THE DIGESTIVE SYSTEM

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1

Alimentary Canal

also known as GI Tract

2

Accessory Digestive Organs includes

teeth, tongue, gallbladder,

salivary glands, liver and pancreas.

3

what are the 6 major digestive process

1. ingestion

2. propulsion

3. mechanical digestion

4. chemical digestion

5. absorption

6. defecation

4

Ingestion

taking food into the digestive tract (eating)

5

Propulsion

movement of food through the alimentary canal. This includes swallowing and peristalsis. (swallowing)

6

Mechanical Digestion

physically prepares food for chemical digestion. This includes chewing,

mixing of food with enzymes, churning food in the stomach and segmentation (rhythmic, local

constrictions of the intestines). (chewing)

7

Segmentation mixes food with digestive juices and it increase

the rate of absorption.

mechanical digestion

8

Chemical Digestion

occurs as enzymes break down food materials into their primary

components. Much of this occurs in the lumen of the alimentary canal.

9

Absorption

the passage of digested end products with vitamins, mineral and water, from the

lumen of the GI Tract into the blood or lymph.

10

Defecation

the process through which indigestible wastes are removed from the body in the

form of feces.

11

Peritoneal cavity

covers the external surfaces of the digestive organs and the parietal peritoneum lines the body wall

12

Peritoneum

is a serous membrane the covers the abdominopelvic cavity

13

Most of the digestive organs reside in the

abdominopelvic cavity

14

Mesentery

double layer peritoneum that extends to the digestive organs from the body wall.

15

Mesentery functions by

providing routes for blood vessels, lymphatics and nerves to

reach the digestive viscera, holding organs in place and storing fat.

16

Intraperitoneal organs

are covered by and held on place by mesentery

17

Retroperitoneal organs

lose their mesentery and lie posterior to the peritoneum

18

Submucosal nerve plexus-

control smooth muscle in the mucosa

19

Myenteric nerve plexus-

GI tact motility

20

Hepatic portal circulation

–Drains nutrient-rich blood from digestive organs

–Delivers it to the liver for processing

21

Mucosa: three sub layers

Epithelium
Lamina propria
Muscularis mucosae

22

Layers of the alimentary canal

mucosa

submucosa

muscularis externa

serosa

23

muscularis externa

longitudinal muscle

circular muscle

24

serosa

Epithelium (mesothelium)
Connective tissue
Lumen
Mucosa- associated lymphoid tissue

25

Long Reflexes

response outside the “gut brain”

26

what reflex involves

External stimuli (sight, smell, taste, thought, of food)

long reflexes

27

Short Reflexes

local (intrinsic) nerve plexus “only gut brain”

28

what reflex involve Internal (GI tract) stimuli

short reflexes

29

Three key concepts regulate GI activity

Mechanical and chemical stimuli
Effectors
Neurons

30

serosa

also known as the Visceral Peritoneum, this is the outermost, protective layer
around a digestive organ.

31

two major Nerve Plexuses found in the walls of the alimentary canal

the submucosal nerve plexus

the myenteric nerve plexus

32

The Submucosal Nerve Plexus

located in the submucosa, this nerve plexus generally
regulates the activity of glands and smooth muscle in the mucosa.

33

The Myenteric Nerve Plexus

lies in the smooth muscle of the muscularis externa.
a. Enteric neurons here regulate GI tract motility.

34

Associated organs include

Tongue
Salivary glands
Teeth

35

Mouth consist of

Upper lip
Superior labial frenulum
Hard palate
Soft palate- close of the nasopharynx during swallowing
Uvula
Lingual frnulum
Oral vestibule – the lining of the tongue
Lower lip

36

Oral Orifice

The opening of the mouth

37

The Labial Frenulum

a fold of tissue that joins the internal aspect of each lip to
the gum.

