1. Ch. 23 The Digestive System– Part 1
Part 1: 18 slides (excluding student assignment and photos

2. I. Basic Concepts & Processes Shared By Most Digestive Organs
A. Two Groups of Organs:
*Alimentary canal =
*Organs: Students Do
*Accessory digestive organs =

3. B. Digestive Processes Do Basic Definitions for all below: *Ingestion
2. *Propulsion
*Peristalsis
3. *Mechanical digestion
*Mastication
*Segmentation
4. * Chemical digestion
5. * Absorption
6. *Defecation
Ingestion
Propulsion
Mechanical Digestion
Absorption
Defacation

4. C. Blood Supply Branches of Abdominal Aorta Review
*Celiac Trunk and 3 branches
*Gastric Artery
* Splenic Artery
* Hepatic Artery
*Superior Mesenteric Artery
*Inferior Mesenteric Artery

5. D. Peritoneum Students Do
*Peritoneum: Visceral and Parietal layers
* Mesentery
* Greater Omentum
Dorsal
mesentery
Parietal
peritoneum
Visceral
peritoneum
Ventral
mesentery
Peritoneal
cavity
Alimentary
canal organ
Liver
Figure 23.5a

6. E. General Histology of Alimentary Canal
*Mucosa
Epithelium
Lamina
Propria
Muscularis
Mucosae
*Submucosa
Areolar
Many blood
vessels
3. *Muscularis externa
Circular (inner)
Longitudinal
Sphincters
4. *Serosa = Visceral Peritoneum
Mucosa
• Epithelium
• Lamina propria
• Muscularis
mucosae
Submucosa
Muscularis
externa
• Longitudinal
muscle
• Circular muscle
Serosa
Lumen

7. II. Digestive System Organs of the Head and
II. Digestive System Organs of the Head and Thorax: Anatomy & Function A. The Mouth & Associated Organs
Students Do Following
1. Mouth Anatomy
* Tissue Lining:
* Palate: Hard &Soft
* Uvula:
2. Overall Functions:
Ingestion, Mechanical Digestions
* Chemical digestion: amylase digests what?
Swallowing (Deglutition)
READ

8. 2. * The Tongue STUDENTS DO
* Basic Composition:
* Functions: 3
* Bolus
Lingual Tonsil
Lingual Lipase

9. 3. * The Salivary Glands Students Do * 3 pairs of Glands: * Functions:
* Composition of
Saliva
1. Lubrication
2. hydration of food
3. chemical digestion
4. protection from microbes
(clinical medium)
Tongue
Parotid
gland
Parotid duct
Ducts of
sublingual
gland
Submandibular
duct
Masseter muscle
Sublingual
gland
Body of
mandible (cut)
Submandibular
gland

10. B. Pharynx * Regions: Students Do Lining: squamous e.t.
skeletal muscle for
* Function:
Oropharynx
Laryngopharynx

11. C. Esophagus = propulsion only
READ & FILL IN
= Muscular Tube
Function: Propulsion/Peristalsis
* Esophageal hiatus
* Upper & Lower Esophageal Sphincters (Lower = Gastroesophageal Sphincter)
Histology:
stratified
squamous
Diaphragm

12. D. Digestive Processes– Mouth to Esophagus: SWALLOWING & Propulsion towards Stomach
READ = Involves coordinated action of tongue, pharyngeal muscles, esophageal muscles (including the sphincters), and layngeal muscles.
Bolus of food
Tongue
Pharynx
Epiglottis
Glottis
Trachea

13. III. Digestive Organs of the Abdomen-Pelvis A. The Stomach: 1
III. Digestive Organs of the Abdomen-Pelvis A. The Stomach: *Overall Functions a) b) c) d) 2. *Gross Anatomy
Cardia
Fundus
Serosa
Body
a) * Regions
Body
Cardia
Pyloric
Fundus
b) *Rugae
Lesser
curvature
Rugae of
mucosa
Pyloric sphincter
Pyloric Region
Greater
curvature
Duodenum
Figure 23.14a

14. A. The Stomach … 2. Gross Anatomy …
Cardia
Fundus
c) *Curvatures
Greater
Lesser
d) *Sphincters
Cardiac
Pyloric
Serosa
Body
Lesser
curvature
Rugae of
mucosa
Pyloric sphincter
Pyloric Region
Greater
curvature
Duodenum
(a)
Figure 23.14a

15. The Stomach: … Gross Anatomy …
Cardia
READ
f) Muscular tunic has extra 3rd layer = inner most oblique layer = churning action
Fundus
Serosa
Body
Lesser
curvature
Rugae of
mucosa
Pyloric sphincter
(valve) at pylorus
Pyloric
canal
Greater
curvature
Pyloric
antrum
Duodenum
(a)
Figure 23.14a

