Nutrition Nutrients are the constituents of food necessary

Nutrition Nutrients are the constituents of food necessary to sustain the normal functions of the body. All energy is provided by three classes of nutrients: fats, carbohydrates, protein, and in some diets, ethanol. The intake of these energy-rich molecules is larger than that of the other dietary nutrients. Therefore, they are called the macronutrients. This lecture focus on the kinds and amounts of macronutrients that are needed to maintain optimal health and prevent chronic disease in adults. Those nutrients needed in lesser amounts, such as vitamins and minerals, are called the micronutrients are also mentioned.

Learning Objectives 1. How Are the Metabolic Pathways Connected? 2. How Can Biochemistry Help Us Understand Nutrition? 3. What Are Hormones and Second Messengers? 4. How Are Hormones Involved in the Control of Metabolism? 5. What Are the Many Effects of Insulin?

Fig. 24 -1, p. 663

p. 664

Table 24 -1, p. 665

Table 24 -2, p. 666

In humans, the choice of diet becomes important in the interest of obtaining enough of essential nutrients while avoiding excesses of others, such as saturated fats, where excess is known to play a role in the development of health problems. In 1992, a food guide pyramid was published to explain nutrition basics to the public.

Fig. 24 -2, p. 668

The previous pyramid is currently being replaced by a newer version that recognizes the differences between various types of fats and carbohydrates instead of just sending the message that all fats are bad and all carbohydrates are good.

Fig. 24 -3, p. 669

Leptin is a hormone that affects metabolism. It affects the brain to suppress appetite and it affects metabolism directly by stimulating fatty acid oxidation and inhibiting fatty acid synthesis.

Leptin is a protein that's made in the fat cells, circulates in the bloodstream, and goes to the brain. "Leptin is the way your fat cells tell your brain that your energy thermostat is set right, " Leptin tells your brain that you have enough energy stored in your fat cells to engage in normal, relatively expensive metabolic processes, “ like exercise.

Leptin activates AMPdependent pro- tein kinase (AMPK), which regulates many aspects of fuel metabolism. Fig. 24 -4, p. 670

Fig. 24 -5, p. 671

Fig. 24 -6, p. 671

Table 24 -3, p. 672

Fig. 24 -7, p. 673

Fig. 24 -8, p. 674

Fig. 24 -9 a, p. 675

Fig. 24 -9 b, p. 675

Fig. 24 -10, p. 676

p. 676

Fig. 24 -11, p. 677

Fig. 24 -12 a, p. 678

Fig. 24 -12 b, p. 678

epidermal growth factor fibroblast growth factor Fig. 24 -13, p. 679

p. 681

Fig. 24 -14, p. 682

Fig. 24 -15, p. 683

Fig. 24 -16, p. 684

Fig. 24 -17, p. 685

Table 24 -4, p. 685

It has been shown that the GLUT 4 transporter responds to physical activity. When a person is active, the transporter is active and responds well to insulin. After a few days of detraining, this transporter shows only half of the activity it did before. GLUT 4 is one of the glucose transporters on muscle cells. It responds to insulin to move glucose out of the blood and into the cell. In type II diabetes, insulin is present, but does not have the same effect. It takes more insulin to accomplish the same movement out of the blood and into the cell. People with type II diabetes often show classical signs of obesity, and there is a correlation between diminishing GLUT 4 activity, obesity, and diabetes.

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