BIOD 331 Module 7
Module 7.1 — Anatomy & Physiology Review
Key Concepts
● Functions of the GI tract: digestion & absorption →
Notes:
○ amylase - carb bd, lipase - fat breakdown.
○ Emulsification - stomach - mechanical agitation; duodenum -chemical digestion -
bile and pancreatic lipase help
○ In stomach - pepsin - carb/protein digestion
○ Absorption → process of moving nutrients and other materials from external
environment of the GI tract into the internal environment
○ Small int. - DJI - duodenum, jejunum, ileum; large int. (reabsorbs water mainly, and
stores waste) - cecum, colon (ascending, transverse, descending, sigmoid),
rectum, anal canal
○ Liver —> largest visceral organ in body; receives 25% of the resting cardiac
output
■ Unique feature of the liver: dual blood supply (hepatic artery & portal
vein)
● has a venous (portal) blood supply (comes from digestive
tract, pancreas, and spleen) through the hepatic portal vein
that receives 75% of blood per min, AND an arterial supply
through the hepatic artery that receives the remaining 25%
of remaining blood.
■ Hepatic vein in liver drains into IVC below the diaphragm
■ Liver can store 500-1000ml of blood
■ Produces bile
■ Metabolizes hormones and drugs
■ Synthesizes proteins, glucose, and clotting factors
■ Stores vitamins and minerals and converts them to usable material for
body to use
■ Ammonia → urea
■ Fatty acids → ketones
■ Glucose stores → glycogen —- through glycogenesis
■ Can also make glucose from amino acids, glycerol and lactic acid
during fasting – gluconeogenesis
■ Excess carbs → triglycerides for storage
,● Layers of the GI wall: (innermost) mucosa / submucosa / muscularis / serosa
(outermost) → Notes:
○ Mucosal layer - first,inner. epithelium, has underlying CT lamina propria and sm
musc. Cells that can contract and change shape and surface area of mucosal
layer
■ Functions:
● Produces mucus that lubricates and protects the inner surface of
the alimentary canal
● Secretes digestive enzymes
● Absorbs the breakdown products of digestion
● Maintains a barrier to prevent entry of noxious substances and
pathogenic organisms ■ ET cells replaced every 5d.
○ Submucosal layer - dense CT and adipose tissue. Blood vessels, nerves and
structures that secrete digestive enzymes.
○ Muscularis externa - circularly arranged smooth muscle cells and outer layer of
longitudinally arranged smooth muscle layers. Alternatively contract through the
GI tract - peristalsis
○ Serosal layer - serous membrane - visceral peritoneum
■ Peritoneum: LARGEST serous membrane in the body
● 2 continuous layers → visceral and parietal peritoneum
○ Parietal peritoneum - lines walls of the abdominopelvic
cavity
○ Between parietal and visceral layer - peritoneal cavity -
potential space containing fluid secreted by serous
membranes - fluid keeps moist surface to prevent friction
between moving abdominal organs
● Mesentery: double layer of peritoneum that holds organs and
stores fat
→ Notes:
○ Attaches to abdominal wall
○ Blood vessels, nerves, lymphatic vessels that supply the
intestinal wall
○ Holds organs in place and stores fat
● Omentum: double layered fold of peritoneum that hangs from
stomach to adjacent organs in abdominal cavity
○ Greater omentum - connects stomach and covers the
transverse colon and the folds of intestine
■ Contains fat and has a lot of mobility to follow the
movements of the intestines
■ Can form adhesions (fibrous scar tissue) adjacent to
inflamed organs like the appendix
■ Cushions abdominal organs against injury
■ Provides insulation against the loss of body heat
, ○ Lesser omentum - extends between liver and lesser
curvature of stomach
🧠 Knowledge Check
● What is the largest serous membrane in the body? → Answer: peritoneum
● The double layer of peritoneum that holds the organs in place and stores fat is called
what? → Answer: mesentery
● True/False: The GI tract produces both enzymes and hormones. → Answer: true
● True/False: A unique feature of the liver is that it has a dual blood supply. → Answer:
true
Module 7.2 — A&P Review II (Motility & Hormones)
Key Concepts
● Motility - important; propels food and fluids forward to be digested and absorbed
○ Rhythmic movements: intermittent contractions to mix & move food
■ Esophagus
■ Antrum of stomach ■
Small intestines
○ Tonic movements: constant tone without regular relaxation
■ Lower esophagus
■ Upper region of stomach
■ Ileocecal valve
■ Internal anal sphincter
● Contractile tissue in GI Tract → smooth muscle, low resistance pathways called gap
junctions that electrically couple the cells.
○ Electrical signals initiate muscle contractions move rapidly from one fiber to
the next within each bundle
○ Specialized cells → Interstitial cells of Cajal: GI pacemaker cells that generate
slow waves (rhythmic, spontaneous oscillations in membrane potential) 3/min in
stomach 12/min in duodenum
■ amplitude and frequency of slow waves regulated by:
Module 7.1 — Anatomy & Physiology Review
Key Concepts
● Functions of the GI tract: digestion & absorption →
Notes:
○ amylase - carb bd, lipase - fat breakdown.
