length of individual sarcomeres, a concept known as the length-tension relationship.

A single stimulation produces a single contraction, or

twitch

a single stimulus produces a rapid rise and slow decline in tension what is it called

twitch

The middle ear contains three tiny ear bones, collectively called auditory ossicles These ear bones connect the

tympanic membrane with the internal ear The articulations between the auditory ossicles are the smallest synovial joints in the body. Each has a tiny joint capsule and supporting extracapsular ligaments.

a pleasant, savory taste imparted by the amino acid glutamate.

unami they are present in taste buds of the vallate papillae.

The choroid (KOR-oyd) is a

vascular layer that separates the fibrous layer and the inner layer posterior to the ora serrata. The choroid is covered by the sclera and attached to the outermost layer of the retina. An extensive capillary network in the choroid delivers oxygen and nutrients to the retina. The choroid also contains melanocytes, which are especially numerous near the sclera.

The macula of saccule is sensitive to changes in

vertical movement. As in the ampullae, the hair cell processes are embedded in a gelatinous structure, here the otolithic membrane. This membrane's surface contains densely packed calcium carbonate crystals called otoliths

The skin covering the visible surface of the eyelid is

very thin. Deep to the skin lie the muscle fibers of the orbicularis oculi and levator palpebrae superioris. These skeletal muscles close the eyelids and raise the upper eyelid, respectively.

what controls gravity and acceleration

vestibule 2 receptors (urticle, saccule) linear movements

the visual pathways begin at the photoreceptors and end at the

visual cortex of the cerebral hemispheres. In other sensory pathways we have examined, only one synapse lies between a receptor and a sensory neuron that delivers information to the CNS.

Our eyes are elaborate structures containing our

visual receptors that enable us not only to detect light, but also to create detailed visual images.