Sleep & Anaesthesia Flashcards

1
Q

What is the circadian rhythm?

A
  1. 00 - Midnight
  2. 00 - Deepest sleep
  3. 30 - Lowest body temperature
  4. 00 - Morning
  5. 45 - Sharpest rise in blood pressure
  6. 30 - Melatonin secretion stops
  7. 00 - Highest testosterone secretion
  8. 00 - Highest alertness
  9. 00 - Noon
  10. 30 - Best coordination
  11. 30 - Fastest reaction time
  12. 00 - Greatest cardiovascular efficiency + muscle strength
  13. 00 - Evening
  14. 30 - Highest blood pressure
  15. 00 - Highest body temperature
  16. 00 - Melatonin secretion starts
  17. 00 - Midnight
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The hormone ______ is involved in

A

melatonin

synchronising circadian rhythm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Clock - A circadian clock

A

is a 24hour timing mechanism that is composed of molecular oscillators

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Circadian rhythm

A

a biological rhythm with an approx. 24 hr period that persists in constant conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Oscillator is

A

a system of components that interact to produce a rhythm that occurs with a definable period length.
A circadian oscillator can drive a rhythmic output but needs other oscillators (known as pacemakers) for its function.
A circadian oscillator can therefore be self-sustained but cannot operate properly independently of other oscillators.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Circadian pacemaker

A

is a specialised oscillator that operates independently of other oscillators to drive rhythmic outputs, either directly or through other oscillators, and is entrained by environmental cues.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Entrainment

A

Process by which an environmental rhythm e.g light-dark cycle, regulates the period and phase relationship of a self-sustained oscillator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Zeitgeber

A

Any external or environmental cue that synchronises an organism’s biological rhythm to Earth’s 24-hour light/dark cycle and 12 month cycle e.g. light, temperature, exercise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the suprachiasmatic nucleus?

A

A small region of the brain that sits on top of the optic chiasm in the anteroventral region of hypothalamus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

SCN is a type of

A

specialised oscillator - pacemaker

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

SCN can regulate process such as

A

locomotor activity

electrical firing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where may some other oscillators be present?

A

Heart
Lung
Liver
Kidney

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q
Heart
Lung
Liver
Kidney
all may regulate processes such as
A

heart rate, systolic blood pressure, vasodilation, gene expression, melatonin levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How is the brain kept awake? What may lead to constant sleep?

A

the activity of the Ascending Reticular Formation

lesions to this brain area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Melatonin has ______ actions on SCN

A

inhibitory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

EEG stands for __________________. It measures

A

electroencephalograpgh.

electrical activity produced by the brain (cerebral cortex) and recorded from electrodes placed on scalp.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

From highest to lowest frequency, what waves do EEGs detect?

A

beta
alpha
theta
delta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which radio wave is present during alert wakefulness?

A

beta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Which radio wave is present during quiet wakefulness?

A

alpha

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which radio wave is present during Stage 1 sleep?

A

low voltage and spindles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Which radio wave is present during Stage 2 and 3 sleep?

A

Theta waves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Which radio wave is present during Stage 4 slow wave sleep?

A

Delta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Which radio wave is present during Stage 5 REM sleep?

A

Beta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Stages and what happens during sleep cycle

A

Stage 1 - interim between consciousness and sleep
Stage 2 - Heat rate slows, brain does less complicated sleep
Stage 3 - Body makes repairs
Stage 4 - Body temperature and BP decrease
Stage 5 - Increase in eye movement, heart rate, breathing, BP and temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

The awake stage is characterised by

A

high frequency activity with variable amplitude, combined with active electromyography (EMG)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

The REM stage is characterised by

A

high frequency activity with high amplitude and no active EMG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

The non-REM stage 4 sleep is characterised by

A

low frequency and high amplitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Stage 4 occurs during the

A

first hour of going to sleep

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

REM has _____ body muscle activity than Stage 4

A

more

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Stage 5/ REM sleep is also known as

A

paradoxical sleep

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the most refreshing part of sleep? What occurs during this stage?

