Senses

Question 1

Explain how the middle ear is connected to the nasopharynx.

Answer 1

Via the eustachian tube

Question 2

Outer Ear

Describe the main role of the tympanic membrane

Answer 2

• The tympanic membrane [eardrum] is a thin semi transparent partition between the external auditory canal and the middle ear.
• Its role is to transmit sound from the outer ear to the auditory ossicles.
• It converts sound waves into mechanical vibration carried across the bones of the middle ear.

Question 3

Middle Ear

List the THREE ‘ossicles’ found in the middle ear.

Answer 3

We have Malleus, Incus and Stapes.

Question 4

Middle Ear:
Explain the role of the ‘stapedius’.

Answer 4

Stapedias is a very small muscle that dampens large vibrations and is innovated by the facial nerve

Question 5

Inner Ear

Describe specifically the structure of the inner ear.

Answer 5

The innner ear provides information on balance and hearing.

Outer Bony labyrinth that encloses an inner membranous labyrinth.

Bony labyrinth consists of a series of cavities in the temporal bone, divided into
- 3 semi circular canals for balance
- vestibule for balance
- Cochlea for hearing

Question 6

Inner Ear

Explain how loud noises can affect the inner ear.

Answer 6

The inner ear contains epithelial cells lined with hair cells. These are called stereocilia.

Strong movement of fluid [which occurs from very loud noise] can kill hair cells

Question 7

Inner Ear

TWO main functions of the inner ear.

Answer 7

balance and hearing

Question 8

Inner Ear

Describe how ‘stereocilia’ trigger an electrical impulse.

Answer 8

Fluid movement [vibration] causes stereocilia movement and initiates an electrical impulse along cranial nerve #8.

Question 9

Inner Ear

Name which cranial nerve provides sensory information for hearing and balance.

Answer 9

8. The vestibularcochlear

Question 10

Describe in specific detail how external sound waves are perceived as ‘sound’ in the cerebrum of the brain.

Answer 10

Step 1: Soundwaves. Outer ear
1st we need the initial sound waves. They are collected by the auricle and directed down into the auditory canal where they hit the tympanic membrane

Step 2: Mechanical Vibration Middle ear
In the middle ear the tympanic membrane vibrates and creates this mechanical vibration across the three auditory ossicles – malleus, incus and stapes

Step 3: Fluid Waves Inner ear
We then get a fluid wave in the inner ear. the bending of the sterocilia creates a receptor potential generating an action potential.

Step 4: Nerve Impulse
Finally this leads to a nerve impulse via the vestibularcochlear nerve to the brainstem carrying info about hearing to the hearing area in the cerebrum

Question 11

Describe the difference between ‘pitch’ and ‘volume’ of sound waves.

Answer 11

Pitch refers to the frequency of sound waves and is measured in Hertz. The higher the frequency of vibration the higher the pitch.

Volume refers to the amplitude of sound waves and is measured in Decibels

Question 12

Identify the decibel rating above which can contribute to hearing loss.

Answer 12

140dB

Prolonged over 90dB can also lead to hearing loss

Question 13

Explain the main function of white noise.

Answer 13

White noise is a constant noise that contains all the different frequencies of sound .

It is a background noise that the brain ignores is used to mask other sounds.

This is useful to enhance privacy, for sleep and to mask tinnitus

Question 14

List TWO functions of the Eustachian tube.

Answer 14

Connects the middle ear to the nasopharynx which is the top of the pharynx.

• It equalises pressure between the middle ear and the atmosphere.Why do we need this? Is ascential that air can escape the middle ear otherwise damage could occur with pressure changes.. eg: if you yawn or swallow you can feel your ears pop and this is opening the tube
• It functions to drain mucus.

Question 15

Explain why children are more prone to middle ear infections.

Answer 15

The eustachian tube is a common route for infection to spread. It is more horizontal in children which makes spread easier

Question 16

Inner Ear

Describe the structure of the ‘otolithic’ membrane’.

Answer 16

A dense layer of calcium carbonate crystals that extends over and rests on the stereocilia. it helps with balance

Question 17

List THREE ways in which the cerebellum can make postural adjustments to maintain balance.

Answer 17

• Vestibular feedback from the inner ear
• visual feedback from the eyes
• proprioceptors in the skeletal muscles, joints and surrounding ligaments

The three sources of information are coordinated and efferent impulses passed the cerebrum and skeletal muscles

Question 18

Using definitions compare the following:

a. Otitis externa

b. Otitis media

c. Otitis interna -

Answer 18

a. Otitis externa - also known as swimmers ear. It’s an inflammation of the outer ear associated with a bacterial infection in 90% of cases, and fungal or allergic in the remaining cases.

b. Otitis media - inflammation of the middle ear. The most common cause of earache in children because of the horizontal nature of the eustachian tube

c. Otitis interna - a balance disorder associated with the inflammation of the membranous labyrinth of the inner ear.