○ Emulsification - stomach - mechanical agitation; duodenum -chemical digestion -
bile and pancreatic lipase help
○ In stomach - pepsin - carb/protein digestion
○ Absorption → process of moving nutrients and other materials from external
environment of the GI tract into the internal environment
○ Small int. - DJI - duodenum, jejunum, ileum; large int. (reabsorbs water mainly, and
stores waste) - cecum, colon (ascending, transverse, descending, sigmoid),
rectum, anal canal
○ Liver —> largest visceral organ in body; receives 25% of the resting cardiac
output
■ Unique feature of the liver: dual blood supply (hepatic artery & portal
vein)
● has a venous (portal) blood supply (comes from digestive
tract, pancreas, and spleen) through the hepatic portal vein
that receives 75% of blood per min, AND an arterial supply
through the hepatic artery that receives the remaining 25%
of remaining blood.
■ Hepatic vein in liver drains into IVC below the diaphragm
■ Liver can store 500-1000ml of blood
■ Produces bile
■ Metabolizes hormones and drugs
■ Synthesizes proteins, glucose, and clotting factors
■ Stores vitamins and minerals and converts them to usable material for
body to use
■ Ammonia → urea
■ Fatty acids → ketones
■ Glucose stores → glycogen —- through glycogenesis
■ Can also make glucose from amino acids, glycerol and lactic acid
during fasting – gluconeogenesis
■ Excess carbs → triglycerides for storage
,● Layers of the GI wall: (innermost) mucosa / submucosa / muscularis / serosa
(outermost) → Notes:
○ Mucosal layer - first,inner. epithelium, has underlying CT lamina propria and sm
musc. Cells that can contract and change shape and surface area of mucosal
layer
■ Functions:
● Produces mucus that lubricates and protects the inner surface of
the alimentary canal
● Secretes digestive enzymes
● Absorbs the breakdown products of digestion
● Maintains a barrier to prevent entry of noxious substances and
pathogenic organisms ■ ET cells replaced every 5d.
○ Submucosal layer - dense CT and adipose tissue. Blood vessels, nerves and
structures that secrete digestive enzymes.
○ Muscularis externa - circularly arranged smooth muscle cells and outer layer of
longitudinally arranged smooth muscle layers. Alternatively contract through the
GI tract - peristalsis
○ Serosal layer - serous membrane - visceral peritoneum
■ Peritoneum: LARGEST serous membrane in the body
● 2 continuous layers → visceral and parietal peritoneum
○ Parietal peritoneum - lines walls of the abdominopelvic
cavity
○ Between parietal and visceral layer - peritoneal cavity -
potential space containing fluid secreted by serous
membranes - fluid keeps moist surface to prevent friction
between moving abdominal organs
● Mesentery: double layer of peritoneum that holds organs and
stores fat
→ Notes:
○ Attaches to abdominal wall
○ Blood vessels, nerves, lymphatic vessels that supply the
intestinal wall
○ Holds organs in place and stores fat
● Omentum: double layered fold of peritoneum that hangs from
stomach to adjacent organs in abdominal cavity
○ Greater omentum - connects stomach and covers the
transverse colon and the folds of intestine
■ Contains fat and has a lot of mobility to follow the
movements of the intestines
■ Can form adhesions (fibrous scar tissue) adjacent to
inflamed organs like the appendix
■ Cushions abdominal organs against injury
■ Provides insulation against the loss of body heat
, ○ Lesser omentum - extends between liver and lesser
curvature of stomach
🧠 Knowledge Check
● What is the largest serous membrane in the body? → Answer: peritoneum
● The double layer of peritoneum that holds the organs in place and stores fat is called
what? → Answer: mesentery
● True/False: The GI tract produces both enzymes and hormones. → Answer: true
● True/False: A unique feature of the liver is that it has a dual blood supply. → Answer:
true
Module 7.2 — A&P Review II (Motility & Hormones)
Key Concepts
● Motility - important; propels food and fluids forward to be digested and absorbed
○ Rhythmic movements: intermittent contractions to mix & move food
■ Esophagus
■ Antrum of stomach ■
Small intestines
○ Tonic movements: constant tone without regular relaxation
■ Lower esophagus
■ Upper region of stomach
■ Ileocecal valve
■ Internal anal sphincter
● Contractile tissue in GI Tract → smooth muscle, low resistance pathways called gap
junctions that electrically couple the cells.
○ Electrical signals initiate muscle contractions move rapidly from one fiber to
the next within each bundle
○ Specialized cells → Interstitial cells of Cajal: GI pacemaker cells that generate
slow waves (rhythmic, spontaneous oscillations in membrane potential) 3/min in
stomach 12/min in duodenum
■ amplitude and frequency of slow waves regulated by:
