Week 10: Regulation Of Metabolism And Feeding Flashcards
1
Q
Define Caloric homeostasis
A
Maintenence of energy balance in the body. Preserves cellular metabolism; we store energy for when food is scarce and bridge gaps between meals
2
Q
Define Orexigenic
A
Appetite stimulating
3
Q
Define Anorexigenic
A
Appetite inhibiting
4
Q
Define Anabolic
A
Building/storing
5
Q
Define Catabolic
A
Breaking down/ using
6
Q
Define prandjal
A
Relating to meals
7
Q
Define phagia
A
(Suffix) to eat
8
Q
What is Adiposity?
A
Amount of body fat
9
Q
What does Hunger and satiation govern?
A
Meal-by-meal eating behaviour
10
Q
What does hypothalamic circuitry coordinate?
A
Daily food intake With long term, homeostatic, and feedback regulation of energy balance and body weight
11
Q
What is Prandial or Fed state?
A
Insulin promotes use and storage (anabolic)
12
Q
Postabsorptive or Fasted state?
A
Absence of insulin; mobilisation of stores (catabolic)
13
Q
What does liver do?
A
Oxidizes many lipids Stores carbohydrates
14
Q
What do most tissues e.g. muscles do?
A
Oxidise glucose or lipids
15
Q
What does CNS do?
A
Oxidises mainly glucose
16
Q
What does adipose tissue do?
A
Stores lipids
17
Q
What is the cephalic phase?
A
Hypothalamus drives the parasympathetic NS stimulation of pancreatic insulin secretion
18
Q
What is the GI phase?
A
Gut hormone stimulate insulin secretion
19
Q
What is substrate phase?
A
Insulin secretion stimulated by metabolites (glucose)
20
Q
What is the gastric signal?
A
Stomach distension - vagus nerve > nucleus tracts solitarius ( NTS)
21
Q
What are the post-gastric signals (I.e. intestinal)
A
Cholecystokinin Glucagon-like peptide-1 (GLP-1) / peptide YY (PYY) Liver signals Increased plasma osmolality
22
Q
Cholecystokinin
A
Enteroendocrine cells secrete CCK when fatty acids are detected - acts in vagus (synergises with stretch) - hormonal and neural
23
Q
GLP-1/ PYY
A
Taste carbohydrates in gut, GLP-1 increases insulin secretion and both act centrally - hormonal
24
Q
Liver signals
A
Detect absorbed nutrients/insulin - satiation signals via vagus - neural
25
Increased plasma osmolality
Sensors in brain (caudal brainstem) or viscera
26
When do meals terminate?
Before nutrient homeostasis occurrs
27
What happens when satiation signals disappear?
Hunger can re-emerge and another meal is initiated
28
What are the internal hunger and satiation signals?
Hunger pangs/ stretch Various blood chemicals relating to body state including insulin, glucose, CCK, GLP-1, ghrelin, osmolality
29
What are the internal contextual factors?
Mood; habit; memory
30
What are the external quality cues?
Appearance and smell of food
31
What are the external context cue ?
Safe time to eat Social setting Cultural factors Time of day
32
What are the internal hunger and satiation signals?
Hunger pangs/ stretch Various blood chemicals relating to body state including insulin, glucose, CCK, GLP-1, ghrelin, osmolality
33
What are the internal contextual factors?
Mood; habit; memory
34
What are the external quality cues?
Appearance and smell of food
35
What are the external context cue ?
Safe time to eat Social setting Cultural factors Time of day
36
What are two physiological functions of body weight?
Food intake Intestinal absorption
37
The brainstem mediated important reflexes via what route?
Dorsal Vagal Complex (DVC) Parabrachial nucleus (PBN)
38
What are higher centres required for?
Modification and integration of signals Learning, adipocyte factors and circadian rhythms (daily cycle)
39
What does the reflex arc act to modulate?
Absorption and incorporation of other metabolites
40
What is the NTS closely associated with?
Dorsal Medial vagus Area postrema
41
What does the reflex arc act to modulate?
Absorption and incorporation of other metabolites Allow more or less food to be absorbed at the hypothalamus levels
42
What is the NTS closely associated with?
Dorsal Medial vagus Area postrema
43
What is satiation signals associated with?
Body weight (adipocyte)
44
What does Adiposity influence?
Food intake indirectly
45
What is the main centre for control of body weight?
Hypothalamus
46
What is Leptin?
A satiation signal of Adiposity
47
What does Leptos mean?