Question 19

Explain why insufficient earwax can predispose to ear infections.

Answer 19

Ear wax contains lysozymes and oil that create an acidic, lubricating coat. This inhibits bacterial and fungal growth.

On the other hand excess wax causing obstruction can also predispose to ear infections.

Question 20

Name TWO pathologies that increase the risk of otitis externa.

Answer 20

Diabetes mellitus and HIV

Question 21

TWO signs and / or symptoms of otitis externa.

Answer 21

• Pain (especially with movement of Pinna)
• Discharge [often purulent], swelling, itchy, red, swollen auditory canal
• Hearing deficit

Question 22

Otitis Media
1. List TWO causes of otitis media.
2. Explain how the tympanic membrane appears in otitis media.

Answer 22

1. • Allergy
   • Infectious organisms typically spread from the nasopharynx
2. You can get bulging of the tympanic membrane

Question 23

Secretory Ititis Media

1. Describe how ‘secretory otitis media’ can result in hearing impairment.
2. Explain how a ‘grommet’ can relieve secretory otitis media.

Answer 23

1. The gluey fluid of glue ear dampens the tympanic membrane and ossicle vibrations which leads to hearing impairment.
2. A grommet is a tiny pipe inserted into the ear drum under anaesthetic and fluid is drained, air circulates in the middle ear and hearing improves.

They typically fall out within 6 to 12 months and the whole usually hears heels

Question 24

Otitus Interna

Describe TWO characteristic signs and / or symptoms of otitis interna.

Answer 24

• Sudden and severe a vertico that is not triggered by movement
• Sudden unilateral hearing loss
• Nausea and vomiting
• tinnitus

Question 25

Using definitions, compare ‘Meniere’s disease’ and ‘tinnitus’

Answer 25

. Menier’s disease is a disorder of the inner ear that is caused by a change in fluid volume in labyrinth and typically affects balance and hearing. Associated with progressive distension of the membrane's labyrinth. **Tinnitus is a sign/symptom of Menieres disease** Tinnitus is the perception of sound originating from within the head when no external sound source is present. **Tinnitus can be caused by underlying health conditions such as Meniere's disease**.

Question 26

Meniere's disease 1. List ONE autoimmune cause of Meniere’s disease. 2. List TWO signs and / or symptoms of Meniere’s disease. 3. Explain why a low salt diet is recommended in Meniere’s disease.

Answer 26

1. RA and SLE 2. * Vertigo * Tinnitus * Hearing loss 3. Reduce fluid build up in the inner ear. Where there's salt there's fluid!

Question 27

List TWO causes of: a. Objective tinnitus b. Subjective tinnitus Redo answer. Have not defined subjective and have not given causes for subjective

Answer 27

a. Objective tinnitus Pulsatile - rhythmic or pulsating sensations or sounds related to blood flow or pressure abnormalities in the arteries or heart valves. Muscular (spasm of Tympanic muscles) b. Subjective tinnitus * Ear origin (Meniere’s, ear infection, wax) * Neurological (head injury, MS, tumour) * infections (meningitis) * drug-related (NSAIDs, loop diuretics) * TMJ (jaw) dysfunction.

Question 28

Describe the key difference between ‘conductive’ and ‘sensory’ hearing impairment.

Answer 28

Conductive: hearing impairment refers to ear canal obstructions, optical abnormalities, ruptured tympanic membrane Sensory: Poor hair cell function - can be due to a congenital condition, infection or noise trauma

Question 29

List TWO viral causes of hearing impairment.

Answer 29

Measles, viral meningitis, mumps (auditory nerve damage), rubella.

Question 31

Name the THREE layers of the eyeball.

Answer 31

1. Outer fibrous Layer: Sclera and Cornea 2. Middle vascular Layer: Uvea (the choroid, ciliary body and Iris) 3. Inner nervous tissue layer: Retina

Question 32

Describe the main role of the ‘iris’.

Answer 32

The iris controls the amount of light reaching the retina by adjusting pupil size

Question 33

Describe how the following protect the eye: a. Eyebrows b. Eyelids / eyelashes c. Blinking d. Conjunctiva

Answer 33

a. Eyebrows – Stop sweat and dirt from getting in b. Eyelids / eyelashes – protect the eye, spread secretions over the eye c. Blinking – spreads tears, close for protection d. Conjunctiva – Thin transparent mucous membrane lining the internal eyelids and anterior eyeball. Protects the cornea

Question 34

Explain how tears play an important immune role.

