EQ WHAT IS THE DIFFERENCE BETWEEN THE ALIMENTARY

EQ: WHAT IS THE DIFFERENCE BETWEEN THE ALIMENTARY CANAL AND THE ACCESSORY DIGESTIVE ORGANS? PGS 469470 If you missed exam on Thursday/Friday, must be made up by Thursday!

OBJECTIVES To compare and contrast chemical vs. mechanical digestion. To explain the general characteristics of the alimentary canal. To explain the process of swallowing and peristalsis. To identify the structures of the mouth and explain their function. To understand the necessity of salivary glands and name each type.

DIGESTION Chemical digestion- complex molecules are broken down into smaller molecules Mechanical digestion- physical movement of food that breaks it down into smaller pieces Ex. Chewing, grinding, mashing Chewing is called “mastication”

COMPONENTS OF DIGESTIVE SYSTEM Alimentary Canal “digestive tract” Mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anal canal Accessory Structures: Salivary glands, liver, gallbladder, & pancreas

COMPLETE TABLE- GIVE NO MORE THAN 3 WORDS TO DESCRIBE FUNCTION PGS 470 -481 FRONT OF PAPER BACK OF PAPER Structure (Alimentary Canal) Structure (Accessory Organs) Mouth Salivary Glands Pharynx Liver Esophagus Gallbladder Stomach Pancreas Small Intestine Large Intestine

EQ: DESCRIBE THE 4 BASIC TISSUE LAYERS, OR TUNICS OF THE ALIMENTARY CANAL. PG 472 (ESOPHAGUS) 1. Grab Digestive System Diagram off front table. 2. Be sure to check Absent folder if you have missed days 3. If you missed exam on Thursday/Friday, must be made up by Thursday!

ALIMENTARY CANAL Muscular tube that passes through the body’s ventral cavity 9 meters long Contains 4 layers

ALIMENTARY CANAL 1. Mucosa: (innermost) Epithelial Tissue Protects the tissues beneath it & carries out secretion/absorption 2. Submucosa: Nourishes surrounding tissue and carries away absorbed materials

ALIMENTARY CANAL 3. Muscular Layer: Two layers of smooth muscle & nerves Fibers of inner coat, lengthwise Contraction= shortening Fibers on outer coat circular Contraction= decreased diameter 4. Serosa: (outermost) Protects underlying tissues and secrete serous fluid

MOUTH Mechanical Digestion Reduces size of solid particles/mixes with saliva ORAL CAVITY

SALIVARY GLANDS Secrete saliva Amylase (enzyme that breaks down carbs) Mucus to bind to food and lubricate during swallowing. Salivary Glands Parotid Submandibular Sublingual

PHARYNX Transports bolus (digesting food) to esophagus

ESOPHAGUS About 25 cm long Connects pharynx to the stomach Separated from the stomach by the cardiac sphincter. Pharynx Tongue Esophagus Cardiac sphincter

DO NOW Read the story about William Beaumont and his work with St. Martin in the early 1800 s. Write a short summary of what you read.

SWALLOWING MECHANISM 1. Food is chewed and mixed with saliva, 2. Tongue rolls this into a bolus forcing it into the pharynx 3. Food stimulates sensory receptors around the pharyngeal opening triggering the swallowing reflex. 4. Momentarily inhibits breathing, peristalsis transports food into the esophagus and to the stomach.

MOVEMENTS OF THE ALIMENTARY CANAL Mixing Movement Muscles contract rhythmically Mixes food with digestive juices secreted by the mucosa Peristalsis-propelling movement

DO NOW Read the story about William Beaumont and his work with St. Martin in the early 1800 s. Write a short summary of what you read.

EQ: WHY IS IT NECESSARY FOR THE STOMACH TO BE SO ACIDIC? PGS 485 -487 (ACTIVITIES OF THE STOMACH) Periods 1, 3, 5 - turn in Reading Logs from before spring break if you have not already done so.

