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10. The endocrine regulation of energy balance Flashcards

1
Q

what are our sources pf ENERGY INPUT

A

food & drink

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2
Q

what are our sources of ENERGY OUTPUT (3)

A

RESTING METABOLISM

THERMIC EFFECT of FOOD

ACTIVITY

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3
Q

what factors INFLUENCE ENERGY BALANCE

A

BIOLOGICAL (inherited or
acquired – eg drugs, disease)

PSYCHOLOGICAL (affect CNS)

SOCIAL (affect CNS)

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4
Q

if you intake 100 kcal excess every day, how many extra kcal & kg of fat in a year?

A

36,500 kcal
5kg of extra fat

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5
Q

how is ENERGY EXPENDITURE in HEAVIER people

A

EXPEND MORE ENERGY

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6
Q

how do you measure ENERGY EXPENDITURE

A

whole-body calorimeter

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7
Q

REGULATION of FOOD INTAKE is largely CONTROLLED by…

A

the CNS
- particularly HYPOTHALAMUS

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8
Q

Food Intake can be modified by HEDONIC FACTORS:

A

TASTE
MEMORY
BEHAVIOURAL FACTORS

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9
Q

what are APETITE SIGNALS

A

FALLING GLUCOSE
FALLING NUTRIENTS (other)

GHRELIN (Increases) from stomach

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10
Q

what INDICATE FULLNESS

A

stomach STRETCHING
absorbing of NUTRIENTS
CHEMORECEPTORS (detect nutrients)
GUT HOROMES - tell brain we are full

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11
Q

what does GI TRACT do when regulating food intake

A

sends HORMONES & NEURAL SIGNALS via VAGUS NERVE or BLOOD to NTS of BRAIN

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12
Q

what area of the BRAIN receives hormones/neural signals from GI Tract and communicates with Hypothalamus

A

NTS
- NUCLEUS TRACTUS SOLLITARIUS

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13
Q

2 important NUCLEI of HYPOTHALAMUS in regulation of food intake

A

ARC
PVN

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14
Q

what are the ADIPOSITY SIGNALS in regulation of food intake

A
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15
Q

what are the ADIPOSITY SIGNALS in regulation of food intake

A

FAT MASS

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16
Q

what is the MAIN SIGNAL indicating FAT MASS in regulation of food intake

A

LEPTIN

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17
Q

what are the GUT HORMONES in regulation of food intake

A
  • AMYLIN
  • CHOLECYSTOKININ
    (also stimulates gallbladder contractions after a meal)
  • GLP-1 : GLYCOGEN-LIKE PEPTIDE 1
    (also stimulates insulin secretion after a meal)
  • PYY : PEPTIDE YY
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18
Q

what is the STOMACH HORMONE that STIMULATES APPETITE & INCREASES FOOD INTAKE

A

GHRELIN

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19
Q

what does GHRELIN also promote

A

FAT STORAGE

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20
Q

GHRELIN also has a role in regulation of …. release

A

GROWTH HORMONE RELEASE

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21
Q

GHRELIN RECEPTORS AKA

A

GHS-R
GROWTH HORMONE SECRETAGOGUE RECEPTOR

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22
Q

where do you find GHRELIN RECEPTORS / GHS-R

A

NPY/AgRP NEURONES in HYPOTHALAMIC ARCUATE NUCLEUS (arc)

