Energy Balance Flashcards
The physiological system controlling food intake & energy expenditure is composed of: (3)
• Long-term & short-term signals (from gut & adipose tissue)
inform the brain of an individual’s energy status
• Brain centers (most important: in the hypothalamus) integrate this information
• Regulation of the intensity of hunger and the level of energy expenditure
Cholecystokinin (CCK):
Cholecystokinin (CCK): regulates key components of digestion & reduces appetite
• Secreted by enteroendocrine cells in duodenum (induced by HCl, amino acids, fatty acids)
Glucagon-like peptide 1 (GLP-1)
- Glucagon-like peptide 1 (GLP-1): ↑ insulin, ↓ glucagon, reduces appetite
- Secreted by enteroendocrine cells in ileum/colon in response to nutrients
Peptide YY
Peptide YY: increases increases water/electrolyte absorption in colon, reduces appetite
• Secreted by enteroendocrine cells in ileum/colon in response to fats
All - GI tract
All: peptide hormones that act on G-protein coupled receptors; exert short-term effects: affect satiation (the feeling of fullness that contributes to the decision to stop eating a meal)
Ghrelin
Ghrelin: “hunger hormone”
• Increases appetite; also stimulates GH release & other effects (e.g., reward cognition)
• Secreted by enteroendocrine cells, primarily in stomach
(stimulated by fasting, and also increases immediately before a meal; suppressed by eating)
Leptin
secreted by white adipose tissue
(basally, circulating leptin levels correlate with fat mass)
Suppresses appetite
Long-term indicator of energy stores: doesn’t change with meals, or acutely affect meal size;
decreasing leptin levels communicate that there is a negative energy balance/
diminishing fat stores, which leads to compensatory responses to replenish these store
Leptin receptor: ……
Ligand binding/receptor homodimerization
leads to ___ recruitment & ultimately the
activation of ____
• Leptin receptor: a class I cytokine receptor
• Ligand binding/receptor homodimerization
leads to JAK2 recruitment & ultimately the
activation of STAT3
There are numerous endocrine adaptations to weight loss which ____ to weight ___:
• There are numerous endocrine adapta?ons to weight loss which predispose to weight regain:
Two adjacent groups of neurons in the ___
nucleus of the ____ act as the primary site
for integrating these inputs from the body
Two adjacent groups of neurons in the arcuate
nucleus of the hypothalamus act as the primary site
for integrating these inputs from the body
Neuropeptide Y (NPY & AgRP)-releasing neurons:
neuropeptides stimulate appetite (___);
Stimulated by ___; Inhibited by PYY, CCK, leptin, GLP-1
Neuropeptide Y (NPY & AgRP)-releasing neurons:
neuropeptides stimulate appetite (orexigenic);
Stimulated by ghrelin; Inhibited by PYY, CCK, leptin, GLP-1
Pro-opimelancortin (____)-releasing neurons:
neuropeptides ____ appetite (____);
Stimulated by leptin & GLP-1
Pro-opimelancortin (POMC & CART)-releasing neurons:
neuropeptides inhibit appetite (anorexigenic);
Stimulated by leptin & GLP-1
Balance of activity of ____-releasing
neurons ultimately determines appetite/
energy expenditure
Balance of activity of NPY- and POMC-releasing
neurons ultimately determines appetite/
energy expenditure
• The hypothalamic neurons release neuropeptides
(orexigenic ___; or
anorexigenic ___& ___- and
___-regulated transcript, ___)
to signal to other parts of the hypothalamus
and other brain regions
The hypothalamic neurons release neuropeptides
(orexigenic NPY & agouti-related peptide, AgRP; or
anorexigenic α-MSH & cocaine- and
amphetamine-regulated transcript, CART)
to signal to other parts of the hypothalamus
and other brain regions
α-melanocyte stimulating hormone (α-MSH) is
a _____ derivative of ___
(processed by specific proteases)
α-melanocyte stimulating hormone (α-MSH) is
a post-translational derivative of POMC
(processed by specific proteases)
α-MSH and AgRP act on a common receptor,
the ____ (MC4R):
α-MSH ___ it and AgRP is an ____
α-MSH and AgRP act on a common receptor,
the melanocortin-4 receptor (MC4R):
α-MSH activates it and AgRP is an antagonist
Energy expenditure: The brain modulates various processes that \_\_\_\_\_ such as locomotor activity and thermogenesis • Involves \_\_\_\_ (\_\_\_ and \_\_\_\_\_ nervous system) and endocrine regulation
Thyroid hormone = ___
Energy expenditure: The brain modulates
various processes that consume energy,
such as locomotor activity and thermogenesis
• Involves neural outputs (sympathetic and
parasympathetic nervous system) and
endocrine regula?on
Thyroid hormone = key hormonal regulator
of metabolism and energy expenditure
Adipose tissue:___
• Adipose tissue: contains inflammatory/immune cells, and adipocytes secretes signaling molecules (including hormones, such as leptin and adiponectin) that inhibit or enhance insulin signaling (among other effects)
Adiponectin
Secreted by adipocytes (inversely correlated with fat mass); improves insulin sensitivity via its effects on liver and muscle
• “Full”/enlarged adipocytes ____ and these ectopic lipid stores affect functioning of those tissues
(inflammation, reduced insulin sensitivity of the tissues, etc.)
• “Full”/enlarged adipocytes release fatty acids into circulation, where they may collect in
other cell types, and these ectopic lipid stores affect functioning of those tissues
(inflammation, reduced insulin sensitivity of the tissues, etc.)
Metabolic syndrome
Metabolic syndrome: a cluster of conditions
that increase risk of developing heart disease,
stroke and/or type 2 diabetes.
(but other complications, too…
e.g., nonalcoholic fatty liver disease,
some cancers, reproductive effects)