Answer 34

They contain IgA and Lysozymes that protect the eye from infection

Question 35

Name the cranial nerve that controls tear secretion.

Answer 35

Nerve no 6: Trigeminal Nerve

Question 36

List THREE ways in which clear vision is achieved by the eyes.

Answer 36

Light must be focused on the retina. This involves 1. Refraction (bending) of the light rays 2. Accommodation - adjustment of the lens. This is the ability of the eye to switch focus, enabling clear vision of objects at different distances. 3. Changing the size of pupils

Question 37

Refraction: Name ONE eye component that refracts most light rays.

Answer 37

Primarily the Cornea, but also the retina to a lesser extent. The refraction of light rays helps to focus the image on the retina

Question 38

Refraction: Describe in detail the difference between: (HINT: Think ciliary muscles >>>suspensory ligaments >>> what happens to the lens) a. Greater refraction b. Less refraction

Answer 38

The lens is able to change its refractive power. This is determined by the amount of pull the suspensory muscle places on the suspensory ligaments. a. Greater refraction When an object is close, the ciliary muscle contracts. This reduces suspensory ligament tension and the lens becomes more convex b. Less refraction when an object is far away, the ciliary muscle relaxes. This increases tension on the ligament and the lens becomes less convex – flattens the lens.

Question 39

Describe how the pupil size is affected by: a. Sympathetic nervous system b. Parasympathetic nervous system

Answer 39

a. Sympathetic stimulation, dilates the iris by contracting the **radial muscles**. b. Parasympathetic stimulation constricts the pupil by contracting, the **circular muscles**

Question 40

Accomodation? Explain why an individual may experience ‘double vision’.

Answer 40

It occurs when convergence is not complete and two images are sent to the brain. Ordinarily there is convergence between the two eyeballs so that both are directed towards the object. Extra ocular muscles move the eyes in a coordinated way.

Question 41

Accomodation? Describe what is meant by ‘binocular vision’.

Answer 41

The ability to perceive a single, 3 dimensional image of the environment by integrating visual input from both eyes simultaneously. Two images from two eyes are fused in the cerebrum so that only one image is perceived. The point of which the two images crossover in the brain is called the optic chiasma

Question 42

Name the location where the optic nerve crosses over in the brain.

Answer 42

Optic Chiasma

Question 43

Explain why a pituitary tumour can cause ‘tunnel vision’.

Answer 43

The Optic Chiasma, where the optic nerve crosses over in the brain, is located next to the pituitary gland. If the pituitary gland has a tumour it can interfere with the function of the optic chiasma leading to tunnel vision

Question 44

Name one investigative tool that can be used to view the retina.

Answer 44

Opthalmoscope

Question 45

Retina Question: Name the location where the optic nerve exits the eyeball.

Answer 45

The optic disc

Question 46

Retina Question: List TWO layers of the retina.

Answer 46

A pigmented later or melanin-containing epithelial cells A layer of photoreceptors - specialised visual cells. Two types, Rod cells and Cone cells.

Question 47

Retina Question: Describe THREE differences between ‘rod cells’ and ‘cone cells’.

Answer 47

Rod Vs Cone 120 million cells Vs 6 Million cells 1 type Vs 3 types - blue red and green Provide black/White and grey scale Vs Provide colour vision More plentiful at the periphery of the retina and not found in the fovea centralis Vs Found in the Fovea Centralis

Question 48

Retina Question: Describe TWO features of the ‘fovea centralis’.

Answer 48

Fovea centralis is a small depression in the centre of the Macula Lutea - It contains only cone cells - It is the area of highest visual acuity (The macula lutea is a yellowish spot at the exact centre of the retina)

Question 49

Retina Question: State where you would expect to find ‘rod cells’ in the retina.

Answer 49

The periphery of the retina. Not in the Fovea Centralis

Question 50

Retina Question: Describe how light affects photo pigments.

Answer 50

A photo pigment is a transmembrane protein with the discs of both rod and cone cells. When light hits the photo pigment it changes shape initiating an action potential Essentially – It is the conversion of light signals into electrical signals that the brain can interpret as vision.

Question 51

State where Vitamin A is stored in the eye.

Answer 51

The pigmented layer In the retina, vitamin A is in the form of retinal and binds to a protein called opsin to produce photoprint pigments

Question 52

Retina Question: Name the protein bound to Vitamin A in the eye.