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23
Q

when do GHRELIN levels RISE

A

BEFORE a meal, when stomach is EMPTY

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24
Q

when do GHRELIN levels FALL

A

shortly AFTER a meal, when stomach is FULL

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25
how does GHRELIN CHANGE with WEIGHT LOSS
after you LOSE weight: HIGHER GHRELIN LEVELS - therefore feel more HUNGRY (hard to maintain weight loss)
26
when does PYY 3-36 INCREASE
AFTER MEALS (feel FULL)
27
how are PYY levels in OBESE people as opposed to lean people
LOW - therefore feel HUNGRY
28
affects of GLP-1 in food intake
- REDUCES FOOD INTAKE - ACTIVATES BRAIN areas involved in SATIETY : NEURONS in PVN and AMYGLADA
29
what is another SIGNAL of SATIETY that helps DECREASE FOOD INTAKE
INSULIN - ANOREXIGENIC EFFECT
30
INSULIN secreted by
PACREATIC BETA CELLS
31
what does INSULIN SIGNAL to the HYPOTHALAMUS
that you are FED / FULL
32
INSULIN has what effect
ANOREXIGENIC EFFECT - decrease food intake
33
where are INSULIN RECEPTORS HIGHLY EXPRESSED
CNS especially in: - OLFACTORY BULBS - HYPOTHALAMIC ARCUATE NUCLEUS
34
what happens when there is a NEURON-SPECIFIC DISRUPTION of INSULIN RECEPTOR GENE
INCREASED FOOD INTAKE & OBESITY - with INCREASED BODY FAT & PLASMA LEPTIN LEVELS
35
what is a KEY HYPOTHALAMIC NUCLEUS in the REGULATION of APPETITE
hypothalamic ARCUATE NUCLEUS (ARC) also Ventromedial Nucleus
36
how does GHRELIN INCREASE FOOD INTAKE
STIMULATES NPY in ARC - activates NPY Y5 RECEPTORS in PVN - increased food intake
37
how does PYY INHIBIT FOOD INTAKE
INHIBITS NPY inhibits activation of NPY Y5 RECEPTORS
38
NPY NEURONES in ARCUATE nucleus ACTIVATE NPY Y5 RECEPTORS in PVN to..
INCREASE FOOD INTAKE (& INHIBIT MC4 & CART RECEPTORS)
39
POMC CART NEUROTENSIN ACTIVATES MC4 (melanocortin 4) RECEPTOR / CART RECEPTOR to...
DECREASE FOOD INTAKE (inhibitory mechanism)
40
how does GLP-1 DECREASE FOOD INTAKE
INHIBITS NPY ACTIVATES POMC CART
41
how does LEPTIN DECREASE FOOD INTAKE
ACTIVATES POMC CART - ACTIVATES MC4 & CART RECEPTORS & INHIBITS NPY
42
what does CLEAVAGE of POMC produce
MELANOCORTINS
43
how do we get CLEAVAGE of POMC
by PROHOMONE CONVERTASES: PC1 & PC2
44
what does targeted DELETION of MC4-R result in (in mice)
HYPERPHAGIA (excessive eating) & OBESITY
45
ADIPOSE TISSUE is LOOSE CONNECTIVE TISSUE comprising of: (2)
- ADIPOCYTES - STROMOVASCULAR CELLS (and immune cells)
46
ADIPOCYTES make up what proportion of our total cells
20-40% majority is WHITE ADIPOSE CELLS
47
STROMOVASCULAR COMPONENT of ADIPOSE TISSUE consists of:
* ADIPOSE PRECURSORS * VASCULAR cells * IMMUNE cells * FIBROBLASTS * NERVE cells
48
ADIPOCYTES are .... CELLS
LIPID-STORING cells Safely STORE excess calories - overnutrition - Free fatty acids (FFAs) and their products can be toxic when stored elsewhere
49
ADIPOCYTES release..
energy-nutritional deprivation - RESERVE when levels are low
50
what happens in ADIPOCYTES during POST-PRANDIAL PHASE (after eating)
LIPOGENESIS FREE FATTY ACIDS are ESTERIFIED to TRIGLYCERIDES / triacylglycerols TAGs (glucose converted to glycerol, merges with ffa) stored in adipose tissue (under influence of insulin)
51
what happens in ADIPOCYTES during FASTING (low insuline)
TAGs/TRIGLYCERIDES HYDROLYSED to FREE FATTY ACIDS and GLYCEROL LIPASE activated - used as a source of ENERGY
52
ADIPOSE TISSUE also acts as an...
ENDOCRINE ORGAN secretes ADIPOKINES
53
ADIPOKINES/HORMONES secreted by ADIPOSE TISSUE
