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PS1003 > PS1003 Andrew: Homeostasis, Cicadian Rhythms and Sleep > Flashcards

PS1003 Andrew: Homeostasis, Cicadian Rhythms and Sleep Flashcards

1
Q

Where does control of analgesia lie?

A

From the control grey matter, will go through the Raphe nuclei and Rostroventral medulla (morphine and SP would come from here) Have the nociceptive pathway blocked.

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2
Q

What is homeostasis?

A

Maintenance of equilibrium by active regulation of internal states

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3
Q

What things are controlled under homeostasis?

A

Body temperature, food ad energy regulation, fluid regulation (water and vital salts that take with water such as sodium and potassium- key to neuronal communication)

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4
Q

How does homeostasis work?

A

Change happens, at either high level (hyper-) and low level (hypo-) this feeds into the sensor, then the brain then effector this then brings it back to the correct level (set point)

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5
Q

How does the sensory interact with the brain?

A

It detects the compound that we are looking at

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6
Q

What does the brain and the effector do during homeostasis?

A

• The brain does the processing which then gets sent to the effector- this then gets sent to some mechanism which then corrects the value- if that level changes it results in hyper or hypo. Aim is to try and maintain this set level

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7
Q

What sort of responses are set off due to the changes?

A

Automatic (ANS- autonomic nervous system) responses such as shivereing when it is cold, or having the heart at a normal rate are responses which we cannot control but work as a way to tell the brain what to do or to try and maintain homeostasis such as sweating when it is hot. There are even behavioural responses that may result in such as taking off a jumper hen it is too hot to maintain the stable body temperature.

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8
Q

How does food and energy regulation work?

A

stomach is empty and produced, blocks arcuate nucleus, stimulates food intake. When stomach is full- ghrelin switched off, so no longer inhibiting the blocker for food intake (arcuate nucleus [AN}), it also activates vagus nerve (feeds into brain stem) and activate food intake and block AN, again activates CCK (peptide-cholecystokinin) blocks AN (food intake).

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9
Q

Where is the arcuate nucleus?

A

In the hypothalamus

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10
Q

How does the arcuate nucleus and ghrelin work when it comes to food and energy regulation?

A

The AN blocks food intake but when ghrelin is produced it inhibits this so that the AN is blocked therefore allowing food intake. However when CCK, the vagus nerve is activated and ghrelin is switched off then AN is activate and blocks food intake (inhibits)

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11
Q

What are the three distinct mechanisms which when activated stop food intake?

A

CCK (choleckystonkini), vagus nerve and the stopping of ghreblin hormone

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12
Q

What may cause over eating?

A

one of the following being defected CCK (choleckystonkini), vagus nerve and the stopping of ghreblin hormone

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13
Q

Example of homeostatic control: what happens during sleeping?

A

temperature, heart rate and respiration rate decreases due to energy conservation as don’t need to process this

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14
Q

What are biorhythms?

A

Biological rhythms are the natural cycle of change in our body’s chemicals or functions. It’s like an internal master “clock” that coordinates

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15
Q

What are circadian rhythms?

A

A circadian rhythm is a roughly 24 hour cycle in the physiological processes of living beings, including plants, animals, fungi and cyanobacteria. Daily cycle.

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16
Q

Examples of circadian rhythms:

A

Body temperature, heart rate, respiration, sleep. Even without sleep, oOther cycles will always maintain their innate circadian rhythms- so a 2am when you should be sleeping the body temperature and heart rate change

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17
Q

What are circannual rhythms and where are they commonly seen?

A

They are yearly cycles and more common in the animal kingdom- linked with seasons and can be seen in hibernation, mating behaviour and migration

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18
Q

What are biorhythms linked to?

A

light/dark and season as length of day would be critical

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19
Q

What are bodily functions linked to?

A

day length as light/dark cycles would be an important determinant

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20
Q

How does light/dark information affect body systems?

A

usually awake during the light and asleep during the dark

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21
Q

What happens if an optic tract lesion occurs?