Answer 52

Opsin

Question 53

Retina Question: List two food sources of: a. Pre-formed vitamin A b. Carotenoids

Answer 53

a. Pre-formed vitamin A Liver Eggs b. Carotenoids Leafy greens Pumpkin, Carrots, Mango, Squash, sweet potato

Question 54

Retina Question: Explain why carotenoids are not considered to be toxic.

Answer 54

Because absorption is regulated unlike preformed Vitamin A

Question 55

Retina Question: Describe how the eyes adjust in the following situations: a. Moving from dark to light sensitivity b. Moving from light to dark sensitivity

Answer 55

a. Moving from dark to light sensitivity Light Adaption: Quite quick. The visual system adapts in seconds by decreasing its sensitivity b. Moving from light to dark sensitivity Happen slowly over some minutes.

Question 56

Retina Question: Explain how quickly rod and cone cells regenerate.

Answer 56

Rods and cones must regenerate photo pigments. Cones regenerate within the first 8 minutes, rod cells take much longer.

Question 57

Using definitions compare ‘blepharitis’ with a ‘stye’.

Answer 57

Blepharitis is an inflammation of the eyelid margin. It can be acute or chronic. A stye is an inflammation of the sebaceous glands Both are often related to staphylococcus

Question 58

Using signs and / or symptoms, compare ‘blepharitis’ with a ‘stye’.

Answer 58

Blepharitis: * Red eyelid margins * Sore, gritty eyes * Scales and flakes * Can block sebaceous glands and cause recurrent styes Styes: Red, swollen lump usually on the upper eyelid. Usually upper eyelid

Question 59

List ONE endocrine pathology that increases the risk of styes.

Answer 59

Diabetes Mellitus

Question 60

What is conjunctivitis and what are the signs and symptroms?

Answer 60

A highly contagious (not when an allergy) inflammation of the conjunctiva. Presents as - red eye, irritated and uncomfortable. - watering eye

Question 61

State TWO parts of the uvea affected in uveitis.

Answer 61

Refers to inflammation of any part of the uvea. There are 3 parts so it could be the Iris, ciliary body or choroid.

Question 62

List ONE viral cause of uveitis.

Answer 62

Herpes Other causes: - Fungus; parasites - Autoimmune link to HLA-B27 and ankylosing spondylitis - Trauma to eye such as contact lenses use and hygiene

Question 63

Describe THREE characteristic signs and / or symptoms of uveitis.

Answer 63

- Progressive broad redness in the eye with pain - Associated with blurred vision and reduced visual accuity - Pain sensitivity to light (photophobia) - Watery discharge

Question 64

Explain why a corneal ulcer is a medical emergency.

Answer 64

Can lead to loss of sight

Question 65

List ONE pathology that can cause ‘strabismus’.

Answer 65

Strabismus is a squint. Pathology that damage cranial nerves 3, 4, and 6 would be implicated here – no 3, the oculomotor nerve supplying extra ocular muscles. Also 4, trochlear and 6, abducens. If nerve on one side is damaged it leads to imbalance and can pull the eyes in our out. Stroke, Brain tumour.

Question 66

Describe the difference between a healthy lens and a lens affected by cataracts.

Answer 66

A healthy lens is transparent due to the regular arrangement of lens fibres. In cataracts, new fibres are produced and become disorganised within cytoplasm and you get a silvery grey appearance to the lens. The lens sits behind the iris.

Question 67

List TWO causes (not age) of cataracts.

Answer 67

* Diabetes Mellitus more common * Long term steroid use – through break down of proteins in connective tissue in the lens. * Smoking

Question 68

List TWO signs and/or symptoms of cataracts

Answer 68

* Gradual loss of vision * Diplopia (double visions)

Question 69

Define age related macular degeneration (AMD)

Answer 69

Macula is the central part of the retina where we get the highest visual acuity. The age related changes occur in the macula. Age is relevant and we see this typically in over 55’s

Question 70

List TWO causes (not age) of AMD.

Answer 70

* Smoking * Family History * Cardio vascular disease risk factors

Question 71

Describe how vision is affected in AMD.

Answer 71

* Reduced visual acuity, particularly difficulty with near vision. * Gradual and progressive loss of central vision

Question 72

Describe how an individual experiences ‘floaters’.

Answer 72

Very common. The vitreous humor is a transparent, colorless, gel-like substance located in the posterior chamber of the eye. Little fragments form of shrunken vitreous humor. Collagen fibres to create these more condensed structures which are not transparent. These squiggly dark shapes create shadows in the retina when the light is incoming.

