chapter 16 The digestive system

Question 1

What is the function of the digestive system?

Answer 1

changes complex organic nutrient molecules into simple organic and inorganic molecules that can then be absorbed into the blood or lymph to be transported to cells

Question 2

What are the two divisions of the digestive system?

Answer 2

The alimentary tube and the accessory organs

Question 3

What is the alimentary tube?

Answer 3

extends from the mouth to the anus

consists of the oral cavity, pharynx, esophagus, stomach, small intestine, and large intestine

Question 4

What are the accessory organs?

Answer 4

Teeth, tongue, salivary glands, liver, gallbladder, and pancreas

digestion does not take place here but the organs contribute to the process

Question 5

Where does digestion take place?

Answer 5

•oral cavity,
•stomach,
•small intestine- where most absorption of nutrients takes places

Question 6

What are the two types of digestion?

Answer 6

Mechanical and chemical

Question 7

What is Mechanical digestion?

Answer 7

the physical breaking up of food into smaller pieces

Question 8

What is Chemical digestion?

Answer 8

enzymes break complex molecules into simpler chemical molecules that the body can use to

Question 9

What are the three types of complex organic molecules found in food?

Answer 9

carbohydrates- digested into monosaccharides

proteins-digested to amino acids

fats-digested into fatty acids and glycerol

Question 10

What is the function of teeth?

Answer 10

mechanically break down food

Question 11

What are the two sets of teeth?

Answer 11

deciduous and permanent

Question 12

What are the deciduous teeth?

Answer 12

they erupt through the gums about 6 months of age and the set of 20 teeth is usually complete by age 2

Question 13

What are the permanent teeth?

Answer 13

replace the deciduous teeth

first set of molars emerge at age 6

complete set consists of 32 teeth

Question 14

What is the periodontal membrane?

Answer 14

lines the socket and produces a bone like cement that anchors the tooth

Question 15

What is the outermost layer of the crown of tooth?

Answer 15

Enamel- made by cells called ameloblasts

Question 16

what is dentin?

Answer 16

within the enamel and is similar to bone

produced by cells called odontoblasts

Question 17

What is the pulp cavity?

Answer 17

inner most portion of tooth

contains blood vessels and nerve rndings

Question 18

What is the function of the tongue?

Answer 18

aids in keeping food between teeth and mixing it with saliva

hypoglossal nerves

sensory nerves for taste cranial nerves:facial glossopharangeal

Question 19

What are papillae?

Answer 19

on the upper surface of the tongue many of which contains taste buds

Question 20

What is the first step of swallowing?

Answer 20

elevation of the tongue

voluntary action

Question 21

What is the digestive secretion in the oral cavity?

Answer 21

saliva

produced by 3 pairs salivary glands: parotid, submandibular, sublingual

cranial nerves are the facial and glossopharyngeal

takes saliva to the oral cavity

Question 22

What increases saliva secretion?

Answer 22

presence, sight or smell of food,

parasympathetic response

Question 23

What decreases saliva secretion?

Answer 23

stress situations- makes mouth dry

sympathetic stimulation

Question 24

what does lysozyme in saliva do?

Answer 24

inhibit the growth of many kinds of bacteria, does not outright kill them but slows it down

Question 25

What is the digestive enzyme salivary amylase?

Answer 25

breaks down starch molecules to shorter chains of glucose, molecules, or to maltose a disaccharide

Question 26

what is the primary function of the pharynx?

Answer 26

swallowing connects the oral cavity to the esophagus no digestion takes place here epligottis- covers thr larynx so food or liquid dont get in

Question 27

What are the actions of swallowing?

Answer 27

•constriction of the pharynx •cessation of breathing •elevation if the soft palate to block the nasopharynx •elevation of the larynx •closure of the epiglottis and peristalsis of the esophagus

Question 28

What is the esophagus?

Answer 28

a muscular tube that takes food from the pharynx to the stomach no digestion takes place here

Question 29

What does peristalsis of the esophagus do?

Answer 29

propels food in one direction and ensures that food gets to stomach

Question 30

What is the lower esophageal sphincter? (cardiac sphincter)

Answer 30

circular smooth muscle relaxes to permit food to enter the stomach, contracts to prevent the backup of the stomach contests

Question 31

Layers of the alimentary tube

Answer 31

mucosa, submucosa, external muscle layer, and serosa

Question 32

Mucosa

Answer 32

lining of the alimentary tube made of epithelial tissue, areolar connective tissue and two thin layers of smooth muscle secretes mucous, lubricates the passage of food, secretes digestive enzymes of the stomach and small intestine

Question 33

submucosa

Answer 33

made of areolar connective tissue with blood vessels and lymphatic vessels has millions of nerve fibers called the Enteric nervous system

Question 34

What are the nerve networks in the submucosa called?

Answer 34

Meissner’s plexus- they innervate the mucosa to regulate secretions parasympathetic increase secretions sympathetic decreases secretions

Question 35

External muscle layer

Answer 35

contractions of the muscle layer help break up food and mix it with digestive juices contractions of peristalsis move food toward the anus Auerbach’s plexus is the portion if the enteric nervous system sympathetic-decrease contractions and peristalsis parasympathetic- increases contractions and peristalsis

Question 36

Stomach

Answer 36

is a sac that is a reservoir for food when the stomach is empty the mucosa appears wrinkled or folded

Question 37

what is the rugae?

Answer 37

folds that flatten out at the stomach is filled and permit expansion of the lining without tearing it

Question 38

What are the gastric pits of the stomach?

Answer 38

glands of stomach and consist of several types of cells secrete gastric juice

Question 39

what do chief cells secrete?

Answer 39

pepsinogen- inactive form of the enzyme pepsin it converts proteins to polypeptides

Question 40

what do parietal cells secrete?

Answer 40

hydrochloric acid- converts pepsinogen to pepsin destroys pathogens intrinsic factor- prevent digestion of vitamin b 12

Question 41

What do mucous cells secrete?

Answer 41

mucous- coats the lining, prevents erosion

Question 42

What is gastrin?

Answer 42

secreted by g cells hormone that stimulates the secretion of greater amounts of gastric juice

Question 43

What is the livers function?

Answer 43

production of bile

Question 44

function of the hepatic duct?

Answer 44

takes bile out of liver unites with cystic duct of the gallbladder to form common bile duct, while takes bile to duodenum

Question 45

What do bile salts do?

Answer 45

emulsify fats in the small intenstine

Question 46

what is production of bile stimulated by?

Answer 46

secretin produced by duodenum when food enters the small intestine

Question 47

function of the gall bladder?

Answer 47

stores bile until it is need in the small intestine cystic duct joins the hepatic duct to form the common bile duct Cholecystokinin- produced by the enteroendoceine cells of the duodenum-stimulates contraction of the gall bladder

Question 48

biacarbonate juice of pancreas

Answer 48

alkaline;neutralizes the gastric juice to prevent damage secretion of pancreatic juice is stimulated by hormones secretin and cholecystokinin

Question 49

Enzyme pancreatic juice contains enzymes for 3 food types

Answer 49

amaylase- digest starch to maltose trypsin-digests polypeptides to peptides lipase-digest emulsified fats to fatty acids and glycerol

Question 50

secretin

Answer 50

stimulates the production of bicarbonate juice by pancreas

Question 51

cholecystokinin

Answer 51

stimulates secretion of the pancreatic enzymes