Digestive System

Front 1

digestive system

Back 1

breaks down the food you eat into nutrients needed for metabolic processes, such as making ATP, and rids the body of materials that cannot be used such as fiber.

Front 2

Organs of the Alimentary Canal

Accessory organs

Back 2

ANATOMY OF THE DIGESTIVE SYSTEM

Front 3

ALIMENTARY CANAL

Back 3

• Also called the “gastrointestinal (GI) tract” or gut, is a continuous, coiled, hollow muscular tube that winds through the ventral body cavity from the mouth to anus.

• It is approx. 9 meters (about 30 ft long), but in a living person, it is considerable shorter because of its muscle tone.

Front 4

1. Mouth

2. Pharynx

3. Esophagus

4. Stomach

5. Small Intestine

6. Large Intestine

Back 4

ORGANS OF THE ALIMENTARY CANAL

Front 5

MOUTH

Back 5

• Food enters the digestive tract through the (?), a mucous membrane-lined cavity.

• The lips or labia, protect its anterior opening; the cheeks form its lateral walls; the hard palate forms its anterior roof, and the soft palate forms the its posterior roof.

• The uvula is a fleshy finger-like projection of the soft palate, which dangles from the posterior edge of the soft palate.

• The space between the lips and cheeks externally and the teeth and gums internally is the vestibule.

Front 6

lips/labia

Back 6

mouth:

protect its anterior opening

Front 7

cheeks

Back 7

mouth:

form its lateral walls;

Front 8

hard palate

Back 8

mouth:

forms its anterior roof

Front 9

soft palate

Back 9

mouth:

forms the its posterior roof.

Front 10

uvula

Back 10

mouth:

fleshy finger-like projection of the soft palate, which dangles from the posterior edge of the soft palate

Front 11

vestibule

Back 11

mouth:

The space between the lips and cheeks externally and the teeth and gums internally

Front 12

tongue

Back 12

mouth:

occupies the floor of the mouth. The (?) has several bony attachments – two of these are to the hyoid bone and the styloid processes of the skull.

Front 13

Lingual frenulum

Back 13

mouth:

a fold of mucous membrane that secures the tongue to the floor of the mouth and limits its posterior movements

Front 14

Bolus

Back 14

mouth:

a small round mass of a substance, especially food that has been chewed to make it soft before it is swallowed.

Front 15

tonsils

Back 15

Masses of lymphatic tissue which are part of the body’s defense system. They become inflamed and enlarge, they partially block the entrance into the throat (pharynx), making swallowing difficult and painful.

• Palatine tonsils

• Lingual Tonsils

Front 16

PHARYNX

Back 16

Food passes posteriorly into the oropharynx and laryngopharynx, both of which are common passageways for food, fluids, and air.

Front 17

• Longitudinal muscles

• Circular/constrictor muscles

Back 17

The walls of the pharynx contain two (2) skeletal muscle layers:

Front 18

Circular/constrictor muscles

Back 18

Alternating contractions of these two (2) muscle layers propel food through the pharynx inferiorly into the esophagus

Front 19

ESOPHAGUS

Back 19

• Also known as the ”gullet”, runs from the pharynx through the diaphragm to the stomach (approx. 25 meters or 10 inches long)

• It is an essential passageway that conducts food (by peristalsis) to the stomach

• Esophageal sphincter – valve preventing backflow of food to esophagus

Front 20

Esophageal sphincter

Back 20

valve preventing backflow of food to esophagus

Front 21

GASTROESOPHAGEAL REFLUX DISEASE (GERD)

Back 21

It is a digestive disorder that occurs when acidic stomach juices, or food and fluids back up from the stomach into the esophagus due to weakness or unusual relaxation of the esophageal sphincter

Front 22

acid reflux

Back 22

The main symptom of GERD is (?) which can cause an uncomfortable burning feeling in your chest often known as heartburn

Front 23

ALIMENTARY CANAL

Back 23

The walls of the (?) organs from the esophagus to the large intestine are made up of the same four (4) tissue layers, or tunica:

1. Mucosa

2. Submucosa

3. Muscularis externa

4. Serosa

Front 24

Mucosa

Back 24

innermost layer; moist mucous membrane lining the hollow cavities of the organ

Front 25

Submucosa

Back 25

soft connective tissue containing blood vessels, nerve endings, and lymphatic vessels

Front 26

Muscularis externa

Back 26

muscle layer (circular and longitudinal smooth muscles)

Front 27

Serosa

Back 27

outermost layer

Front 28

1. Visceral peritoneum

2. Parietal peritoneum

3. Mesentery

Back 28

SEROSA parts

Front 29

Visceral peritoneum

Back 29

serosa:

organs

Front 30

Parietal peritoneum

Back 30

serosa:

interior wall of the abdominal cavity

Front 31

Mesentery

Back 31

serosa:

fold of membrane that attaches the intestine to the abdominal wall and holds it in place

