The Human Eye Anatomy Quiz

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Questions and Answers

What happens to the pupil diameter when light intensity decreases?

The pupil diameter remains the same

The pupil diameter increases (correct)

The pupil diameter decreases

The pupil diameter fluctuates

What type of light rays require more refraction for near objects?

Monochromatic light rays

Divergent light rays (correct)

Convergent light rays

Vertical light rays

Which type of iris muscles respond to increased light intensity?

Circular muscles (correct)

Constrictor muscles

Dilator muscles

Radial muscles

What is the role of the radial muscles in changing pupil diameter?

They relax to widen the pupil Signup and view all the answers

In what situation would eye accommodation require less refraction?

When focusing on distant objects Signup and view all the answers

What is the primary role of auxins in phototropism?

They influence growth direction in response to light. Signup and view all the answers

What effect do high concentrations of auxins have on shoots?

They stimulate shoot growth. Signup and view all the answers

How do roots respond to unilateral light according to phototropism?

Roots grow away from the light. Signup and view all the answers

Where are auxins produced in plants?

In the apical meristems at shoot and root tips. Signup and view all the answers

What happens to the shaded side of a shoot when exposed to unilateral light?

It grows faster than the illuminated side. Signup and view all the answers

What is the first structure that light rays pass through when entering the eye?

Cornea Signup and view all the answers

What type of image is formed on the retina?

Real and inverted Signup and view all the answers

What role do photoreceptors play in vision?

They generate nerve impulses Signup and view all the answers

After light stimulation, where do nerve impulses travel to in order to interpret visual information?

The visual centre of the brain Signup and view all the answers

What happens if an image is formed on the blind spot?

It is not perceived at all Signup and view all the answers

Which structure focuses light rays onto the retina?

Lens Signup and view all the answers

Which of the following is a function of the vitreous humour?

To maintain the shape of the eye Signup and view all the answers

What must occur for vision to be achieved after nerve impulses are sent to the brain?

The brain must interpret the nerve impulses Signup and view all the answers

What fluid fills the central canal of the cochlea?

Endolymph Signup and view all the answers

What occurs after the sensory hair cells in the cochlea are stimulated?

They bend and send nerve impulses along the auditory nerve. Signup and view all the answers

Which part of the ear collects sound waves before they enter the auditory canal?

Pinna Signup and view all the answers

What causes the eardrum to vibrate when sound waves are present?

Sound waves hitting the eardrum Signup and view all the answers

What are the two types of fluid found in the cochlea?

Endolymph and perilymph Signup and view all the answers

What is the role of the auditory nerve in hearing?

It sends nerve impulses to the auditory center of the brain. Signup and view all the answers

Where are sensory hair cells located within the ear?

In the cochlea Signup and view all the answers

What is the primary function of the cochlea in the inner ear?

To convert sound waves into electrical signals. Signup and view all the answers

What is the primary function of the sclera in the human eye?

Provides shape and protection Signup and view all the answers

What is the role of the tear gland in the human eye?

Produces tears that contain lysozyme Signup and view all the answers

What is the function of the ciliary body?

To change the shape of the lens Signup and view all the answers

What is the purpose of eyelashes in relation to the human eye?

To trap dirt and debris Signup and view all the answers

What structure controls the size of the pupil in the human eye?

Iris Signup and view all the answers

Which part of the human eye is responsible for refracting light?

Cornea Signup and view all the answers

What is the function of the optic nerve in the human eye?

To lead signals to the brain Signup and view all the answers

What is the primary property of the lens in the human eye?

Transparent and elastic Signup and view all the answers

Which layer of the human eye contains blood vessels for nutrient supply?

Middle layer Signup and view all the answers

What primarily causes the pupil to appear black?

Absence of light reflection Signup and view all the answers

What is a key function of the upper and lower eyelids?

To protect the eye from objects and light Signup and view all the answers

What does the choroid layer of the human eye contain?

Pigment and blood vessels Signup and view all the answers

What is the function of the tear duct?

To drain tears to the nasal cavity Signup and view all the answers

How do eye muscles contribute to vision?

