Special Senses (Extra Lecture :/) Flashcards
(68 cards)
1
Q
What are the five special senses?
A
touch, sight, smell, taste, hearing
2
Q
What can special sense receptors be?
A
Either large organs (eyes, ears), or localised clusters of receptors (e.g taste buds and olfactory epithelium)
3
Q
What does it mean that the sensory inputs are overlapping?
A
That what we experience in the world is a blend of stimuli
4
Q
Special senses - Which special sense requires the most learning?
A
Sight/Vision - It can be easily fooled
5
Q
Special senses - How do photoreceptors send signals?
A
(photoreceptors are sensitive to light) - They send signals along the optic nerve, and then to the brain’s occipital cortex
6
Q
What is the lens in the eye made up of?
A
A crystal like protein. It IS flexible
7
Q
How can the lens in the eye be focussed?
A
By changing shape - This is achieved via the ciliary muscles that surround the lens
8
Q
What is eye movement controlled by?
A
Six extrinsic muscles that surround the sclera (white of the eyes)
9
Q
EYE - Quick note: The images received by the retina are upside down. Your brain changes them so they are facing the right way up
A
10
Q
Where is the lacrimal gland? What is its function?
A
Located in the inner corner of the eye, the lacrimal gland produces tears (keeping the front layer of the eye moist, and allowing cells to gain oxygen and nutrients and remove wastes in the absence of blood vessels
11
Q
Lacrimal gland - NOTES :It also contains Lysozyme providing defence against any foreign material entering the eye. The lacrimal fluid drains through the lacrimal canals eventually exiting in the upper nose.
A
12
Q
Special Senses - Anatomy of the eye:
Optical components: cornea
What is the function of the cornea
A
The cornea acts as the main window of the eye. This is the major important refractive element of the eye.
13
Q
Special Senses - Anatomy of the eye:
Optical components: Aqueous Humour
What is the aqueous humour? Where is it found in the eye?
A
- Is a watery fluid in the anterior and posterior chambers that is secreted by the ciliary body
- Provides nutrients to lens and cornea of the eye
14
Q
Special Senses - Anatomy of the eye:
Optical components: Lens
What is the lens? What is its function?
A
- The lens is the second most important (to the cornea) in terms of the refraction of light rays. It is elastic, so that the lens can undergo minor changes in response to tension of the ciliary muscle).
15
Q
A
16
Q
What can special sense receptors be?
A
Either large organs (e.g eyes, ears), or localised clusters of receptors (e.g tastebuds, olfactory epithelium)…
17
Q
What does it mean that our special senses are overlapping?
A
That what we experience in the world is a blend of stimuli
18
Q
What do optic tracts do?
A
Carry information from the eyes to the brain
19
Q
How many nerve fibres do optic tracts contain?
A
Over 1 million
20
Q
How do photoreceptors in the eye send signals?
A
Along the optic nerve, and then to the brain’s occipital cortex
21
Q
What is the lens of the eye made up of? What is its function? Where is it located in the eye
A
A crystal like protein (it is flexible). It functions to direct incoming light to the retina. Found just behind the pupil
22
Q
How can the lens be focussed?
A
By changing shape. This is done via the ciliary muscles that surround the lens of the eye. It is the second most in importance to the cornea in the refraction of light rays. It is elastic, so that the shape of the lens can undergo minor changes in response to tension of the ciliary muscle.
23
Q
What is eye movement controlled by?
A
Six extrinsic muscles that surround the sclera (white) of the eye
24
Q
NOTE: Images received by the retina have passed through the lens and are upside down. Your brain turns the image the right way up…
A
25
What does the lacrimal gland do?
Produce tears to keep the front of the eye moist, and enabling cells to gain oxygen and nutrients and the removal of wastes in the absence of blood vessels.
26
Which enzyme does the lacrimal gland contain? Why?
