Digestive System

System that is the breaking down of food you eat into nutrients to be absorbed by your blood and needed for metabollic processes and gets rid of indigestible materials.

Digestive System

4 Digestive System Functions

Ingestion

Digestion

Absorption

Defecation/Excretion

taking in food

Ingestion

breaking food into nutrient molecules

Digestion

movement of nutrients into the bloodstream

Absorption

excretes to rid the body of indigestible waste

Defecation

2 Main Groups of Organs

Alimentary Canal

Accessory Digestive Organs

continuous, coiled, hollow tube where organs ingewwst, digest, absorb, and defecate.

Alimentary Canal

It includes teeth, tongue, and several large digestive organs that assist digestion in various ways.

Accessory Digestive Organs

Organs of Alimentary Canal

Mouth

Pharynx

Esophagus

Stomach

Small Intestine

Large Intestine

Anus

Mucous membrane-lined cavity

Mouth

Protect the anterior opening

Lips (Labia)

Form the lateral walls

Cheeks

Forms the anterior roof

Hard palate

Forms the posterior roof

Soft palate

Fleshy projection of the soft palate

Uvula

Space between lips externally and teeth and gums internally

Vestibule

Area contained by the teeh

Oral cavity proper

attached at hyoid bone and styloid processes of the skull, and by the lingual frenulum to the floor of the mouth

Tongue

2 Types of Tonsils

Palatine

Lingual

pair of tonsils located at posterior end of oral cavity

Palatine

single tonsil located at the base of the tongue

Lingual

Functions of the Mouth

• Mastication (chewing) of food

• Tongue mixes masticated food with saliva

• Tongue initiates swallowing

• Taste buds on the tongue allow for taste

serves as passageway for foods, fluids, and air

Pharynx

2 types of pharynx involved in the digestive system

oropharynx

Laryngopharynx

2 skeletal muscle layers in the pharynx that propells food into the esophagus

longitudinal outer layer

circular inner layer

Alternating contractions of the muscle layers that propels the food

Peristalsis

about 10 inches long that runs from the pharynx to stomach through the diaphragm

Esophagus

C-shaped organ located on the left side of the abdominal cavity

Stomach

where food enters from the esophagus

cardioesophageal sphincter

valve where food empties into the small intestine

pyloric sphincter

Regions of the Stomach

Cardial

Fundus

Body

Pylorus

near the heart and surrounds the cardioesophageal sphincter

Cardial

expanded portion lateral to the cardiac region

Fundus

midportion of the stomach

Body

convex lateral surface of the stomach

Greater curvature

concave medial surface of the stomach

Lesser curvature

how many liters/gallon of food can the stomach hold when full

4 Liters/ 1 Gallon

Internal folds of the mucosa present when the stomach is empty

Rugae

Double layer of peritoneum

Lesser omentum

Another extension of the peritoneum. Covers the abdominal organs

Greater omentum

4 Stomach cells

Chief cells

Parietal cells

Mucous neck cells

Enteroendocrine cells

produce protein-digesting enzymes (pepsinogens)

Chief cells

produce hydrochloric acid that activates enzymes

Parietal cells

produce thin acidic musus

Mucous neck cells

produce local hormones such as gastrin

Enteroendocrine cells

site of most digestive activity

Pyloric region

Body’s major digestive organ

Longest portion of the alimentary tube

Site of nutrient absorption

Small Intestine

3 Subdivisions of Small Intestine

Duodenum

Jejunum

Ileum

• Ileocecal valve

formed by the liver, enters the duodenum via bile duct

Bile

location where the main pancreatic duct and bile ducts join

Hepatopancreatic ampulla

fingerlike projections formed by the mucosa

Villi

tiny projections of the plasma membrane

Microvilli

deep folds of mucosa and submucosa

Circular folds

Collections of lymphatic tissues

Increase in number toward the end of the small intestine

Peyer’s Patches

Larger in diameter, but shorter in length than small intestine

Eliminates feces

Large intestine

5 Subdivisions of the Large Intestine

Cecum

Appendix

Colon

Rectum

Anal Canal

saclike first part of the large intestine

Cecum

hangs from the cecum

Appendix

Accumulation of lymphoid tissue that sometimes becomes inflamed in the appendix

Appendicitis

4 Regions of the Colon

Ascending

Transverse

Descending

Sigmoid

travels up right side of abdomen and makes a turn at the right colic (hepatic) flexure

Ascending

travels across the abdominal cavity and turns at the left colic (splenic) flexure

Transverse

travels down the left side

Descending

S-shaped region; enters the pelvis

Sigmoid

located in the pelvis

sigmoid colon

rectum

anal canal

produce alkaline mucus to lubricate the passage of feces

Goblet cells

Muscularis externa layer is reduced to three bands of muscle called

Teniae coli

Organs of the Accessory Digestive Organs

Teeth

Salivary Glands

Pancreas

Liver

Gallbladder

masticate (chew) food into smaller fragments

Teeth

known as the baby or milk teeth

Deciduous teeth

how many teeth does a baby have at the age of 2

20 teeth

replace deciduous teeth between ages 6 and 12

Permanent teeth

how many teeth does a fullset have

32 teeth

Classifications of teeth

Incisors - cutting

Canines - tearing/piercing

Premolars - crushing/grinding

Molars - crushing/grinding

3 pairs of salivary glands that empty secretions into the mouth

Parotid glands

Submandibular glands

Sublingual glands

found anterior to the ears that mumps affects

Parotid glands

both of these glands empty saliva into the floor of the mouth through small ducts

Submandibular and sublingual glands

mixture of mucus and serous fluids that helps moisten and bind food together into a mass calaled a bolus

Saliva

begins starch digestion

salivary amylase

inhibit bacteria

lysozymes and antibodies

soft, pink triangular gland posterior to the parietal peritoneum

produce a wide spectrum of digestive enzymes that break down all categories of food

Pancreas

Hormones produced by pancreas

insulin

glucagon

Largest gland in the body

located on the right side of the body under the diaphragm

Liver

Yellow-green; Emulsifies (breaks down) fats

Bile

Green sac found in a shallow fossa in the inferior surface of the liver

Spurts out stored bile

Gallbladder

movement of foods from one region of the digestive system to another

Propulsion

small intestine moves food back and forth to mix with digestive juices

Segmentation

Release of pancreatic juice from the pancreas into the duodenum is stimulated by:

Vagus nerves

Local hormones that travel via blood to influence the release of pancreatic juice and bile

Secretin

Cholecystokinin (CCK)

Hormone that stimulates release of gastic juice and stomach emptying

Gastrin

Hormone that stimulates gastic secretion and empyting

Intestinal gastrin

Hormone that activates parietal cells to secrete hydrochloric acid

Histamine

Hormone that inhibits secretion of gastric juice and pancreatic juice, and emptying of stomach and gallbladder

Somatostatin

Hormone that increases output of pancreatic juice rich in bicarbonate ions, increases bile output by liver, and inhibits gastic mobility

Secretin

Hormone that increases output of enzyme-rich pancreatic juice

CCK

Hormone that inhibits secretion of gastic juice and stimulates insulin release

Gastic inhibitory peptide (GIP)

Feces contains:

undigested food residues

mucus

bacteria

water

movements occurring most frequently in the large intestine

Haustral contractions

includes all bacteria, viruses, parasites and fungi in or on the human body

Microbiota