Biology 30 Eye and Ear

What is the primary function of sense organs?

To detect environmental stimuli and transform them into nerve impulses.

What is sensory adaptation?

A process that allows for the filtering of stimuli considered not important due to constant exposure.

What is the role of the conjunctiva in the eye?

It is a clear layer over the sclera that lubricates the eye with mucus and tears, and helps prevent microbial entry.

What is the function of the choroid layer?

It contains blood vessels and a black pigment to prevent stray light from bouncing inside the eye.

What is the function of the cornea?

It is the transparent front cover of the eye that protects it and refracts light toward the pupil.

What determines the amount of light entering the eye?

The size of the pupil, which is an opening in the center of the iris.

What is the function of the lens?

It is a transparent, biconvex structure that changes shape to help focus light.

Where is the clearest point of vision located in the eye?

The fovea centralis, located in the center of the macula on the retina.

What is the accommodation reflex?

The process where the lens changes shape to focus on near or far objects.

How does the lens change shape to focus on a near image?

Ciliary muscles contract and suspensory ligaments relax, causing the lens to become more rounded.

How does the lens change shape to focus on a far image?

Ciliary muscles relax and suspensory ligaments become taut, causing the lens to flatten.

What is the role of rods in the retina?

They contain rhodopsin and are responsible for dim light vision, producing shades of gray.

What happens to rhodopsin in very bright light?

It breaks down faster than it can be restored, temporarily incapacitating the rods.

What is the function of cones?

They detect color and are concentrated in the fovea centralis.

What are the three primary colors of light detected by cones?

Red, green, and blue.

What is the role of bipolar cells in vision?

They act as intermediaries between photoreceptors (rods/cones) and ganglion cells to transmit signals.

How does light activation affect a photoreceptor cell?

Activation causes hyperpolarization of the cell, which stops the release of inhibitory neurotransmitters, allowing the bipolar cell to excite the ganglion cell.

What are the two major sensory functions of the ear?

Hearing and balance (equilibrium).

What is the role of the Eustachian tube?

It connects the middle ear to the pharynx to allow for the equalization of air pressure on both sides of the eardrum.

Name the three ossicles and their function.

The malleus (hammer), incus (anvil), and stapes (stirrup); they transmit and magnify or dampen vibrations from the eardrum to the oval window.

What is the function of the cochlea?

It is a coiled tube that identifies sounds and converts them into nerve impulses.

What is conductive hearing loss?

Hearing loss often caused by middle ear infections, perforated eardrums, or impacted earwax, which can frequently be corrected medically or surgically.