Question 73

Explain why floaters develop in diabetic retinopathy.

Answer 73

Small quantities of bleeding in the retina

Question 74

Identify the following pathology: ‘Floaters in vision, flashing lights, curtains descending over vision’.

Answer 74

Retinal Detachment

Question 75

Explain how the pathology of Retinal Detachment develops.

Answer 75

The retina has 2 layers - the neuro sensory layer rod and cone layer and the pigmented epithelium. These become separated and fluid builds up in the sub retinal space. It can lead to permanent blindness, so it is an emergency.

Question 76

Describe specifically how glaucoma produces eye symptoms.

Answer 76

It is a condition where the pressure within the eyeball builds up. Normal pressure is 10-21 mmHg. When it gets beyond 21 it starts to compress the retina and optic nerve, causing damage. > 40 it can cause significant damage and lead to blindness.

Question 77

List ONE lifestyle factor that may cause glaucoma.

Answer 77

Smoking

Question 78

List TWO signs and / or symptoms associated with: a. Mild acute glaucoma: b. Severe acute glaucoma

Answer 78

a. Mild acute glaucoma: * Pain and maybe pressure in the eyes * Halos around lights * Symptoms alleviated by sleep when draining is improved. b. Severe acute glaucoma * Raid deterioration of vision * Intense eye pain * Redness and watering of eye * Significant sensitivity to light/

Question 79

List TWO signs/symptoms of late chronic glaucoma.

Answer 79

Often there are no symptoms until permanent damage has occurred. Then we might see: * loss of peripheral vision * blurring of objects directly in front of the person * loss of night vision

Question 80

Describe the pathophysiology of diabetic retinopathy.

Answer 80

Diabetes is associated with hyperglycaemia. Chronic Hyperglycaemia has been associated with many complications which are predominantly vascular. Eg: High chronic levels of blood sugar can lead to damage of very small delicate blood vessels such as those in the retina leading to diabetic retinopathy. 1. Microvascular damage occurs, which occludes branches of the retinal artery, causing neovascularisation (new vessel formation in an attempt to revascularise), 2. The vessel walls become physically weak, and Leeky, leading to micro haemorrhages and micro aneurisms. 3. The outcome is decline in vision and floaters

Question 81

Name three eye pathologies that smoking is a risk factor.

Answer 81

* Cataracts * Age-related Macular degenration * Glaucoma

Question 82

Name three eye pathologies and one hearing pathology where diabetes is a risk factor.

Answer 82

Cataracts Styes Diabetic retinopathy Otitis Externa

Question 83

Name the cranial nerve responsible for sense of smell.

Answer 83

Olfactory Nerve

Question 84

Describe how decreased sensitivity to odours occurs rapidly.

Answer 84

Adaption - Decreased sensitivity to odours occurs rapidly. Olfactory receptors adapt by 50% in first second. Odours seem 80% less powerful after a few minutes of exposure. - Prevents smelling bad odours; e.g. working near a foul odour gets to the point where olfactory adaptation is 100%.

Question 85

Explain the main function of ‘olfactory adaptation’.

Answer 85

To protect from danger — if the scent is not a danger, olfaction re-calibrates to be able to detect other smells which might indicate harm

Question 86

Name the cranial nerve which innervates the tongue.

Answer 86

Hypoglossal Nerve innervates the 8 muscles on the tongue

Question 87

Describe the role of the following in relation to taste buds: a. Gustatory receptor cells b. Basal cells

Answer 87

5. Describe the role of the following in relation to taste buds: a. Gustatory receptor cells - Detect taste b. Basal cells - Stem cells that produce new receptor cells

Question 88

Explain what is meant by ‘papillae’.

Answer 88

Elevations on the tongue where we find taste buds

Question 89

Describe the difference between the following: a. Circumvallate papillae b. Fungiform papillae c. Foliate papillae

Answer 89

Describe the difference between the following: a. Circumvallate papillae – Large in the shape of a V at the back of the tongue. b. Fungiform papillae – Mushroom shaped and all over the tongue. Contain at least 5 taste buds each. c. Foliate papillae - Located in small trenches at lateral margins of tongue; most degenerate in childhood. Used for tasting milk as babies.

Question 90

Name FIVE tastes.

Answer 90

Sweet, sour, salty, umami and bitter

Question 91

Name TWO cranial nerves involved in taste physiology.

Answer 91

Facial Glossopharyngeal

Question 92

Name TWO cranial nerves involved in tongue sensation and touch

Answer 92

Trigeminal Glossopharyngeal