3.4: Physiology of the GI Tract

Question 1

The digestive system has four main roles that it performs what are they?.

Answer 1

ingestion, digestion, absorption, and defecation

Question 2

______ is when food enters the mouth.

Answer 2

Ingestion

Question 3

______ occurs when food is moved, mixed, and exposed to enzymes along the gastrointestinal tract.

Answer 3

Digestion or food breakdown

Question 4

Digestion can be divided into two parts what are they?

Answer 4

mechanical digestion and chemical digestion

Question 5

______ digestion occurs when food is physically broken down into smaller pieces.

Answer 5

Mechanical

Question 6

______ digestion occurs when the teeth chew food, when the stomach churns and mixes food, and as food is moved and squeezed along the gastrointestinal tract.

Answer 6

Mechanical

Question 7

_____ digestion is the chemical breakdown of food by enzymes into smaller nutrients.

Answer 7

Chemical

Question 8

______ is the process of moving digested food into the bloodstream.

Answer 8

Absorption

Question 9

______ is the excretion of indigestible food from the anus.

Answer 9

Defecation

Question 10

True or False: The mouth is where digestion begins, but only mechanical.

Answer 10

False. The mouth is where digestion begins, BOTH mechanical AND chemical.

Question 11

How does the mouth Chemically digest food?

Answer 11

Chemically, saliva is released by the salivary glands. NOTE the locations of the parotid, sublingual, and submandibular glands

Question 12

The enzyme___1___ contained in the saliva begins the chemical breakdown of ___2___.

Answer 12

1. salivary amylase
2. starches

Question 13

How does the mouth Mechanically digest food?

Answer 13

Mechanically, the food is broken down into smaller physical pieces by both the teeth and tongue.

Question 14

What is the food in the mouth called after it has been chewed?

Answer 14

The food is then called a bolus.

Question 15

______, rhythmic muscular contractions, moves the food along the esophagus to the stomach.

Answer 15

Peristalsis

Question 16

What is Peristalsis?

Answer 16

Rhythmic muscular contractions that moves food along the esophagus to the stomach.

Question 17

True or False: No ingestion, digestion, absorption, or defecation takes place in the pharynx or esophagus. These structures only transport the food from the mouth to stomach by peristalsis.

Answer 17

True

Question 18

Answer 18

Midsagittal view of the oral cavity and associated salivary glands (parotid, sublingual, and submandibular)

Question 19

Once in the stomach, mechanical and chemical breakdown of food continues with the secretion of ______.

Answer 19

digestive juices

Question 20

True or False: Substantial nutrient absorption occurs in the stomach.

Answer 20

False. Very little to no nutrient absorption occurs in the stomach.

Question 21

The stomach’s main function is for ______.

Answer 21

mechanical and chemical breakdown of food

Question 22

The ___1___ stimulates the stomach to secrete gastric juices, which contains: ___2___, ___3___, and ___4___

Answer 22

1. hormone gastrin
2. pepsinogens
3. mucus
4. hydrochloric acid

Question 23

The ___1___ secrete hydrochloric acid, generating a pH of ___2___.

Answer 23

1. parietal cells (located in the wall of the stomach body)
2. 1.3-3.5

Question 24

The parietal cells (located in the wall of the stomach body) secrete ______, generating a pH of 1.3-3.5.

Answer 24

hydrochloric acid

Question 25

True or False: The very acidic pH of the hydrochloric acid produced by the Parietal cells of the stomach kill many of the bacteria ingested along with food. In addition, the low pH stops the activity of salivary amylase.

Answer 25

True

Question 26

The secretion of hydrochloric acid is essential in the activation of ______.

Answer 26

pepsin

Question 27

______ is secreted by the chief cells in the stomach.

Answer 27

Pepsinogen (a pro-enzyme)

Question 28

Hydrochloric acid converts the___1___ into the active enzyme pepsin, which begins the breakdown of ___2___.

Answer 28

1. inactive pepsinogen (secreted by the chief cells) 2. proteins

Question 29

______ protects the stomach lining from the hydrochloric acid and pepsinogens.

Answer 29

Mucus

Question 30

The ______ churns and mixes the food, breaking it into smaller pieces.

Answer 30

muscularis externa

Question 31

The smaller pieces allow for more ___1___ of the food to be exposed to the enzymes in the stomach to form ___2___.

Answer 31

1. surface area 2. chyme

Question 32

___1___ moves the food toward the small intestine where the ___2___ controls the slow release of chyme into the ___3___.

Answer 32

1. Peristalsis 2. pyloric sphincter 3. duodenum

Question 33

In the small intestine digestion continues and ______ begins.

