T HE D IGESTIVE S YSTEM HBO 11 A.MacAskill

I NTERESTING F ACTS Individuals produce 1.7 liters of saliva each day. Every day 11.5 liters of digested food, liquids and digestive juices flow through the digestive system, but only 100 mls is lost in feces. An adults stomach can hold ~1.5 liters of material. 70-year-olds may produce as little as half the enzymes they produced when they were 20. Small intestine is ~ 23 feet long and Large intestine is ~ 5 feet long Individuals “pass gas” ~ 14 times per day

B ODY N UTRIENT R EQUIREMENTS Our bodies require 5 essential nutrients to function properly and survive: Carbohydrates Fats Proteins Vitamins Minerals Humans cannot survive without water

C ARBOHYDRATES (C ARBS ) Carbs are the body’s major energy source. There are 3 types of carbohydrates: Monosaccharaides ( mono= one, saccharide = sweet) Ex: Glucose, fructose, galactose Disaccharides (di = two) are two monosaccharaides linked together. Ex: glucose +fructose = sucrose Polysaccharides ( poly=many) are composed of many monosaccharaides linked together into long chains. Ex: glucose + glucose+ glucose + glucose = starch

MORE ABOUT CARBOHYDRATES… When the body does not have adequate amounts of carbs. The body breaks down structural proteins to meet the body’s energy needs. Glucose is important and its amount in the blood is monitored at all times ( blood sugar level ) Sources of carbs: whole grains, starchy vegetables or fruits

WHAT IS THE STRUCTURE OF FAT? Fats provide twice the amount of energy per gram when compared to carbs or proteins Two main structural parts: Glycerol Three fatty acid chains (a long carbon chain) This is called a triglyceride Two types of Fat: Saturated: molecule has no double bonds Solid at room temperature, typically animal fats Unsaturated: molecule has double bonds Liquid at room temperature, typically vegetable fats

Fats continued… Trans Fats are known as “Bad cholesterol” because they increase the risk of developing heart disease Fats have two functions in the body: Necessary to dissolve fat-soluble vitamins A, D, E and K Protect the internal organs and maintain body temperature E xcess carbohydrates are turned into fats and stored in the adipose tissues of the body

WHAT ARE PROTEINS? Proteins are comprised of many amino acids. There are only 22 amino acids in the body, the order, sequence, and number of amino acids determine the protein. Essential amino acids: amino acids the body cannot make for itself There are eight essential amino acids in the body

Function of Proteins Proteins are essential for the building, repair and maintenance of body tissues. Play an important role in the balance of fluids and nutrients inside and outside of the cell.