Neural basis of physiological functions Flashcards
1
Q
Feeding behaviour
A
- Hypothalamus: Ventromedial hypothalamus acts as satiety centre while lateral hypothalamus acts as a feeding centre
- ghrelin and neuropeptide Y act as mediators of increased appetite (orexigenic)
- leptin, cholecystokinin and serotonin act as mediators of satiety (anorexigenic)
2
Q
Ghrelin
A
- only orexigenic substance produced outside of the CNS
- synthesised in the gastric mucosa
3
Q
Leptin
A
- anorexigenic
- synthesised by adipose cells
4
Q
Dopamine and food
A
- food and food cues increase dopaminergic activity in the nucleus accumbens (reward centre)
- destruction of dopamine pathways reduces eating behaviour
- in obesity, D2 receptors are reduced in the striatum
5
Q
Temperature control
A
- 2 centres in the hypothalamus
- preoptic anterior hypothalamus acts as the hypothermic centre- stimulation makes you cool down
- posterior hypothalamus acts as the hyperthermic centre-stimulation makes you warm up
6
Q
Hyperthermia
A
- some drugs may induce malignant hyperthermia but not through the hypothalamic mechanism- this is probably due to abnormal excitation-contraction of skeletal muscles
- also seen in NMS induce by neuroleptic use or levodopa withdrawal
7
Q
Diurnal temperature variation
A
-lesions in the median eminence reduce diurnal temperature variation
8
Q
Pain
A
Thalamus is crucial for pain perception nbut higher cortical centres are central to the localisation and interpretation of pain signal
9
Q
Pain fibres
A
- thin unmyelinated C fibres or sparsely myelinated A-delta fibres carry pain to dorsal horn of the spinal cord
- fast transmission takes place along the lateral spinothalamic route
- slow transmission takes place through reticulothalamic tract to aid subjective sensation
10
Q
Opioid receptors
A
- opioid receptors in the dorsal horn and possibly in the brain steam (PAG) modulate pain intensity
- descending fibres from serotonergic raphe nuclei also modulate pain perception- this is why TCAs might help with pain
11
Q
Thalamic pain syndrome
A
- occur in cases of stroke involving thalamoperforating branches of posterior cerebral artery
- patients have a contralateral loss of sensation with burning or aching pain triggered by light cutaneous stimulation
12
Q
Thirst
A
- subfornical organ and organum vasculosum of the lamina terminalis are circumventricular organs and play vital role in perception of thirst
- hypothalamic paraventricular nucleus is also involved in the regulation of thirst
- Angiotensin II acts as neurotransmitted to send thirst signals to hypothalamus
- hypotension stimulates thirst through baroreceptors on the aorta and carotid
13
Q
ADH
A
-ADH increases water reabsorption at renal tubules and helps maintain fluid balance
14
Q
SIADH
A
- syndrome of inappropriate secretion of ADH may result from damage to periventricular and supraoptic hypothalamic nuclei
- may also occur due to carbamazepine or chlorpromaxine
- some tumours such as lung cancer also produce excess ADH
- low sodium and reduced osmolarity is noted in the presence of normal renal excretion of sodium and high urine osmolality
15
Q
Kluver-Bucy syndrome
A
- bilateral lesions of amygdala and hippocampus
- results in placidity
- hyperorality
- hypersexuality
- hypermetamorphosis (objects are repeatedly examined as if they were novel)