A

REM sleep

  • muscle relaxation
  • increased heart rate
  • dreaming
  • deep regular breathing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Prolonged activity of the brain may cause production of a ‘sleep producing substance’

A

Glucose is the main nutrient of the brain, carried by blood.
The more the brain is active, the more glucose needed.
Surrounding astrocytes supply extra energy in the form of glycogen
Glycogen metabolism increases adenosine level
Adenosine accumulation induces higher delta activity in the next sleep session
If sleep does not take place, accumulation of adenosine causes cognitive and emotional effects seen after sleep deprivation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Sleep regulatory substances seem to be involved in ________ scaling

A

synaptic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Synaptic scaling is a slow

A

homeostatic process that occurs over hours/ days; it serves in part to balance/ to scale Hebbian plasticity changes that occur rapidly as a consequence of neuronal activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

During wake period
- synaptic __________
-
- ________ regulation

A

potentiation
learning
circadian

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

During sleep period
- synaptic __________
-
- ________ regulation

A

homeostasis
memory consolidation
circadian regulation

37
Q

Lesioning the brain can cause

A

sleep disorders

38
Q

What are some causes of insomnia? and examples

A
  • Physical e.g pain
  • Physiological e.g. noise, caffeinated/ stimulant drinks
  • Psychological e.g excitement, stress
  • Psychiatric e.g. depression
  • Drug induced e.g beta blockers
  • Unknown cause
39
Q

What are three degrees/ types of insomnia?

A
  • Transient: jet-lag, novel environment
  • Short-term: occupational stress
  • Chronic: psychiatric illness
40
Q

Hypnotics are

A

short-to-medium acting (so that they enable the person to fall asleep) but their action is not so long that it presents problems of waking up at the right time

41
Q

What are the most commonly-used drugs used for the treatment of insomnia?

A

Benzodiazepine

42
Q

How do BZs work?

A

Enhance actions of inhibitory GABA neurotransmitter. This acts on GABA chloride channel

43
Q

BZs reduce the …….
and increase the ……
but both effects…

A

time taken to get to sleep
duration of sleep
decline with continued use (tolerance)

44
Q

Because of their CNS depressant effects, all hypnotics have a tendency to depress

A

REM sleep.

45
Q

BZs depress REM ____ than other agents

A

less

46
Q

Delta wave (slow, deep) sleep is also reduced by

A

BZs

47
Q

Ideal hypnotic is one that

A

acts long enough to allow the person to get sleep but doesn’t depress REM or delta wave sleep

48
Q

How does ethanol depress neuronal activity?

A

disruption to cell membrane

49
Q

Ethanol acts on GABA receptor which is a _______ _______ modulator. It also acts on ______ receptor which is a negative allosteric modulation. It also works on adenosine reuptake inhibitor

A

positive allosteric

NMDA

50
Q

Problems with long acting hypnotics?

A
  • may cause problems with hang over effects
  • high doses may increase risk of hang over without prolonging sleep
  • withdrawal may induce nightmares (increased REM)
51
Q

It is generally considered that hypnotic agents should not be used for long periods of time, with the maximum being about _________. An alternative approach is to use the agents _______, as required, so that REM ________, and subsequent rebound _________ REM does not occur.

A

2 weeks
intermittently
deprivation
increased

52
Q

Which gland releases melatonin?

A

Pineal

53
Q

Normally, AP is generated by opening of VG sodium channels, which allow influx of sodium and thus depolarisation. Local anaesthetics…

A

block VG sodium channel, prevents depolarisation and thus prevents propagation of AP

54
Q

Most local anaesthetics are weak ___, with a pKa between 8 and 9, so they are mainly but not completely ionised at physiological pH. What is the pharmacology?

A
bases
uncharged species (B) penetrates nerve sheath and axonal membrane and is then converted into BH+ active form, which then blocks sodium channels
55
Q

Many local anaesthetics are use dependent…

A

because the molecules gain access more readily when the channel is open

56
Q

Local anaesthetics block conduction in which order? This means that _______ and _______ transmission are blocked first

A
small myelinated
non myelinated
large myelinated
nociceptive
sympathetic
57
Q

What are the four different types of local anaesthetics?

A
  • surface anaesthesia; drug applied directly to surface that is the be anaesthetised e.g cornea
  • topical anaesthesia; drug applied to skin in form of cream
  • infiltration; drug injected below skin at multiple sites close to area to be anaesthetised. Permits incision/ excision of the anaesthetised tissue
  • nerve block; inject local anaesthesia into major nerve bundle. All nerve conduction to or form tissues to nerve block are inhibited
58
Q

Benefits of epidural anaesthesia instead of spinal anaesthesia, for example during childbirth, is?

A

the ability to anaesthetise a defined area e.g. pelvic organs without disrupting more distal tissues e.g. legs

59
Q

The extent of block with spinal anaesthesia depends on site of injection, thus

A

anaesthesia in lower spine anaesthetises a more limited area than anaesthesia in cervical region (upper spine)

60
Q

More lipid soluble anaesthetics have a _____ duration of action

A

greater

61
Q

Local anaesthetics are only effective when they are

A

blocking the VG sodium channel. They lose efficacy as the drug diffuses from the channel and away from the site of action. Once the drug has diffused away, the nerve function is fully regained.

