Basic Processes of Nutrition

Question 1

Nutrition is…

Answer 1

A process that involves hunger, ingestion, digestion, absorption, transportation, utilization/metabolize, storage, and excretion of nutrients.

Question 2

What drives us to eat?

Answer 2

Appetite and Hunger

Question 3

Appetite

Answer 3

Psychological drive to eat (specific).
Overwhelming of our senses.
Advertising/marketing of food is targeted to our appetite (psychological drive).

Question 4

Hunger

Answer 4

Physiological drive to eat (non-specific).

Question 5

What signals use to stop eating?

Answer 5

Satiety is the signal to stop eating (feeling of fullness).

Question 6

Hunger, satiety and the brain…

Answer 6

Hypothalamus integrates nerve and blood signals to trigger hunger or satiety.

Question 7

Hypothalamus Signals

Answer 7

Specialized cells in stomach and small intestine.
-Enteric Nervous System involved
Hormones

Question 8

Enteric Nervous System

Answer 8

Detects changes in pressure in the stomach and small intestine.
Not a lot of volume with processed foods which allows you to eat more before stomach and small intestine begin to stretch compared to whole foods.

Question 9

Hormones

Answer 9

Blood glucose levels affect levels of insulin and glucagon (follows negative feedback loop).
-insulin decreases blood sugar
-glucagon increases blood sugar
Low blood glucose is a last resort hunger signal.
Insulin can reduce hunger independently and through stimulation of a hormone called leptin.
Hunger = ghrelin, neuropeptide Y, galanin
Satiety = leptin, CCK, serotonin, PYY 3-36

Question 10

Process when the stomach is empty…

Answer 10

1) Ghrelin secreted (produced by stomach duodenum) from stretch receptors indicating stomach is empty.
2) Ghrelin reacts with receptors in the hypothalamus and releases neuropeptide Y.
3) Hunger increased.
4) Eat and fill stomach.
*cycle repeats.

Question 11

Satiety Signal Process A

Answer 11

1) Stomach is full.
2) Chyme passes into small intestine (duodenum).
3) Chyme stimulates the intestinal cells to secrete CCK; energy content stimulates the release of PYY.
4) Hunger decreased (satiety = stop eating)

Question 12

Satiety Signal Process B

Answer 12

1) Stomach is full.
2) Chyme passes into small intestine (duodenum).
3) Macronutrients absorbed into bloodstream.
4) Insulin released which stores fats in adipose tissue.
5) Adipocyte releases leptin
-gives sensation of feeling full
-can get overwhelmed quickly and stop working as efficiently or at all.
6) Leptin inhibits neuropeptide Y which prevents feeling hungry (satiety = stop eating).

Question 13

Three Factors Affecting Satiety

Answer 13

Food Type
Food Amount
Food Form

Question 14

Food Type

Answer 14

Protein and fat have a higher satiety value than CHO.
Why?
-protein stimulates PYY and CCK to a greater degree than CHO which makes you feel fuller quicker and longer.
-fat has a higher energy density
-more fats = more than 2 times the calories when detected by small intestine which increases leptin secretion to decrease hunger

Question 15

Food Amount

Answer 15

Bulky foods stretch the stomach and small intestine and send nervous and hormonal signals back to the brain.
Don’t uptake nutrients (glucose) when consume more fibre.
-fibre latches on and doesn’t allow nutrients to get absorbed
-usually glucose and some fats
Think volumetrics.

Question 16

Food Form

Answer 16

Solid and semisolid foods have higher satiety value than beverages.
-chewing theory, digestion theory, psychology

Question 17

Chewing Theory

Answer 17

Act of chewing food for longer starts cascade of neural and endocrine responses that indicate your eating.
Increases physiological responses.

Question 18

Digestion Theory

Answer 18

Whole foods more slowly digested.
Takes longer to break parts down.

Question 19

Psychology

Answer 19

Our perceptions of food matter.
Snack vs meal studies.