Psychology Chapter 7 - Sensory Receptors

Questions and Answers

What are the five senses that help us connect with the external world?

Touch, taste, smell, sight, and hearing.

How do special sense receptors differ from general sense receptors?

Special sense receptors are either complex sensory organs like the eyes and ears or localized clusters like taste buds, unlike general receptors that are widespread.

What is the diameter of an adult human eye?

About 1 inch or 2.5 cm.

What protects the surface of the eye?

The eyelids and a cushion of fat, along with the bony walls of the orbit. Signup and view all the answers

What are some of the accessory structures of the eye?

Extrinsic eye muscles, eyelids, conjunctiva, and lacrimal apparatus. Signup and view all the answers

Describe the relationship between sensory inputs and motor outputs in the context of the nervous system.

Sensory inputs, such as vision detecting a moving ball, can trigger motor outputs that help us react, like moving out of the ball's path. Signup and view all the answers

What role does the blending of stimulus effects play in our sensory experience?

It enhances our overall perception of the world, allowing us to interpret complex stimuli. Signup and view all the answers

Where is only one-sixth of the eye’s surface normally visible?

The anterior part of the eye. Signup and view all the answers

What is the primary function of the cornea in the eye?

The cornea acts as a 'window' that allows light to enter the eye. Signup and view all the answers

How does the structure of the sclera contribute to the eye's protection?

The sclera consists of thick white connective tissue that provides structure and protection to the eye. Signup and view all the answers

What types of cells are considered photoreceptors in the retina?

The rods and cones are the photoreceptor cells in the retina. Signup and view all the answers

What happens when the cornea is touched?

Touching the cornea triggers blinking and increased tear production. Signup and view all the answers

Why is the optic disc significant in vision?

The optic disc is significant because it lacks photoreceptors, resulting in a blind spot in the visual field. Signup and view all the answers

What unique property does the cornea have regarding transplantation?

The cornea can be transplanted from one person to another without rejection concerns. Signup and view all the answers

Describe the pathway of electrical signals from photoreceptors to the brain.

Electrical signals pass from photoreceptors through bipolar cells to ganglion cells, then leave the retina via the optic nerve. Signup and view all the answers

What role do nerve endings in the cornea play?

Nerve endings in the cornea primarily respond to pain stimuli. Signup and view all the answers

What occurs to light rays from a distant object as they reach the eye?

Light rays from a distant object are nearly parallel and can be focused without changes in lens convexity. Signup and view all the answers

How does the lens of the eye adjust for focusing on a close object?

The lens bulges more to accommodate the diverging light rays from a close object. Signup and view all the answers

Define refraction in the context of the eye's anatomy.

Refraction is the bending of light rays when they pass through substances of different densities in the eye. Signup and view all the answers

What is astigmatism and how does it affect vision?

Astigmatism is a condition where the cornea's curvature prevents light rays from focusing evenly on the retina, leading to blurred vision. Signup and view all the answers

Explain the term 'accommodation' in relation to vision.

Accommodation is the process of adjusting the eye's lens shape to focus on objects at varying distances. Signup and view all the answers

What are the characteristics of light rays coming from close objects?

Light rays from close objects tend to scatter and diverge as they approach the eye. Signup and view all the answers

What is emmetropia?

Emmetropia is the term for normal vision where light is focused directly on the retina without refractive errors. Signup and view all the answers

Describe hyperopia and its impact on vision.

Hyperopia, or farsightedness, occurs when light rays focus behind the retina, making it difficult to see close objects clearly. Signup and view all the answers

What is the function of the lateral rectus muscle?

The lateral rectus muscle moves the eye laterally. Signup and view all the answers

Which cranial nerve is responsible for controlling the superior oblique muscle?

The superior oblique muscle is controlled by cranial nerve IV, the trochlear nerve. Signup and view all the answers

Describe the action of the medial rectus muscle.

The medial rectus muscle moves the eye medially. Signup and view all the answers

Which muscles are primarily responsible for elevating the eye?

The superior rectus and inferior oblique muscles are responsible for elevating the eye. Signup and view all the answers

What are the functions of the inferior rectus muscle?

The inferior rectus muscle depresses the eye and turns it medially. Signup and view all the answers

What is the combined action of the inferior oblique muscle?

The inferior oblique muscle elevates the eye and turns it laterally. Signup and view all the answers

How does the superior oblique muscle contribute to eye movement?

The superior oblique muscle depresses the eye and turns it laterally. Signup and view all the answers

Identify the role of the conjunctiva in the context of eye muscles.