Assist in rotating the eyeball Signup and view all the answers

Study Notes

The Human Eye

The human eye is a spherical sense organ that detects light.
The eye is situated in the orbit of the skull.
The orbit encloses and protects the eye.
Eye muscles attach the eyeball to the orbit and contract and relax to rotate the eye.
The optic nerve leads from the eye to the brain.
Eyebrows prevent sweat from entering the eye.
Eyelashes trap dirt before it can enter the eye.
The upper and lower eyelids can close to protect the eye from foreign objects and strong light.
The tear gland secretes tears which contain lysozyme (an antibacterial enzyme), keep the eye surface moist, and clean.
The tear duct drains tears to the nasal cavity.

Internal Structure of the Eye

The wall of the eyeball is composed of three layers: the outer layer, the middle layer, and the inner layer.
The outer layer consists of the sclera and the cornea.
The sclera, a white, opaque, fibrous coat, gives shape to the eyeball, protects the inner structures, and provides an attachment surface for eye muscles.
The cornea is transparent to allow light to pass through and refracts light into the eye.
The middle layer consists of the choroid, ciliary body, and iris.
The choroid contains blood vessels that supply nutrients to cells and remove wastes.
The choroid also contains black pigment which absorbs light to prevent light reflection in the eye.
The ciliary body is a ring of muscular tissue that surrounds the edge of the lens, containing ciliary muscles that contract and relax to change the shape of the lens.
The lens is a transparent, elastic, biconvex structure composed of living cells that refracts and focuses light onto the retina.
The suspensory ligaments connect the lens to the ciliary body.
The iris contains pigment that gives the eye its color. It consists of circular muscles and radial muscles.
The pupil is the central hole of the iris that allows light to enter the eye.
The size of the pupil is controlled by the circular muscles and radial muscles of the iris.
The iris varies in color among individuals.

How We See

Light rays from an object are refracted by the cornea, aqueous humor, lens, and vitreous humor.
The light rays focus on the retina to form an image.
The image formed on the retina is a real, vertically and laterally inverted image that is smaller than the object.
The light rays focused onto the retina stimulate the photoreceptors, which generate and send nerve impulses along the optic nerve to the visual center of the brain.
The brain interprets the nerve impulses and produces vision, resulting in an upright image.

Eye Accommodation

Eye Accommodation is the ability of the eye to focus on objects at different distances.
Near objects require more refraction than distant objects.
The shape of the lens changes to accommodate objects at different distances.
To focus on near objects, the ciliary muscles contract, making the lens more rounded and increasing the refractive power.
To focus on distant objects, the ciliary muscles relax, making the lens flatter and decreasing the refractive power.

The Human Ear

The ear is a sensory organ composed of three parts: the outer ear, middle ear, and inner ear.
The outer ear collects sound waves into the auditory canal.
The sound waves cause the eardrum to vibrate.
The middle ear contains three tiny bones: the hammer, anvil, and stirrup.
The vibration of the eardrum is transmitted to the hammer, anvil, and stirrup.
The stirrup vibrates against the oval window of the inner ear.
The inner ear contains the cochlea and semicircular canals.
The cochlea is a coiled, fluid-filled tube responsible for hearing.
The semicircular canals are responsible for balance.
The movements of the endolymph in the cochlea cause the hairs of the sensory hair cells to bend.
The sensory hair cells are stimulated and send nerve impulses along the auditory nerve to the auditory center of the brain.

How We Hear

The pinna collects sound waves in the auditory canal.
The sound waves cause the eardrum to vibrate.
The vibrations are transmitted through the middle ear bones: the hammer, anvil, and stirrup.
The vibrations reach the oval window of the inner ear.
The fluid in the cochlea moves, causing the hairs of the sensory hair cells to bend.
The sensory hair cells are stimulated and send nerve impulses along the auditory nerve to the auditory center of the brain.
The brain interprets these impulses as sound.

Phototropic Responses in Plants

Phototropism refers to the directional growth movement of a plant part in response to unilateral light.
Shoots are positively phototropic, meaning they bend towards light.
Roots are negatively phototropic, meaning they bend away from light.
Phototropism is controlled by the plant hormone auxin.
Auxin is produced in the shoot tips and root tips and is transported to the regions of elongation.
High concentrations of auxin promote shoot growth but inhibit root growth.

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Description

Test your knowledge about the structure and function of the human eye. This quiz covers the anatomy, protective features, and internal organization of the eye, including details about the optic nerve and eyelids. Perfect for biology students looking to reinforce their understanding of ocular anatomy.