Physiology Spring Lecture 22 Study Guide: Chapter 16
The Digestive System 1 (p 565 - 597)
1. What is the primary function of the gastrointestinal system? (p. 566)
The primary function of the gastrointestinal system is to transfer nutrients, water, and
electrolytes from the food we eat to the body’s internal environment.
2. What are the four basic digestive processes? (p. 566)
1) Motility: muscular contractions that mix and move forward the contents within the
tract.
2) Secretion: consists of water, electrolytes, and specific organic constituents
important in the digestive process, such as enzymes, bile salts, or mucus.
3) Digestion: chemically break down structurally complex foodstuff of the diet into
smaller, absorbable units.
4) Absorption: small absorbable units that result from digestion, along with water,
vitamins, and electrolytes, are transferred from the digestive tract lumen into the blood
or lymph.
3. How are the following macronutrients broken down in the process of digestion: (p. 566)
Chemical name Common name/description examples/what it is found in
Monosaccharides “one-sugar” molecules Examples: Glucose, fructose,
galactose
Polysaccharide “many-sugar” molecules Example: Starch- contains
amylose and amylopectin
Glycogen Highly branched polysaccharide Found in: meat
storage form of glucose in
muscle
Indigestible dietary Insoluble fiber Found in: plant walls
polysaccharides Example: cellulose
Indigestible dietary Soluble fiber Found in: plant walls
polysaccharides Example: pectin
4. List the accessory digestive organs and their function (p. 569)
1. Salivary Glands: Lie outside the oral cavity and discharge saliva through short ducts into the
mouth.
2. Exocrine Pancreas: secrete digestive juices into the digestive tract lumen on appropriate neural
or hormonal stimulation.
3. Biliary system: composed of the liver and gallbladder; secretes bile into the duodenal lumen.
5. Why are these organs considered exocrine organs? (p. 569)
These organs are considered exocrine organs because they lie outside the digestive tract and
empty their secretions through ducts into the digestive tract lumen.
6. List the organs in the digestive tract in the order that nutrients would naturally flow
through (p. 570)
1. Mouth
2. Pharynx
3. esophagus
4. stomach
5. small intestine
6. large intestine
, 7. anus
7. (p.570)
Layers of the Components Function Contains
digestive tract
Mucosa Mucous Inner epithelial layer Exocrine gland cells for the secretion of
membrane that serves as a digestive juices and endocrine gland
protective surface cells for the secretion of blood Bourne
GI hormones epithelial cells specialized
for absorbing nutrients
Lamina Propria Thin middle layer of Houses the gut-associated
connective tissue on lymphoid tissue (GALT), which is
which the epithelium important in defense against
rests disease-causing intestinal bacteria
Muscularis Sparse outermost layer N/A
mucosa of smooth muscle
Submucosa (left intentionally Thick layer of Contains the larger blood and lymph
blank) connective tissue that vessels, both of which send branches
provides the digestive inwards to the mucosal layer and
outward to the surrounding thick muscle
tract with distensibility
layer.
and elasticity
Also, contains a nerve network known
as submucous plexus.
Muscularis Externa (left intentionally Major smooth muscle Consists of two layers: an inner circular
blank) coat of the digestive layer and an outer longitudinal layer.
tube Also contains a nerve network known as
myenteric plexus.
Inner circular Run circularly around Contraction of these fibers
layer the tube. decreases the diameter of the tube
Constricts the tube at
the point of
contraction.
Outer Shortens the tube Contraction of these fibers
longitudinal layer decreases the length of the tube
Serosa Covers the Secretes watery, Continuous with the mesentery,
digestive tract slippery fluid (serous which suspends the digestive
fluid) that lubricates organs from the inner wall of the
and prevents friction abdominal cavity.
between the digestive
organs and the
surrounding viscera
8. What are the fours ways the digestive function is regulate? (p.571, 572)
Regulatory mode Type of activity Function
Autonomous smooth muscle Slow-wave potentials; Rhythmic, wavelike fluctuations in
function Also referred to as basic membrane potential that cyclically
electrical rhythm (BER) bring the membrane closer to or
farther from threshold potential.
