Regions(of(the(Alimentary(Canal( Func
7
Regions of the Alimentary Canal •Oral cavity •Pharynx •Esophagus •Stomach •Small intes<ne •Large intes<ne •Anus 1 Func<ons of the Diges<ve System •Inges<on •Mas<ca<on •Propulsion (deglu<<on and peristalsis) •Mixing of lumenal contents •Secre<on •Diges<on •Absorp<on •Elimina<on 2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Small intestine Cecum Appendix Liver Gallbladder Diaphragm Rectum Anal canal Pancreas Bile duct Anus Stomach Esophagus Pharynx Parotid gland Sublingual gland Tongue Teeth Oral cavity Submandibular gland Transverse colon Descending colon Ascending colon Sigmoid colon 3 4 5 6
Transcript of Regions(of(the(Alimentary(Canal( Func
-
Regions of the Alimentary Canal
• Oral cavity • Pharynx
• Esophagus
• Stomach • Small intes
-
7 8
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Liver Gallbladder Stomach
(a) (b)
Jejunum Mesentery
Mesocolon
Ascending colon
Small intestine
Lesser omentum
Greater omentum
Greater omentum (retracted)
Transverse colon
Descending colon
Sigmoid colon
9 10
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Epiglottis
Root
Body
Hyoid bone Mylohyoid m.
Sublingual gland
Submandibular gland
Mandible Genioglossus m. Hyoglossus m.
Styloglossus m. 1st molar Buccinator m. Intrinsic muscles of the tongue
(a) Superior view (b) Frontal section, anterior view
Lingual tonsils
Palatine tonsil Terminal sulcus Vallate papillae
Foliate papillae
Fungiform papillae
11
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Names of teeth
2nd molar
1st molar
Canine Lateral incisor
Central incisor 6–9
16–20
12–16
20–26
Names of teeth
(a) Deciduous (baby) teeth
(b) Permanent teeth
Central incisor Lateral incisor
1st premolar 2nd premolar
1st molar
Canine
2nd molar
6–8 7–9
9–12 10–12
10–12
6–7
1 1–13 17–25
Age at eruption (months)
7– 11
Age at eruption (years)
3rd molar (wisdom tooth)
12
-
13 14
15 16
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Stomach Constriction
Relaxation
5
(a)
Lower esophageal sphincter relaxes to admit bolus to stomach.
Lower esophageal sphincter
Cardiac orifice
17 18
-
19 20
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
0 +
+
+
0
Vagus nerve Vagus nerve Vagus nerve
Long (vagovagal) reflex: Sensory fibers Motor fibers
Gastrin Histamine Intestinal gastrin
Sympathetic nerve
1 2 3
Stimulation Inhibition Reduced or no effect
Key +
Sensory and mental input
Secretin and CCK
Intestinal phase Intestinal gastrin briefly stimulates the stomach, but then secretin, CCK, and the enterogastric reflex inhibit gastric secretion and motility while the duodenum processes the chyme already in it. Sympathetic nerve fibers suppress gastric activity, while vagal (parasympathetic) stimulation of the stomach is now inhibited.
Gastric phase Food stretches the stomach and activates myenteric and vagovagal reflexes. These reflexes stimulate gastric secretion. Histamine and gastrin also stimulate acid and enzyme
Cephalic phase Vagus nerve stimulates gastric secretion even before food is swallowed.
–
+ + – –
–
Enterogastric reflex
Short (myenteric) reflex
21 22
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Pyloric gland Gastric gland
G cells secrete gastrin
G cell
Partially digested protein Pepsin (active enzyme)
Mucous cell Parietal cell Chief cell
HCI Pepsinogen (zymogen)
HCI converts pepsinogen to pepsin
Pepsin digests dietary protein
Oligopeptides and amino acids buffer stomach acid
Oligopeptides directly stimulate G cells
Elevated pH stimulates G cells
Ingested food buffers stomach acid
Chief cells secrete pepsinogen
Parietal cells secrete HCI
Gastrin stimulates chief cells and parietal cells
23 24
-
25 26
27 28
29 30
-
31 32
33 34
35 36
-
37 38
39 40
41 42
