Chat with AIExam 11: Senses
Rods have their highest concentration in the optic disk.
(33) 
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Describe the structure of the external ear.
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Answered by Examlex AI CopilotThe external ear, also known as the outer ear, is the visible portion of the ear that serves as the initial part of the hearing pathway, capturing sound waves and directing them into the ear canal. The structure of the external ear can be divided into two main parts: the auricle (or pinna) and the external auditory canal (or ear canal).
1. Auricle (Pinna): The auricle is the most visible part of the external ear and is made of cartilage covered by skin. Its primary function is to collect sound waves from the environment and funnel them into the ear canal. The auricle has several distinct features:
- Helix: The outer rim of the ear, which curls around to form a border.
- Antihelix: A ridge of cartilage just inside the helix.
- Concha: The bowl-shaped area adjacent to the ear canal that helps to gather sound waves.
- Tragus: A small, pointed piece of cartilage that protrudes in front of the ear canal.
- Antitragus: Located opposite the tragus, it is another small protrusion of cartilage.
- Lobule (Earlobe): The fleshy, lower part of the auricle that contains no cartilage and is often the site for ear piercings.
The shape and folds of the auricle are unique to each individual and play a role in helping to determine the direction and source of sounds.
2. External Auditory Canal: The external auditory canal is a tube-like structure that extends from the concha to the eardrum (tympanic membrane). It is approximately 2.5 centimeters in length and has an S-shaped curve in adults. The canal is lined with skin and contains hair follicles, sebaceous glands, and ceruminous glands, which produce earwax (cerumen). The earwax helps to protect the ear by trapping dust, debris, and microorganisms, and also provides lubrication.
At the end of the external auditory canal lies the tympanic membrane, which marks the boundary between the external ear and the middle ear. The tympanic membrane is a thin, cone-shaped membrane that vibrates in response to sound waves, initiating the process of hearing by transmitting these vibrations to the bones of the middle ear.
Overall, the external ear's structure is designed to efficiently collect and channel sound waves toward the middle ear, where they can be further processed and eventually interpreted by the brain as sound.
Explain the two types of strabismus.
(36) Answered by Examlex AI CopilotStrabismus, also known as crossed eyes or squint, is a condition where the eyes do not align properly. There are two main types of strabismus: esotropia and exotropia.
Esotropia is a type of strabismus where one or both eyes turn inward. This can be constant or intermittent, and can occur in one or both eyes. It is often referred to as "cross-eyed" and can lead to double vision if not treated.
Exotropia, on the other hand, is a type of strabismus where one or both eyes turn outward. This can also be constant or intermittent, and can occur in one or both eyes. It is often referred to as "wall-eyed" and can also lead to double vision if not treated.
Both types of strabismus can be caused by a variety of factors, including problems with the muscles that control eye movement, issues with the nerves that control the eye muscles, or even refractive errors such as nearsightedness or farsightedness. Treatment for strabismus may include glasses, vision therapy, or in some cases, surgery to correct the alignment of the eyes. It is important to seek treatment for strabismus as early as possible to prevent long-term vision problems.
Describe the inner ear. Which parts of the inner ear are involved in the sense of balance, and which parts are involved in the sense of hearing?
(30) Which of the following structures in the inner ear is the organ of hearing?
(40) Which structure is important to your sense of balance and equilibrium?
(32) The inner ear consists of the vestibule, the semicircular canal, and the cochlea.
(36) Match each structure of the eye with its corresponding description or function.
-A hole in the eye that lets in light
(33) The senses of taste and smell are both considered chemoreceptors.
(42) Light passes through all of the following structures to get to the retina except the
(28) Match each structure of the eye with its corresponding description or function.
-The middle layer of the eyeball that contains dark pigment
(35) Match each structure of the eye with its corresponding description or function.
-Receptor that responds in dim light and is used for night vision
(36) The pupil is not really a structure but is the lack of a structure.
(28) Because of the route of the olfactory pathway, there is a close link between odor and emotion.
(25) The incus presses against a membrane that covers the oval window of the inner ear.
(40) Proprioceptors respond to stimuli from inside the body rather than from outside the body.
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