Interstitial cells of Cajal These pacemakers generate the
slow-wave potentials that propagate
The Digestive System 1 (p 565 - 597)
1. What is the primary function of the gastrointestinal system? (p. 566)
The primary function of the gastrointestinal system is to transfer nutrients, water, and
electrolytes from the food we eat to the body’s internal environment.
2. What are the four basic digestive processes? (p. 566)
1) Motility: muscular contractions that mix and move forward the contents within the
tract.
2) Secretion: consists of water, electrolytes, and specific organic constituents
important in the digestive process, such as enzymes, bile salts, or mucus.
3) Digestion: chemically break down structurally complex foodstuff of the diet into
smaller, absorbable units.
4) Absorption: small absorbable units that result from digestion, along with water,
vitamins, and electrolytes, are transferred from the digestive tract lumen into the blood
or lymph.
3. How are the following macronutrients broken down in the process of digestion: (p. 566)
Chemical name Common name/description examples/what it is found in
Monosaccharides “one-sugar” molecules Examples: Glucose, fructose,
galactose
Polysaccharide “many-sugar” molecules Example: Starch- contains
amylose and amylopectin
Glycogen Highly branched polysaccharide Found in: meat
storage form of glucose in
muscle
Indigestible dietary Insoluble fiber Found in: plant walls
polysaccharides Example: cellulose
Indigestible dietary Soluble fiber Found in: plant walls
polysaccharides Example: pectin
4. List the accessory digestive organs and their function (p. 569)
1. Salivary Glands: Lie outside the oral cavity and discharge saliva through short ducts into the
mouth.
2. Exocrine Pancreas: secrete digestive juices into the digestive tract lumen on appropriate neural
or hormonal stimulation.
3. Biliary system: composed of the liver and gallbladder; secretes bile into the duodenal lumen.
5. Why are these organs considered exocrine organs? (p. 569)
These organs are considered exocrine organs because they lie outside the digestive tract and
empty their secretions through ducts into the digestive tract lumen.
6. List the organs in the digestive tract in the order that nutrients would naturally flow
through (p. 570)
1. Mouth
2. Pharynx
3. esophagus
4. stomach
5. small intestine
6. large intestine
, 7. anus
7. (p.570)
Layers of the Components Function Contains
digestive tract
Mucosa Mucous Inner epithelial layer Exocrine gland cells for the secretion of
membrane that serves as a digestive juices and endocrine gland
protective surface cells for the secretion of blood Bourne
GI hormones epithelial cells specialized
for absorbing nutrients
Lamina Propria Thin middle layer of Houses the gut-associated
connective tissue on lymphoid tissue (GALT), which is
which the epithelium important in defense against
rests disease-causing intestinal bacteria
Muscularis Sparse outermost layer N/A
mucosa of smooth muscle
Submucosa (left intentionally Thick layer of Contains the larger blood and lymph
blank) connective tissue that vessels, both of which send branches
provides the digestive inwards to the mucosal layer and
outward to the surrounding thick muscle
tract with distensibility
layer.
and elasticity
Also, contains a nerve network known
as submucous plexus.
Muscularis Externa (left intentionally Major smooth muscle Consists of two layers: an inner circular
blank) coat of the digestive layer and an outer longitudinal layer.
tube Also contains a nerve network known as
myenteric plexus.
Inner circular Run circularly around Contraction of these fibers
layer the tube. decreases the diameter of the tube
Constricts the tube at
the point of
contraction.
Outer Shortens the tube Contraction of these fibers
longitudinal layer decreases the length of the tube
Serosa Covers the Secretes watery, Continuous with the mesentery,
digestive tract slippery fluid (serous which suspends the digestive
fluid) that lubricates organs from the inner wall of the
and prevents friction abdominal cavity.
between the digestive
organs and the
surrounding viscera
8. What are the fours ways the digestive function is regulate? (p.571, 572)
Regulatory mode Type of activity Function
Autonomous smooth muscle Slow-wave potentials; Rhythmic, wavelike fluctuations in
function Also referred to as basic membrane potential that cyclically
electrical rhythm (BER) bring the membrane closer to or
farther from threshold potential.
Interstitial cells of Cajal These pacemakers generate the
slow-wave potentials that propagate
