HUMAN BIOLOGY

DiGestioN aND NUtritioN 221

reVieW Questions

1. What are the main functions of the stomach? What roles do
   enzymes and hormones play?


2. Explain the differences between the digestion roles of the
   small and large intestines. Does the appendix also have a
   digestive function?


3. List the organs and accessory organs of the digestive
   system. On a separate piece of paper, list the main
   functions of each organ.


4. Define peristalsis, and list the regions of the GI tract where
   it occurs. Be sure to mention segmentation in your answer.


5. Using the black lines shown in Figure 11.27, name the types
   of nutrient molecules present at each site that are small
   enough to be absorbed across the small intestine’s lining.

seLF-Quiz Answers in Appendix VI

1. Different regions of the digestive system specialize in
   and food and in unabsorbed food
   residues.


2. Maintaining normal body weight requires that
   intake be balanced by output.


3. The preferred energy sources for the body are.


4. The human body cannot produce its own vitamins or
   minerals, nor can it produce certain
   and.


5. Digestion is completed and products are absorbed in
   the.
   a. mouth c. small intestine
   b. stomach d. large intestine

Figure 11.27 Fill in the blanks for substances that cross the

lining of the small intestine. (© Cengage Learning)

Major components

Mouth Start of digestive system, where food is

(oral cavity) moistened and chewed; polysaccharide

digestion begins

Pharynx Entrance to tubular parts of digestive and

respiratory systems

Esophagus Muscular tube, moistened by saliva, that

moves food from pharynx to stomach

Stomach Sac where food mixes with gastric fluid and

protein digestion begins; stretches to store

food taken in faster than can be processed;

gastric fluid destroys many microbes

Small The first part (duodenum) receives secretions

intestine from the liver, gallbladder, and pancreas

Most nutrients are digested, absorbed in

second part (jejunum)

Some nutrients absorbed in last part (ileum),

which delivers unabsorbed material to colon

Colon (large Concentrates and stores undigested matter

intestine) (by absorbing mineral ions and water)

Rectum Distension triggers expulsion of feces

Anus Terminal opening of digestive system

accessory organs

Salivary Glands (three main pairs, many minor ones)

glands that secrete saliva, a fluid with polysaccharide-

digesting enzymes, buffers, and mucus

(which moistens and lubricates ingested food)

Pancreas Secretes enzymes that digest all major food

molecules and buffers against HCl from

stomach

Liver Secretes bile (used in fat emulsification);

role in carbohydrate, fat, and protein

metabolism

Gallbladder Stores and concentrates bile from the liver

Table 11.9 Summary of the Digestive System

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