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Unit 10 > Week 1: Ingestive behaviour > Flashcards

Week 1: Ingestive behaviour Flashcards

1
Q

What are the two basic physiological reasons why we need to eat?

A

Feul - energy supply
Nutrition - essential chemicals, such as amino acids that can not be manufactured in the body

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2
Q

Give examples of biological factors contributing to indigestive behaviour

A

Genetics
Neonatal complication
History of dieting
Metabolism
Co-morbidities

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3
Q

Give some exampls of psychological factors contributing to indigestive behaviours.

A

Perfectionism
Difficulty regulating emotions
Body dissatisfaction
health knowledge
Actitivty and eating habits

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4
Q

Give some examples of social factors that contribute to indigestive behaviour

A

Pressure to be thin/Muscular
Bullying and teasing
Lack of social support
School and government education around healthy eating
Socioeconomic status
Food policy

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5
Q

Describe how food can become a form of self-medication in stressful situations.

A

Eating triggers the release of dopamine within the mesolimbic pathway in the brain.
This leads to reduced stress and increased feeling of pressure.
By associative learning food can become associated with reduced stress and pleasure
Hence a habit forms where by food is used as a form of self medication in stressful times

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6
Q

What methods physiological methods control indigestive behaviours?

A

Satiety mechanisms
Detectors that monitor system variables

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7
Q

Define satiety mechanisms?

A

Brain based mechanisms that reduce hunger or thirst after behaviours resulting in adequate intake of nutrients or water.

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8
Q

What do satiety mechanisms measure? How does this relate to how indigestive patterns are controlled?

A

Satiety mechanisms monitor correctional behaviour mechanisms (stretch on stomach) rather that the system variables them selves (low bp).
This means the body system replenishment can be delayed after the need of consumption/ decreased consumption occurs and the appropriate behaviour occurs.

Low BP detected - feel thirst - drink more - signal to stop drinking - blood pressure increases and returns to normal

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9
Q

What type of correction system monitors our indigestive behaviour?

A

Negative feedback triggering correctional mechanisms

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10
Q

What is plasma osmolarity?
What receptors detect changes in osmolarity?

A

The level of different solutes (na+, Cl-) in plasma
Osmoreceptrs detect the changes in osmolarity

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11
Q

Give a basic summary mechanism of how the sensation of thirst is activated in the brain.

A

Plasma osmolarity increases and is detected by osmoreceptors.
Results in circulating angiotensin 11.
Additionally low blood pressure may be detected by baroreceptors and GI hormones can indicate a need to drink.
During pregnancy relaxin may also be circulating.
This stimulates subfornical organ (SFO) and organum vasculosum of the lamina terminaslis (OVLT)
Results in stimulation of the meidan preoptic nucleus (MnPO) which relays signals to the insula and congulate cortex to increase thirst.

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12
Q

What is role of the Insula in thirst regulation?

A

Interoception - interprets and detects afferent signals from the body that tell the brain of the body state.

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13
Q

What is the role of the cingulate cortex in regulation of thirst?

A

Motivation/emotional processing
Pleasure you feel after drinking when you are thirsty.

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14
Q

What regions of the CNS influence hunger?

A

The hypothalamus
Particularly the lateral hypothalamus and the ventromedial hypothalamus

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15
Q

What is the role of the lateral hypothalamus in regulating eating behaviours?

A

Later hypothalamus - initiates hunger signals

If damaged leads to reduced hunger signals, weight loss and potentially anorexic behaviour

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16
Q

What role does the stomach have in the feedback mechanism of food intake?

A

Stretch receptors in the stomach
Action potential generated when the stomach is full and stretched
Activated sensory afferent pathways in the vagus nerve to inhibit food intake

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17
Q

What GI hormones can decrease hunger signals?

A

Peptide YY (PYY)
Cholecystokinin CCK
Insulin

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18
Q

What role does leptin have in regualting appetite?

A

Leptin is a hormone produces by fat cells as they increase in size
It inhibits food intake and regulates metabolism

19
Q

What is the role of ghrelin in regulating appetite?

A

Released by the stomach during fasting (reduced after a meal)
Binds to the hypothalamus
Increases hunger signals and increases the appetite.
Leads to decreased metabolism of fats

20
Q

What is the role of peptide YY in regualting appetite?

A

Released by the small intestine and colon after a meal.
Release is proportional to the calories that were just ingested.
Decreases hunger signals

21
Q

What is the role of CCK in regulating appetite?

