Flashcards in Module 10.3 Deck (25)
Enzymes for the digestion of what type of nutrients are present in saliva?
Enzymes for the digestion of what type of nutrients are present in the stomach?
Enzymes for the digestion of what type of nutrients are present in the small intestine?
fats, carbohydrates, and proteins
From which structure is digested food absorbed?
The small intestine
Why do newborn mammals stop nursing as they grow older?
The milk dries up, the mother pushes them away, they begin to try other food, and they lose lactase (which is necessary for metabolizing lactose).
Discuss the evidence that humans are a partial exception to the principle of lactose intolerance in adults.
Many adults have enough lactase levels to consume milk and other dairy products throughout life. Asians lack the gene to metabolize lactose. In Africa, the ability to metabolize lactose varies from place to place. Europeans can metabolize lactose easily.
List the factors that may influence food selection.
You are likely to select sweet foods, avoid bitter ones, and eat salty or sour foods in moderation. People prefer anything that tastes familiar. People acquire their culture's food preferences.
Summarize the evidence for the importance of oral factors in hunger and satiety. What is the evidence that these factors are not sufficient to end a meal normally?
Studies show that people who took a pill instead of eating, were not satisfied and people who tasted and ingested food, but the food was not digested, were also not satisfied.
How did Deutsh et all. demonstrate the importance of stomach distension in regulating meal size?
They attached an inflatable cuff at the connection between the stomach and small intestine. When they inflated the cuff, food could not pass from the stomach to the duodenum. With the cuff inflated, the animal ate a normal-size meal and then stopped.
What is the difference between the two nerves that convey the stomach's satiety signals?
The vagus nerve conveys information about the stretching of the stomach walls, providing a major basis of satiety. The splanchnic nerves convey information about the nutrient content of the stomach.
What is CCK?
a hormone released by duodenum in response to food distension and it helps you to feel full
What are two ways that CCK induces satiety?
by closing the sphinter muscle between the stomach and the duodenum, causing the stomach to hold its contents and fill more quickly than usual and by stimulating the vagus nerve causing cells in the hypothalamus to release a neurotransmitter that is a shorter version of the CCK molecule
What is the effect of insulin on blood glucose?
Insulin enables glucose to enter cells
In what ways does insulin affect hunger?
High levels of insulin decrease appetitite
Compare the effects of glucagon with those of insulin/
Glucagon stimulates the liver to convert some of its stored glycogen to glucose
Why do people with untreated diabetes eat a lot but gain little weight? How is this similar to, and different from, the effects of high levels of insulin?
People with diabetes have low levels of insulin and eat more food than normal because their cells are starving, but they excrete most of their glucose and lose weight.High levels of insulin and low levels of insulin both increase hunger. High levels increase weight; low levels decrease weight.
Where is leptin produced?
in fat cells
What are the effects of leptin?
Leptin signals the brain about the body's fat reserves, providing a long term indicator of whether meals are too large or too small
Why can't obesity be treated with leptin?
High levels of leptin don't decrease hunger for everyone
What do the two types of cells in the arcuate nucleus do?
one set of cells are sensitive to hunger cells and the other set are sensitive to satiety
What chemical differences are seen in bulimics compared with other people?
People with bulimia have decreased release of CCK, increased release of ghrelin, and alterations of several other hormones and neurotransmitters associated with eating.
Describe the evidence that the lateral hypothalamus is important for hunger.
An animal with damage to the this area refuses food and water.
By what four mechanisms does the lateral hypothalamus contribute to feeding?
1. It sends messages to make the food taste better when it detects hunger.
2. Facilities ingestion and swallowing and causes cortical cells to increase their response to taste, smell, or sight of food.
3. Increases the pituitary gland's secretion of hormones that increase insulin secretion.
4. Sends axons to spinal cord. controlling autonomic responses such as digestive secretions.
Describe the various behavior changes produced by lesions of the ventromedial hypothalamus, ventral noradrenergic bundle, and surrounding areas.
overeating and weight gain