001 Why Eat? Flashcards
What is Ghrelin?
A short term orexigenic hormone (appetite stimulating)
When does the concentration of Ghrelin peak/drop?
It will peak during normal meal times to stimulate gastric acid in anticipation of digestion. It decreases at different rates as you gain nutrients.
What are satiety signals?
Signals such as CCK, Amylin, glucon that signal the feeling of “fullness”
How can satiety signals work?
They interact with receptors on nerves that innervate the GI tract. This leads to inhibit ion of gastric emptying which slows down the rate of digestion. Some also act to cause feeling of nausea at high levels.
What is Leptin?
A long term adiposity satiety signal released by white adipose tissues. It reflects subcutaneous fat.
What is Insulin?
A long term adiposity signal secreted in response to carbohydrate intake, with levels reflecting visceral body fat.
How do insulin and leptin levels work to act as long term adiposity signals?
- Insulin and Leptin travel to the hypothalamic arcuate nuclei.
- Different levels of these hormones activate neurons found in the nuclei that produce neuropeptide Y and pro-opiomelanocortin (POMC)
- These innervate the paraventricular nucleus (PVN) and lateral hypothalamic area (LHA).
- When activated, these secrete neuropeptides that change senitivity of NTS to satiety signals received from the GI tract (through vagus nerve).
What happens when there are high insulin and leptin levels.
This increases secretion of POMC, which stimulates the PVN, causing higher sensitivity to satiety signals and resulting in smaller meals.
What response to leptin and insulin would obesity be associated with?
Both insulin and leptin resistance, as body deals with weight loss much more than weight gain.
Why can we taste sweetness when ingesting carbohydrates?
Salivary amylase breaks down starch to release sugars that taste sweet even if there are complex carbohydrates.
How do we we detect the sweet taste?
G-protein coupled receptors on taste receptor cells.
Why do we have an innate aversion to sourness?
It is part of the body’s mechanism to regulate pH.
What are TAS2R receptors?
Receptors that encode bitter taste receptors. This is the largest family of taste receptors.
Why are there “non-tasters” and “tasters” of PROP/PTC paper?
There is a different TAS2R receptor for each compound, so there is heritable variation.
What are some clinical signals of nontasters and tasters
Non tasters prefer sweet, high fat foods and have a higher risk of alcoholism. Tasters have lower preference for citrus fruit and cruciferous vegetables.