A

Amount released is proportional to the amount of nutrients (particularly fats) that the duodenum recives from the stomach.
CCK could potentially provide a satiety signal to the brain
However, it does not act on the brain directly.
Acts on receptors located in the junction between the stomach and the duodenum

22
Q

How does blood glucose levels relate to regulating appetite?

A

Low blood glucose - low insulin - reduced inhibitory effect on appetite

High blood glucose - high insulin - brain detects insulin present in the blood - indicates the body is absorbing nutrients and inhibits hunger signals.

23
Q

What role does the liver have in regulating appetite?

A

Nutrient receptors in the liver send neural signal to the brain indicating that ingested food is being broken down and decreasing hunger signals.

24
Q

What is the difference between short term satiety and long term satiety?

A

Short term - stops after a sing meal
Long term satiety - arises in the adipose tissue, controls long-term nutrient behaviour

25
Q

What is the role of RBP4 in regulating appetite and metabolism?

A

Rises with fat levels and reduces other tissues responsiveness to insulin
Can encourage weight loss

26
Q

What is the role of adiponectin in regulating appetite and metabolism?

A

Enhances cellular responses to glucose and insulin - can encourage weight gain
Antagonists RBP4
Levels fall in obesity.

27
Q

What are the different sources that the hypothalamus can recieves signals from to regulate appetite and metabolism?

A

Neuronal signals from the GI tract on sensory information about stomach filling
Chemical signals in the bloof that signify satiety
GI hormone signals
Hormones released by adipose tissue
Signals from the cerebral cortex that influence feeding behaviour

28
Q

What is an anorexigenic substance?

A

Substance that inhibit feeding

29
Q

What is an orexigenic substance?

A

Substances that stimulate feeding (increase appetite)

30
Q

What neuron type is mainly involved in the thirst pathway?

A

Glutaminergic neurons

31
Q

How can certain recreational drugs regulate appetite?

A

Cocaine and amephetaimine-regulate transcript - decrease appetite

Endocannabinoids - increase appetite

32
Q

What are the different probable chemical receptors in taste cells?

A

13 in total
2 sodium receptors
2 potassium receptors
1 chloride receptor
1 adenosine receptor
1 inosine receptor
2 sweer receptors
2 bitter receptors
1 glutamatee receptor
1 hydrogen ion receptor

33
Q

What are the five general modalities of taste that taste chemical receptors have been grouped into?
What food may activate each group?

A

Sour - acids/H+
Salty - ionised salts Na+
Sweet - sugars, alcohols, ketones, esters, AA, some acids, amides, aldehydes
Bitter - long chain organic substances containing nitrogen and alkaloids
Umami - containing L-glutamate such as meat and againg cheese

34
Q

Why is the bitter taste important to survival?

A

Receptors can be activated by alkaloids, alkaloids are found naturally in poisonous plants and toxins
A high intensity bitter taste can cause the person to regect the food
An safety mechanism against poisons

35
Q

How can taste by modified?

A

By endocrine and cytokine messengers
Suggests that the state of the body alters our enjoyment of the food we ingest

36
Q

How does angiotensin 2 alter taste?

A

Decreased sensitivity to salty taste (so eat more salt)
Increases sensitivity to sweet taste

37
Q

How does glucagon influence our taste?

A

Increased sensitivity to sweet taste
Acts as a preventative for hyperglycemia and glucagon activates gluconeogenesis and glycogenolysis

38
Q

How does TNFalpha influence our taste?

A

Decreases sensitivity to bitter tasting foods
Can explain taste abnormalities and decreased food uptake during chronic infection

39
Q

What is the physiological mechanism behind Pica?

A

Mechanism is unclear with no clear link to dietary requirements
Craving for non-food item may be associated with a variety of micronutrient deficiency e.g iron, Vitamin D etc
Is an eating disorder

40
Q

What tests should be completed as a precaution alongside a diagnosis of Pica?

A

Anaemia
Test for intestinal blockages
Toxic side effects of substances consumed - e.g lead in paint, bacteria from dirt etc.

41
Q

What is the purpose of sodium appetite?

A

Can be regulated, is negativly proportional to the amount of sodium ions in the body
Deficiency of sodium ion leads to increased sodium appetite encourages to eat more salty foods

42
Q

What regulates the sodium appetite?

A

Sodium depletion
Increased activation of aldosterone-activated HSD2 neurons in the nucleus tractus solitarii
These contain c-Fos immunoreactive nuclei
Thought to be responsive for increased sodium appetite.

43
Q

What is the role of the ventromedial nucleus of the hypothalamus in hunger control?

A

Produces satiety singla s
If damaged caused to overeat and obesity

Unit 10 (37 decks)

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