Answer 33

absorption

Question 34

Enzymes from the ___1___ enter the small intestine to continue digestion of ___2___, and begin digestion of ___3___.

Answer 34

1. pancreatic juices 2. starches and proteins 3. fat

Question 35

______, which result from the first step in protein digestion, are digested by peptidases to amino acids.

Answer 35

Peptides

Question 36

Peptides, which result from the first step in protein digestion, are digested by ___1___ to ___2___.

Answer 36

1. peptidases 2. amino acids

Question 37

______, which results from the first step in starch digestion, is digested by maltase to glucose.

Answer 37

Maltose

Question 38

Maltose, which results from the first step in starch digestion, is digested by ___1___ to ___2___.

Answer 38

1. maltase 2. glucose

Question 39

Pancreatic juice includes three enzymes. What are they and what do they digest?

Answer 39

1. amylase digests starch 2. trypsin digests proteins 3. lipase digests fats

Question 40

______, which is also contained in the pancreatic juice, neutralizes the acidic chyme.

Answer 40

Bicarbonate

Question 41

Bicarbonate, which is also contained in the pancreatic juice, neutralizes the ______.

Answer 41

acidic chyme

Question 42

Chyme stimulates the small intestine to secrete two hormones:

Answer 42

cholecystokinin and secretin

Question 43

______causes the gallbladder to secrete bile.

Answer 43

Cholecystokinin

Question 44

______ causes the liver to secrete bile.

Answer 44

Secretin

Question 45

Both Cholecystokinin and Secretin cause the ___1___ to ___2___.

Answer 45

1. pancreas 2. secrete its juices

Question 46

______ breaks down fat into smaller pieces and is needed for the absorption of fats.

Answer 46

Bile

Question 47

True or False: When food reaches the end of the small intestine, digestion is complete and most absorption of nutrients into the bloodstream has happened.

Answer 47

True

Question 48

When food reaches the end of the small intestine, ___1___ is complete and most ___2___ has happened.

Answer 48

1. digestion 2. absorption of nutrients into the bloodstream

Question 49

What remains of the food enters the large intestine by the ______.

Answer 49

ileocecal valve

Question 50

In the large intestine, the undigested food is compacted in order to be prepared for ______.

Answer 50

defecation

Question 51

Water is absorbed to form ___1___. ___2___ are absorbed as well.

Answer 51

1. Feces 2. Vitamins and ions

Question 52

Bacteria metabolize the remaining nutrients, producing vitamins ___1___ and ___2___ in the process.

Answer 52

1. K 2. B

Question 53

Feces travel to the ___1___ where it is defecated via the ___2___.

Answer 53

1. rectum 2. anus

Question 54

Answer 54

Overview of digestive processes carried out from the mouth to the small intestine.

Question 55

______ is the internal drive to find and eat food and is often experienced as a negative sensation such as churning, growling, or a painful sensation in the stomach.

Answer 55

Hunger

Question 56

The ______ is a region of the brain that plays a role in hunger, satiety, and the feeling of “being full”.

Answer 56

hypothalamus

Question 57

The amount of ______ in the blood begin to decline if a person has not eaten in a long period of time.

Answer 57

nutrients

Question 58

The drop in nutrients in the blood stimulates the ______ in the hypothalamus and signals the body to feel “hungry” and desire to eat.

Answer 58

feeding center

Question 59

True or False: If a portion of the hypothalamus is damaged or destroyed, from certain chemicals, trauma, surgery, or cancers, the regulation of hunger and satiety can be lost. In such an instance, the body no longer receives signals to stop eating and weight gain is almost certain.

Answer 59

True

Question 60

Answer 60

Midsagittal view of the brain and brainstem. The hypothalamus (blue) is responsible for the regulation and monitoring of many processes in the body, such as hunger and satiety.

Question 61

As the stomach expands from food intake and the nutrients consumed are absorbed, receptors within the stomach wall ______.

Answer 61

send signals to the brain and the desire to eat declines

Question 62

The human body produces a variety of ______ that work together to balance our hunger and satiety.

Answer 62

hormones

Question 63

______are compounds secreted into the bloodstream by one type of cell that acts to control the function of another type of cell.

Answer 63

Hormones

Question 64

What are Hormones?

Answer 64

Compounds secreted into the bloodstream by one type of cell that acts to control the function of another type of cell

Question 65

What are the types of Hormones related to increased hunger?