IL-6 TNF ALPHA - inflammatory mediators PAI - modifies blood coagulation ANGIOTENSINOGEN - regulates vascular tone LEPTIN - appetite regulation ADIPONECTIN - insulin sensitivity
54
what is the main FUNCTION of LEPTIN
DECREASE FOOD INTAKE
55
where is LEPTIN almost exclusively expressed
ADIPOSE TISSUE
56
what is LEPTIN
SMALL POLYPEPTIDE - 167 amino acids
57
LEPTIN is encoded by which gene
LEP GENE aka Ob gene
58
effect of FATTY FOODS on LEPTIN
causes LEPTIN RELEASE due to increased blood lipids
59
another FUNCTION of LEPTIN
Regulates Activity of GONADAL and THYROID axis
60
MUTATION in LEPTIN GENE (LEP) or LEPTIN RECEPTOR GENE results in
INTENSE HYPERPHAGIA (intense overeating) and consequently OBESITY
61
what is ADIPONECTIN
highly secreted hormone from ADIPOSE TISSUE - most ABUNDANT ADIPOKINE
62
FUNCTION of ADIPONECTIN
ENHANCES INSULIN SENSITIVITY in LIVER and PERIPHERAL tissue
63
ADIPONECTIN acts via.. to enhance insulin sensitivity
ADIPOR1 & ADIPOR2 RECEPTORS
64
what is the correlation between ADIPOSE TISSUE and ADIPONECTIN
HIGHER ADIPOSE TISSUE LEVELS = LOWER ADIPONECTIN secretion Paradoxically for an adipocyte-derived hormone, expression and secretion is diminished in central obesity
65
ADIPONECTIN is an excellent biomarker for INSULIN RESISTANCE. when there is LOW ADIPONECTIN...
HIGH INSULIN RESISTANCE
66
ADIPONECTIN SECRETION is STIMULATED by...
THIAZOLIDINEDIONES (antidiabetic agents)
67
what are the 2 TYPES of ADIPOSE TISSUE
WHITE adipose tissue BROWN adipose tissue
68
ROLE of WHITE ADIPOSE TISSUE
STORES (excess) ENERGY as triglycerides & SECRETES SIGNALLING FACTORS that regulate APPETITE & ENERGY HOMEOSTASIS - leptin & adiponectin
69
ROLE of BROWN ADIPOSE TISSUE
GENERATES BODY HEAT - helps SURVIVE COLD TEMPERATURES by transferring ENERGY FROM FOOD into HEAT
70
CELLS in WHITE ADIPOSE TISSUE contain...
a SINGLE LARGE FAT DROPLET - which forces the NUCLEUS to be SQUEEZED into a THIN RIM at the PERIPHERY
71
WHITE ADIPOSE TISSUE responds to/ has RECEPTORS for...
INSULIN SEX HORMONES NORADRENALINE GLUCOCORTICOIDS
72
what does BROWN ADIPOSE TISSUE consist of
SMALL LIPID DROPLETS numerous IRON-RICH MITOCHONDRIA (gives brown appearance)
73
what gives BROWN ADIPOSE TISSUE its brown appearance
IRON-RICH MITOCHONDRIA
74
where is BROWN ADIPOSE TISSUE (BAT) adundant
in SMALL MAMMALS and NEWBORNS (some found in adults)
75
OBESITY is associated with
INCREASE in ADIPOSE TISSUE MASS
76
OBESITY occurs as a result of...
chronic IMBALANCE between ENERGY INTAKE and EXPENDITURE involves interaction between GENETIC and ENVIRONMENTAL FACTORS
77
GENETIC OBESITY CAUSES
- Leptin deficiency - Leptin Receptor deficiency - deficiency in production of alpha MSH due to problems in POMC - deficiency in PC1 enzyme (POMC to MC4 receptor) - Mutations in MC4 Receptor
78
EFFECTS of WEIGHT LOSS from Dieting
- DECREASED LEPTIN - DECREASED PYY & GLP-1 - INCREASED GHRELIN (feel hungry) - DECREASED ENERGY EXPENDITURE due to lower size therefore hard to maintain weight loss
79
Examples of treatments for obesity - drugs that modify appetite control
- LEPTIN TREATMENT - Setmelanotide drug - MC4R RECEPTOR for MC4R deficiency - Semaglutide - GLP1 AGONIST (drugs that act on leptin pathway or melanocortin system)
80
what is the action of Melanocortin Peptides eg (alpha-melanocyte-stimulating hormone) MSH released from ARC POMC NEURONS
BINDS to MELANOCORTIN RECEPTORS - MC4-Rs to INHIBIT FOOD INTAKE

ENDOCRINOLOGY (11 decks)

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