16. 3. Microscopic Anatomy of the Stomach - Has all Layers

17. 3. Microscopic Anatomy of Stomach … a) Mucosa i) *Tissue?
Esophagus
ii) *Gastric Pits: lead to the
Gastric Glands which produce
Gastric Juice– with mucus, enzymes (gastrin), and hormones in it
iii) Cells of Gastric Glands
(1) Muscus Neck Cells
Produce Alkaline mucus w/ bicarbonate
Function: protect cells from very low pH (1.5 – 3.5) gastric juice
READ
Stomach
Gastric Pits
Mucous neck cells
Gastric Glands
Figure 23.12b

18. iii) Gastric Gland Cells …
(2) Parietal Cells
Function: Produces Hydrochloric Acid (HCl) for activation of enzyme pepsinogen AND
Produces intrinsic factor for B12 absorption
Slide: Round, large, pinkish cells
(3) Chief Cells
Function: produce enzyme Pepsinogen
which activates to Pepsin
Slide: Small, purplish cells
(4) Enteroendocrine Cells: produce Gastrin
Gastric pits
Gastric
pit
Surface epithelium
(mucous cells)
Gastric
gland
Mucous neck cells
HCl
Parietal cell
Pepsinogen
Pepsin
Chief cell
Enteroendocrine cell
(b) Enlarged view of gastric pits
and gastric glands

19. STOMACH

20. Stomach

21. 4. Digestive Processes Occurring in the Stomach
a) Introduction
i) Secretions: Up to 3L per day
ii) Nervous Control:
Parasympathetic NS via Vagus Nerve: stimulates glands
Sympathetic NS: decreases secretary action
iii) Hormonal Control
Gastrin, most important hormone
Stimulates secretion of enzymes, HCl, & intestinal enzymes
READ

22. 4. Digestive Processes occurring in the Stomach …
b) Regulation of Gastric Secretion
3 Phases
i) Cephalic (reflex) phase:
Stimulatory events
READ
Cephalic
phase
Sight and thought
of food 1
Cerebral cortex
Conditioned reflex
Stimulation of
taste and smell
receptors 2
Hypothalamus
and medulla
oblongata
Vagus
nerve
Are Stimuli
Sight and Thoughts & Tastes and Smells  Hypothalamus  Medulla nuclei  Vagus Nerve  Stomach  RESULT = increased secretions
- Takes a few min.
Stomach
secretory
activity
Figure 23.17

23. 2. Regulation of …
Are Stimuli
ii) Gastric Phase:
Stomach Distention, Food Chemicals (proteins), and increasing HCl  RESULT = Increased gastric juices AND Release of Gastrin which causes Parietal Cells to Increase HCl secretion
The increase in acidity (low pH) activates pepsinogen to pepsin which catalyzes the break down of proteins
Negatie Feedback Loop: Low H+ (High pH) stimulates release of Gastrin AND High H+ (low pH) inhibits release of Gastrin
READ
Stimulatory events
Inhibitory events
Stomach
distension
activates
stretch
receptors 1
Vagovagal
reflexes
Medulla
Vagus
nerve
Gastrin
secretion
declines
G cells
1. Excessive
acidity
(pH <2)
in stomach
Excessive
acidity
(pH <2)
in stomach 1
Stomach
distension
activates
stretch
receptors 1
Vagovagal
reflexes
Medulla
Vagus
nerve
Gastrin
secretion
declines
G cells
Gastric
phase
Local
reflexes
Ach
Overrides
parasym-
pathetic
controls
Sympathetic
nervous
system
activation
Emotional
upset 2
Local
reflexes
Overrides
parasym-
pathetic
controls
Sympathetic
nervous
system
activation
2. Emotional
upset
Food chemicals
(especially peptides and
caffeine) and rising pH
activate chemoreceptors 2
G cells
Gastrin
release
to blood
Food chemicals
(especially peptides and caffeine) and rising pH activate chemoreceptors 2
G cells
Gastrin
release
to blood
Stomach
secretory
activity
Stomach
secretory
activity
Stimulate
Entero-
gastric
reflex
Local
reflexes 1
Inhibit
Figure 23.17
Presence

24. c. Intestinal Phase– in Duodenum
READ
Begins when stomach starts to empty partially digested food (chyme) to duodenum
(1) Partially digested food & low pH  release Intestinal Gastrin  RESULT = Stomach glands continue to secrete gastric fluids briefly
(2) Distension of Duodenum & very low pH Inhibits gastric secretions and closes the Pyloric Sphincter
Stomach
secretory
activity
Stimulatory events
Presence of low
pH, partially digested
foods, fats, or
hypertonic solution
in duodenum when
stomach begins to
empty 1
Intestinal
(enteric)
gastrin
release
to blood
Intestinal
phase
Are Stimuli
Brief
effect
Stimulate
Figure 23.17
Inhibit
Are Stimuli
to move a small bit of chyme into duodenum so as to protect it from over-distension
Release of intestinal Hormones: Cholecystokinin (CCK) and Secretin TO BE CONTINUED ON SLIDE #

