sublingual salivary glands : submaxillary liver gallbladder duodenum ascending colon cecum appendix...
TRANSCRIPT
SublingualSalivary glands:
Submaxillary
LiverGallbladder
Duodenum
Ascending colon
Cecum
Appendix
Ileum
Parotid salivary gland
Pharynx
Esophagus
Stomach
Pancreas
Transverse colon
Descending colon
Jejunum
Sigmoid
Rectum
Functional Sphincters
• UES
• LES
• Pyloric
• Ileal
• IAS
• EAS
Aorta
(200)
Celiac(700)
PortalVein
Superior Mesenteric (700)
InferiorMesenteri
c (400)
LIVER
STOMACH
SPLEEN
PANCREAS
SMALLINTESTINE
COLON
To Systemic Circulation
(1800) mls/min
HEPATIC
Rates:
ml/min
Lymph node
Myenteric plexusSubmucosal plexus Gland in
submucosa
Villus
Epithelium and Mucosa
Muscularis mucosa
Submucosa (contains most nerves
and bloood vessels)
Circular muscleLongitudinal muscle
Serosa (connective tissue)
Cross-Section of the Alimentary Canal
•Epithelial Cell Barrier
Microvilli: Brush Border Glycocalyx: Digestive Surface
1. Traps Nutrients2. Increases Local Viscosity3. Harbors Enzymes
-Protective Barrier, Tight Junctions
- INTRINSIC REGULATION: ENTERIC PLEXI
- EXTRINSIC REGULATION: Central Nervous System
Autonomic Nervous System
Neural Regulation of GI Function
Interganglionicfiber tract
Myentericganglion
Circular muscle
Submucosalganglion
200 um
Mucosa
LongitudinalMuscle
Intrinsic Neural Regulation
(-)
G
(+)(+)
to CNS
(+)
S(-)
Protein
from CNS
Submucosalplexus
Pressurereceptor
Mucosa
S
H+
Signal Integration in the Plexi
Extrinsic Regulation : Primarily Synapses onto Plexi
• CNS Autonomics
• Sympathetic (generally inhibits GI function); Norepi
• Parasympathetic (generally stimulated GI function) Vagus Nerve; Acetylcholine (Ach)
• Coordinates Functions through Long Reflexes
• Direct Innervation f Vascular Smooth Muscle by Sympathetic Nerves: Inhibits Blood Flow
Autonomic Nervous System: Regulation of GI Function
Vagalnuclei
SacralSpinal cord
Pelvic nerves
Vagusnerves
Enteric nervous system
CNSPreganglionic
fibers
Postganglionic fibers
Myentericplexus
Submucosalplexus
Smoothmuscle
Secretorycells
Endocrine(G) cells
Bloodvessels
Parasympatheticdivision Sympathetic
division
Sympatheticganglia
Pancreas andGall Bladder
Autonomic Nervous System
Hormone: Classical Definition.
A Chemical Messenger Produced and Secreted by a Specialized Gland, and Released into the Blood Where it is
Circulated to Distant Organs to Elicit a Physiological Response.
- Effects are Exerted Relatively Slowly, but for Prolonged Periods
Aorta
(200)
Celiac(700)
PortalVein
Superior Mesenteric (700)
InferiorMesenteri
c (400)
LIVER
STOMACH
SPLEEN
PANCREAS
SMALLINTESTINE
COLON
To Systemic Circulation
(1800) mls/min
HEPATIC
Rates:
ml/min
TABLE 1. Characteristics of the Major Gastrointestinal Hormones
• Gastrin G17 peptide (2117 mw) peptides, amino acid secretion, 3 min G34 peptide (3988 mw) acids, distention Gastric growth 12 min
• Secretin peptide (3056 mw) duodenal acidity pancreatic 3 min bicarbonate
secretion
• CCK-PZ peptide (3919 mw) fatty acids gallbladder contraction amino acids in pancreatic enzyme 5 min
the sm. intestine secretion and growth
• (GIP) peptide (5105 mw) glucose, fatty insulin release 21 min Glucose- dependent acids in the small insulinotropic peptide intestine
Local Stimuli Physiologic Circulating Name Composition for Release Action(s) Half-life
• Secretin Family: Activates Adenylate Cyclase Secretin Increasing cAMP
VIP GIP
Glucagon
• Gastrin Family: Increases Intracellular Ca2+
Gastrin CCK
• Receptor Specificity
Blood vesselsLymph vesselsNervesSmooth muscleConnective tissuelymphocytesPlasma cellsEosinophiles
Villousepithelium
Undifferentiated GobletMitosesEndocrine cells
Paneth cells
CryptEpithelium
Cryptlumen
Muscularismucosa
Absorp-tive cells
Gobletcells
Endocrine cells
Peptide Released by Actions
• Pancreatic polypeptide Intestinal Inhibits Pancreatic HCO3-
Protein, Fat and Enzyme Secretion Glucose
• Motilin ? Distal Gastric Motility Intestinal Motility
• Enteroglucagon (GLP-1) Intestinal ? Fat, Sugar
From, F-cells of pancreatic islets
Candidate Hormones
• VIP Mucosa and Relaxes Muscle; Smooth Muscle Activates Cl-
Channels
• GRP or Gastric Mucosa Stimulates Gastrin Bombesin Release
• Enkephalins Neurons in Mucosa Increases Smooth and Visceral Muscle Muscle Tone
• Substance P Salivary Glands Activates Blood Flow
• Neuropeptide Y Neurons in Mucosa Decreases Secretion and Visceral Muscle and Sphincter Tone
• CCK Enteric and Hypothalamic Inhibits Propulsion Neurons Activates Satiety
Peptide Site of Action Actions
Neurocrines: NANC Neurotransmitters
NANC: Non-Adrenergic Non-Cholinergic
Factor Location Actions
• Somatostatin Stomach: Decreases Gastrin Pyloric Gland Secretion
• Histamine* Stomach and Increases Gastric Intestinal Mucosa Acid Secretion
Paracrine