A

They will still have the cycle- so it is not mediated with light although the periodicty may change (25/6hrs instead of 24hr cycle)

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22
Q

What happens if the suprachiasmatic nucleus (SCN) has a lesion?

A

The circadian rhythm abolished. No periodicity (constant shifting in waking and sleeping), therefore SCN important to CR.

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23
Q

Where is the suprachiasmatic nucleus located?

A

in the hypothalamus just above the optic chiasm

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24
Q

How is the suprachiasmatic nucleus (SCN) related to circadian rhythm?

A

cells in SCN show ossillation of activity- believed to form the ‘biological clock’.

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25
Q

What does phase locked mean?

A

That the phases of the biorhythms such as sleeping are locked to light/dark

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26
Q

How many hours must there be in a cycle for the SCN to influence?

A

24hours, if there are 23 hours that the animal would have already gone into the phase.

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27
Q

How does light information reach the SCN?

A

In mammals a direct pathway from the eyes to the SCN. It carries light to SCN, rods and cones influence

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28
Q

Can SCN still have light information without the cones and rods?

A

Yes which means that there are other light receptors present in the eye

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29
Q

What is a ‘free running’ sleep patterns?

A

Free-running sleep is a sleep pattern that is not adjusted (entrained) to the 24-hour cycle in nature nor to any artificial cycle.

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30
Q

How are circadian rhythms entrained?

A

Through light and dark and emdiated through SCN activity

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31
Q

How does jet-lad or shift work effect the sleep cycle?

A

There are rapid shifts in light/dark cycle. It takes a few days for endogenous rhythm to re-entrain.

32
Q

What did Bremer (c1930) do?

A

surgically separated midbrain from forebrain cats, which resulted in the animals remaining permanently asleep. This may have been due to the absence of sensory input to the cortex so it become quiescent (sleep/dormant).

33
Q

What can cause loss of sleep?

A

Anxiety

34
Q

What happens due to lack of sleep?

A

Can change mood and outlook as well as lack of energy.

35
Q

What did Moruzzi and Magoun (1960s) find?

A

Electrical stimulation of the midbrain woke sleeping animals and lesions to this area cause persistent sleep.

36
Q

What happens when you wake up?

A

Midbrain is activated which then activates the cortex

37
Q

What happens if there is a lack of tonic?

A

lack of tonic activating influence of midbrain causes cortical neurones to cease firing and sleep to ensue

38
Q

Why is activating the system in the midbrain important?

A

Activating system is important for the attention.

39
Q

What kind of engagement is the system in the brain?

A

It is actively engaging and focused, and not just a passive absence of firing.

40
Q

How do the midbrain and cortex relate?

A

The midbrain feeds into the cortex

41
Q

What is the brain activity during being awake?

A

Low amplitude and high frequency EEG

42
Q

What is the brain activity during Light sleep?

A

increasing amplitude and decreasing frequency EEG

43
Q

What is the brain activity during Deep sleep?

A

High amplitude and low frequency EEG

44
Q

What is the brain activity during Rapid eye movement (REM) sleep?

A

Low amplitude and high frequency EEG (similar to being awake)

45
Q

What does amplitude represent?

A

Different neurones firing at different times, so amplitude is the number of neuones firing at any one time.

46
Q

What are sleep spindles?

A

We do not know except for the fact that they occur during sleep.

47
Q

What kind of waves do we have during deep sleep?

A

Delta waves

48
Q

What happens with delta waves?

A

The waves of activity go to the cortex, and then this activity becomes synchronised, therefore the neurones fire together and produce a high amplitude but low frequency

49
Q

How is REM sleep and being awake similar?

A

Similar EEG and there is quite strong neuronal activity occurring during REM.

50
Q

What are the different stages of sleep?

A

REM sleep follows on from deep sleep, so there are short periods of wakefulness which is when dreaming occurs (REM)

51
Q

What is Electroencephalographic (EEG)?

A

Electroencephalography (EEG) is an electrophysiological monitoring method to record electrical activity of the brain. It is typically noninvasive, with the electrodes placed along the scalp, although invasive electrodes are sometimes used in specific applications.