Front 32

CONTROL OF THE ALIMENTARY CANAL

Back 32

The alimentary canal wall contains two (2) important intrinsic nerve plexuses:

1. Submucosal nerve plexus

2. Myenteric (“intestinal muscle”) nerve plexus

Front 33

1. Submucosal nerve plexus

2. Myenteric (“intestinal muscle”) nerve plexus

Back 33

The alimentary canal wall contains two (2) important intrinsic nerve plexuses:

Front 34

Submucosal nerve plexus

Myenteric (“intestinal muscle”) nerve plexus

Back 34

These networks of nerve fibers are actual parts of the autonomic nervous system. They helps regulate the mobility and secretory activity of GI tract organs

Front 35

Lesser Omentum

Greater Omentum

Back 35

OMENTUM parts

Front 36

Lesser Omentum

Back 36

double layer of peritoneum from the liver to the lesser curvature of the stomach

Front 37

Greater Omentum

Back 37

another extension of the peritoneum which covers the abdominal organs; contains macrophages and defensive cells

Front 38

STOMACH

Back 38

C-shaped and is located on the left side of the abdominal cavity, nearly hidden by the liver and diaphragm.

Front 39

STOMACH

Back 39

Regions:

1. Cardial region or cardia

2. Fundus

3. Body

4. Pyloric antrum

5. Pylorus

Front 40

Cardial region or cardia

Back 40

food enters from the esophagus

Front 41

Fundus

Back 41

expanded part of the stomach

Front 42

Body

Back 42

midportion of the stomach

Front 43

Pylorus

Back 43

terminal part continuous with the small intestine

Front 44

Cardioesophageal sphincter

Pyloric sphincter or pyloric valve

Back 44

stomach valves

Front 45

Cardioesophageal sphincter

Back 45

prevents backflow of food to the esophagus

Front 46

Pyloric sphincter or pyloric valve

Back 46

controls the outflow of gastric contents into the duodenum

Front 47

15 to 25cm (6-10in)

Back 47

The stomach varies from (?) in length, but its diameter and volume depends on how much food it contains.

Front 48

Rugae

Back 48

series of ridges produced by folding of the walls of the stomach

Front 49

STOMACH

Back 49

Storage, mixing and breakdown of food (chemical breakdown of proteins)

• Gastric juice

• Gastric pits

• Gastrin

Front 50

Gastric juice

Back 50

variable mixture of water, hydrochloric acid, electrolytes (sodium, calcium, phosphate, sulfate, and bicarbonate), and organic substances (mucus, pepsins, and protein)

Front 51

Gastric pits

Back 51

openings leading to gastric glands that secrete gastric juice

Front 52

Gastrin

Back 52

hormone produced by ”G”cells in the lining of the stomach; stimulates secretion of gastric juice

Front 53

GASTRITIS

Back 53

It is a condition that inflames the stomach lining (the mucosa), causing belly pain, indigestion (dyspepsia), bloating and nausea.

Front 54

GASTRITIS

Back 54

It is often caused by bacterial infection (Helicobacter pylori), excessive drinking or smoking, unhealthy diet or nutrient deficiencies, excessive spicy or acidic food, prolonged use of Non-Steroidal AntiInflammatory Drugs (NSAIDs).

Front 55

GASTRITIS

Back 55

It can progress into an ulcer or an open sore in the lining of the stomach

• Treatment: Antacids, Antibiotics, Proton pump inhibitors

Front 56

SMALL INTESTINE

Back 56

The body’s ”Major Digestive Organ”

Front 57

SMALL INTESTINE

Back 57

Longest section of the alimentary canal; It is a muscular tube hanging in sausage-like coils extending from the pyloric sphincter to the large intestine

Front 58

1. Duodenum

2. Jejunum

3. Ileum

Back 58

small intestine three (3) subdivisions:

Front 59

Chyme

Back 59

semifluid mass of partly digested food expelled by the stomach into the duodenum

Front 60

Pancreatic Juice

Back 60

contains digestive enzymes

Front 61

Pancreatic ducts

Back 61

openings at the duodenum that lead into the pancreas

Front 62

Bile

Back 62

fluid that breaks down fats into fatty acids

Front 63

Bile duct

Back 63

opening at the duodenum leading into the liver

Front 64

Chyme

Pancreatic Juice

Pancreatic ducts

Bile

Bile duct

Back 64

SMALL INTESTINE – DIGESTION

Front 65

SMALL INTESTINE – ABSORPTION

Back 65

Nearly all nutrient absorption occurs in the small intestine (water and electrolytes)