25. B. Small Intestine 1. Gross Anatomy-- Length 20 feet
Subdivisions: Duodenum (10 inches), Jejunum, and Ileum
Plicae Circulares—deep inner folds
Duodenum
Functions: Most chemical digestion occurs here & it receives bile from liver & enzymes and bicarbonate from pancreas
i) Hepatopancreatic Ampulla: Bulb-like point where Bile duct and main pancreatic duct join
Major Duodenal Papilla:
READ
Small
intestine
Duodenum
Jejunum
Ileum
Opening into Duodenum for entry of bile from the Liver and digestive enzymes and bicarbonate from Pancreas
Bile & Pancreatic Ducts
Major Duodenal Papilla
Hepatopancreatic Ampulla
Plicae Circulares

26. Attached to Jejunum and large intestine Both framed by Large Intestine
Bile duct and sphincter
Major duodenal
papilla
Plicae Circulares
Main pancreatic duct
and sphincter
Hepatopancreatic
ampulla and sphincter
Duodenum
READ
b) Jejunum
Attached to Duodenum
c) Ileum
Attached to Jejunum and large intestine
Both framed by Large Intestine

27. a. Mucosa w/ folds & loops *=
2. Microscopic Anatomy …
a. Mucosa w/ folds & loops *=
Contain: Blood vessels, nerves, and lacteal
ii) *Cells with Microvilli:
Digestive Enzymes embedded in microvilli
*Function of folds and loops:
READ & Fill in

28. 2. Microscopic Anatomy Small Intestine

29. Small Intestine

30. Enteroendocrine cells secrete Cholecystokinin (CCK) and Secretin
2. Microscopic Anatomy …
ii) Intestinal Glands or Crypts = tubular glands beneath villi formed by folding down of mucosa
Function: produce intestinal juice: water, some mucus, slightly alkaline (pH = ), but low in enzymes
Enteroendocrine cells secrete Cholecystokinin (CCK) and Secretin
iii) Lamnia Propria
- Have agregations of intestinal nodules
READ
Lacteal
Absorptive cells
Goblet cell
Vilus
Intestinal crypt
Enteroendocrine
cells
Lymphatic vessel
Submucosa
Duodenal gland

31. b) Submucosa of small intestine - Areolar Tissue
READ
Peyer’s patches = clumps of lymphatic tissue that protect distal regions against bacteria
Have lymphocytes
Duodenal (Brunner’s) glands: in duodenum; secrete alkaline (bicarbonate) mucus to neutralize the acidic chime coming in from stomach. (Enzymes within the small intestine only function in a non-acidic environment.)
c. Muscularis Externa
d. Serosa
Submucosa
Duodenal gland
Peyer’s Patches

33. Small Intestine
Submucosa .
Brunner’s Glands

34. END PPT
 NEXT FILE

35. Review Questions
The mucosa of the lower pharanx and esophagus has _________ __________ epithelia.
___________, i.e. swallowing, involves over 22 muscle groups and moves a _________ from the oral cavity to the stomach.
stratified squamous
Deglutition
bolus

36. Review Questions amylase
Enzymes in saliva include _________, which is responsible for starch breakdown.
2I, 1C, 2PM, 3M

37. enteric nerve plexuses
Review Questions
Short reflexes of the GI tract are housed and completed within _____ ____ ______ while _______ reflexes involve the CNS.
enteric nerve plexuses
long

38. Review Questions
In the small intestine, ___________ __________, __________, and ___________ all contribute to expanding the surface area for adequate __________.
plicae circulares
villi
microvilli
absorption

39. Review Questions
From the esophagus to the anus, the GI tract contains how many layers?
Which 2 layers contain smooth muscle?
4: mucosa, submucosa, muscularis externa, serosa
Mucosa & muscularis externa

40. Participating… gastric
The _________ phase is responsible for the production of most gastric secretions by releasing the hormone _________.
What other 2 hormones promote gastric secretions?
gastrin
ACh and Histamine

41. Review Questions Parietal gastric
________ cells of _______ glands produce HCl and ___________ __________. __________ cells produce pepsinogen.
What is intrinsic factor for?
intrinsic factor
Chief
B12 absorption

42. 100 million bacteria/mL of saliva!
Serous & Mucous Cells
Water content
Enzyme =
Mucin
Control of Salivation:
Parasym. Sys. via chemo-
& mechano-receptors
100 million bacteria/mL of saliva!

43. Homeostatic Imbalance
Peptic or gastric ulcers: erosion of stomach wall
Helicobacter pylori bacteria
Bacteria
Mucosa
layer of
stomach
(a) A gastric ulcer lesion
(b) H. pylori bacteria

44. Propulsion& Segmentation
From
mouth
(a) Peristalsis: successive waves of contraction move food distally (1-way).
(b) Segmentation: Food mixing/slow food propulsion occurs.
Figure 23.3

45. Histology of Alimentary Canal …#6
Glands in submucosa
Mucosa
• Epithelium
• Lamina propria
• Muscularis
mucosae
Submucosa
Muscularis
externa
• Longitudinal
muscle
• Circular muscle
Serosa
Nerve
Lumen
Gland in mucosa
• Epithelium
Artery
• Connective
tissue
Vein
Mucosa-associated
lymphoid tissue (MALT)
Lymphatic
vessel
Mesentery