Chapter 16 - Senses

Contrast hyperopia and myopia

Hyperopia- Farsightedness—a condition in which the eyeball is too short. The retina lies in front of the focal point of the lens, and the light rays have not yet come into focus when they reach the retina. Causes the greatest difficulty when viewing nearby objects. Myopia- Nearsightedness—a condition in which the eyeball is too long. Light rays come into focus before they reach the retina and begin to diverge again by the time they fall on it

List other features that can affect taste perception

Food texture, aroma, temperature, appearance, and one's state of mind, among other things. Many flavors depend on smell; without their aromas,

Define gustation and olfaction

Gustation - Taste Olfacation- Smell

Explain the importance of pain

The absence of pain makes people unaware of minor injuries. They neglect them, so the injuries often become infected and worsen to the point that the victim may lose fingers, toes, or entire limbs.

Describe the structure and function of eyebrows and eyelashes

The eyebrows enhance facial expressions and nonverbal communication but may also protect the eyes from glare and keep perspiration from running into the eye. The eyelashes are guard hairs that help to keep debris from the eye. Touching the eyelashes stimulates hair receptors and triggers the blink reflex.

Describe the saccule and utricle

The saccule and utricle each contain a 2 × 3 mm patch of hair cells and supporting cells called a macula.The macula sacculi lies nearly vertically on the wall of the saccule, and the macula utriculi lies nearly horizontally on the floor of the utricle. Each hair cell of a macula has 40 to 70 stereocilia and one true cilium called a kinocilium.

Explain how the brain compensates for the blind spot

This occurs because the brain uses the image surrounding the blind spot to fill in the area with similar but imaginary information. The brain acts as if it is better to assume that the unseen area probably looks like its surroundings than to allow a dark blotch to disturb your vision.

Describe the conjunctiva

a transparent mucous membrane that covers the inner surface of the eyelid and anterior surface of the eyeball, except for the cornea.

List physical responses to odors

sneezing or coughing, the secretion of saliva and stomach acid, or vomiting.

List the 5 primary taste sensations

1. Salty, produced by metal ions such as sodium and potassium. 2. Sweet, produced by many organic compounds, especially sugars. 3. Sour, usually associated with acids (H+) in such foods as citrus fruits. 4. Bitter, associated with spoiled foods and alkaloids such as nicotine, caffeine, quinine, and morphine. 5.Umami is a "meaty" taste produced by amino acids such as aspartic and glutamic acids

Describe the location of olfactory receptors

A patch of epithelium, the olfactory mucosa, is in the roof of the nasal cavity. This location places the olfactory cells close to the brain.

Describes the ways in which the CNS modulation pain

In the CNS, opioids are found especially in the central gray matter of the midbrain and the posterior horn of the spinal cord. They are neuromodulators that can block the transmission of pain signals and produce feelings of pleasure and euphoria.

Compare fast and slow pain

Myelinated- produce the sensation of fast (first) pain—a feeling of sharp, localized, stabbing pain perceived at the time of injury. Unmyelinated pain fibers produce the slow (second) pain that follows—a longer-lasting, dull, diffuse feeling.

Describe how the receptors for olfaction are stimulated

an odorant molecule must bind to a receptor on one of the olfactory hairs. Hydrophilic odorants diffuse freely through the mucus of the olfactory epithelium and bind directly to a receptor. Hydrophobic odorants are transported to the receptor by an odorant-binding protein in the mucus. When the receptor binds an odorant, it activates a G protein and through it, the cyclic adenosine monophosphate (cAMP) second-messenger system. The cAMP system ultimately opens ion channels in the plasma membrane, admitting cations (Na+ or Ca2+) into the cell and depolarizing it, creating a receptor potential. This triggers action potentials in the axon of the olfactory cell, and a signal is transmitted to the brain.

Explain the effects of a detached retina

detached retina may cause blurry areas in the field of vision. It leads to blindness if the retina remains separated for too long from the choroid, on which it depends for oxygen, nutrition, and waste removal.

Control of coordination and balance

equilibrium

List the areas of the brain which receive olfactory signals

orbitofrontal cortex olfactory tract insula hypothalamus amygdala primary olfactory cortex Hippocampus

Describe the role of otoliths and stereocilia in static and dynamic equilibrium

otolith- which add to the weight and inertia of the membrane and enhance the sense of gravity and motion. The tips of the stereocilia and kinocilium are embedded in a gelatinous otolithic membrane.

Explain why hot pepper is not a "taste"

pepper are due to stimulation of free endings of the trigeminal nerve rather than taste buds.

Explain how the length of lifespan of an olfactory cell is different from other neurons

they have a life span of only 60 days. they are replaceable. The basal cells continually divide and differentiate into new olfactory cells.

Explain the result of synaptic inhibition in the olfactory bulbs

they synapse with the dendrites of neurons called mitral cells and tufted cells. Olfactory axons reach up and mitral and tufted cell dendrites reach down to meet each other in spherical clusters called glomeruli

Describe the receptors for taste

1. Filiform papillae are tiny spikes without taste buds. sense of the texture of food. 2. Foliate papillae . They form parallel ridges on the sides of the tongue about two-thirds of the way back from the tip, adjacent to the molar and premolar teeth, where most chewing occurs and most flavor chemicals are released from the food. 3. Fungiform papillae are shaped somewhat like mushrooms. 4. Vallate (circumvallate) papillae are large papillae arranged in a V at the rear of the tongue.