62
Q

Sometimes, local anaesthetics are injected along with _____ in order to limit the _______ of the anaesthetic, and thus extending the __________

A

adrenaline, vasoconstriction
diffusion
duration of action

63
Q

Name a epidural anaesthetic

A

Ropivacaine

64
Q

Name a surface + infiltration anaesthetic

A

Lignocaine

65
Q

General anaesthetics are divided into two distinct classes

with different mechanisms of action and different uses:

A
  • inhalation anaesthetics e.g. gases, vapours

- intravenous anaesthetics

66
Q

Lipid theory of anaesthesia?

A

Drugs act by dissolving into and disrupting function of cell membrane

67
Q

Protein theory of anaesthesia?

A

anaesthetics act by interacting with proteins within the cell membrane, most notably ion channels and receptor proteins.

68
Q

Place these intravenous general anaesthetics in order of ultra-short acting, to short acting, to longer acting

A

Thiopentone
Etomidate
Methohexitone

69
Q

What is ketamine used for?

A

NMDA receptor antagonist

- used for induction and to maintain anaesthesia

70
Q

What is propofol for?

A

it potentiates GABAa receptor activity
General IV anaesthetic
Doesn’t cause analgesia therefore should be combined with fentanyl to alleviate pain

71
Q

Anaesthetic practice says to induce anaesthesia with ______ and then maintain with

A

IV agent

inhalation agent

72
Q

Balanced anaesthesia has 3 aspects to it:

A
  • Hypnosis (suppression of consciousness)
  • Analgesia (suppression of physiological response to stimuli)
  • Relaxation (suppression of muscle tone)
73
Q

Name three inhalation agents

A

Nitrous oxide
Halothane
Isoflurane

74
Q

Nitrous oxide is a ____ anaesthetic agent but a very ______ analgesic agent. It cannot be used alone as an analgesic as it will cause ______. Therefore, Entonox is give which is ___% N2O and ___ % ____. It is used in anaesthesia mainly for its ______ properties

A
weak
potent
hypoxia
50
50
O2
analgesic
75
Q

Halothane and Isoflurane are both

A

potent anaesthetics but poor analgesic agents.

76
Q

Which out of halothane and isoflurane is more cardiotoxic?

A

halothane

77
Q

Which out of halothane and isoflurane causes greater respiratory depression?

A

Isoflurane

78
Q

Which out of halothane and isoflurane can be used for children?

A

halothane

79
Q

Which out of halothane and isoflurane can cause hepatic dysfunction/ problems?

A

halothane

80
Q

Cardiac out must be considered when giving anaesthesia. Why? When there is decreased cardiac output, there is decreased perfusion

A

of tissues e.g. muscle/ fat therefore need to increase concentration of anaesthetic agent that accumulates in the brain

81
Q

Recovery from general anaesthetic is due to redistribution of drug away from brain and

A

back to the lungs for excretion

82
Q

In obese patients, great distribution of anaesthetic to fat stores therefore _____ recovery time from anaesthesia. This is because there is _______ excreton

A

longer

slower

83
Q

What are the stages of anaesthesia?

A
  1. Analgesia
  2. Excitement
  3. Surgical anaesthesia
  4. Represents medullary depression
84
Q

What are the stages of anaesthesia?

A
  1. Analgesia
  2. Excitement
  3. Surgical anaesthesia
  4. Represents medullary depression
    Patient passes through steps 1-3, but in reverse, during recovery.
85
Q

What else can be administered along with anaesthetic agents?

A
  • BZ - reduce patient anxiety
86
Q

What happens during stage 1 of anaesthesia? When can this stage be useful?

A

Analgesia
Patient conscious but drowsy, reduced response to painful stimuli
Using nitrous oxide during child birth

87
Q

What happens during stage 2 of anaesthesia?

A

w

88
Q

What happens during stage 2 of anaesthesia?

A

Excitement
This stage occurs because inhibition is lost before consciousness.
May result in euphoria + uncontrolled laughing

89
Q

What happens during stage 3 of anaesthesia?

A

Surgical anaesthesia
All reflexes are lost. Respiration is regular and muscle tone is eventually lost.
Loss of thoracic muscle tone may necessitate mechanical ventilation for maintenance of breathing and loss of vasc