Physiology of Eating - L7
FS21
FS21
Kartei Details
Karten | 12 |
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Sprache | Deutsch |
Kategorie | Biologie |
Stufe | Universität |
Erstellt / Aktualisiert | 15.05.2021 / 08.06.2021 |
Lizenzierung | Keine Angabe |
Weblink |
https://card2brain.ch/box/20210515_physiology_anatomy_l7
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Einbinden |
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3 parts of the brain important in eating control (6)
1. hypothalamus -> eating + regulation of energy (meal initiation)
- PVN, LH, ARC
2. caudal brainstem -> meal-related signals (meal termination)
- NTS, AP
3. forebrain -> memories + external modalities (reward & hedonic control of eating)
- PVN, LH, VTA, Amygdala, Hippocampus
Hypothalamus integrates 3 types of signals to initiate meals
1. interoceptive humoral signals -> related to energy homeostasis
2. meal-related signals from GI tract -> via vagus nerve, spinal cord + ascending connections from hindbrain
3. information related to memores & external modalities -> via descencing connections from the forebrain
Hypothalamic Agrp/NPY neurons
(5)
- located in ARC, regulated by circulating hormones
- stimulate eating + decrease energy expenditure
- activated by ghrelin, + low levels of insulin/leptin
- 1 effect: blocking of PomC/Cart & MC4 -> increased food intake
- 2 effect: direct effect on lateral hypothalamic area
Agouti Peptide (2) + agouti-related peptide (agrp) (5)
1. = inverse agonist to peripheral MC1 receptors
2. -> paracrine signaling molecule that causes hair follicle melanocytes to synthesize pheomelanin, a yellow pigment
(mice expressing agouti peptide gene -> yellow pigment)
1. MC3/MC4 receptor inverse agonist
2. similar to agouti + has peripheral effects on hair or adipocytes
3. brain: only expressed in hypothalamic ArC neurons
4. inverse agonist on alpha-melanocyte-stimulating hormone in PVN
5. has effects on LH
Reward-related input for the hypothalamus:
(3)
1. Lateral hypothalamic area neurons integrate reward-related input from Nac with information related to energy homeostasis from ARC
2. Fasting & low insulin/leptin levles & high ghrelin levels -> increase rewarding properties of food and have direct effects on the ventral striatum and indirect effects in LHA
3. LHA is in a KEY position & connects to other areas
Lateral hypothalamic ares:
integrates.. (3)
Function (4)
1. humoral + nerval interoceptive information (energy homeostasis)
2. information related to memories + external modalities
3. information related to circadian rhythm
1. primary anabolic function: expresses ORX A, B and MCH
-> MHC: stimulate eating via forebrain projections
-> ORX A, B: stimulate eating via projection to all parts of cerebrospinal axis
-> ORX neurons can also be activated by hypoglycemia (linking metabolism & alertness)
MC4R (4)
1. polymorphisms: most frequent monogenetic factor that influences BW in humans
2. inactivation -> dramatic weight gain in mice
3. human loss or gain-of-function MC4R variants shape body weight
-> gain of functions: decreased BW
-> loss of functions: increased BW
4. influences meal size -> inactivation: no satation
Caudal brainstem (NTS, AP)
Integration of adiposity & satiation signals (4)
1. Leptin acts on AgrP & PomC (hypothalamus) + on hindbrain areas (NTS - caudal brainstem)
2. Satiation signals activate vagal afferents that terminate in the NTS -> this is influenced by descending projections from PVN & ARC (e.g. oxytoci, aMSH)
-> leptin enables satiation signals to act properly (lack of leptin diminishes responsiveness to satiation signals)