HUMANBIOLOGY_CHAPTERTWENTYEIGHT

digestive system

organ system consisting of the intestines and other organs that ingest and dismantle food, absorb nutrients, and eliminate wastes

autotroph

organism that produces organic molecules by acquiring carbon from inorganic sources; a primary producer

macronutrient

nutrient required in large amounts

Calorie

a measure of the energy content in food; equal to 1000 calories or 1 kilocalorie

obesity

condition characterized by an unhealthy amount of body fat; body mass index greater than 30

anorexia nervosa

eating disorder characterized by unhealthy restriction of food intake

bulimia

eating disorder in which a person eats large quantities and then intentionally vomits or uses laxatives shortly afterward

stomach

J-shaped compartment that mechanically and chemically breaks down food received from the esophagus

gastric juice

mixture of water, mucus, ions, hydrochloric acid, and enzymes produced at the stomach lining

small intestine

the part of the digestive tract that connects the stomach with the large intestine; site of most chemical digestion and absorption

intestinal villus (pl. villi)

tiny projection on the inner lining of the small intestine

microvillus (pl. microvilli)

extension of the cell membrane; increases the surface area of an epithelial cell of an intestinal villus

pancreas

gland between the spleen and the small intestine; produces hormones, digestive enzymes, and bicarbonate

bile

digestive biochemical that emulsifies fats

liver

organ that produces bile and has many other functions

gallbladder

organ that stores bile from the liver and releases it into the small intestine

large intestine

part of the digestive tract that connects the small intestine to the anus; absorbs water and ions and eliminates wastes

A digestive system is adaptive because it allows animals to ______ in different types of environments.

extract nutrients from foods and liquids

An organism that uses inorganic materials and an energy source to build organic molecules is called a(n) ______.

autotroph

Water, carbohydrates, proteins, and lipids are four ______.

macronutrients

A standard measurement of the amount of energy contained in a food is the

calorie

Parrots have a different diet and therefore a slightly different digestive system than penguins and roadrunners.

True

Parrots have a different diet and therefore a slightly different digestive system than penguins and roadrunners.

anorexia nervosa

Nutrition labels list a food's energy content in units called _____.

calories

How is Body Mass Index (BMI) calculated?

Divide a person's weight in kilograms by squared height in meters.

Ingestion and the beginning of digestion take place in an area of the gastrointestinal tract called the ______.

mouth

People with ______ unhealthfully restrict energy intake due to a distorted view of their appearance or fear of gaining weight. Individuals with ______ eat but then intentionally vomit the stomach contents or use a laxative to eliminate the food in their gut.

anorexia nervosa; bulimia

Completion of food digestion and the majority of nutrient absorption takes place in what long, tubular organ of the digestive system?

small intestine

Smooth muscles underlying the entire digestive tract undergo ______, which are rhythmic waves of contraction.

peristalsis

The first 25 centimeters of the small intestine is called the ______.

duodenum

The villi and microvilli greatly increase the ______ of the small intestine, which allows for faster absorption of nutrients into the bloodstream.

surface area

Capillaries inside each villus of the small intestine empty into a vein that transports nutrient-laden ______ to the ______.

blood; liver

Ducts from the liver and pancreas release their products into the duodenum of the ______.

small intestine

Cells lining the small intestine release ______ that break down short polysaccharides and disaccharides into simple sugars, which are immediately absorbed.

digestive enzymes

The lining of the small intestine is composed of millions of finger-like projections called ______, which are lined with epithelial cells that have extensions of the cell membrane called ______.

villi; microvilli

Bile is released into the small intestine to help with the digestion of

fats

Within each villus of the small intestine, a ______ takes up digested fats.

lymph capillary

Most of the digestive enzymes in the small intestine are produced in the ______. 

pancreas

The function of bile is to

emulsify fat into small droplets to increase surface area for lipase.

Genetics can play a small part in obesity risk because some genes encode proteins that affect the transport of ______ hormones, which affect metabolic rate.

thyroid

After nutrients are absorbed in the small intestine, veins carry the nutrient-laden blood to the ______, which removes bacteria and toxins from the blood and can also store nutrients.

liver

What organ of the digestive system extends from the small intestine to the anus and functions to absorb water and ions and eliminate wastes as feces?

large intestine