Thin
48
What happens if there is a genetic mutation in the peptide ob/ob or its receptor db/db?
are obese
49
What happens to tissue if someone has more adipose tissue?
The tissue is less responsive to insulin
50
What effect does leptin and insulin have?
Catabolic effects on metabolism
51
What is Ghrelin?
Hunger signal
52
What is ghrelin and where is it secreted from?
Peptide and by the stomach during fasting
53
When is Ghrelin secreted?
Just prior to meals suggesting it has a role in the initiation of meals
54
What does Ghrelin affect?
Dopamine reward pathways
55
What does levels of Ghrelin correlate with?
Hunger scores
56
What is hyperphagia?
Abnormally great desire for food
57
What is hypophagia?
Reduction in food intake and eating behaviour
58
What is dorsomedial involved in?
Circadian rhythms Feeding (inhibition) Emotions
59
What is ventromedial involved in?
Inhibits feeding (satiety centre)
60
What is the Lateral hypothalamic area Involved in?
Eating, drinking
61
What does VMH lesions disrupt?
Autonomic tone - decreasing sympathetic/ increasing parasympathetic, Vagal tone
62
What does LHA lesion disrupt?
Sensorimotor integration - reward and motor systems
63
What is the main centre for appetite regulation?
Arcuate nucleus
64
What 2 neurones are key to regulation of food intake and metabolism?
Dopamine neurons GHRH
65
What is the precursor for melanocortin peptides (alpha MSH)?
Pro-opiomelanocortin (POMC)
66
Where does POMC act on?
Melanocortin receptors (e.g. MCR4)
67
What does POMC play an important role in?
Inhibit feeding (anorexigenic effects)
68
What does deficiency of POMC lead to?
Hyperphagia and obesity
69
Where are melanocortin receptor 4 found in?
Numerous projection sites of Arcuate POMC neurons
70
What is MCR4 expresses by?
PVH neurons which surpresses food intake
71
What does melanocortin stimulation of MC4R cause?
Increase in energy expenditure and maintain glucose homeostasis
72
What does genetic deletion of MC4R in life and human result in?
Severe hyperphagic obesity
73
What is neuropeptide Y?
Orexigenic - effects lasts 1-2 hours
74
What does agouti-related peptide have?
Longer acting Orexigenic effect; acts as a melanocortin receptor antagonist
75
What does injection of NPY into the PVN cause?
Increased food intake and negatively controls sympathetic outflow Directly inhibits MC4R expressing cells
76
What does ablation of NPY/AgRP In adults result in?
Profound decrease in food intake and body weight
77
What are satiety signals?
Both hormonal and neural
78
Where does bidirectional flow of information occur?
Brainstem and hypothalamus
79
What does leptin/insulin in Arcuate nucleus stimulate?
POMC anorexigenic cells Inhibits NPY/ AGRP Orexigenic cells
80
What does low level of insulin and leptin release?
NPY/AgRP/GABA cells from inhibitory satiety Control
81
What stimulates feeding behaviour?
High Ghrelin levels from Vagal input and hypothalamic circuits
82
What is Lateral hypothalamic area?
Orexigenic site - driving feeding as well as central to anabolic effects
83
Where does the enteroendocrine peptides act on?
ARC system
84
What are other satiety factors ?
GLP-1 and PYY
85
What does GLP-1 and PYY act ?
Stimulate POMC and inhibit NPY cells
86
What has therapeutic potential in obesity treatment?
GLP-1 agonists
87
What does global deficiency of 5-HT2C or 5-HT1B receptors result in?
Hyperphagia Obesity Disturbed glucose homeostasis
88
What is mood controlled by?
Serotonergic systems
89
What is serotonergic systems?
Implication for interaction of mood with eating behaviours
90
What does low level of insulin and leptin release?
NPY/AgRP/GABA cells from inhibitory satiety Control
91
What stimulates feeding behaviour?
High Ghrelin levels from Vagal input and hypothalamic circuits
92
What is Lateral hypothalamic area?
Orexigenic site - driving feeding as well as central to anabolic effects
93
Where does the enteroendocrine peptides act on?
ARC system
94
What are other satiety factors ?
GLP-1 and PYY
95
What does GLP-1 and PYY act ?
Stimulate POMC and inhibit NPY cells
96
What has therapeutic potential in obesity treatment?
GLP-1 agonists
97
What does global deficiency of 5-HT2C or 5-HT1B receptors result in?
Hyperphagia Obesity Disturbed glucose homeostasis
98
What is mood controlled by?
