Visualizing Human Bio Ch 8

Somatic senses

Involve receptors from more than one place in the body and help coordinate muscle movement; maintain body temperature.

Special senses

Extremely sensitive receptors that supply us with detailed information about the world around us (sight, sound, smell, taste).

Photoreceptors

Special senses include photoreceptors for vision.

Mechanoreceptors

Special senses include mechanoreceptors for hearing and balance.

Chemoreceptors

Special senses include chemoreceptors for smell and taste.

Olfaction

Smelling occurs in the upper chambers of the nasal passages, where sensory receptors respond to chemicals dissolved in mucus.

Olfactory bulb

When a receptor binds its specific odor molecule, a sensory impulse is sent to the olfactory bulb and on to the brain.

Limbic system

Neural connections between the olfactory bulb and the limbic system explain why smells trigger memories and emotions.

Gustation

Receptors for taste are in roughly 10,000 taste buds, most of which are on the tongue, in small bumps called papillae.

Taste categories

Taste buds can distinguish five categories of taste: sweet, sour, salty, bitter, and umami (savory).

Outer ear

Composed of the pinna and external auditory canal, both of which capture sound waves and funnel them to the middle ear.

Middle ear

Ear drum, or tympanic membrane, marks the beginning of the middle ear and converts sound into mechanical motion.

Tympanic membrane

Compression waves in the air (sound) cause the tympanic membrane to vibrate.

Malleus

The vibrating tympanic membrane moves the malleus, which in turn moves the incus through a synovial joint.

Stapes

The stapes is the final small bone, or ossicle, of the middle ear.

Inner ear

Beyond the stapes lies the oval window, which creates fluid waves in the inner ear.

Dynamic equilibrium

Detects acceleration or deceleration of your head.

Static equilibrium

The physical response to gravity that tells us which direction is down.

Conduction deafness

Sound is poorly conducted from the outer ear to the inner ear; hearing aids can help by increasing the amplitude of sound.

Nerve deafness

Auditory troubles caused by nerve deafness cannot be resolved by a hearing aid.

Cochlear implants

Convert sound vibrations into electrical impulses and have shown some promise in treating nerve deafness.

Sclera

The fibrous layer of the eye.

Choroid

The vascular layer of the eye.

Retina

The nervous layer of the eye that converts light into nerve impulses.

Visual acuity

The ability of the eye to focus on entering light onto the retina.

Accommodation

The changing lens shape to view nearby objects, which becomes more difficult with age.

Nearsightedness

A vision impairment where the eye is too long for the lens to focus light on the retina, causing far-off images to be fuzzy.

Farsightedness

A vision impairment where the eye shape causes difficulty in seeing nearby objects clearly.

Astigmatism

A condition where the cornea is imperfectly shaped, resulting in an uneven pattern of light hitting the retina.

Vitreous humor

A gel-like fluid that holds the retina in place.

Rods

Photoreceptors in the retina that detect light and function in low levels of light.

Cones

Photoreceptors in the retina that respond to bright light and provide color vision.

Bipolar cells

Interneurons that carry action potentials generated by photoreceptors to the brain.

Ganglionic cells

Cells that collect impulses from bipolar cells and pass them to the brain via the optic nerve.

Rhodopsin

A visual pigment in rods that responds to low levels of white light.

Retinal and opsin

Visual pigments used by cones for color vision.

Cornea

The part of the eye that admits and refracts light.

Iris

The colored, muscular part of the eye that controls the size of the pupil.

Lens

The part of the eye that reflects light.

Visual nerve impulses

Impulses that travel from photoreceptors to the brain.

Optic nerve

The nerve that carries visual impulses from the ganglionic cells to the brain.

Thalamus

The brain structure that visual impulses pass through before reaching the occipital lobe.

Occipital lobe

The part of the brain where visual impulses are processed.