5.1 Flashcards
main Physiological functions of the GI system
- mechanical
- secretion
- absorption
- excretion
- immune
Assimilation of nutrients
- AA, monosacarides, FA
- Fluids
- Electrolytes
- Trace elements
- Vitamins
Digestion is composed of:
- Mechanical disruption
2. Chemical degragation
How does the GI tract serves the Assimilation of nutrients?
- Motility
- Secretion
- Chemiacl digestion
- Absorption
STOMACH-
- Motility
- Secretion
- Chemiacl digestion
- Absorption
- Motility= peristaltic mixing
- Secretion= HCl, Pepsinogen, Gastric lipase, HCO3-, Gastrin, Histamin
- Chemiacl digestion= Proteins, fats
- Absorption= Alcohol, Aspirin
Role of Spincters?
- They maintain positive pressure in their lumens
- Regulate the caudal movement of bowel
Accsessory glands?
salivary
Liver
Gallbladder
Pancreas
Paneth cells release?
Antimicrobial peptides
GALT components
Paneth cells
Payer’s patches
whos responsible for chewing and swallowing?
CNS
Submucosal plexus=
meissner’s
ENS from where to where?
lower 1/3 of esophagus until outer rectal spincter
ENS local control on?
- motility
- secretion
- blood flow
- immune responce
types of ENS neurons
Afferent neurons
Interneurons
Efferent neurons
Efferent neurons of ENS innervates
- Enteric smooth muscle
- Interstitial cells of Cajal
- Epithelial cells
- Endocrine and paracrine cells
- Vascular cells
Autonomic NS Parasympathetic division
- Vagal nuclei
2. Sacral Spinal cord
Autonomic NS Sympathetic division
Thoraco-Lumbar region -> Sympathetic Ggl (Celiac, SM, IM)
modulation of ENS by Parasympathetic NS
**Preganglionic, cholinergic
Mainly stimulates motility and secretion
modulation of ENS by Sympathetic NS
- *Postganglionic, adrenergic
- Indirect (suppresses motility and secretion by a2
- Direct (vessels vasoconstriction and spincter contraction by a1)
Excitatory Transmitters of Sensory neurons
ACh
Substance P
CGRP
Excitatory Transmitters of Interneurons
ACh
Substance P
ATP
Glu
Inhibatory Transmitters of Interneurons
Opioid peptides
SST
Excitatory Transmitters of Motorneurons
ACh
Substance P
Inhibatory Transmitters of Motorneurons
NO
ATP
VIP
PACAP
what is the important of Symp activation of a1 R?
vasoconstriction of blood vessels to limit blood flowinto the GI tract
4 GI peptides are classified as hormones:
Gastrin
CCK
Secretin
Glucose-Dependent-Insulinotropic-Peptide
what are paracrines?
peptides secreted by endocrine cells of GI
they act locally wuthun the same tissue
paracrines of the GI?
Somatostatins- Inhibatory actions throughout the GI
**also Histamine, but its not a peptide
Neuorocrine substance of the GI?
ACh NE VIP NO GRP substance P
Gastrin action
- H+ secretion by gastric Parietal cells
- Growth of the Gastric Mucose
what cell secrete Gastrin?
G cells in the antrum of the stomach
CCK (CholeCystoKinin) aim
Fat digestion and absorption
what cell secrete CCK?
I cells in duodenum and jejunum In response to FA and AA
CCK action
- Gallbladder contraction
- Pancretic enzyme secretion
- HCO3- secretion from pancreas
- Growth of exocrine pancreas and Gallbladder
- Inhibition of gastric emptying
Glucose-Dependent-Insulinotropic-Peptide secreted by?
K cells in duodenum and jejunum in response to allllll nutrients
glucos AA FA
major phisyologic action of Glucose-Dependent-Insulinotropic-Peptide
stimulation of Insulin secretion
Secretin is secreted by?
S cells of Duodenum in response to H+ and FA in the lumen of the small intestine
Function od Secretin?
Promote the secretion of pancreatic and biliary HCO3- which neutraliza H+ in the lumen of the small intestine
which cells secrete SST?
D cells of the GI in response to decreased luminal pH
