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Z Phase 1 Others > Week 11 > Flashcards

Week 11 Flashcards

1
Q

What is temperature homeostasis controlled by?

A

the thermoregulatory centre in the hypothalamus

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2
Q

Describe the thermoreceptors

A

2 sets
receptors in hypothalamus measures temperature of blood passing through brain (core temperature)
receptors in skin measures external temperature

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3
Q

What is the body’s response in there is a low core temperature?

A

vasoconstriction
increased metabolic rate
shivering
hair raised

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4
Q

What is the body’s response if there is a high core temperature?

A

vasodilation
decreased metabolic rate
sweating hair lowered

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5
Q

What is pyrexia?

A

also known as fever
any elevation of the body temperature above normal
Defensive mechanism to fight infection

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6
Q

Describe the mechanism of pyrexia

A

When bacteria or viruses damage body tissue, WBCs secrete pyrogens
Pyrogens are carried in the blood to the hypothalamus
they inhibit the heat-sensing neurons and excite the cold-sensing neurones
The hypothalamic thermostat “set-point” is raised

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7
Q

What are the high temperatures in pyrexia thought to achieve?

A

stimulate leukocyte activity
may directly kill or inhibit the growth of some viruses and bacteria

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8
Q

Describe paracetamol

A

Also known as acetaminophen
small molecule
not NSAID
no anti-inflammatory properties

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9
Q

describe how paracetamol is thought to work?

A

acts directly on the CNS, increasing pain thresholds by inhibiting cyclooxygenases, COX1, COX2 and COX3 - enzymes involved in prostaglandin synthesis
antipyretic properties due to effects on the heat-regulating centres of the hypothalamus resulting in peripheral vasodilation, sweating and hence heat dissipation

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10
Q

Describe the external ear

A

Extending from the side of the head is the pinna (auricle)
canal leading inwards is external acoustic meatus
canal covered in epithelium, some of which contain hair and modified sweat glands producing cerumen

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11
Q

Describe the tympanic membrane

A

separates the external acoustic meatus form the middle ear
Connective tissue core lined with epithelium on the outside and mucous membrane on the inside
Attaches to the malleus and the umbo of the tympanic membrane

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12
Q

Describe the middle ear

A

malleus, incus, stapes
stapes attached to the lateral wall of the internal ear at the oval window
middle ear muscles

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13
Q

Describe the inner ear

A

Vestibular apparatus - sensory structures for balance and head movements
cochlea- contains sensory epithelium for hearing, the organ of corti

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14
Q

Describe the amplification of sound that occurs in the ear

A

pinna acts as directional filter, amplifying sounds from some directions more than others
The pinna and the ear canal increase the sound pressure level by up to 20dB
Since the area of the tympanic membrane is greater than the of the footplate at the oval window sound is further amplified by about 25dB

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15
Q

Describe how vibrations get into the cochlea

A

oval window faces into the vestibule
vestibule contains sensory epithelia for vestibular apparatus
vestibule leads into the scala vestibuli. Waves of pressure pass through the scala vestibuli to and back out through the scala tympani, terminating at the round window

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16
Q

Describe the scala media

A

organ of corti - sensory epithelium containing hair cells
stria vascular - regulates ionic and metabolic environment of the scala media

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17
Q

Describe resonant frequency

A

objects vibrate most strongly at their resonant frequency
the mass and stiffness of an object determines its resonant frequency
resonant frequency goes up with increasing stiffness and down with increasing mass

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18
Q

What mass and stiffness would a high frequency sound resonate best in?

A

stiff and light

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19
Q

What mass and stiffness would a low frequency sound resonate best in

A

flexible and bendy

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20
Q

Describe the basilar membrane

A

stiff and light at one end
flexible and heavy at the other
thus its resonant frequency varies over its length
Populated by “hair cells”

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21
Q

Describe the structure of a hair cell

A

epithelial origin, resembling the cells that line the stomach
steriocilia form a bundle at the apical pole of the hair cell

22
Q

What do inner hair cells do?

A

turn vibrations into neural signals

23
Q

What do outer hair cells do?

A

amplify vibrations

24
Q

Describe outer hair cells

A

motile
when stimulated, can change their shape and stiffness
Act as amplifiers, increasing the amount of vibration on the basilar membrane

25
Q

What would happen if outer hair cels were lost?

A

vibration isn’t significantly amplified

26
Q

What would happen if inner hair cells were lost?

A

no signal to the brain

27
Q

What can damage hair cells?

A

noise
infections
ageing
certain drugs
wear and tear

28
Q

Describe the “tonotopic” map

A

maintained throughout much of the auditory system

29
Q

Describe otitis media

A

inflammation of the inner ear
build up of fluid behind the tympanic membrane
usually bacterial
more common in children - more difficult for fluid to drain out through eustachian tube

30
Q

What are the three types of antibiotic use?

A

guided therapy
empirical therapy
prophylactic therapy

31
Q

when is guided therapy used?

A

mild infections that can wait a few days to be treated
rationalising therapy in patients in patients already on treatment

32
Q

When is empirical therapy used?

A

patients with more severe infection
delay in therapy would result in worsening of condition
need to cover all likely causes

33
Q

When is prophylactic therapy used?

A

healthy people exposed to surgery, injury, infected material
immunocompromised individuals - HIV, transplantation, splenectomy

34
Q

What are the ideal characteristics of the target effects of antibiotics?

A

highly toxic to bacteria causing infection
penetrate the body area affected by infection
limit release of toxins from bacteria

35
Q

What are the ideal characterises of the co-lateral damage of antibiotics?

A

non-toxic to patient
limited effect on colonising bacteria
low potential for bacteria to escape treatment through developing resistance

36
Q

What type of antibiotics are usually used for guided therapy?

A

narrow spectrum

37
Q

What type of antibiotics are usually used for empirical therapy?

A

broad spectrum

38
Q

Give an example of a bactericidal antibiotic

A

penicillin

39
Q

Give an example of a bacteriostatic antibiotic

A

calrithromyocin

40
Q

What do bactericidal antibiotics do?

A

directly kill bacteria
lysis of bacteria can lead to toxin release

41
Q

What do bacteriostatic antibiotics do?

A

suppresses growth but doesn’t directly kill bacteria
requires immune mediated killing to clear bacteria

42
Q

Give examples of cell wall agents

A

pencillins
glycopeptides

43
Q

Give examples of antibiotics that target ribosomes

A

macrolides
aminoglycosides

44
Q

Give examples of antibiotics that target DNA

A

Quinolones

45
Q

Give examples of antibiotics that target cell metabolism

A

thimethoprim

46
Q

Describe resistance mechanisms

A

mutation of target sites
inactivating of enzymes
limit access - reduce permeability, increased efflux
genes mediating resistance can often be easily transferred

47
Q

What is the innervation of the eye?

A

optic nerve (CNII)
extra-ocular muscles by cranial nerves III, IV and VI

48
Q

Describe tear production

A

From lacrimal gland
function - lubricate movement, remove debris
drains into nose

49
Q

Describe the nose

A

warms, humidifies and filters air
rich, superficial blood supply
mucous provides moisture
mucous and hair trap particles

50
Q

Describe olfaction

A

olfactory nerve (CNI)
converts chemical signal to electrical
superior surface of nasal cavity
conchae increase surface area

51
Q

What is the innervation of the tongue?

A

Lingual nerve (CNV5) and chorda tympani nerve (CNVII) -taste and sensation to anterior 2/3
glossopharyngeal taste and sensation to posterior 1/3
hypoglossal motor control

Z Phase 1 Others (11 decks)

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