Week 1 Flashcards
What is the tympanic membrane : oval window ratio?
18:1 (impedance matching air to liquid) - leads to pressure gain of x22
What two muscles open the resting state of the eustachian tube?
- Tensor veli palatini
2. Levator palatine
What does dysfunction of the eustachian tube lead to?
Middle ear negative pressure
What are the two openinsg of the chochlea to the middle ear?
Oval and round window
What do the oval and round windows permit?
Transmission of pressure wave in enclosed canal and vibration of teh basilar membrane
Give two features of the inner ear as a receiver and transducer?
Curved spiral lamina
2 half turns around central modiolus
What is scala media in the cochlea?
Endolymph
What is scala tympani and scala vestibuli?
Perilymph
Name the structure in the cochlea of the inner ear which produces nerve impulses in response to sound vibrations?
Organ of corgi (has hair cells)
What do the hair cells in the organ of corgi do?
Transduction - conversion of mechanical bending force into electrical impulse
In relation to hair cell function when does depolarisation occur?
When deflected towards longest
Hyperpolarisation occurs when deflected away
How is the cochlea organised?
Tonotopically
Where is the primary auditory cortex?
Superior temporal gyrus,
brodman areas 41/42
What do the superior canal and posterior canal of the labrynth connect to?
Common orus
What are the vestibular end organs?
Maculae of the utricle and saccule - otolith organs
Ampullae of lateral, posterior and superior semicircular canals
What do the maculae of utricle and saccule (otolith organs) have?
Stereocilia projecting upwards into a gelatinous matrix with otoconia
What direction are the stereocilia orientated?
In all directions so all movements perceived by depolarisation/hyperpolarisation
What are otoconia?
Calcium carbonate crystals
Where does the cupula sit?
In the ampulla of a semiciorcular canal
What is deflection of the cupula caused by?
Movement of perilymph - bending causes stereocilia to deflect
What is the term for when the eyes move without a cognitive, visual or vestibular stimulus?
Spontaneous nystagmus
What is a vestibular schwannoma?
Tumour of VIII nerve sheath (schwann) cells - imbalance due to slowly progressive loss of function
What type of receptors are receptors for taste and smell?
Chemoreceptors which are stimulated by binding to particular chemicals
What is taste perception influenced by?
Information from smell receptors
What are the sense organs of taste?
Taste buds
What do taste buds consist of that are arranged like slices of orange?
Sensory receptor cells and support cells
What is the life span of taste receptor cells?
10 days
What are taste receptor cells replaced from?
Basal cells within the taste buds
Name four places taste buds are present?
Tongue
Palate
Epiglottis
Pharynx
Where do the majority of taste buds sit?
In the papillae in the tongue
What are the four types of papillae?
Filliform - do not contain taste buds
Fungiform
Vallate
Foliate
Where do taste signals conveyed by cranial nerves via the brainstem and thalamus go?
To cortical gustatory areas
What are the five primary tastes?
- Salty
- Sour
- Sweet
- Bitter
- Umani (meat or savory) - triggered by glutamate
What is ageusia?
Loss of taste function
What is dysgeusia?
Distortion of taste function
What three cell types does olfactory mucosa contain?
Olfactory receptor cells
Supporting cells
Basal cells - secrete mucus
What does each neuron in olfactory receptors have?
Thick short dendrite and an expanded end called an olfactory rod
What do odorants bind to?
Cilia
What is the life span of olfactory receptors?
2 months - basal cells act as precursors for new olfactory receptor cells
What do afferent fibres of olfactory nerve pierce?
Cribiform plate of ethmoid bone and enter the olfactory bulbs
During quiet breathing how do odorants reach smell receptors?
By diffusion
What might hyposmia be an early sign of?
Parkinson’s disease
How do you diagnose infections of the throat and pharynx?
Well taken throat swab
What are the vast majority of sore throat causes?
Viral - do not need antibiotics
What is the most common cause of bacterial sore throat?
Streptococcus pyogenes (group A streptococcus)
How do you treat acute follicular tonsilitis (bacterial sore throat)?
Oral penicillin - clarithromycin if allergic
Give three complications of streptococcal sore throat?>
- Peritonsillar abscess (quinsy)
- Sinusitis/otitis media
- Scarlet fever
What are 2 late complications of streptococcal sore throat?
