Chapter 25: Nutrition, Metabolism, and Temperature Regulation

Nutrition:

• the process by which living organism assimilates food and uses it for growth and for replacement of tissues

Nutrients:

**chemicals used by body to produce energy, provide building blocks or function in other chemical reactions

• water

• carbohydrates

• proteins

• lipids

• vitamins

• minerals

Essential nutrients:

**must be ingested because the body cannot manufacture itself or is unable to manufacture adequate amounts 

• certain amino acids and fatty acids

• most vitamins and minerals

• water

• minimum number of carbohydrates 

Carbohydrates:

**Can be ingested in different forms (most come from plants)

• Monosaccharides:

• glucose, fructose, galactose

Carbohydrates:

**Can be ingested in different forms (most come from plants)

• Disaccharides:

• sucrose, maltose, lactose

Carbohydrates:

**Can be ingested in different forms (most come from plants)

• Polysaccharides: 

• starch, glycogen, cellulose (complex) 

• Polysaccharides and disaccharides are converted to glucose 

—> can be used for energy or stored as glycogen or fat 

Carbohydrates: Uses in the body:

Digestion:

• breaks polysaccharides and disaccharides into monosaccharides before absorption

Carbohydrates: Uses in the body:

Liver: 

• converts monosaccharides into glucose which is then used as an energy source to produce ATP

Carbohydrates: Uses in the body:

Excess glucose: 

• converted to glycogen and stored in muscles and liver cells

• excess beyond storage is converted to fat 

Carbohydrates: Uses in the body:

Sugars: 

• can also become part of DNA, RNA, and ATP, glycoproteins, glycolipids

Lipids:

• can be ingested as: Triglycerides (95%) or cholesterol, phospholipids, and linoleic acids (5%)

Lipids:

Triglycerides:

• used for energy or stored in adipose tissue and liver

Lipids: 

Cholesterol:

• forms other molecules, such as steroid hormones

• cholesterol and phospholipids are part of the plasma membrane 

Lipids:

Linoleic acids: 

• essential fatty acids 

• found in seeds, nuts, legumes, grains and green leaves 

Lipids: Uses in the body

Triglycerides:

• used to produce ATP

• excess stored in adipose tissue or liver

Lipids: Uses in the body

Cholesterol:

• can be ingested or manufactured in body

• can be modified to form bile salts and steroids

Lipids: Uses in the body

Eicosanoids derived from fatty acids: 

• involved in inflammation, blood clotting, tissue repair, smooth muscle contraction

Lipids: Uses in the body

Phospholipids: 

• part of plasma membrane and used to construct the myelin sheath 

• part of bile 

Proteins:

• ingested and broken down into amino acids

• chains of amino acids

Types of amino acids:

Essential:

• must be obtained in diet

Types of amino acids:

Nonessential: 

• body can synthesize 

Complete proteins:

• contain all necessary amino acids

• meat, fish, poultry, milk, cheese, eggs

Proteins: Uses in the body:

Protection:

• protect against (defense) foreign antibodies

Proteins: Uses in the body:

Regulation:

• enzymes, hormones

Proteins: Uses in the body:

Structure: 

collagen

Proteins: Uses in the body:

Muscle contraction: 

• actin and myosin 

Proteins: Uses in the body:

Transportation: 

Anddd receptors 

• hemoglobin transport proteins 

How many kilocalories a gram of fat?

9 kcal

How many kilocalories a gram of protein?

4 kcal

How many kilocalories a gram of carbohydrates?

4 kcal 

How to calculate total kcal:

Metabolism:

sum of all chemical changes that occur within the body:

Catabolism:

• The breakdown of larger molecules into smaller molecules

—> energy is released

Anabolism:

• the building up of smaller molecules to form a larger molecule 

—> energy is required

***The energy in carbs, lipids, and proteins is used to produce ATP through oxidation-reduction reactions