Chapter 25: Animal Nutrition and the Digestive System

alimentary canal

tubular digestive system with a mouth and anus

aminopeptidase

protease that breaks down peptides to single amino acids; secreted by the brush border of small intestine

anus

exit point for waste material

bile

digestive juice produced by the liver; important for digestion of lipids

bolus

mass of food resulting from chewing action and wetting by saliva

carboxypeptidase

protease that breaks down peptides to single amino acids; secreted by the brush border of the small intestine

carnivore

animal that consumes animal flesh

cephalic phase

first phase of digestion, controlled by the neural response to the stimulus provided by food

cholecystokinin

hormone that stimulates the contraction of the gallbladder to release bile

chylomicron

small lipid globule

chyme

mixture of partially digested food and stomach juices

chymotrypsin

pancreatic protease

digestion

mechanical and chemical break down of food into small organic fragments

dipeptidase

protease that breaks down peptides to single amino acids; secreted by the brush border of small intestine

duodenum

first part of the small intestine where a large part of digestion of carbohydrates and fats occurs

elastase

pancreatic protease

endocrine system

system that controls the response of the various glands in the body and the release of hormones at the appropriate times

esophagus

tubular organ that connects the mouth to the stomach

essential nutrient

nutrient that cannot be synthesized by the body; it must be obtained from food

gallbladder

organ that stores and concentrates bile

gastric inhibitory peptide

hormone secreted by the small intestine in the presence of fatty acids and sugars; it also inhibits acid production and peristalsis in order to slow down the rate at which food enters the small intestine

gastric phase

digestive phase beginning once food enters the stomach; gastric acids and enzymes process the ingested materials

gastrin

hormone which stimulates hydrochloric acid secretion in the stomach

gastrovascular cavity

digestive system consisting of a single opening

gizzard

muscular organ that grinds food

herbivore

animal that consumes strictly plant diet

ileum

last part of the small intestine; connects the small intestine to the large intestine; important for absorption of B-12

ingestion

act of taking in food

intestinal phase

third digestive phase; begins when chyme enters the small intestine triggering digestive secretions and controlling the rate of gastric emptying

jejunum

second part of the small intestine

lactase

enzyme that breaks down lactose into glucose and galactose

large intestine

digestive system organ that reabsorbs water from undigested material and processes waste matter

lipase

enzyme that chemically breaks down lipids

liver

organ that produces bile for digestion and processes vitamins and lipids

maltase

enzyme that breaks down maltose into glucose

mineral

inorganic, elemental molecule that carries out important roles in the body

monogastric

digestive system that consists of a single-chambered stomach

omnivore

animal that consumes both plants and animals

pancreas

gland that secretes digestive juices

pepsin

enzyme found in the stomach whose main role is protein digestion

pepsinogen

inactive form of pepsin

peristalsis

wave-like movements of muscle tissue

proventriculus

glandular part of a bird’s stomach

rectum

area of the body where feces is stored until elimination

roughage

component of food that is low in energy and high in fiber

ruminant

animal with a stomach divided into four compartments

salivary amylase

enzyme found in saliva, which converts carbohydrates to maltose

secretin

hormone which stimulates sodium bicarbonate secretion in the small intestine

small intestine

organ where digestion of protein, fats, and carbohydrates is completed

somatostatin

hormone released to stop acid secretion when the stomach is empty

sphincter

band of muscle that controls movement of materials throughout the digestive tract

stomach

saclike organ containing acidic digestive juices

sucrase

enzyme that breaks down sucrose into glucose and fructose

trypsin

pancreatic protease that breaks down protein

villi

folds on the inner surface of the small intestine whose role is to increase absorption area

vitamin

organic substance necessary in small amounts to sustain life