Digestive System 1

Question 1

What are the 8 functions of the digestive system?

Answer 1

Ingestion
Mastication
Propulsion
Mixing
Secretion
Digestion
Absorption
Elimination

Question 2

What is the digestive tract also known as?

Answer 2

Alimentary Tract/Canal

Question 3

What is the digestive tract?

Answer 3

Tube from oral cavity to anus
GI tract: Refers to stomach and intestines

Question 4

What are the accessory organs of the digestive tract?

Answer 4

Primarily glands which secrete fluid into tract

Question 5

What is meant by the term ingestion?

Answer 5

introduction of food into stomach

Question 6

What is mastication as a function of the digestive system?

Answer 6

Chewing- Increases surface area

Question 7

What is propulsion and what are the two key factors to it?

Answer 7

Deglutition- Swallowing
Peristalsis- moves material through digestive tract

Question 8

How is mixing a function of the digestive system?

Answer 8

Contract to increase contact with enzymes

Question 9

What is the steps to mixing of the digestive system?

Answer 9

1.Wave of smooth muscle relaxation moves ahead of bolus (food), allowing digestive tract to expand
2. Wave of contraction of smooth muscle behind bolus propels it through digestive tract

Question 10

What substances is secreted within the digestive tract to help digestion?

Answer 10

mucus
water
bile
enzymes

Question 11

How does mucus secreted by Digestive system tract help digestion?

Answer 11

secreted along entire digestive tract

lubricates food and lining, protects from mechanical digestion, acid and digestive enzymes

Question 12

How does water secreted by Digestive system tract help digestion?

Answer 12

makes food easier to digest and absorb

Question 13

How does bile secreted by Digestive system tract help digestion?

Answer 13

emulsifies fats

Question 14

How does enzymes secreted by Digestive system tract help digestion?

Answer 14

chemical digestion

Question 15

How does absorption aid digestive system?

Answer 15

Movement from tract into circulation
or lymph

Question 16

How does elimination aid digestive system?

Answer 16

Waste products removed from body;
Defecation

Question 17

What are the two different types of digestion?

Answer 17

mechanical

chemical

Question 18

What is the mucosa of the digestive tract?

Answer 18

inner most layer - lumen
consists of 3 layers :
Mucous epithelium
Lamina propria - loose Connective tissue
Muscularis mucosae- smooth muscle.

Question 19

Mucosa extends into l____ p_____ in places to form i_____ glands or c______.

Answer 19

Mucosa extends into lamina propria in places to form intestinal glands or crypts.

Question 20

What is the submucosa of the digestive tract?

Answer 20

Thick connective tissue layer with nerves, blood vessels, small glands. Parasympathetic submucosal plexus.

Question 21

What are the 4 layers of digestive tract?

Answer 21

Mucosa
Submucosa
Muscularis
Serosa or adventitia

Question 22

What are the characteristics of the muscularis layer of digestive tract?

Answer 22

2 or 3 layers of smooth muscle,
including circular and longitudinal layers.

contains the myenteric plexus
between circular and longitudinal layers.

Plexus controls movements along GI tract.

Question 23

What is the serosa or adventitia layer made of?

Answer 23

Connective tissue

Question 24

How is the digestive system regulated?

Answer 24

Nervous
Chemical

Question 25

How does the nervous system regulate the digestive system?

Answer 25

Local: enteric nervous system
◦ Coordinates peristalsis and
regulates local reflexes

General: coordination with the
CNS.
◦ May initiate reflexes because of
sight, smell, or taste of food.
◦ Primarily parasympathetic

Question 26

How is the digestive system regulated by chemical?

Answer 26

Local: Production of hormones
– Gastrin, secretin

General: Production of paracrine
chemicals like histamine

Question 27

Saliva is produced by c____ a_____ salivary glands

Answer 27

Compound alveolar salivary glands

Question 28

What are the purposes of saliva?

Answer 28

Prevents bacterial infection
◦ Lubrication
◦ Contains salivary amylase that breaks down starch into disaccharides maltose and isomaltose.
◦ Helps to form bolus for swallowing
◦ Parasympathetic input causes salivary production

Question 29

What are the two openings of the stomach?

Answer 29

Gastroesophageal: from oesophagus
Pyloric: to duodenum

Question 30

What is the 4 stages of the cephalic phase?

Answer 30

1. Medulla oblongata is stimulated by chemoreceptors such as taste, smell, or thought of food

2.Vagus nerves carry parasympathetic action potentials to stomach, where enteric plexus neurons are activates

3.Postganglionic neurons stimulate secretion by parietal and chief cells and stimulate gastrin and histamine secretion by endocrine cells

4. Gastrin is carried through circulation back to stomach where, along with histamine, stimulates secretion

Question 31

What are the 4 steps to the gastric phase?

Answer 31

1. Distention of stomach stimulates mechanoreceptors (stretch receptors) and activates a parasympathetic reflex. Action potentials generated by mechanoreceptors are carried by vagus nerves to medulla oblongata

2.The medulla oblongata increases action potentials in vagus nerves that stimulate secretion by parietal and chief cells and stimulate gastrin and histamine secretion by endocrine cells

3. Distention of stomach also activates local reflexes that increase stomach secretions

4.Gastrin is carried through the circulation back to the stomach , where along with histamine, stimulates secretion

Question 32

What are the 4 stages to the intestinal phase?

Answer 32

1. Chyme- in duodenum pH less than 2 or containing fat digestion products (lipids) inhibits gastric secretion by three mechanisms
2. Chemoreceptors in duodenum stimulated by H+ (Low pH) or lipids. Action potentials generated by chemoreceptors are carried by vagus nerves to medulla oblongata where they inhibit parasympathetic action potentials- decrease gastric secretions

3.Local reflexes activated by H+ or lipids also inhibit gastric secretion

4.Secretin and cholecystokinin produced by duodenum decrease gastric secretions in stomach

Question 33

What is the duodenum?

Answer 33

the first part of the small intestine immediately beyond the stomach

Question 34

What part of the digestive system is the site of greatest amount of
digestion and absorption of nutrients and water?

Answer 34

small intestine

Question 35

What are the three division of the small intestine?

Answer 35

Duodenum- first 25 cm
Jejunum- 2.5 m
Ileum- 3.5 m

Question 36

What part of the small intestine is the major sites of nutrient absorption?

Answer 36

Duodenum and Jejunum are the major site of nutrient absorption

Question 37

What are the characteristics of the Jejunum and Ileum of the small intestine?

Answer 37

Similar in structure to the duodenum
Gradual decrease in:
* Diameter
* Thickness of intestinal walls
* Number of circular folds
* Number of vili

Answer 38

The regions of the digestive tract from beginning to end include the mouth, pharynx,
esophagus
, stomach,
small

intestine
, large intestine and anus.