Lyzozyme - This enzyme is responsible for providing defence against any foreign material entering the eye. Lacrimal fluid drains through the lacrimal canals; eventually entering through the upper nose
27
Anatomy of the eye - Optical components:
- Cornea: What is the function of the cornea? Where is it located?
- The cornea functions as the main window of the eye. It is the major refractive element in the eye.
- *Located at the front of the eye - covering the iris and pupil*
28
Anatomy of the eye - Optical components:
- Aqueous humour: What is it? What is its function?
- Aqueous humour is a watery fluid found in the anterior and posterior chambers of the eye and is secreted by the ciliary body.
- It is important in providing nutrients to the lens and cornea of the eye.
29
Anatomy of the eye - Optical components:
- Vitreous body: What is it? What is its function?
- The vitreous body is the surrounding mass of the vitreous humour - a clear, gel like substance made mostly of water*
- The vitreous body acts as a shock absorber that protects the retina during rapid eye movements, and helps to maintain the structure of the eye.
30
Anatomy of the eye - Neural components:
- Retina
- What is the retina?
- Function?
- Location?
- A cup shaped outgrowth of the brain (back of the eye). It is a thin, transparent membrane attached at two points:
- the optic disc (where the optic nerve leaves the rear of the eye), and the ora serrata (the junction between the retina and the ciliary body)
- *converts light into electrical signals the brain can convert into images*
31
Anatomy of the eye - Neural components:
- What is the 'macula lutea' in the eye?
- A patch of cells (about 3mm in diameter) that are found in the retina
- In the centre of this patch is a small pit called the fovea centralis, which produces finely detailed images
32
What can cause a detached retina? What does a detached retina mean in terms of vision?
- A blow to the head, or inadequate pressure from the vitreous body.
- Since the retina normally attaches to and depends on the choroid for oxygen, nutrition and waste removal, prolonged detachment of the retina from the choroid can lead to blindness.
33
Anatomy of the eye: Neural components
- Neural retina NOTES
The neural retina contains light-sensitive receptors and complex neural networks, and the retinal pigment epithelium (RPE). It consists largely of photoreceptor cells called retinal rods and cones.
34
Anatomy of the eye:
What makes the pupil appear black?
What is the function of the pupil?
- Due to the heavily pigmented back of the eye
- The pupil functions to control and regulate the amount of light passing through the lens to reach the retina via size change
35
Special senses - Sight:
NOTES
Light rays enter the eye passing through cornea and lens causing rays to cross over
Image is received by the retina to be inverted and transposed
Refraction of the cornea and shape of the lens adjust to the distance
From retina they are converted to nerve impulses that are transmitted along the optic nerve
The images received from the left and right eyes are slightly different.
The brain brings these together in a single 3D image (green area)
36
Special senses: Sight
- How your eye captures an image: What causes long and short sightedness?
- For a clear image, light must be focussed ON the retina.
- For people with short sightedness/blurred vision (myopia) as light is focussed in FRONT of the retina, while long sightedness causes light to be focussed BEHIND the retina, also blurring images (hyperopia).
- In both cases the lens is unable to produce the correct focus. This can be corrected by adding an additional correcting lens in front of the eye such as spectacles or contact lenses. Lazik surgery uses a computer controlled laser to reshape the cornea.
37
Special senses: The retina
What does the retina consist of?
Light absorbing rods and cones.
38
Special senses: The retina
Where in the retina are rods usually found?
In the peripheral part of the retina
39
Special senses: The retina
What do rods in the retina do?
Rods are sensitive to low light responding to all wavelengths. Helps you to see in dim or dark light (cannot detect colour)
40
Special senses: The retina
What do cones in the retina do? Where specifically in the retina are they found?
Work best in bright light
Responsible for colour vision and sharp detail
Concentrated in the fovea (center of the retina)
There are three types, each tuned to a different color
41
Special senses: The retina
What are the colours of cones in the retina?
