Human Digestive System

the vertebrate digestive system is a _____, running from _____ to _____. it has several accessory glands, including the _____ and _____.

tubular gut, mouth, anus, liver, pancreas

digestive system function

mechanical and chemical breakdown of food and the absorption of nutrients

digestive system consists of (2)

alimentary canal and accessory organs

circular muscle layer

nerve net between muscle layers

longitudinal muscle layer

4 characteristics of the canal

mucosa, submucosa, muscular layer, serosa

mucosa

protects tissues and carries absorption

____ carries absorption

mucosa

_____ includes glands, blood vessels, and nerves

submucosa

muscular layer

smooth muscle, pushes food (peristalsis)

serosa

lubricates surfaces

gut epithelium plus the underlying connective tissue are called the

mucosa

the submucosa has _____ and _____ that carry ____ to the rest of the body, plus _____ that control the _____ functions of the gut

blood and lymph vessels, absorbed nutrients, neurons, secretory

the two layers of smooth muscle surround the submucosa

circular and longitudinal

the two layers of smooth muscle surround the submucosa:

circular muscle are _____ cells oriented around the gut that _____ the gut

innermost, constrict

the two layers of smooth muscle surround the submucosa:

longitudinal muscle are _____ cells oriented along the gut that _____ the gut

outermost, shorten

the two layers of smooth muscle surround the submucosa:

between the two layers are _____ that _____ of the gut

nerves, coordinate movement

tissues of the gut wall are arranged in _____ layers

concentric

gut epithelium contains mostly _____ cells that secrete _____. also has _____ and _____ cellls.

digestive absorption cells, digestive enzymes, mucus secreting, endocrine

food materials are pushed along by waves of contraction called

peristalsis

______ also control food movement. they encircle the gut and contract so tightly that they _____

sphincter muscles, seal off one part of the gut from another

neurons in the gut make up the _____ system, part of the _____ nervous system

enteric, autonomic

digestive enzymes break bonds by ______

hydrolysis

digestive enzymes are classified according to

the type of molecules they digest

_____ hydrolyze fats

lipases

proteases and peptidases hydrolyze _____

proteins

carbohydrates hydrolyze _____

bonds between sugar units in carbohydrates

starch glycogen → salivary amylase → short branched polysaccharides (______) → monosaccharides (_____)

limit dextrins, glucose

starch glycogen → salivary amylase → disaccharides (maltose) → monosaccharides (____)

2 glucose

starch glycogen → salivary amylase → disaccharides (sucrose) → monosaccharides (____)

1 glucose, 1 fructose

starch glycogen → salivary amylase → disaccharides (lactase) → monosaccharides (____)

1 glucose, 1 galactose

protein digest begins in the _____ by _____ and the enzyme _____

stomach, hydrochloric acid, pepsin

protein-digesting enzymes are secreted from the ____ into the ____

pancreas, small intestine

absorbed amino acids enter the blood and travel to the ____

liver

the liver regulates distribution of _____ to the rest of the body

amino acids

protein-digesting enzymes are also secreted from the

brush border

the ____ is the major site of protein digestion; final digestion occurs here

small intestine

a small amount of ____ is lost in the ____

dietary protein, feces

the digestion of a short protein by three protein-digesting enzymes

trypsin, chymotrypsin, carboxypeptidase B

protein → large polypeptides → (_____) → (_____)

small peptides and amino acids, amino acids

digestive enzymes are also classified by where they act:

______ enzymes digest food molecules in the lumen

intraluminal

digestive enzymes are also classified by where they act:

membrane-associated enzymes are attached to the

epithelial cells lining the gut lumen

digestive enzymes are also classified by where they act:

____ enzymes are inside some gut epithelial cells

intracellular