- Rheumatic fever
2. Glomerulonephritis
After streptococcal sore throat what are the signs of rheumatic fever complication?
3 weeks post sore throat
Fever, arthritis and pancarditis
After streptococcal sore throat what are the signs of glomerulonephritis?
1-3 weeks post sore throat
Haematuria, albuminuria and oedema
What condition has a severe sore throat with a grey white membrane across the pharynx The organism produces a potent exotoxin which is cardiotoxic and neurotoxic?
Diphtheria
How do you treat diphtheria?
Antitoxin and supportive and penicillin/erythromycin
What condition presents with white patches on red, raw mucous membranes in throat/muth?
Thrush
Nystatin suspension topically
What is the term for an upper respiratory tract infection involving the middle ear by extension up the eustachian tube?
Acute otitis
What does otitis media present with?
Earache - predominantly infants and children
What are the three most common bacteria to infect the middle ear?
Haemophilus influenzae
Streptococcus pneumonia
Streptococcus pyogenes
What is the treatment of infections of the middle ear?
80% resolve in 4 days with no antibiotics
Amoxocillin if bilateral under 2 years of age and AOM with otorrhoea
How is acute sinusitis treated?
If uncomplicated avoid antibiotics as 80% resolves in 14 days
Otherwise 1st line penicillin V, 2nd line deoxycycline but not in chilren
What condition involves redness and swelling of skin of outer ear canal, may be itchy, can become sore and painful, may be discharge or increased ear wax?
Otitis externa
Give three bacterial causes of otitis externa?
- Staphylococcus aureus
- Proteuis spp
- Pseudomoas aeruginosa
Give two fungal causes of otitis externa?
- Aspergillus niger
2. Candida albicans
How is otitis externa treated?
Topical aural toilet. or if cultured - topical clotrimazole for fungal or topical gentamicin for pseudomonas infection
What condition presents with fever, pharyngitis and lymphadenopathy?
Glandular fever - infectious mononucleosis
What do half of patients with glandular fever present with>
Splenomegaly
What two blood conditions are seen in glandular fever?
Anemia and thrombocytopenia
Why should sport be avoided in glandular fever?
Risk of splenic rupture
What virus causes glandular fever?
Epstein-Barr virus
What are the two phase sof primary infection with EBV?
Primary infection in early childhood rarely results in infectious mononucleosis
Primary infection in those greater than 10 often causes infectious mononucleosis
What is the kissing disease?
Glandular fever
How is glandular feve confirmed in the lab?
Epstei-Barr virus IgM
Heterophile antibody - PaulBunnel test, Monospot test
Blood count and film
LFTS
aFTER PRIMARY INFECTION WHat happens to HSV-1?
latent - in trigeminal ganglia
What is herpetic whitlow?
Abscess at end of finger
What causes herpangina?
Coxsackie viruses
What are non viral, selflimiting recurring painful ulcers of the mouth that are round or ovoid and have inflammatory halos?
Apthous ulcers
What condition causes recurrent oral ulcers, genital ulcers, uveitis, can involve visceral organs such as GI tract, pulmonary, MSK, CVS and neurological systems and it is commonest in middle east and asia?
Behcets disease
What term is given to chronic otitis media and perforated tympanic membrane?
Cholesteatoma
What is the normal lining of the middle ear?
Cuboidal or columnar glandular epithelium
What should you consider if there are bilateral vestibular schwannomas?
NF type 2
Name three other features of NF type 2 other than vestibular schwannomas?
Multiple meningiomas
Gliomas
Cafe au lait spots
What should you consider if a young patient presents with nasal polyps?
Cystic fibrosis
What carcinoma has a strong association with Epstein Barr virus?
Nasopharyngeal carcinoma
What tumour is related to HPV exposure types 6 and 11 and has peaks of incidence at less than 5 years and between 20 and 40?
Squamous papilloma
What is a paraganglioma?
Tumours arising in clusters of neuroendocrine cells dispersed throughout the body
Give two biggest risk factors for squamous cell carcinoma?
Smoking and alcohol
What tumour is benign, common in parotid gland, more common in over 50 ladies and are poorly circumsised?
Pleomorphic adenoma
Name a benign tumour which is common in parotid gland, associated with smoking in older males and is a mixture of bilayer of oncocytic epithelium with dense lymphoid infiltrate?
Warthins tumour
What is the most common ENT malignancy?
Mucoepidermoid carcinoma
