Nutrition/ Diet 3 - Physiology of Feeding and Satiety Flashcards Preview

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Flashcards in Nutrition/ Diet 3 - Physiology of Feeding and Satiety Deck (51)
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1

Energy Homeostasis

Physiological process whereby energy intake is matched to energy expenditure over time

2

What 2 factors cause obesity?
What are the 2 major factors that influence obesity

Accessible, tasty calorie dense food
Sedentary lifestyle

Genetics
Environment

3

What is metabolic syndrome (syndrome X)?

Central obesity plus 2 of:
Blood pressure greater than or equal to 130/85
Triglycerides greater than or equal to 1.7 mol/L
HDL less than 1.03 in males and 1.29 in females (mol/L)
Fasting glucose greater than or equal to 5.6mmol/L
Diabetes mellitus

4

Possible consequences of metabolic syndrome? (4)

CV disease
Dibetes Mellitus
Gallstones
Cancers
More in list

5

What is the equation for BMI?

Wegith (kg) / square of height (m)

6

Categories of BMI?

Up to 25 = thin or normal
25-29.9 = overweight
30-39.9 = obese
greater than or equal to 40.0 = morbidly obese

7

What are some of the consequences of obesity (9)

Stroke (hypertension)
Respiratory disease (sleep apnoea)
Heart disease (lipids, diabetes, hypertension)
Gallbladder disease
Osteoarthritis
Dementia
NAFLD (fatty liver)
Diabetes
Cancer(Uterus, breast, prostate, colon)
Hyperuricemia, gout

8

Why do we need fat? (3)

Energy storage
Prevention of starvation
Energy buffer during prolonged illness

9

What is one of the reasons why it is difficult to lose weight?

Increased fat alters brain function in order that the brain views the fat as normal and dieting as a threat to body survival

10

How does the CNS influence energy balance and body weight (3)?

Behaviour - feeding and physical activity
ANS activity - regulates energy expenditure
Neuroendocrine system - secretion of hormones
(integration of these determines final output - feeding behaviour)

11

Where does the CNS influences on energy balance get integrated (in order to produce final behaviour)
How do we know this

In the hypothalamus in the brain

Lesioning ventromedial hypothalamus causes obesity
Lesioning lateral hypothalamus causes leaness

12

What 3 basic concepts underline the control system of energy intake and body weight?

Satiety signalling
Adiposity negative feedback signalling
Food reward

13

What is satiation?

Sensation of fullness generated during a meal

14

What is satiety?

Period of time between termination of one meal and the initiation of the next

15

What is adiposity?

The state of being obese

16

What does the satiation and satiety processes regulate?

Meal intimation, termination and inter-meal frequency

17

When satiation signals increase

During meal to limit meal size

18

What are the satiation signals? (5)

Cholecystokinin (CCK)
Peptide YY (PYY3-36)
Glucagon-like peptide 1 (GLP-1)
Oxyntomodulin (OXM)
Obestatin

19

Cholecystokinin (CKK)?

Secreted from enteroendocrine cells in duodenum and jejunum
Released in proportion to lipids and proteins in meal
Signals via sensory nerves to hindbrain and stimulates hindbrain directly (Nucleus of solitary tract)

20

Peptide YY (PYY3-36)?

Secreted from endocrine mucosal L-cells of GI tract
Levels increase rapidly post-prandially
Inhibits gastric motility, slows emptying and reduces food intake (Hypo)

21

Glucagon-like peptide 1 (GLP-1)

Product of pro-glucagon gene
Also released from L cells in response to food ingestion
Inhibits gastric emptying reduces food intake (Hypo, NTS)

22

Oxyntomodulin (OXM)?

Also from pro-glucagon gene and released from oxyntic cells of small intestine after meal
Acts to suppress appetite - mechanism unclear

23

Obestatin

Peptide produced from gene that encodes gherkin and released from cells lining stomach/ small intestine
Suggested t reduce food intake - may act to antagonise the actions of gherkin - actions unclear at present

24

What is a hunger signal?

Ghrelin

25

What is Gherkin?
Where is it produced and secreted?
How do its levels range?

Octanoylated peptide
Oxyntic cells in stomach
Levels increase before meals and decrease after meals
Levels are raised by fasting and hypoglycaemia

26

What does peripheral gherkin stimulate?
what does it decrease?

Food intake (hypo) and decreases fat utilisation

27

What doe gherkin-containing neurons in the hypothalamus do?

Help control fat metabolism, increasing lipogenesis (liver and adipose)

28

What do feedback loops which control overall energy balance do?
How does this work basically?

they act to maintain constancy of total body energy stores - why weight is stable in lean and obese individuals
Signals are produced in response to body nutritional status
These are sensed in the hypothalamus
These act to modulate food intake and energy expenditure

29

What central appetite controllers increase food intake when injected into the hypothalamic centres? (3)

Glutamate
Gaba
Opiods
(effects modest/ short lasting)

30

What central appetite controller acts to suppress food intake?

Monoamines (many drugs developed to suppress food intake but most were withdrawn due to side-effects)