Nutritional Requirements Nutritional Requirements

Marie ČernáMarie Černá

A nutritionally adequate diet A nutritionally adequate diet satisfies three needs:satisfies three needs:

• chemical energy for all cellular work of the body,

the generation of ATP by cellular respiration,

from the oxidation of organic molecules

(carbohydrates, proteins and fats)• the organic raw materials are used in biosynthesis

(carbon skeletons to make many of own molecules)• essential nutrients,

substances cannot be made from any raw material, but must be obtained in food in prefabricated form

Nutritional termsNutritional terms

• over nourishment - obesity (caloric excess)

- storing the excess calories in the form of

glycogen (liver and muscles) and fat (adipose tissue)• undernourishment (caloric deficiency)

- breaking down its own proteins (muscles and brain)• malnourishment (mineral or protein deficiencies)

- missing one or more essential nutrients

Homeostatic mechanism in Homeostatic mechanism in nutritional requirements:nutritional requirements:

• The human body tends to hoard fat, to immediately store any excess fat molecules obtained from food instead of using them for fuel or biosynthesis.

• By contrast, when we eat an excess of carbohydrates, the body tends to increase the rate of carbohydrate consumption.

• Thus, the amount of fat in the diet can have a more direct effect on weight gain than carbohydrates.

Paleolithic huntersPaleolithic hunters

Fat hoarding can be a liability today, but it may have provided a degree of fitness for our hunting/gathering ancestors. Individuals with genes promoting the storage of high-energy molecules during feasts may have been those that survived famines.

Complex feedback mechanisms Complex feedback mechanisms regulate fat storageregulate fat storage

Leptin – a hormone produced by adipose cells↑ of body fat (in adipose tissue) increases leptin levels

in the blood→ signaling the brain to depress appetite andincrease energy-consuming muscular activity

and body heat production↓ of body fat (in adipose tissue) decreases leptin levels

in the blood→ signaling the brain to increase appetite and

weight gain

There are four classes of There are four classes of essential nutrients:essential nutrients:

essential amino acids (9 of 20 required amino acids)sources: animal products: meat, eggs, cheese

essential fatty acids (unsaturated fatty acids)for phospholipids in membranes

vitamins (0.01 – 100 mg per day)- water-soluble (B + C) - their excesses are excreted in urine, moderate overdoses are harmless- fat-soluble (A, D, E, K) - their excesses are not excreted but are deposited in body fat, overdoses result in their accumulation to toxic levels

minerals (1 – 2500 mg per day)

VitaminsVitaminsWater-soluble

Vitamin B1 (thiamine)

Vitamin B2 (riboflavin)

Vitamin B6 (pyridoxine)

Vitamin B12

Folic acid (folacin)Pantothenic acidNiacinBiotinVitamin C (ascorbic acid)

Fat-solubleVitamin A (retinol)Provitamin A (beta-carotene)Vitamin DVitamin E (tocopherol)Vitamin K (phylloquinone)

MineralsMineralshigher quantity

Calcium (Ca)

Phosphorus (P)

Sulfur (S)

Potassium (K)

Sodium (Na)

Chlorine (Cl)

Iron (Fe)

Iodine (I)

Fluorine (F)

lower quantity

Magnesium (Mg)

Zinc (Zn)

Cooper (Cu)

Manganese (Mn)

Cobalt (Co)

Selenium (Se)

Chromium (Cr)

Molybdenum (Mo)

LiteratureLiteratureBiology, eighth edition,

Campbell, Reece

Unit seven: Animal Form and Function

Chapter 41: Animal Nutrition

Concept 41.1: An animal’s diet must supply chemical energy, organic molecules, and essential nutrients

Concept 41.5: Homeostatic mechanisms contribute to an animal’s energy balance

Pages 875 – 880, 893 – 896