Front 66

Circular Folds

Villi

Microvilli

Back 66

Three (3) structures absorption:

Front 67

Circular Folds

Back 67

deep folds on the mucosa and submucosa layer

Front 68

Villi

Back 68

fingerlike projections of the mucosa with abundant capillaries

Front 69

Microvilli

Back 69

”brush border”; tiny projections of the plasma membrane containing enzymes that complete digestion of proteins and carbohydrates

Front 70

SMALL INTESTINE – Peyer’s Patches

Back 70

collections of lymphatic tissue in the submucosa

Front 71

Peyer’s Patches

Back 71

Important part of the immune system by monitoring intestinal bacteria populations and preventing the growth of pathogenic bacteria in the intestines

Front 72

LARGE INTESTINE

Back 72

Also known as the ”large bowel” – largest part of the digestive system

Front 73

LARGE INTESTINE

Back 73

Water absorption; elimination of residues

Front 74

Cecum

Colon – ascending, transverse, descending, Sigmoid colon

Rectum

Back 74

large intestine three (3) subdivisions

Front 75

CECUM

Back 75

first part of the large intestine

Front 76

Appendix

Back 76

narrow, finger-shaped pouch that projects out from the cecum

Front 77

Appendix

Back 77

• No known function

• It is an ideal location for bacteria to accumulate and multiply which can lead to Appendicitis.

Front 78

Anal Canal

Back 78

has two valves that opens and closes the anus

Front 79

External Anal Sphincter

Back 79

voluntary skeletal muscle

Front 80

Internal Anal Sphincter

Back 80

involuntary smooth muscle

Front 81

TEETH

SALIVARY GLANDS

PANCREAS

LIVER AND GALL BLADDER

Back 81

ACESSORY DIGESTIVE ORGANS

Front 82

MASTICATION

Back 82

chewing by opening and closing of jaws and moving from side to side while using our tongue and cheek muscles to keep food in between

Front 83

Deciduous teeth

Back 83

(baby or milk teeth) begin to erupt around 6mos until a baby has a full set (20 teeth) by the age of 2 years

Front 84

Permanent teeth

Back 84

develops between the ages of 6-12 years old

Front 85

Third molars (wisdom teeth)

Back 85

usually erupt between 17-25 years

Front 86

32 permanent full set of teeth

Back 86

Overall, there are (?) but there are times that wisdom teeth fail to erupt or sometimes completely absent

Front 87

Enamel

Back 87

thick ceramic-like substance; hardest substance in the body which bears the force of chewing

Front 88

Dentin

Back 88

bone-like material underlies the enamel and forms the bulk of the tooth

Front 89

Pulp cavity

Back 89

contains pulp (connective tissue, blood vessels, and nerve fibers)

Front 90

Root/Root Canal

Back 90

extension of the pulp cavity which provides a route for blood vessels, nerves and the other pulp structures

Front 91

1. Parotid glands

2. Submandibular glands

3. Sublingual glands

Back 91

Three (3) pairs of salivary glands:

Front 92

Saliva

Back 92

mixture of mucus and serous fluids which moistens and helps to bind food together into a mass called a bolus.

Front 93

Salivary amylase

Back 93

enzyme that begins the process of starch digestion in the mouth

Front 94

Saliva

Back 94

Lysozyme and IgA antibodies that inhibit bacteria

Front 95

PANCREAS

Back 95

Soft, pink, triangular gland that extends across the abdomen from the spleen to the duodenum

Front 96

pancreas

Back 96

Only the (?) produces enzymes that break down all categories of digestible food

Front 97

Pancreatic juice

Back 97

neutralizes the acidic chyme coming in from the stomach

Front 98

LIVER

Back 98

Largest gland in the body

Front 99

LIVER

Back 99

Located under the diaphragm at the right side of the body and overlies the stomach

Front 100

LIVER

Back 100

has four (4) lobes and is suspended from the diaphragm and abdominal wall by delicate mesentery cord, the falciform ligament.

Front 101

LIVER

Back 101

has many critical metabolic and regulatory roles; however, its digestive function is to produce bile

Front 102

LIVER

Back 102

(?) cells detoxify drugs and alcohol and degrade hormones

Front 103

Bile

Back 103

a yellow-to-green, watery solution bile salts, bile pigments (bilirubin), cholesterol, phospholipids, and electrolytes

Front 104

Bile

Back 104

(?) salts physically break large fat globules into smaller ones

Front 105

Bile

Back 105

exits the liver via the common hepatic duct

Front 106

Hepatitis

Back 106

an inflammation of the liver resulting from drinking contaminated water or transmitted in blood via transfusion or contaminated

Front 107

Cirrhosis

Back 107

chronic inflammatory condition in which the liver is severely damaged and becomes hard and fibrous; caused by excess alcoholic beverage consumption for many years

Front 108

GALL BLADDER

Back 108

Small, thin-walled green sac in the inferior surface of the liver

Front 109

cystic

Back 109

Bile enters the gall bladder via the (?) duct where it is stored when food digestion does not occur

Front 110

gallbladder

Back 110

While in the (?), bile is concentrated by the removal of water

Front 111

Gall stones

Back 111

crystalize cholesterol formed when bile is stored in the gall bladder for too long or when too much water is removed

Front 112

digestion and absorption.