Red, green, blue
42
Special senses: The retina
NOTES: Light received by the rods and cones is converted to an impulse which passes from the bipolar cells to the ganglion cells and to the optic nerve. The optic nerve carries the impulse to the occipital lobe of the brain.
The brain receives the impulses and converts them to an image that we see, which is the right way up.
43
Special Senses: Sight (colour blindness)
What is red-green colour deficiency?
The most common type of colour vision deficiency, which makes it hard to tell the difference between green and red.
44
Special senses: Sight (colour blindness)
What are the three types of red-green colour deficiency?
Deuteranomaly is the most common type of red-green colour vision deficiency. It makes certain shades of green look more red. This type is mild and doesn’t usually get in the way of normal activities.
Protanomaly makes certain shades of red look more green and less bright. This type is mild and usually doesn’t get in the way of normal activities.
Protanopia and deuteranopia both make someone unable to tell the difference between red and green
45
Special senses: Sight (colour blindness)
- What are the two types of blue-yellow colour deficiency?
- Tritanomaly makes it hard to tell the difference between blue and green and between yellow and red.
- Tritanopia makes someone unable to tell the difference between blue and green, purple and red, and yellow and pink. It also makes colours look less bright.
46
Special senses: Sight (colour blindness)
Complete colour vision deficiency: NOTES
If you have complete colour vision deficiency, you can’t see colours at all. This is also called monochromacy or achromatopsia, and it’s rare.
Depending on the type, you may also have trouble seeing clearly, and you may be more sensitive to light.
47
Special senses: Sight
- Eye conditions and diseases:
- Age related macular degeneration
- Cataracts
- Colour blindness
- Diabetic retinopathy
- Hyperopia (far sighted)
- Glaucoma
- Low vision
- Myopia (near sighted)
- Pink eye (Conjunctivitis)
- Retinal detachment
48
Special senses: Hearing and balance
What is the purpose of the ear?
To receive vibrations from the air and convert them to nerve impulses
49
Special senses: Hearing and balance
What is the outer part of the ear called?
What is its function?
- The auracle (pinna) (together with ear canal forms outer ear)
- Used to collect and concentrate sound waves from the ear canal to the ear drum
50
Special senses: Hearing and balance
How is the middle part of the ear seperated from the outer part?
Via the ear drum
51
Special senses: Hearing and balance
What three bones make up the middle part of the ear? What is their function?
- Collectively known as the ossicles (malleus, incus, stapes)
- Their role is to amplify the vibrations on the ear drum. When the sound reaches the eardrum, the first part of the middle ear, it converts the sound into mechanical vibration.
52
Special senses: Hearing and balance
What two organs does the inner ear contain?
The cochlea, semicircular canals
53
Special senses: Hearing and balance
Inner ear:
What is the cochlea?
What is the function of the cochlea?
- The cochlea is a spiral, fluid filled chamber within the skull, lined with thousands of sensory cells known as hair cells. These tiny cells rest on a flexible membrane that moves when the oval window vibrates. The outer hair cells boost soft sounds and dampen loud sounds, and the inner hair cells transfer the sound to the auditory nerve.
- It is where the vibrations from the ossicles cause the hairs to move. This movement is converted to impulses and transported to the brain by the auditory nerve (vestibulocochlear nerve)
54
Special senses: Hearing and balance
Inner ear:
What are the semicircular canals?
What are their function?
- Three fluid filled loops found in the inner ear
- Not responsible for hearing in any way, rather important for balance and spatial orientation
55
Special Senses: Hearing and balance:
- Middle part of the ear: The ossicles NOTES
The stape or inner most bone of the ossicles presses against a membrane in the cochlea known as the oval window which transmits the amplified vibrations through to the cochlea fluid. The hairs range from short which respond to high frequencies through to long hairs which respond to low frequency sounds. The short hairs are most easily damaged and high frequency hearing diminishes with age. The range of human hearing is from 20 hertz (very low) through to 20,000 hertz (very high).
