Ghrelin is a hormone produced in the stomach that stimulates hunger. It is also known as the “hunger hormone” or the “appetite hormone”. Ghrelin levels are highest before meals and decrease after meals. Ghrelin is secreted by the stomach and small intestine. It acts on the hypothalamus, which is a region of the brain that controls hunger and appetite.
Ghrelin: The “Hunger Hormone”
Ghrelin, often referred to as the “hunger hormone,” is a peptide hormone primarily produced by the stomach and plays a crucial role in regulating appetite and energy balance. Here’s a structured overview of Ghrelin:
Definition and Nature
- Peptide hormone produced primarily by the stomach, especially by X/A-like cells in the gastric fundus.
- Classified as an orexigenic hormone, meaning it stimulates hunger and food intake.
Physiological Functions
- Appetite Regulation: Ghrelin levels rise before meals and stimulate hunger, contributing to meal initiation.
- Energy Balance: Ghrelin promotes energy storage by inhibiting thermogenesis (heat production) and increasing lipogenesis (fat storage).
- Gastric Secretion and Motility: Ghrelin enhances gastric acid secretion and motility, facilitating food digestion.
- Glucagon and Insulin Secretion: Ghrelin stimulates glucagon secretion from the pancreas and inhibits insulin secretion, contributing to elevated blood glucose levels.
Regulation of Ghrelin Secretion
- Hunger and Food Intake: Ghrelin levels are highest before meals and decrease after food consumption.
- Circadian Rhythm: Ghrelin secretion follows a diurnal rhythm, peaking during the sleep-wake transition and declining throughout the day.
- Body Weight and Obesity: Obesity is associated with decreased ghrelin levels compared to lean individuals.
- Pathologies: Ghrelin levels can be altered in conditions such as anorexia nervosa, growth hormone deficiency, and gastrointestinal disorders.
Role in Metabolism and Energy Homeostasis
- Stimulates Adipogenesis: Ghrelin promotes the formation and growth of fat cells, contributing to energy storage.
- Regulates Triglyceride Metabolism: Ghrelin modulates triglyceride utilization and storage, influencing lipid metabolism.
- Influences Energy Expenditure: Ghrelin affects energy expenditure by regulating thermogenesis and activity levels.
Question 1: What is ghrelin in terms of AP Psychology?
Answer: Ghrelin is a hormone produced by the stomach and small intestine that stimulates appetite and hunger.
Question 2: How does ghrelin regulate food intake?
Answer: Ghrelin levels rise before meals, signaling the brain to increase hunger and stimulate food intake. After eating, ghrelin levels decrease, signaling the brain to decrease hunger and reduce food intake.
Question 3: What role does ghrelin play in obesity?
Answer: Ghrelin levels are typically higher in obese individuals, suggesting that it may contribute to the development and maintenance of obesity by increasing hunger and food intake.
Alright, folks, that’s it for our crash course on ghrelin. I hope you found this little deep-dive into your hunger hormone enlightening. Remember, knowledge is food for the brain, and I’m always cooking up new articles to keep you well-nourished. Swing by my page again soon for more science-y goodness. Until next time, stay curious and keep your appetites in check!