Answer 65

Hormones that increase hunger – Ghrelin, Endorphins, Neuropeptide-Y

Question 66

What are the types of Hormones related to satiety or decreased hunger?

Answer 66

Hormones that cause satiety (decrease hunger) – Leptin, Serotonin, Cholecystokinin (CCK)

Question 67

There are two key hormones in relation to hunger and satiety, what are they?

Answer 67

leptin and ghrelin

Question 68

Leptin is produced by ______.

Answer 68

adipose tissue (fat cells)

Question 69

The role of ______ is to alert the brain to turn off the hunger center in the brain and activate the satiety center when consuming a meal.

Answer 69

leptin

Question 70

Ghrelin is produced by ______.

Answer 70

the stomach

Question 71

______ travels to the brain and stimulates the hunger center as it deactivates the satiety center.

Answer 71

Ghrelin

Question 72

True or Fales: Ideally, leptin and ghrelin work together to balance hunger and satiety.

Answer 72

True

Question 73

What are the three major biochemical categories of food that the body needs in large amounts?

Answer 73

Carbohydrates, proteins, and lipids

Question 74

True or False: Vitamins and minerals are also needed by the body but in much smaller amounts.

Answer 74

False: Vitamins and minerals are also needed by the body but in much LARGER amounts.

Question 75

______ are classified as starches and sugars.

Answer 75

Carbohydrates

Question 76

Milk and fruits, such as apples or peaches, contain ______.

Answer 76

sugar

Question 77

Grains such as wheat and vegetables such as potatoes contain ______.

Answer 77

starches

Question 78

Lipids can be divided into three categories what are they?

Answer 78

saturated fat, unsaturated fat, and cholesterol

Question 79

Meat and dairy products, such as butter, contain ___1___ fats, while nuts and vegetable oils, such as olive oil, contain ___2___.

Answer 79

1. saturated 2. unsaturated fats

Question 80

______ is made by our bodies but can also be ingested by eating animal products, such as meat (beef), cheese, and eggs (yolk).

Answer 80

Cholesterol

Question 81

Proteins (which are made up of amino acids) can be categorized as ___1___ proteins or ___2___ proteins.

Answer 81

1. complete 2. Incomplete

Question 82

Examples of ______proteins are meat, poultry, eggs, milk, dairy products, and soybeans.

Answer 82

complete

Question 83

______ proteins are food such as grains, legumes, seeds, and nuts.

Answer 83

Incomplete

Question 84

There are ___1___ amino acids called ___2___ amino acids required in an adult human diet (with ___3___ required in an infant’s diet).

Answer 84

1. 9 2. essential 3. 10

Question 85

They are called essential amino acids because ______.

Answer 85

the body is unable to make these amino acids

Question 86

True or Fales: Incomplete proteins contain all nine essential amino acids but complete proteins do not.

Answer 86

False. COMPLETE proteins contain all nine essential amino acids but INCOMPLETE proteins do not.

Question 87

______ are organic compounds that are not consumed in metabolic reaction but help enzymes carry out the metabolic reactions, which convert nutrients to materials needed by the body.

Answer 87

Vitamins

Question 88

Vitamins can be classified as ___1___ soluble or ___2___ soluble.

Answer 88

1. water 2. Fat

Question 89

______soluble vitamins are not able to be stored in the body and are excreted in urine.

Answer 89

Water

Question 90

______soluble vitamins are stored in body fat.

Answer 90

Fat

Question 91

True or False: Ingestion of excessive amounts of fat-soluble vitamins can be problematic.

Answer 91

True

Question 92

True or False: Vitamins are not needed in the diet to maintain growth and good cellular health.

Answer 92

False. Vitamins ARE NEEDED in the diet to maintain growth and good cellular health.

Question 93

______are inorganic compounds that, like vitamins, are not used as fuel in metabolic reactions but are combined with other nutrients to form necessary body substances.

Answer 93

Minerals

Question 94

What are minerals?

Answer 94

Inorganic compounds that, like vitamins, are not used as fuel in metabolic reactions but are combined with other nutrients to form necessary body substances.

Question 95

Humans need what seven minerals in their diets?

Answer 95

calcium chloride magnesium phosphorus potassium sodium sulfur

Question 96

How many other minerals outside the 7 necessary ones are needed in trace amounts?

Answer 96

There are twelve other minerals needed in trace amounts.

Question 97

True or False: Foods such as milk, some meats, legumes, and vegetables are the best sources of minerals.

Answer 97

True

Question 98

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Question 99

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Question 100

Answer 100

Question 101

Answer 101