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1

consists of 2 essential parts

1. digestive tract
2. accessory organs

2

digestive tract
-definition
-known as 2 other names

muscular tube from mouth to anus
-gastrointestinal tract and alimentary canal

3

the accessory organs
-mostly
-7

glands
-1. liver
2. gallbladder
3. pancreas
4. salivary glands
5. teeth
6. tongue
7. gastric and intestinal glands

4

functions of the digestive system

1. ingestion
2. mechanical digestion
3. digestion
4. secretion
5. absorption
6. excretion

5

ingestion

materials entering digestive tract through the mouth

6

mechanical digestion

crushing and breaking up of ingested material

7

digestion

chemical breakdown of food into smaller molecules suitable for absorption

8

secretion

release of H2O acids, enzymes, buffer and salts along the digestive tract

9

absorption

movement of organic substances, ions, vitamins, and H2O from digestive into interstitial fluids

10

excretion

removal of waste products

11

digestive tract
-

1. oral cavity (mouth)
2. pharynx
3. esophagus
4. stomach
5. small intestine
6. large intestine

12

small intestine
-why is it known as small
-3 parts

-in diameter
-1. 1st duodenum (10 in)
2. Jejunum (8 ft)
3. iliem (12 ft)

13

Large intestine
-why is it known as large
-4 parts

-in diameter
-1. cecum
2. colon
3. rectum
4. anus

14

colon
-4 parts

1. Ascending
2. transverse
3. descending
4. sigmoid

15

Histological organization of digestive tract
-4 layers

1. mucosa
2. submucosa
3. muscularis externa
4. serosa

16

mucosa
-innermost or outermost layer
-lines what
-function

-innermost
-lumen
-secretes mucus

17

mucosa
-3 layers

1. muscularis mucosa
2. lamina propria
3. epithelium

18

muscularis mucosa
-definition
-function

-thin layer of smooth muscle
-alters lumen shape

19

lamina propria
-contains

areolar CT, blood vessels and lymphatics

20

epithelium of the mucosa
-type of epithelium
-contains what

-simple columnar
-goblet cells

21

submucosa
-contains

CT, blood and lymphatic vessels

22

muscularis externa
-definition
-controlled by

-double layer of smooth muscle cells
-controlled by the myenteric plexus

23

serosa
-structure
-does not cover

-peritoneum
-oral cavity, pharynx, esophagus or rectum

24

submucosal gland
-type of gland
-function

-exocrine gland
-secretes buffers and enzymes

25

meissner plexus

sensory and autonomic

26

2 movements of digestive materials

1. mixing
2. peristalsis

27

mixing
-known as
-definition
-where does it occur
-what does it do
-are movements well coordinated
-contractions of

-segmentation
-constricting the tube and dividing its contents
-mostly in the small intestine
-mixes material being digested with intestinal secretions
-no
-muscularis externa and muscularis mucosa

28

peristalsis
-definition
-depends on
-circular layer
-longitudinal layer
-moves materials toward

-coordinated wave of muscular contraction that propels material through the tube
-coordinated contractions of the muscularis externa
-contracts behind the material while relaxing in front of it
-contracts ahead of the material and shortens the tube
-toward the anus

29

Oral cavity
-mouth
-lined by

-opens into the oral (buccal) cavity
-oral mucosa

30

oral mucosa

stratified squamous epithelium