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Anatomy / Physiology > Chapter 17: Special Senses > Flashcards

Chapter 17: Special Senses Flashcards

1
Q

Sense organ

A

A structure composed of nervous tissue along with other tissues that enhance its response to a certain type of stimulus

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2
Q

Sensory receptors

A

Specialized structures that respond to a stimulus

2 types:
Receptors for somatic sensations: detect tactile, thermal, pain, proprioceptive sensations
Receptors for visceral sensations: detect info from internal organs (such as blood pressure changes)

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3
Q

Functions of eyebrows

A
  • shade the eye from sunlight
  • catch perspiration from the forehead
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4
Q

Functions of the eyelids

A
  • protect eye from foreign objects and excess light
  • spread lubricating secretions over the eye
  • contain eyelashes which trap and sweep away foreign particles
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5
Q

Conjunctiva

A

A transparent, vascular mucous membrane which lines the inner surface of the eyelids and covers the surface of the sclera.

It secretes mucous to moisten the eyes

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6
Q

Extrinsic eye muscles

A

6 skeletal muscles (Orgin - bony orbit, insertion - sclera)

Functions:
- maintain eye shape
- hold eye in orbit
- control precise eye movements

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7
Q

Sty

A

An infected hair follicle at the base of an eyelash

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8
Q

How do blood shot eyes occur?

A

When the vessels in the conjunctiva get irritated and dilated.

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9
Q

Conjunctivitis

A

The inflammation of the conjunctiva by bacteria or virus

aka “pinkeye”

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10
Q

Diplopia

A

The eyeballs can’t be focussed on the same visual field due to paralysis, weak eye muscles, or alcohol consumption.

aka “double vision”

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11
Q

Strabismus

A

Weakness in eye muscles in which the affected eye rotates mediately or laterally.

aka “cross-eyed”

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12
Q

Lacrimal gland (tear gland)

A

Located in the superior-lateral region of each orbit.

  • secretes lacrimal fluid (tears) continuously
  • clears, lubricates, and moistens the eyes
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13
Q

What are tears made of?

A
  • water
  • salt
  • mucous
  • antibodies
  • lysozyme
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14
Q

Lysozyme

A

Antibacterial enzyme that prevents infection

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15
Q

What is the pathway of tears?

A
  1. Lacrimal gland
  2. Lacrimal ducts
  3. Lacrimal fluid flows over the eye
  4. Lacrimal punctual
  5. Lacrimal canaliculus
  6. Lacrimal sac
  7. Nasolacrimal duct
  8. Nasal cavity
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16
Q

Fibrous tunic of the eye

A

The outermost, avascular layer

Contains:
a) Sclera - the posterior part of the fibrous tunic. It is the white of the eye, which maintains eye shape and protects the inner surface.

b) Cornea - the anterior, transparent part of the fibrous tunic. It bends (refracts) light to focus light rays

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17
Q

Why are almost all corneal transplants successful?

A

The cornea is avascular, so rejection is rare because there is no access to the immune system, therefore no blood-borne antibodies.

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18
Q

Vascular tunic

A

The highly vascularized middle layer of the eye

Contains:
Choroid - darkly pigmented layer under sclera which absorbed excess light.
Ciliary body - made of ciliary muscles (regulate shape of eye) and ciliary processes (produce aqueous humour)
Iris - made of circular (makes pupil smaller) and radial (makes pupil bigger) muscles.

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19
Q

Aqueous humor

A

A clear fluid filing the space in the front of the eyeball between the lens and the cornea

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20
Q

Retina

A

Innermost layer of the eye

Consists of 2 layers:
1. Pigmented layer - closest to choroid, and absorbs excess light to reduce scattering.
2. Neural layer - visual part of the retina (contains photoreceptors, bipolar cells, and ganglion cells)

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21
Q

Photoreceptor layer of retina

A

Contains rods, cones, and macula lutea.

Rods - dim light receptors (120mil of them) that produce images in grey.

Cones- bright light receptors (6mil of them) that provide coloured vision.
- 3 kinds (blue, green, red cones)

Macula lutea - yellow flat spot on retina.
- center of it is called the fovea centralis which contains only cones
- site of the greatest visual acuity

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22
Q

Bipolar cell layer of the retina

A

Bipolar cells relay information from photoreceptors to the ganglion cells

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23
Q

Ganglion cell layer of retina

A

Attaches the retina to the back of the eye and forms the optic disc (blind spot) which contain no photoreceptors

24
Q

What is a detached retina?

A

When the pigmented and neural layers of the retina separate and the vitreous humor fills between them.

