Digestive System overview

Question 1

What is the workhouse of the digestive system? & why?

Answer 1

The small intestine.

Because it is responsible for most digestion of nutrients and absorption into blood and lymph.

Question 2

what is the function of the mucus membrane?

Answer 2

produces mucus form get epithelium.

Question 3

what type of epithelium is in the mucosa of mouth, pharynx, esophagus, and anal canal? / and in the small intestine?

Answer 3

Simple squamous non- keratinized epithelium./ simple columnar epithelium.

Question 4

compare between the functions and location of goblet cells and endocrine cells.

Answer 4

they are located in the mucosa of the alimentary canal. - - function of goblet cells: secrete mucus into lumen.
- function of endocrine cells: secrete hormones into interstitial fluid.

Question 5

what are the main tissue layers of the AC?

Answer 5

1- Mucosa 2-Submucosa 3- Muscularis

4- Serosa.

Question 6

What are the subdivisions of the Mucosa?

Answer 6

1- Epithelium 2- Lamina propria (loose connective tissue) 3- muscularis mucosa (internal)

Question 7

why does the epithelium of the mucosa has a short life span of a couple of days - week?

Answer 7

because that way, it preserves the health of the AC.

Question 8

why does the lamina propria contain blood & lymphatic vessels?

Answer 8

to transport nutrients from AC to the body.

Question 9

Why does the lamina propria serve as an immune function?

Answer 9

Because it contains clusters of lymphocytes (MALT) = mucosa associated lymphoid tissue.

Question 10

what is the location and function of Peyer’s patch?

Answer 10

Located in the distal ileum, it protects against pathogens and exposure to bacteria from food.

Question 11

compare between muscularis internal and external.

Answer 11

• internal: subdivision of the Mucosa layer.

- external: one of the 4 main tissue layers of AC.

Question 12

why is the muscularis mucosa (internal) in a constant state of tension?

Answer 12

because its pulling the mucosa of stomach and intestine into folds, to increase surface area for digestion and absorption.

Question 13

The submucosa is a thick layer of connective tissue. what are its functions?

Answer 13

1- connects mucosa (above) to muscularis (under).
2- submucosa glands secrete digestive enzymes.
3- serves as a channel for the ( submucosa plexus) = dense branching of nerves.

Question 14

what are the types of muscularis externa muscles?

Answer 14

1- inner circular 2- outer longitudinal

Question 15

what is the function of muscularis externa in the small intestine?

Answer 15

1- move food along AC. 2- promote mechanical digestion. 3-exposes food to digestive enzymes.

Question 16

what type of muscle is in the most proximal and distal regions of the mouth, pharynx, esophagus, and external anal sphincter?

Answer 16

Skeletal (voluntary) muscle.

Question 17

what is the oblique muscle? and what is its function?

Answer 17

its the 3rd muscle layer in the stomach that is responsible for churning.

Question 18

What is the (Tenia coli)?

Answer 18

Its the longitudinal muscle of the colon, and it is segregated into narrow parallel bands.

Question 19

What is the only region of the AC that is within the abdominal cavity?

Answer 19

The Serosa layer.

Question 20

What is the function of Serosa?

Answer 20

holds the AC in place near the ventral surface ( the front) of the vertebral column.

Question 21

what does the Serosa consist of?

Answer 21

a layer of visceral peritoneum overlying a layer of loose connective tissue (areolar).

Question 22

What does the serosa in the mouth, pharynx, and esophagus consist of?

Answer 22

A dense sheath of collagen fibers (adventitia)

Question 23

where does ingestion occur?

Answer 23

ONLY in the mouth.

Question 24

Amylase and Lipase are secreted during ingestion in the saliva. what are their functions?

Answer 24

1- amyalse: breaks down carbs. 2-lipase: breaks down lipids.

Question 25

compare between voluntary and involuntary propulsion.

Answer 25

1- voluntary: mastication= chewing= increases surface area of food and produces bolus.
2- involuntary: peristalsis= alternating waves of contraction and relaxation of smooth muscle= propels & mixes food with digestive juices.

Question 26

Give an example of how powerful the movement of peristalsis is.

Answer 26

It moves food to stomach even if the person is upside-down.

Question 27

What are the types of mechanical digestion?

Answer 27

1- mastication 2-tongue movement 3-churning of stomach 4- segmentation.

Question 28

Why does the stomach churn?

Answer 28

exposes food to digestive juices which creates chyme.

Question 29

compare between segmentation and peristalsis.

Answer 29

1- segmentation: localized contractions of CIRCULAR muscle = moves food back and forth to subdivide and mix it up.
2- peristalsis: waves of contraction and relaxation of BOTH longitudinal and circular muscles = moves food through digestive tract.

Question 30

what does chemical digestion secrete and where?

Answer 30

secretions vary in composition; but usually contains water, salt, enzymes, and acids.
- secreted in the small intestine.

Question 31

where and how are nutrients absorbed?

Answer 31

nutrients are absorbed from the Lumen to the blood stream via epithelial cells in the mucosa.

Question 32

how are lipids absorbed?

Answer 32

lipids are absorbed through lacteals and are transported to the blood stream via the lymphatic vessels. (subclavian vessels near the heart)

Question 33

where does defecation occur?

Answer 33

ONLY in the anus.

Question 34

where are alcohols and aspirin absorbed?

Answer 34

in the stomach.