The conjunctiva protects the eye and supports the movement of the extrinsic eye muscles. Signup and view all the answers

What is emmetropia, and why is it referred to as 'harmonious vision'?

Emmetropia is the state of the eye where images are correctly focused on the retina, allowing for clear vision. It is called 'harmonious vision' because all distances can be seen clearly and in focus. Signup and view all the answers

Explain the condition myopia and what causes it.

Myopia, or nearsightedness, occurs when distant objects are focused in front of the retina due to an eyeball that is too long, a lens that is too strong, or a curved cornea. This results in clear vision for nearby objects but blurry vision for distant ones. Signup and view all the answers

What corrective lenses are required for myopia, and how do they work?

Concave corrective lenses are needed for myopia; they diverge light rays before they enter the eye, allowing the focus to be correctly directed onto the retina. This compensates for the eye's inability to do so naturally. Signup and view all the answers

Describe hyperopia and how it differs from myopia.

Hyperopia, or farsightedness, occurs when parallel light rays from distant objects are focused behind the retina, often due to an eyeball that is too short or a 'lazy' lens. This contrasts with myopia, where distant objects are incorrectly focused in front of the retina. Signup and view all the answers

What is the physiological basis of nearsightedness?

Nearsightedness is primarily caused by an eyeball that is too long or a lens that is too strong, causing light rays from distant objects to converge before reaching the retina. This physiological change alters the focus point. Signup and view all the answers

How does the lens accommodate and what is its significance in vision?

The lens accommodates by bulging to focus on nearby objects, which is essential for clear near vision. This dynamic adjustment helps the eye maintain focus on varying distances. Signup and view all the answers

What role does the ciliary muscle play in focusing vision?

The ciliary muscle changes the shape of the lens, allowing it to focus properly on objects at different distances. When relaxed, it enables distance vision by flattening the lens to focus light accurately. Signup and view all the answers

What happens to the resting eye during hyperopia?

In the resting eye during hyperopia, the focus of light rays from distant objects falls behind the retina. This occurs because the eye may be too short or the lens not robust enough to focus light appropriately. Signup and view all the answers

Study Notes

General and Special Senses

Humans have five senses: touch, taste, smell, sight, and hearing; touch is a combination of general senses including temperature, pressure, and pain.
Special sense receptors are divided into large complex organs like eyes and ears, or localized clusters such as taste buds.

Anatomy of the Eye

The adult eye is roughly a 1-inch sphere (2.5 cm in diameter).
Only one-sixth of the eye's surface is visible; most is protected by fat and bony structures.
Structures around the eye include extrinsic muscles, eyelids, conjunctiva, and lacrimal apparatus.

Eye Muscles and Movements

Lateral rectus (Cranial Nerve VI): Moves the eye laterally.
Medial rectus (Cranial Nerve III): Moves the eye medially.
Superior rectus (Cranial Nerve III): Elevates and rotates the eye medially.
Inferior rectus (Cranial Nerve III): Depresses and rotates the eye medially.
Inferior oblique (Cranial Nerve III): Elevates and rotates the eye laterally.
Superior oblique (Cranial Nerve IV): Depresses and rotates the eye laterally.

Eye Structure

The fibrous layer, consisting of sclera and cornea, provides protection.
The sclera appears as the "white of the eye" while the cornea is transparent and allows light to enter.
The cornea is rich in nerve endings and has the highest capacity for self-repair.
The optic disc is a blind spot where no photoreceptors are present.

Photoreception and Vision

The retina contains rods and cones, which are photoreceptors that respond to light.
Light passes through a two-neuron pathway: photoreceptors signal bipolar cells, then ganglion cells.
Information is transmitted to the brain via the optic nerve for interpretation.

Image Formation and Refraction

Light refraction occurs as it passes through different eye substances (cornea, aqueous humor, lens, vitreous humor).
Accommodation allows the lens to bulge for focusing on near objects.

Vision Conditions

Emmetropia refers to properly focused images on the retina.
Myopia (nearsightedness) occurs when light fails to reach the retina; the eyeball is usually too long.
Hyperopia (farsightedness) happens when light focuses behind the retina; typically results from a short eyeball or lazy lens.
Corrective lenses help focus light properly for each condition.

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Description

Explore the fascinating world of sensory receptors as presented in Chapter 7 of Psychology. This quiz covers the five senses, focusing on the differences between general and special sense receptors, their structure, and function. Test your understanding of how we perceive the external environment!