1. Ch15 Digestive System
Main function = breakdown food for nutrients for the body
Alimentary canal = tube extending from mouth to anus which secretes substances used in the process of digestion
Organs: Mouth, Pharynx, Esophagus, Stomach, Small Intestines, Large Intestines – rectum and anus

2. 6 Processes of Digestion
Ingestion – taking food into the mouth
Propulsion – using peristalsis to move food along the canal
Chemical digestion – using enzymes to break down food
Mechanical digestion – churning or crushing food into smaller pieces
Absorption – diffusion of nutrients from small intestines to blood
Elimination – removal of waste from the canal

3. Mouth Lined with stratified squamous epithelial tissue
Function of Parts:
Cheeks/lips = expression and keeping food in mouth during chewing
Tongue = taste, speech, and chewing
Palate = chewing, speech
Tonsils = defense
Uvula = blocks oral cavity when sneezing
Teeth = gripping, tearing, and grinding food
Salivary gland = moistens and binds food, helps with taste, contains salivary amylase enzyme that breaks down carbohydrates

4. Pharynx Nasopharynx = by nasal cavity; passageway for air
Oropharynx = by oral cavity; passageway for food and air
Laryngopharynx = by larynx; passageway to esophagus and larynx split
By the time food enters the pharynx it is called a bolus = mixture of saliva and partially broken down food

5. Esophagus Function = passageway for food from pharynx to stomach
Straight, collapsible tube around 25 cm long lined with stratified squamous cells
Layers of the wall = mucous membrane, submucosa, muscular layer, and serous layer
Bolus is moved by peristalsis = wavelike motion of the muscle layer

6. Stomach
Function = mixes food with gastric juices and stores food before releasing it into the small intestines
Structure = J-shaped with 2 muscular sphincters = cardioesophageal and pyloric, inner folds called rugae helps with the churning of food and expansion of stomach; lined with simple columnar for the remainder of the canal
Food is now called chyme = food particles mixed with gastric juice

7. Stomach Substances/enzymes secreted by the stomach:
Gastric juice = released from gastric glands to break down food
Pepsin = breaks down protein
Gastrin = hormone that aids the release of gastric juice
Gastric secretions regulation = when food enters the stomach, the parasympathetic system stimulates the release of gastric juices by increasing the levels of gastrin in the blood

8. Pancreas
Structure = horizontal organ that contains different types of cells to secrete various hormones and enzymes, leads into the small intestines at the duodenum
Functions = regulates blood glucose levels and releases digestive enzymes
Secretions regulation = secretin (hormone) stimulates the release of enzymes to intestine

9. Liver Location = on right side of body under the diaphragm
Functions = makes bile (contains salts and other substances), filters toxin from blood, stores glucose, aids in carb, protein, and lipid metabolism
Purpose of bile salts = breaks down fats (lipids)

10. Gallbladder Function = stores bile
Location = under one of the lobes of the liver and connects to the duodenum of the small intestines
Cholecystokinin (hormone) is released from the small intestine to stimulate the gallbladder to contract and to help neutralize the chyme

11. Small Intestines Function = absorbs nutrients into the blood
Structure: the 3 subdivisions are called duodenum, jejunum, and ileum and the inner walls are lined with villi and microvilli
Nucleosidases are enzymes released into the small intestines that break down nucleic acid
Small intestines are covered by a fatty double folded membrane that drapes from the stomach over the intestines called the greater omentum

12. Large Intestines
Function = absorbs excess water, holds feces before removal from body
Structure: Subdivisions/parts of colon = ascending colon, transverse colon, descending colon, rectum, and anus; the large intestines have a larger diameter than the small intestines; contain internal and external anal sphincters
The connection between small and large intestines is the appendix

13. Videos
Gastric Animation
Gastric Sleeve Surgery