This deprives the neural retina of its blood supply and could result in blindness

25
What is age-related macular disease?
A disorder of the retina in a person 50+ of age. It is when there are abnormalities in the region of the macular lutea and will cause and inability to see straight ahead.
26
Lens
An avascular structure held in place by suspensory ligaments. It can change shape to focus image
27
Anterior cavity
Located in the front of the lens - filled with water aqueous humor - maintains intraocular pressure (16-20mmHg) to support the eyeball - provides oxygen and nutrients to the lens and cornea
28
Posterior cavity
Located behind the lens - filled with gel-like vitreous humor - maintains intraocular pressure - holds the retina in place
29
Light
A wave of energy that radiates from the sun and travels at high velocity. Eyes are sensitive to the wavelengths of light in the range of 400-700nm. This is known as as the visual spectrum of light (ROYGBIV)
30
Visual nervous pathway
1. Light 2. Photoreceptor cells 3. Bipolar neurons 4. Ganglion neurons 5. Optic chiasma 6. Optic tract 7. Thalamus 8. Visual sensory area in the occipital lobe
31
Myopia
(aka "near-sighted") See near clearly, far is blurry Results when an eyeball is too long or the lens is too curved. Corrected by using a concave lens (glasses)
32
Hyperopia
(aka "far-sighted") See far clearly, near is blurry Results when an eyeball is too short or the lens is too flat. Corrected by using a convex lens (glasses)
33
Astigmatism
Irregular curvature of the lens/cornea that results in parts of the image being out of focus
34
Glaucoma
Occurs when drainage of aqueous humor is blocked Retinal cells can die.
35
Physiology of vision
Involves 2 main processes: 1. Retinal image formation 2. Conversion of image to nerve impulse.
36
Retinal image formation
a) **refraction of light rays** which occurs as is passes through the cornea (75%), and as light enters/leaves the lens (25%) b) **accommodation of the lens** to adjust focus by changing lens shape. c) **Constriction of pupil** (for far vision it dilates, for close vision it constricts) d) **Convergence of the eyes** - extrinsic eye muscles turn eyes medically for close vision
37
Conversion of image to nerve impulse
Photoreceptor cells contain photopigments, which contain opsin and retinal proteins. **Opsin** proteins will allow rods and cones to absorb different wavelengths of light.
38
Phototransduction
A process by which light energy is converted into a graded receptor potential A grade potential = a small deviation from resting membrane potential.
39
External ear
Contains 3 regions: 1. **Auricle** - directs sound waves 2. **External acoustic meatus** - contains hair and ceruminous glands to secrete earwax. It also directs sound waves into middle ear. 3. **Tympanic membrane** - vibrates in response to sound waves
40
Middle ear
Air filled, mucus-lined cavity in the temporal bone which connects to the nasopharynx. Contains: **Malleus, Incus, Stapes** to amplify vibrations **Oval and round windows** **Auditory tube** to the nasopharynx
41
Internal ear
Contains the receptors for hearing and equilibrium. - consists of an outer bony labyrinth that encloses an inner membranous labyrinth
42
Bony labyrinth
Part of the internal ear A series of canals in hollowed out bone, therefore lined by periosteum and contains paralymph fluid. - Lined by **periostium** - contains **paralymph fluid** Associated structures: vestibule, semicircular canals, cochlea
43
Membranous labyrinth
Part of the internal ear. - consists of epithelial sacs - line by **endolymph** Associated structures: utricle and saccule, semicircular ducts, cochlear duct
44
Frequency
Differences in sound frequencies are perceived as different pitches. High frequency = higher pitch Measured in hertz (Hz)
45
Intensity
Differences in sound intensities are perceived as differences in loudness Higher intensity = louder sounds Measured in decibels (dB)
46
Pathway of sound
Auricle, external auditory canal, tympanic membrane, ossicles, oval window, scala vestibuli, vestibular membrane, cochlear duct, basilar membrane, organ of corti.
47
Organ of Corti
Spiral organ which contains the hearing receptors (hair cells) Contains: - single row of inner hair cells (send auditory info to brain) - 3 rows of outer hair cells (enhance response of inner cells
48
Pathway of hearing nerve impulse
Cochlear branch of vestibular nerve VIII, medulla, midbrain, thalamus, primary auditory area of temporal lobe
49
Static equilibrium
Refers to control of the position of the head with respect to gravity and linear acceleration. Receptors are found in utricle and saccule which contain patches of hair cells called the **macula** that are embedded in otolith membrane. (Head tilts, otoliths move -> nerve impulse)
50
Dynamic equilibrium
Refers to control of the position of the head during rotational movements. Receptors found in the semicircular ducts. Contains hair cells (**crista ampularis**) embedded in the cupula (movement of cupula causes hair bend -> nerve impulse)
51
Equilibrium nervous pathway
1. Nerve impulse from hair cells (macula and crista ampullaris) 2. Vestibular branch 3. Vestibulaocochlear nerve VIII 4. Vestibular nuclei and cerebellum (balance regulators)
52
What are the chemical senses
Smell and taste.
53
Taste
Contain receptors in the taste buds (gustatory cells) Chemicals from food dissolve in saliva and diffuse into the taste bud and contact the hairs of the cells
54
How often are taste cells replaced
Every 10 days
55
Smell
Receptors are bipolar neurons found on the roof of the nasal cavity. Odours dissolve in mucous and olfactory hairs respond to chemical stimulus
56
Olfactory adaptation
When you can only smell sense for a short time, and then no longer smell the odour even though it's still there because your ion channels close after a few minutes .

Anatomy / Physiology (22 decks)

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