Energy Balance

Question 1

The physiological system controlling food intake & energy expenditure is composed of: (3)

Answer 1

• 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

Question 2

Cholecystokinin (CCK):

Answer 2

Cholecystokinin (CCK): regulates key components of digestion & reduces appetite
• Secreted by enteroendocrine cells in duodenum (induced by HCl, amino acids, fatty acids)

Question 3

Glucagon-like peptide 1 (GLP-1)

Answer 3

• Glucagon-like peptide 1 (GLP-1): ↑ insulin, ↓ glucagon, reduces appetite
• Secreted by enteroendocrine cells in ileum/colon in response to nutrients

Question 4

Peptide YY

Answer 4

Peptide YY: increases increases water/electrolyte absorption in colon, reduces appetite
• Secreted by enteroendocrine cells in ileum/colon in response to fats

Question 5

All - GI tract

Answer 5

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)

Question 6

Ghrelin

Answer 6

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)

Question 7

Leptin

Answer 7

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

Question 8

Leptin receptor: ……

Ligand binding/receptor homodimerization
leads to ___ recruitment & ultimately the
activation of ____

Answer 8

• Leptin receptor: a class I cytokine receptor
• Ligand binding/receptor homodimerization
leads to JAK2 recruitment & ultimately the
activation of STAT3

Question 9

There are numerous endocrine adaptations to weight loss which ____ to weight ___:

Answer 9

• There are numerous endocrine adapta?ons to weight loss which predispose to weight regain:

Question 10

Two adjacent groups of neurons in the ___
nucleus of the ____ act as the primary site
for integrating these inputs from the body

Answer 10

Two adjacent groups of neurons in the arcuate
nucleus of the hypothalamus act as the primary site
for integrating these inputs from the body

Question 11

Neuropeptide Y (NPY & AgRP)-releasing neurons:
neuropeptides stimulate appetite (___);
Stimulated by ___; Inhibited by PYY, CCK, leptin, GLP-1

Answer 11

Neuropeptide Y (NPY & AgRP)-releasing neurons:
neuropeptides stimulate appetite (orexigenic);
Stimulated by ghrelin; Inhibited by PYY, CCK, leptin, GLP-1

Question 12

Pro-opimelancortin (____)-releasing neurons:
neuropeptides ____ appetite (____);
Stimulated by leptin & GLP-1

Answer 12

Pro-opimelancortin (POMC & CART)-releasing neurons:
neuropeptides inhibit appetite (anorexigenic);
Stimulated by leptin & GLP-1

Question 13

Balance of activity of ____-releasing
neurons ultimately determines appetite/
energy expenditure

Answer 13

Balance of activity of NPY- and POMC-releasing
neurons ultimately determines appetite/
energy expenditure

Question 14

• The hypothalamic neurons release neuropeptides
(orexigenic ___; or
anorexigenic ___& ___- and
___-regulated transcript, ___)
to signal to other parts of the hypothalamus
and other brain regions

Answer 14

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

Question 15

α-melanocyte stimulating hormone (α-MSH) is
a _____ derivative of ___
(processed by specific proteases)

Answer 15

α-melanocyte stimulating hormone (α-MSH) is
a post-translational derivative of POMC
(processed by specific proteases)

Question 16

α-MSH and AgRP act on a common receptor,
the ____ (MC4R):
α-MSH ___ it and AgRP is an ____

Answer 16

α-MSH and AgRP act on a common receptor,
the melanocortin-4 receptor (MC4R):
α-MSH activates it and AgRP is an antagonist

Question 17

Energy expenditure: The brain modulates
various processes that 
\_\_\_\_\_
such as locomotor activity and thermogenesis
• Involves \_\_\_\_ (\_\_\_  and
\_\_\_\_\_ nervous system) and
endocrine regulation

Thyroid hormone = ___

Answer 17

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

Question 18

Adipose tissue:___

Answer 18

• 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)

Question 19

Adiponectin

Answer 19

Secreted by
adipocytes (inversely correlated
with fat mass); improves insulin
sensitivity via its effects on liver
and muscle

Question 20

• “Full”/enlarged adipocytes ____ and these ectopic lipid stores affect functioning of those tissues
(inflammation, reduced insulin sensitivity of the tissues, etc.)

Answer 20

• “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.)

Question 21

Metabolic syndrome

Answer 21

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)