52
Q

What do EEG recordings show of neuronal acitvity in the cortex during sleep?

A

They show abundant neuronal activity therefore it is not passive neuronal quiescence.

53
Q

How is the pattern of EEG different from sleep and being awake?

A

It shows that during sleep there are waves of activity, indicating synchronous firing of cortical neurones. This synchronising stimulus coming from sub cortical areas;

54
Q

What is reticular formation?

A

a diffuse network of nerve pathways in the brainstem connecting the spinal cord, cerebrum, and cerebellum, and mediating the overall level of consciousness. IT is seem as important

55
Q

What are the characteristics of slow-wave sleep?

A

decreased spinal reflexes, heart rate, breathing rate, brain temp. and cerebral blood flow. Increased hormone secretion (e.g. growth hormone) and synchronised cortical activity (depicted in the EEG)

56
Q

What are the characteristics of REM sleep?

A

absent spinal reflexes, rapid eye movements behind closed eyes, increased body temp. and cerebral blood flow, desynchronised cortical activity, dreams, all motor outputs suppressed although your REM is envisaging things

57
Q

Why is the reticular formation is important in controlling sleep?

A

Cortex :”kept awake” by ascending activation from midbrain

58
Q

What do 5HT (serotonin receptors) do?

A

5HT inputs inhibits midbrain ‘activating system’ areas therefore promotes sleep

59
Q

What happens if there is stimulation of the area surrounding SCN?

A

It induces slow wave sleep

60
Q

Does REM sleep have one stimulation site?

A

Not one stimulation site can promote REM sleep but a different number of things need to occur for REM sleep.

61
Q

How can we abolish REM sleep?

A

lesions to specific brainstem areas- final common pathway

62
Q

What does noadrenaline do during sleep?

A

inhibition of muscle tone during REM sleep- stops body while brain acts- important to inhibiting the motor output.

63
Q

What does dopamine do during sleep?

A

General arousal

64
Q

What does acetylcholine do during sleep?

A

It is the key transmitter when inducing REM sleep

65
Q

What are ‘sleep-promoting’ substances?

A

DSIP (delta-sleep inducing peptide) &melatonin (reduce jet lag) Modulate circadian rhythmicity (increase chances of sleep as no immediate sleep occurs)

66
Q

What is insomnia?

A

It is the reduction or absence of sleep. Can be transient or persistent. Usually works better to treat the anxiety that causes it than the sleep.

67
Q

What is hypersomnia (narcolespy)?

A

Excessive drowsiness and falling asleep

68
Q

What is sleep-wake schedule disturbance?

A

It can be transient or persistent. Things such as jet lag and shift work fall under this?

69
Q

What is partial arousal?

A

Things such as sleep-walking, and nightmares. May have a defect wth noradrenaline.

70
Q

What may be the reason for sleep disorders?

A

Often associated with anxiety, psychological disturbance or drug taking, but little is know about the causes and there it limited pharmacological treatment available.

71
Q

Hypnotic (somnogenic) drugs: What is morphine used for?

A

sedative

72
Q

Hypnotic (somnogenic) drugs: What is barbiturates used for?

A

sedatives and anasethetics

73
Q

Hypnotic (somnogenic) drugs: What is Benzodiazipines used for?

A

hypnotics (anxiolytic)

74
Q

What are weakly hypnotic drugs?

A

melatonin, serotonin precursor- tryptophan. These induce natural sleep patterns and the better route for treatment

75
Q

How does morphine, barbiturates, benzodiazipines induce sleep?

A

None of these induce natural sleep. There are decreased REM sleep, increased downsiness. And there is importance of decreasing stress/anxiety more than increasing sleep.

76
Q

Summary:

A

Summary
• Homeostasis
o Maintenance of constant conditions
o e.g. hunger / satiety system
• Circadian rhythms
o Biological rhythms with 24 hour periodicity
o Role of SCN as circadian clock: entrainment to light/dark cycle
• Sleep
o Sleep as an active process – EEGs in different stages of sleep
o Characteristics of slow wave sleep and REM sleep
o Disorders of sleep

PS1003 (6 decks)

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