Chapter 3 - Digestion, Absorption, and Transport

Question 1

What is the order that food goes through in the digestive tract?

Answer 1

Mouth to pharynx to epiglottis to esophagus to cardiac sphincter to stomach to pyloric sphincter to small intestine (duodenum, jejunum, ileum) to ileocecal sphincter to large intestine to rectum to anus

Question 2

What are the seven challenges the body has to overcome with digestion?

Answer 2

1. Arranging so swallowing and breathing don’t interfere with each other
2. Making a passage way through the diaphragm to the stomach
3. Moving slow enough that all rxns occur completely
4. Keeping food at the right consistency (lubrication)
5. Reabsorbing water
6. Having cells that are protected against the powerful digestive juices
7. Evacuation needs to occur periodically

Question 3

What is the function of the mouth in the digestive system?

Answer 3

Chew (mastication) and mix food with saliva

Question 4

What is the function of the pharynx in the digestive system?

Answer 4

Direct food from the mouth to the esophagus

Question 5

What is the function of the epiglottis in the digestive system?

Answer 5

To protect the airways during swallowing

Question 6

What is the function of the trachea in the digestive system?

Answer 6

To allow air to pass to and from the lungs

Question 7

What is the function of the esophagus in the digestive system?

Answer 7

To pass food from the mouth to the stomach

Question 8

What is the function of the cardiac sphincter in the digestive system?

Answer 8

To allow passage from mouth to esophagus and from esophagus to stomach; prevents backflow from stomach to esophagus and from esophagus to mouth

Question 9

What is the function of the diaphragm in the digestive system?

Answer 9

To separate the abdomen from the thoracic cavity

Question 10

What is the function of the stomach in the digestive system?

Answer 10

To add acid, enzymes, and fluid; churns, mixes, and grinds food to a liquid mass

Question 11

What is the function of the pyloric sphincter in the digestive system?

Answer 11

To allow passage from the stomach to small intestine; prevents backflow from the small intestine

Question 12

What is the function of the liver in the digestive system?

Answer 12

To produce bile salts (detergent-like substances which help digest fats)

Question 13

What is the function of the bile duct in the digestive system?

Answer 13

To conduct bile from the gallbladder to the small intestine

Question 13

What is the function of the gallbladder in the digestive system?

Answer 13

To store bile until dietary fat is present in the duodenum

Question 14

What is the function of the small intestine in the digestive system?

Answer 14

To secrete enzymes that digest all energy-yielding nutrients to their basic building blocks; cells of wall absorb nutrients into blood and lymph

Question 15

What is the function of the illeocecal valve/sphincter in the digestive system?

Answer 15

To allow passage from the small to large intestine; prevents backflow from the large intestine

Question 16

What is the function of the pancreas in the digestive system?

Answer 16

Manufactures enzymes that are delivered to the lumen of the small intestine to digest all energy-yielding nutrients and release bicarbonate to neutralized acidic chyme that enters the small intestine

Question 17

What is the function of the pancreatic duct in the digestive system?

Answer 17

To conduct pancreatic juice from the pancreas to the small intestine

Question 18

What is the function of the appendix in the digestive system?

Answer 18

To store lymph cells

Question 19

What is the function of the large intestine in the digestive system?

Answer 19

To reabsorb water and minerals; to pass stool (fibre, bacteria, and unabsorbed nutrients) along with water to the rectum

Question 20

What is the function of the rectum in the digestive system?

Answer 20

To store wastes prior to elimination

Question 21

What is the function of the anus in the digestive system?

Answer 21

To hold the rectum closes; open to allow elimination of waste

Question 22

The sense of smell is _____ times _____ sensitive than the sense of taste

Answer 22

1000s, more

Question 23

What are the segments of the small intestine?

Answer 23

Duodenum, jejunum, ileum

Question 24

What are the two organs outside of the GI tract that aid in digestion?

Answer 24

The gallbladder and the pancreas; their enzymes are dripped in by the bile duct into the small intestine

Question 25

How does food travel through the large intestine?

Answer 25

Past the appendix to the ascending colon to the transverse colon to the descending colon, past the sigmoid colon to the rectum

Question 26

Define

Chyme

Answer 26

the semiliquid mass of partly digested food released by the stomach into the duodenum.

Question 27

Define

Motility

Answer 27

The ability of the GI tract muscles to move

Question 28

Define

Peristalsis

Answer 28

wavelike muscular contractions of the GI tract that propel its contents along.

Question 29

Define

Segmentation

Answer 29

periodic squeezing or partitioning of the intestine at intervals along its length by its circular muscles.

Question 30

Does peristalsis differ between organs or is it consistent process throughout?

Answer 30

The rate and intensities differ between organs

ex. 3/minute in the stomach but 10/minute in the small intestine

Question 31

What determines the rate and intensity of peristalsis?

Answer 31

There is a natural rhythm based on the organ’s function, but it can be affected by:
* Stress
* Medication(s)
* Medical conditions (ex. gastroparesis)

Question 32

What are unique features of the stomach that aid in digestion?

Answer 32

It has the thickest walls and strongest muscles of all the GI tract organs; it has three sets of muscles (circular, longitudinal, and diagonal) which aid is churning chyme

Question 33

How often does the pyloric sphincter open?

Answer 33

3/minute, so chyme enters the SI in small portions

Question 34

What is the purpose of segmentation?

Answer 34

To further break apart food particles in producing chyme and promoting close contact with the digestive juices and the absorbing cells of the intestinal walls before letting the contents move slowly along.

Question 35

When does the upper esophageal sphincter open?

Answer 35

In response to swallowing

Question 36

What are the differences between the dietary enzymes and hormones?

Answer 36

All enzymes and some hormones are proteins, but enzymes are not hormones. Enzymes facilitate the making and breaking of bonds in chemical reactions; hormones act as chemical messengers, sometimes regulating enzyme action

Question 37

What rxn are dietary enzymes involved in?

Answer 37

Hydrolysis

Question 38

What is saliva composed of?

Answer 38

Water, salts, mucus and enzymes that initiate the digestion of carbohydrates (salivary amylase)

Question 39

Besides lubricating food, what function does saliva serve?

Answer 39

It protects the teeth, and the linings of the mouth, esophagus, and stomach from substances that might cause damage

ex. saliva neutralizes acids that breakdown enamel and also remineralize the teeth with the minerals within saliva

Question 40

What are gastric juices composed of?

Answer 40

Water, enzymes, and hydrochloric acid

Question 41

What is heartburn?

Answer 41

The sensation of HCl when it refluxes to the near-neutral esophagus

Question 42

Why does stomach acid need to be so strong?

Answer 42

• Prevents bacterial growth and kills bacteria on our food
• Speed up the breakdown of food

Question 43

What enzymes can function within the stomach’s low pH?

Answer 43

Stomach enzymes but not salivary amylase; the salivary enzymes then become additional proteins to digest