Transcript Guided Notes on Accessory Digestive Organs

GUIDED NOTES ON ACCESSORY
DIGESTIVE ORGANS
1. WHAT IS SALIVA, AND WHAT ARE THE
FUNCTIONS OF ITS 2 COMPONENTS?
Saliva is a mixture of mucus and serous fluids
 Mucus moistens and binds food together into a
bolus
 The serous fluid contains an enzyme called
salivary amylase that begins starch digestion

2. LIST THE FOUR TYPES OF PERMANENT
TEETH AND THEIR SHAPES AND FUNCTIONS
Incisors: chisel-shaped for cutting
 Canines: fang-like, for tearing or piercing
 Premolars: (bicuspids) broad crowns for grinding
 Molars: broader crowns with rounded tips for
grinding

3. WHAT DO THE ENZYMES PRODUCED BY
THE PANCREAS DO?
They break down all categories of digestible
foods.
 They are alkaline, so they also neutralize the
acidic chyme from the stomach.

4. WHAT IS THE DIGESTIVE FUNCTION OF
THE LIVER?

The liver produces bile, which enters the
duodenum through the common hepatic duct.
5. WHAT IS BILE COMPOSED OF? WHAT IS
THE FUNCTION OF BILE SALTS?
Bile is a yellow-green, watery solution containing
bile salts, bile pigments, cholesterol,
phospholipids, and electrolytes
 Bile salts emulsify fats by breaking large fat
globules into smaller ones, giving more surface
area for enzymes to work

6. WHEN IS BILE STORED IN THE
GALLBLADDER?

When food digestion is not occurring, bile backs
up into the cystic duct and enters the gallbladder
7. WHAT ARE GALLSTONES?

If bile is stored in the gallbladder too long, the
cholesterol it contains may crystallize into
gallstones
FUNCTIONS OF THE DIGESTIVE SYSTEM
1.
2.
3.
Ingestion: an active, voluntary process of
placing food in the mouth
Propulsion: foods are propelled from one organ
to the next by peristalsis and segmentation
Mechanical Digestion: mixing of food in the
mouth by the tongue; churning of food in the
stomach, segmentation in the small intestine.
FUNCTIONS OF THE DIGESTIVE SYSTEM
4.
5.
6.
Chemical Digestion: large food molecules are
broken down to their building blocks by
enzymes
Absorption: transport of digested end products
from the lumen of the GI tract to the blood or
lymph
Defecation: elimination of indigestible
substances from the body
2. WHAT IS PERISTALSIS?
Peristalsis are involuntary, alternating waves of
contractions of muscles in the walls of the
alimentary canal.
 The net effect is to squeeze food along the
digestive tract

3. WHAT IS THE PURPOSE OF
SEGMENTATION?

Segmentation moves food back and forth across
the internal wall of the organ, serving to mix it
with digestive juices
4. CATEGORIZE THE SUGARS PROCESSED
BY THE STOMACH:

Monosaccharides: Glucose, Fructose, Galactose

Disaccharides: Sucrose, Maltose, Lactose

Polysaccharides: Starch
5. WHAT IS THE PURPOSE OF CELLULOSE
IN THE DIET?

Cellulose helps to move foodstuffs along the
gastrointestinal tract by providing bulk, or fiber
6. DESCRIBE THE PROCESS OF PROTEIN
DIGESTION

Proteins are digested to their building blocks,
amino acids, by enzymes in the stomach and
small intestine
7. LIST THE STIMULI THAT ACTIVATE
DIGESTIVE REFLEXES:
1.
2.
3.
Stretch of the organ by food in the lumen
pH of the contents
Presence of certain breakdown products of
digestion
1. HOW IS FOOD BROKEN DOWN IN THE
MOUTH?
Food is physically broken down by chewing
 Salivary amylase begins the chemical digestion of
starch, breaking it down into maltose

2. WHAT REGULATES THE SECRETION OF
GASTRIC JUICE?
The sight, smell, and taste of food increase the
secretion of gastric juice by the stomach cells
 2 to 3 liters of gastric juice is produced every day
under normal conditions

3. WHAT CAUSES HEARTBURN TO OCCUR?

When the cardioesophageal sphincter fails,
gastric juice backs up into the esophagus, which
has little protection from mucus
4. COMPARE PEPSIN AND RENNIN:
Pepsin is a protein-digesting enzyme that is
activated by hydrochloric acid
 Rennin is a protein-digesting enzyme that works
on milk protein. It is only produced by infants
and children
 Both are produced by the stomach

5. HOW LONG DOES FOOD GENERALLY
REMAIN IN THE STOMACH?

4 hours if the meal is well-balanced

6 hours if it has a high fat content
6. WHAT IS VOMITING?

Vomiting is a reverse peristalsis occurring in the
stomach, accompanied by contraction of the
abdominal muscles and the diaphragm
7. WHAT FOUR FUNCTIONS DO THE
PANCREATIC JUICE ENZYMES PERFORM?
1.
2.
3.
4.
Complete the digestion of starch
Carry out protein digestion
Totally responsible for fat digestion
Digest nucleic acids
8. WHY IS IT IMPORTANT THAT PANCREATIC
JUICE CONTAINS BICARBONATE?

Bicarbonate is basic, so that it can neutralize the
acidic chyme as they enter the small intestine
together
9. HOW ARE WATER AND THE END
PRODUCTS OF DIGESTION ABSORBED?


Most substances are absorbed through the
intestinal cell plasma membranes by active
transport
Lipids are absorbed by diffusion
10. WHAT REMAINS FROM THE PROCESS OF
DIGESTION?
Water
 Indigestible food materials (fiber)
 Large amounts of bacteria

11. WHAT FUNCTIONS DO THE BACTERIA
PERFORM?

They metabolize remaining nutrients and release
gas that contribute to the odor of feces
12. WHAT ARE MASS MOVEMENTS?
Mass movements are long, slow-moving, powerful
contractions that move over the colon 3 or 4 times
daily and force the contents toward the rectum.
 They occur during or just after eating
 Fiber in the diet causes them to increase in
strength

13. WHAT CONDITIONS CAUSE DIARRHEA
TO OCCUR?
When food residue is rushed through the large
intestine before sufficient time for water to be
absorbed
 Usually this is caused by irritation from bacteria