Back 112

The major functions of the digestive tract are usually summarized in two words – (?)

Front 113

1. Ingestion

2. Propulsion

3. Food Breakdown: Mechanical breakdown

4. Food Breakdown: Digestion

5. Absorption

6. Defecation

Back 113

The essential activities of the GI tract include the ff. six (6) processes:

Front 114

INGESTION

Back 114

• It is an active, voluntary process where food is placed into the mouth

• First step to the digestive system process occurring in the oral cavity

Front 115

PROPULSION

Back 115

• It is the process of propelling food from one organ to the next

• Peristalsis – involuntary alternating waves of contraction and relaxation of the longitudinal muscles in the organ wall to move food along the tract (e.g. swallowing)

Front 116

Peristalsis

Back 116

involuntary alternating waves of contraction and relaxation of the longitudinal muscles in the organ wall to move food along the tract (e.g. swallowing)

Front 117

FOOD BREAKDOWN: MECHANICAL BREAKDOWN

Back 117

° It is the process of physically fragmenting food into smaller particles and preparing food for further degradation by enzymes

° Examples of mechanical breakdown are mastication or chewing of food and churning or mixing of food in the stomach

° Segmentation – process where the small intestine moves food back and forth, mixing it with digestive juices

Front 118

Segmentation

Back 118

process where the small intestine moves food back and forth, mixing it with digestive juices

Front 119

FOOD BREAKDOWN: DIGESTION

Back 119

The sequence of steps in which large food molecules are chemically broken down to their building blocks by enzymes

• Organic food molecules:

• Monosaccharides or simple sugars (glucose, fructose, galactose)

• Disaccharides or carbohydrates (sucrose, lactose, maltose, and starch)

• Proteins

• Lipids (fats)

Front 120

HORMONES IN DIGESTION

Back 120

Gastrin – stimulates release of gastric juice

Somastatin – inhibits secretion of gastric and pancreatic juices

Secretin – increases pancreatic juice and bile output

Cholecystikinin (CKK) – stimulates gallbladder to expel stored bile

Front 121

Gastrin

Back 121

stimulates release of gastric juice

Front 122

Somastatin

Back 122

inhibits secretion of gastric and pancreatic juices

Front 123

Secretin

Back 123

increases pancreatic juice and bile output

Front 124

Cholecystikinin (CKK)

Back 124

stimulates gallbladder to expel stored bile

Front 125

ABSORPTION

Back 125

• It is the transport of digestive and products from the lumen of the GI tract to the blood or lymph

• The small intestine is the major absorptive site

• The process of chemical digestion is accelerated as the food now takes 3-6 hour journey through the looping coils and twists of the small intestine until digestion and absorption of all nutrients is completed.

• Absorption by the large intestine is limited to the absorption of vit. K and B, some ions, and most of the remaining water

Front 126

DEFECATION

Back 126

• It is the elimination of indigestible residues from the GI tract via anus in the form of feces

• Haustral contractions – slow segmenting movement in the colon, lasting about 1 minute that occur every 30 minutes or so; propel and mix residue

• Mass movements – long, slow-moving but powerful contractile waves that move over large areas of the colon three or four times daily and force the contents toward the rectum

• Fiber increases the strength of colon contractions and softens the stool

Front 127

Haustral contractions

Back 127

slow segmenting movement in the colon, lasting about 1 minute that occur every 30 minutes or so; propel and mix residue

Front 128

Mass movements

Back 128

long, slow-moving but powerful contractile waves that move over large areas of the colon three or four times daily and force the contents toward the rectum

Front 129

Fiber

Back 129

increases the strength of colon contractions and softens the stool

Front 130

DEFECATION REFLEX

Back 130

a response of the rectum when it is stretched due to presence of feces pushed via mass movements

Front 131

DEFECATION REFLEX

Back 131

It causes the walls of the sigmoid colon and the rectum to contract and the anal sphincters to relax

Front 132

Diarrhea

Back 132

result from any condition that rushes food residue through the large intestine before that organ has had sufficient time to absorb the water (as in irritation of the colon by bacteria)

Front 133

Constipation

Back 133

If food residue remains in the large intestine for extended periods, too much water is absorbed, and the stool becomes hard and difficult to pass