Transcript EQ: What is the difference between the alimentary canal and the

EQ: WHAT IS THE DIFFERENCE BETWEEN THE ALIMENTARY CANAL
AND THE ACCESSORY DIGESTIVE ORGANS? PGS 469-470
 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 1800s.
 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 1800s.
 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 B12
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?