The Digestive System

Question 1

Functions of the digestive system:

Answer 1

1. Ingestion
2. Digestion: 2 types: mechanical/chemical
3. Absorption
4. Compaction
5. Defecation

Question 2

Ingestion:

Answer 2

intake of food

Question 3

Mechanical digestion:

Answer 3

physical breakdown of food into smaller pieces.

Question 4

Chemical digestion:

Answer 4

hydrolysis reactions that break down monomers. This is done by enzymes from salivary gland, stomach, pancreas, and small intestine.

Question 5

Carbohydrates

Answer 5

Starch -> Disaccharides.
Uses the enzyme amylase found in the salivary gland/pancreas.
The 3 disaccharides: maltose, sucrose, and lactose

Question 6

Monosaccharides:

Answer 6

Glucose, Fructose, and Galactose.

The wall of the small intestine breaks down maltase, sucrase, and lactase to form the monosaccharides.

Question 7

Proteins:

Answer 7

protein-> large polypeptide -> peptides -> amino acids.

Pepsin is found in the stomach and is what converts proteins. Stored in an inactive form.

Question 8

Inactive form of Pepsin?

Answer 8

pepsinogen

Question 9

Trypson

Answer 9

Enzyme found in small intestine.

The inactive form is trypsinogen that is activated by enteropeptidase.

Question 10

Triglycerides (Fats)

Answer 10

Enzyme used- lipase found in pancreas.

Question 11

Nucleic Acids

Answer 11

DNA & RNA -> nucleotides -> pentose sugar, nitrogen bases, phosphate ions

Enzymes used: nucleases

Question 12

Absorption:

Answer 12

uptake of nutrients. This is done in small intestine

Question 13

Compaction:

Answer 13

absorbing water and consolidating the indigestible residue into feces.

Question 14

Defecation:

Answer 14

elimination of feces, usually at anus.

Question 15

Digestive Tract:

Answer 15

30 FT long muscular tube from mouth to anus.

Question 16

Accessary Organs:

Answer 16

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

Question 17

GI tract:

Answer 17

stomach and intestines

Question 18

Layers of digestive tract:

Answer 18

Mucosa- inside layer
Submucosa - thicker layer under mucosa
Muscularis externa - 2 layers smooth muscle, has sphincter and is responsible for motility.
Serosa - outside. composed of areolar tissue (if not present you have adventitia)

Question 19

What is the name of the nervous system that controls your digestive tract?

Answer 19

Enteric Nervous System

Question 20

What are the two plexus of the Enteric nervous system?

Answer 20

Submucosa (Meissner) plexus and Muscularis externa (myenteric) plexus

Question 21

Submucosa (Meissner) plexus:

Answer 21

controls glandular secretion in mucosa and the movement of muscularis mucosa

Question 22

Muscularis externa (myenteric) plexus:

Answer 22

controls peristalsis and other contractions

Question 23

Mesenteries:

Answer 23

connective sheets that hold abdominal viscera in place bit allow movement.
4 kinds:
lesser omentum- extends from lesser curvature of stomach to liver
greater omentum- hangs from greater curvature of the stomach
mesentary- anchors small intestine to posterior wall
mesocolon- anchors colon to abdominal wall

Question 24

Retroperitoneal:

Answer 24

outside/behind peritoneal cavity.

Question 25

The hormones apart of digestive tract:

Answer 25

Gastrin, CCK, secretin

Question 26

Gross anatomy from mouth through the esophagus:

Answer 26

Oral cavity has stratified squamous tissue. The tongue, palate (hard and soft), teeth, pharynx, and esophagus.

Question 27

What is the composition of saliva?

Answer 27

mostly water salivary amylase - begins starch digestion lingual lipase- activated by stomach acid mucus- binds and lubricates food lysozyme- kills bacteria immunoglobulin A (IgA) - antibody that inhibits bacterial growth electrolytes- Na+, K+, Cl-

Question 28

What is mastication?

Answer 28

chewing

Question 29

What is the neural control of salivation?

Answer 29

Parasympathetic stimulate glands to produce thin saliva via ingestion of food or the sight, smell, taste, or thought of it. Sympathetic - stimulates to produce thicker saliva. This is done via swallowing food causing bolus.

Question 30

What is the neural control of swallowing?

Answer 30

oral phase- voluntary, pharyngeal- involuntary, esophageal- involuntary

Question 31

What are molars and premolars?

Answer 31

teeth in back used for crushing, shredding, and grinding.

Question 32

What is the pH of saliva?

Answer 32

7

Question 33

What is deglutation?

Answer 33

swallowing | controlled by medulla

Question 34

The anatomy of the stomach:

Answer 34

3 layers of smooth muscle: simple columnar epithelium, fundus pyloric sphincter greater/lesser curvature

Question 35

What is the function of mucus cells?

Answer 35

secrete thick mucus for digestion

Question 36

What is the function of regenerative (stem) cells?

Answer 36

constantly supply with new cells

Question 37

What is the function of parietal cells?

Answer 37

secrete HCl and a hunger hormone called gherlin.

Question 38

What is the function if chief cells?

Answer 38

secrete gastric lipase and pepsinogen

Question 39

what is the function of enteroendocrine cells?

Answer 39

secrete hormones (gastrin)

Question 40

What is gastric juice made up of?

Answer 40

mainly water, HCl, and pepsin

Question 41

What are the secretions of the stomach and their functions?

Answer 41

HCl- activates pepsin and lingual lipase Intrinsic Factor- in small intestine for B12 absorption Pepsinogen- converts pepsinogen into pepsin with HCl Gastric Lipase- minor role in digesting fats Gastrin- stimulates gastric secretions and stomach muscle contractions.

Question 42

How does the stomach produce pepsin?

Answer 42

HCl is added to pepsinogen and then produces pepsin

Question 43

Describe the cephalic phase:

Answer 43

the sight, smell, taste, or thought of food goes to hypothalamus goes to medulla to Vegas nerve stomach starts secreting juices and contracting

Question 44

Describe the gastric phase:

Answer 44

in the stomach | gastrin and histamine are secreted

Question 45

Describe the intestinal phase:

Answer 45

triggered by duodenum | releases CCK & Secretin (inhibit)

Question 46

What does CCK do?

Answer 46

stimulate enzyme-rich pancreatic juice stimulates contraction of gallbladder inhibits stomach

Question 47

What does secretin do?

Answer 47

stimulates secretin to secrete bicarbonate-rich juice stimulates liver to produce bile inhibits stomach

Question 48

Why does diarrhea occur?

Answer 48

Too little water is absorbed by large intestine.

Question 49

When does constipation occur?

Answer 49

when too much water is absorbed in large intestine

Question 50

What is defecation?

Answer 50

pooping