38

The Hard Palate

anterior portion, is supported by the palatine bones and the
palatine processes of the maxillae. This structure forms a thick structure
against which the tongue forces food against during chewing. The mucosa
on either side of the midline of the hard palate is corrugated which helps to
create friction.

39

The Soft Palate

composed of mostly skeletal muscle.
a) The Uvula-projects downward from the free edge of the soft palate

Closes off nasopharynx during swallowing
Uvula projects downward from its free edge

40

what is composed of bundles of skeletal muscle fibers

tongue

41

what produce and secrete saliva into the oral cavity.

the salivary glands

42

Extrinsic Salivary Glands

lie outside of the oral cavity and empty their
secretions into it.

43

Intrinsic Salivary Glands

are scattered throughout the oral cavity mucosa

44

what salivary gland Scattered throughout oral cavity; augment slightly

minor salivary glands

45

what salivary glands

Produce most saliva; lie outside oral cavity
Parotid
Submandibular
Sublingual

major salivary glands

46

The Major Extrinsic Salivary Glands include:

the parotid gland

the submandibular gland

the sublingual gland

47

The Parotid Gland

large, is anterior to the ear between the skin and
masseter muscle. Saliva is carried from this gland to the mouth via the
Parotid Duct which opens in the mouth near the second molar

48

Humans have two sets of teeth:

primary teeth ( baby or milk teeth)

permanent teeth

49

Primary Teeth (Baby or Milk Teeth)

20 of these total. These loosen and
fall out between the ages of 6 and 12.

50

Permanent Teeth

there are typically 32 teeth in the permanent set.

51

stomach

storage and chemical break down of proteins

52

Deglutition (Swallowing)

Involves 22 muscles and occurs through two phases

53

. Buccal Phase

voluntary, occurs in the mouth. In this phase, the tongue contracts to
push the bolus into the oropharynx. Deglutition becomes involuntary at this point.

54

Pharyngeal-Esophageal Phase

controlled by the swallowing center in the medulla and
pons. When food enters the pharynx, breathing is temporarily stopped as: the tongue blocks
the mouth, the epiglottis covers the respiratory passages and the soft palate closes off the
nasopharynx.

55

When the stomach is empty, it collapses throwing its mucosa into folds known
as

rugae

56

organ where chemical breakdown of proteins begins and food is converted into a
material known as

chyme

57

gallbladder

Stores and concentrates bile by absorbing water and ions

58

what is CCK

Cholecystokinin

59

bilirubin

primary pigment in bile. This is a waste product of the heme portion of
hemoglobin.

60

what is actually a breakdown product of erythrocytes

bilirubin

61

small intestine consist of

Duodenum
Jejunum
Ileum

62

what are the Unique features of the large intestine

Teniae coli
Haustra
Epiploic appendages

63

the ascending colon

travels up the right side of the abdominal cavity to the level
of the right kidney where it makes a right-angle turn known as the right colic or
hepatic flexure

64

transverse colon

Anterior to the spleen, the transverse colon bends at the left
colic (splenic) flexure

65

descending colon

descends downward

66

descending colon enters the pelvis, where it becomes

sigmoid colon

67

Internal anal sphincter

smooth muscle: expansion

68

External anal sphincter

skeletal muscle: contraction

69

Vitamin K and B vitamins from bacterial metabolism are absorbed in what?

In large intestine

70

Most water absorbed in

small intestine ( absorption of water)

71

Most ions are transported actively along length of

small intestine ( absorption of electrolytes

72

Fat-soluble vitamins (A, D, E, and K)
Water-soluble vitamins (C and B)
Vitamin B12 binds with intrinsic factor

all of this are absorbed where?

small intestine ( vitamin absorption)

73

what break down to monosaccharide (starts with almysis) : enzyme starch and disaccharides

Carbohydrates

74

what start with the pepsin ( pitide)

protein

75

what start with the lipase: ( liver) breakdown bio in the liver

Lipid (fat)

76

what contain DNA and RNA ( start in the pancreas)

Nucleic acid