30 Questions
Which of the following best describes the goal of a regulatory system?
To keep the system variable near the set point
What is the process by which the effect of a correctional mechanism diminishes or terminates further corrective action?
Satiety
Which of the following is associated with satiety?
Adequate supplies of readily available food and water
What triggers osmometric thirst?
Cells being too big
Which region of the hypothalamus is responsible for the feeling of thirst?
AV3V region
What type of neurons in the AV3V region of the hypothalamus are sensitive to angiotensin?
Osmoreceptors
Which of the following best describes homeostasis?
A process by which substances in the body are regulated
What happens when blood glucose levels are low?
The pancreas releases glucagon
What is the purpose of ingestive behavior?
To survive
Which cells in the body can use glucose without the need for insulin?
Brain cells
What is a characteristic of a classic thermostat?
It is slow to warm up
Why is it important for the body to maintain a set point for temperature?
To predict and prevent extreme temperatures
Which neurons in the arcuate nucleus of the hypothalamus promote hunger?
AGRP/NPY neurons
Which neurons in the arcuate nucleus of the hypothalamus inhibit hunger?
POMC/α-MSH neurons
When leptin levels fall to critically low levels, what happens to the neurons in the paraventricular nucleus (PVN) of the hypothalamus?
They stop firing
What is the term used to describe the elevated leptin set point and reduced response to leptin levels observed in overweight individuals?
Leptin resistance
Which of the following is true about triglycerides?
Triglycerides are broken down into glycerol and fatty acids
What is the function of ghrelin?
Ghrelin increases hunger and food intake
Which of the following factors stops hunger after a meal?
Release of CCK and GLP-1 from the duodenum
How does the liver signal satiety?
By measuring glucose and free fatty acid levels in the blood
Which hormone is secreted by adipocytes and provides a negative feedback signal that decreases hunger?
Leptin
What happens when the brain senses dangerously low blood glucose levels?
Insulin secretion increases
What triggers the emergency feeding circuits when there is not enough body fat?
Low levels of leptin
What can excess insulin signaling or drugs that inhibit glucose metabolism cause?
Hyperglycemia
Which neuropeptides play an important role in regulating the motivational and hedonic effects of hunger?
GLP-1, NPY, orexin, and MCH
What is the most effective form of bariatric surgery?
Roux-en-Y gastric bypass (RYGB)
What is the purpose of bariatric surgery?
To reduce the amount of food that can be eaten
What happens to the rewarding and reinforcing value of food when satiety is reached?
It decreases
What happens to the rewarding and reinforcing value of food when hunger is experienced?
It increases
What is the role of neurons in the medulla and hypothalamus in hunger regulation?
They regulate dopamine neuron activity
Study Notes
Regulatory Systems
- The goal of a regulatory system is to maintain a set point or homeostasis.
Thirst Regulation
- Osmometric thirst is triggered by increased osmolality of the blood.
- The region of the hypothalamus responsible for the feeling of thirst is the anteroventral third ventricle (AV3V).
- Magnocellular neurons in the AV3V region of the hypothalamus are sensitive to angiotensin.
Hunger and Satiety Regulation
- The purpose of ingestive behavior is to maintain energy homeostasis.
- Red blood cells can use glucose without the need for insulin.
- Leptin levels falling to critically low levels activates neurons in the paraventricular nucleus (PVN) of the hypothalamus.
- Overweight individuals have an elevated leptin set point and reduced response to leptin levels, known as leptin resistance.
- Neurons in the arcuate nucleus of the hypothalamus that promote hunger are AgRP/NPY neurons.
- Neurons in the arcuate nucleus of the hypothalamus that inhibit hunger are POMC/CART neurons.
Glucose Regulation
- When blood glucose levels are low, the brain senses it as a life-threatening emergency and triggers the emergency feeding circuits.
- When the brain senses critically low blood glucose levels, it triggers the emergency feeding response to restore blood glucose levels.
Hormones and Metabolism
- Ghrelin is a hormone that stimulates appetite.
- Leptin is a hormone secreted by adipocytes that provides a negative feedback signal that decreases hunger.
- The liver signals satiety through the release of insulin and other hormones.
- Cholecystokinin (CCK) is a hormone that stops hunger after a meal.
Bariatric Surgery
- The purpose of bariatric surgery is to restrict food intake and induce weight loss.
- The most effective form of bariatric surgery is the Roux-en-Y gastric bypass.
Food Reward and Hedonics
- When satiety is reached, the rewarding and reinforcing value of food decreases.
- When hunger is experienced, the rewarding and reinforcing value of food increases.
- The role of neurons in the medulla and hypothalamus is to regulate hunger by integrating sensory information and hormone signals.
- Dopamine and opioid neuropeptides play an important role in regulating the motivational and hedonic effects of hunger.
Test your knowledge on the homeostatic regulation of feeding and the role of leptin in hunger and basal metabolic rate. Explore how leptin signaling affects hunger and the activity of specific neurons in the hypothalamus.
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