Serotonergic systems
99
What is serotonergic systems?
Implication for interaction of mood with eating behaviours
100
What is found in Paraventricular nucleus?
Oxytocin (OXY) Corticotropin releasing hormone (CRH) Both peptides are anorexigenic
101
What does OXY mediate?
CRH effect and stress related decrease in eating
102
What does CRH mediate ?
Increase in sympathetic activity
103
What is involved in Lateral hypothalamic area?
Orexin Melanocortin concentrating hormone (MCH) - they are orexigenic
104
What does orexin cause?
Wakefulness It’s decrease after eating inside drowsiness
105
Where does area postrema lie?
Caudal end of the 4th ventricle adjacent to the nucleus of tractus solitarus, not connected to the hypothalamus
106
Where does area postrema get information from?
Blood and transfers that information into dorsal vagal complex (DVC)
107
What does area postrema detect?
Toxins
108
What does dorsal motor nucleus of vagus control?
Parasympathetic output
109
Where is the input from hypothalamus Via?
Paraventricular nucleus to sympathetic preganglionic neurons in spinal cord
110
What is the main centre for appetite regulation?
Arcuate nucleus
111
Where is arcuate nucleus found?
Median eminence
| Connecting hypothalamus to pituitary gland
112
What does dopamine neuron do?
Inhibit prolactin secretion
113
What does GHRH cause ?
Pulsatile release and growth hormone secretion
114
What are key regulation of food intake and metabolism?
Dopamine neurons
| GHRH
115
Where is the brainstem involved through?
Dorsal vagal complex
| Parabrachial nuclei around superior cerebellar peduncle
116
What does brainstem centre allow?
Reflexive eating behaviours
Distinguishing whether something is good or bad to eat
Recognise how much glucose and salt there are in the bloodstream
117
Decerebrate rat
Do not have cortical input
Distinguish between bitter, salty, sweet flavours and eat accordingly
They don’t eat as much bitter - toxic substance
118
Where does afferent input go to?
Nucleus tract of solitarus
119
What does reflex arc act to modulate?
Absorption and incorporation of other metabolites
120
What is NTS closely associated with?
Dorsal medial vagus
| Area postrema
121
Where is food mainly absorbed by body?
Small intestine (duodenum)
122
What happens after we’ve eaten?
Glucose is absorbed into the blood
Travel to the liver
The liver store glucose as glycogen
123
What is the role of insulin
Stimulate glucose uptake to liver by the blood indirectly
Insulin inhibit secretion of glucose to the blood from liver
Stimulate uptake of glucose to adipocyte to produce more triglyceride
Stimulate uptake glucose to skeletal muscles
124
What does body absorb?
FA
AA
Monoglyceride
Stored as glycogen, protein and triglyceride
125
Fed state
Gluconeogensis
Lipogensis
Protein synthesis
126
What does liver have?
Short term capacity
Releases glucose by breaking down glycogen stores
Produced ketone bodies
127
When is insulin released?
In the presence of glucose in the body
| There are low levels of glucose before meals
128
What is insulin release?
Biphasic
129
What is cephalic Phase activated by?
Thought
Smell
Taste
Sight of food
130
What is the cephalic phase mediated by?
Cholinergic/vagal mechanism Via parasympathetic
131
What does meals generate?
Satiation signals
132
What does stomach have and what does liver release?
Stomach - stretch receptors
| Liver releases CCK, GLP-1
133
What are adipocyte signal?
Leptin
| Insulin
134
What does receptors on stomach fire?
Signals to the brain which say that the stomach is full which inhibit feeding
Activating ventromedial hypothalamus
135
What are CCK and GLP1 releases in proportion to?
Content of fat and protein
136
What does leptin level indicate?
How much fat you have stored in adipose tissue
| The more fat, the higher the leptin level
137
What does sight, taste and smell override?
Biochemical signal and it can cause you to eat more quickly
138
What is satiation signal associated with?
Body weight (adipocity)
139
Scientific approach to obesity
Lack of will power
Lifestyle/environment
Biology/genes
140
What does elevated extracellular glucose level activate?
POMC Neurons
141
What does POMC neurons produce?
Anorectic peptide alpha-melanocyte by posttranscriptional processing of POMC
142
What is alpha-MSH
Main peptide involved in appetite regulation
143
What does alpha-MSH bind to?
Melanocortin receptor 3 and 4 on second order neurons and activate catabolic pathways
Reduced food intake
Increased energy expenditure
144
What does endorphin modulate?
Reward system