Describe the layers of the retina

1. Photoreceptor cells. Photoreceptor cells absorb light and generate a chemical or electrical signal. 2.Bipolar cells. Rods and cones synapse with the dendrites of bipolar cells, the first-order neurons of the visual pathway. 3. Ganglion cells are the largest neurons of the retina, arranged in a single layer close to the vitreous body.

Describe the 3 ways to classify receptors and list examples of each

1. stimulus modality: -Thermoreceptors-respond to heat and cold. -Photoreceptors-the eyes, respond to light. -Nociceptors1- are pain receptors; - Chemoreceptors-respond to chemicals. -Mechanoreceptors respond to physical deformation of a cell or tissue 2. Origin of the stimulus: -Exteroceptors-sense stimuli external to the body. -Interoceptors-detect stimuli in the internal organs -Proprioceptors-sense the position and movements of the body 3. The distribution of receptors in the body: - General (somatosensory, somesthetic) senses employ widely distributed receptors in the skin, muscles, tendons, joints, and viscera. -Special senses are limited to the head, (taste, smell, hear and equilibrium)

Describe how the receptors for taste are stimulated

All primary tastes can be detected throughout the tongue, but some regions are more sensitive to one category than to others. The tip of the tongue is most sensitive to sweet tastes, which trigger such responses as licking, salivation, and swallowing. The lateral margins of the tongue are the most sensitive areas for salty and sour tastes.

List the 6 extrinsic eye muscles

Extrinsic intrinsic lateral rectus superior oblique the trochlea inferior oblique

List the structures that can be observed through ophthalmoscopic examination

Eye examinations can evaluate the visual system; they allow for a direct, noninvasive examination of blood vessels for signs of hypertension, diabetes mellitus, atherosclerosis, and other vascular diseases.

Define sound

Is any audible vibration of molecules.

Describe the cells associated with smell

It consists of 10 to 20 million olfactory cells as well as epithelial supporting cells and basal stem cells. The rest of the nasal cavity is lined by a nonsensory respiratory mucosa.

Describe, draw and label the anatomy of the outer, middle and inner ear

Outer- tympanic membrane (eardrum), auricle (pinna). auditory canal (external acoustic meatus), guard hairs, cerumen (earwax) Middle-Incus, Malleus, Stapes, oval window, auditory (eustachian or pharyngotympanic) tube,auditory ossicles. Inner-perilymph, endolymph, cochlea, Vistibule, modiolus.

Contrast somatic and visceral pain

Pain from the skin, muscles, and joints is called somatic pain, Pain from the viscera is called visceral pain. The latter often results from stretch, chemical irritants, or ischemia, and is often accompanied by nausea.

Explain referred pain

Pain in the viscera is often mistakenly thought to come from the skin or other superficial sites— example, the pain of a heart attack is felt "radiating" along the left shoulder and medial side of the arm.

Explain what happens as the sound waves travel from the outer to inner ear

Sound waves enter the auditory canal on one side and nerve signals exit the inner ear on the other. Connecting these is the middle ear

Contrast static and dynamic equilibrium

Static- The perception of the orientation of the head when the body is stationary dynamic equilibrium- the perception of motion or acceleration.

Describe the crista ampullaris and semicircular ducts

The head also experiences rotary movements, such as when you spin in a rotating chair, walk down a hall and turn a corner, or bend forward to pick something up from the floor. Such movements are detected by the three semicircular ducts crista ampullaris- a mound of hair cells and supporting cells

Define equilibrium and list the anatomical structures associated with the receptors

The original function of the ear in vertebrate evolution was not hearing, but equilibrium—coordination, balance, and orientation in three-dimensional space. In humans, the receptors for equilibrium constitute the vestibular apparatus, which consists of three semicircular ducts and two chambers—an anterior saccule and a posterior utricle.

List and describe the tunics of the eye

The outer fibrous layer (tunica fibrosa). This is divided into two regions: sclera and cornea. The sclera (white of the eye) covers most of the eye surface and consists of dense collagenous connective tissue perforated by blood vessels and nerves. The cornea is the anterior transparent region of modified sclera that admits light into the eye. The middle vascular layer (tunica vasculosa). This is also called the uvea. It consists of three regions—the choroid, ciliary body, and iris. The inner layer (tunica interna). This consists of the retina and beginning of the optic nerve.

Compare rod and cone cells

The visual pigment of the rods is called rhodopsin. It consists of two major parts (moieties): a protein called opsin and a vitamin A derivative called retinal (rhymes with "pal"), also known as retinene. In cones, the pigment is called photopsin (iodopsin). Its retinal moiety is the same as that of rhodopsin, but the opsin moiety has a different amino acid sequence that determines which wavelengths of light the pigment absorbs. There are three kinds of cones, which are identical in appearance but optimally absorb different wavelengths of light. These differences enable us to perceive different colors.

Explain sensory coding of loudness and pitch

Variations in loudness (amplitude) cause variations in the intensity of cochlear vibration. a loud sound vibrates a longer segment of the basilar membrane and thus excites a greater number of hair cells. If the brain detects moderate firing rates associated with hair cells in relatively narrow bands of the cochlea, it interprets this as a soft sound.