LETS REVIEW! Without using any notes, trace the pathway of food through the entire digestive system. Describe what happens to the food between the mouth and the stomach (the remainder of the process, we haven’t discussed yet)

STOMACH J shaped with about a 1 liter capacity. Contains rugae (ridges) which allow it to expand Divided into 4 regions Cardiac Fundic Body Pyloric

STOMACH Mostly Mechanical Digestion Chemical breakdown of protein begins Can absorb only small amounts of water, certain salts, alcohol, and some lipid-soluble drugs. EX: Aspirin

STOMACH Cardiac sphincter Pyloric sphincter Stomach

GASTRIC JUICE HCl Viscous alkaline mucus that coats the stomach Enzymes Pepsinogen + HCL Pepsin (protein breakdown) Intrinsic factor Helps the small intestine absorb B 12

STOMACH JUICES The mixture of gastric juice and the bolus gives us chyme. Stomach contractions push chyme a little at a time through pyloric sphincter into the sm. Intestine. Type of food can effect rate of emptying Fatty food = 3 -6 hrs. in stomach Proteins quicker Carbs are fastest

HEARTBURN! Cardiac sphincter contracts and closes to prevent regurgitation. Heartburn Regurgitation of stomach acid into the esophagus.

STOMACH ULCERS Breaking down of the mucosal lining.

STOMACH

EQ: What is the importance of the microvilli, Villi, and Circular folds in the Small intestine? Pgs 475 -477 (Small Intestine)

SMALL INTESTINE Body’s MAJOR digestive organ -- nutrient absorption into the circulatory system Suspended from posterior abdominal wall by mesentery

SUBDIVISIONS OF SMALL INTESTINE 1. Duodenum -- attached to the stomach (5%) 2. Jejunum – middle section (40%) 3. Ileum – attaches to large intestine (60%)

Duodenum Jejunum Ilium

CHEMICAL DIGESTION IN SMALL INTESTINE 1. FAT digestion begins in the small intestine a. Intestinal & Pancreatic Enzymes b. Bile (liver) enters duodenum 2. Fats fatty acids + glycerol

ANATOMY OF SM. INTESTINE– MEMBRANE LINING 1. Villi—fingerlike structures (“hairs”) 2. Microvilli—tiny projections (“brush border”) 3. Circular Folds- like the rugae of the stomach All meant to increase the surface area of the small intestine for absorption

WHAT IS THE DIFFERENCE BETWEEN PERISTALTIC AND SEGMENTAL MOVEMENTS OF THE DIGESTIVE TRACT? PGS 481 -482

WHAT IS THE DIFFERENCE BETWEEN PERISTALTIC AND SEGMENTAL MOVEMENTS OF THE DIGESTIVE TRACT? PGS 481 -482 Peristaltic- Propulsion Segmental- Mixing

PANCREAS Secretes pancreatic juice into the duodenum through the Pancreatic Duct Pancreatic enzymes: Pancreatic amylase CARBS Pancreatic lipase FATS Nucleases NUCLEIC ACIDS Proteases: trypsin, chymotrypsin & carboxypeptidase PROTEIN

Pancreas Pancreatic Duct

EQ: DESCRIBE THE PROCESS OF FOOD BREAKDOWN AND ABSORPTION IN THE LARGE INTESTINE. PG 492 Check absent folder if you were out this week.

LIVER AND GALLBLADDER Effects carbohydrate, lipid, and protein metabolism. Produces bile Not an enzyme **bile salts emulsify fats (turn them into little globs instead of big globs!) Gallbladder- bile storage when food digestion is not occurring

Liver Gallbladder Common Bile Duct Common Hepatic Duct Pancreas Pancreatic Duct

LARGE INTESTINE (COLON) “Frames” the small intestine Colon : Ascending Transverse Descending Sigmoid Rectum

Colon Transverse Ascending Descending Ileocecal Valve Appendix Rectum Anal Sphincter

DIGESTION OF LG. INTESTINE Main Site for uptake of: WATER Minerals Salts Some Vitamins Whatever is left unabsorbed, forms feces Undigested food residues Mucus Bacteria Some water to allow smooth passage

REVIEW What is the process that occurs after swallowing? What is the scientific name for the digestive tract? How many layers is this tract? What are the 3 parts of the pharynx? What is absorbed in the stomach? What does the pancreas do? Why are bile salts important?