56
Special senses: Hearing and Balance
- What is the outer part of the ear called?
- The auracle (pinna)
57
Special senses: Hearing and balance:
- What is the eardrum attached to in the middle ear?
The ossicles: (stapes, malleus, incus) - small bones
58
Special senses: Hearing and balance:
- Which of the ossicle bones is connected to the oval window (a thin tissue covering an entry point into the fluid-filled inner ear)?
The stapes (stirrup)
- presses against a membrane in the cochlea known as the oval window which transmits the amplified vibrations through to the cochlea fluid. The hairs range from short which respond to high frequencies through to long hairs which respond to low frequency sounds. The short hairs are most easily damaged and high frequency hearing diminishes with age. The range of human hearing is from 20 hertz (very low) through to 20,000 hertz (very high).
59
Special senses: Hearing and balance
- How do ossicles actually amplify sound vibrations?
Through a system of tiny levers
60
Special senses: Hearing and balance -
What is the speed of sound?
343m/s
61
Special senses: Hearing and balance -
What is the distance between the ears?
200mm or 0.2m
62
Special senses: Hearing and balance
What is glue ear?
Tamariki with glue ear have sticky fluid in their middle ear (the space behind the ear drum) and cannot drain through the Eustachian tube
Glue ear can affect one or both ears
The main symptom of glue ear is having trouble hearing
Hearing loss for long periods during the early years may affect speech and language development
Often treated with grommets inserted into the eardrum.(see picture) which allows the fluid to drain.
63
Special senses: Hearing and balance
- Balance: NOTES
he semicircular canals are three fluid filled tubes lined with hairs. Each tube is at right angles to each other.
Depending on the orientation of the head the hairs move and produce impulses which are carried to cerebellum by the vestibular nerve (part of vestibulocochlear nerve)
64
Special senses: Hearing and balance -
- Disorders of heraing and balance:
Balance disorders include:
Benign Paroxysmal Positional Vertigo (BPPV)
Labyrinthitis: Inner ear infection.
Vestibular neuritis: Infection of the vestibular nerve
Meniere’s disease: Inner ear disorder
Ear infections and disorders include:
Glue ear: Fluid build-up in the middle ear
Otitis media: infection behind the eardrum
Otosclerosis: most common form of hearing loss in adults
Tinnitus: Constant ringing or buzzing
Barotruma: Damage due changes in pressure
Acoustic trauma: Loud noise
65
Special senses: Taste and smell
NOTES
Taste and smell are separate senses with their own receptor organs, yet they are intimately entwined.
Tastants, chemicals in foods, are detected by taste buds, which consist of special sensory cells.
When stimulated, these cells send signals to specific areas of the brain, which make us conscious of the perception of taste.
Similarly, specialized cells in the nose pick up odorants, airborne odour molecules.
Odorants stimulate receptor proteins found on hairlike cilia at the tips of the sensory cells, a process that initiates a neural response.
Ultimately, messages about taste and smell converge, allowing us to detect the flavours of food.
Tasting food is complex, as it is a combination of the five tastes; Sweet, Sour, bitter salt, Umami (savoury)detected on the tongue, smells detected in the nose and texture detected in the mouth.
66
Special senses: Smell and taste
What are the most common smell and taste disorders?
Smell:
- Anosmia. Loss of sense of smell
- Hyposmia. Reduced ability to smell
Taste:
- Loss of sense of taste
- Hypogeusia. Reduced ability to taste sweet, sour, bitter, or salty things
67
Special senses: Taste and smell
What causes smell and taste disorders?
- llness (for example, cold or flu, sinus infection, and allergies)
- Head injury
- Hormone changes
- Dental or mouth problems
- Nasal polyps
- Exposure to certain chemicals
- Certain medicines
- Exposure to radiation therapy for head or neck cancer
- Cocaine snorted through the nose
- Cigarette smoking
68
