GIT Control Flashcards
What are the local factors in the digestive tract?
Prostaglandin,histamine and other chemicals are released into the interstitial fluid
It may affect adjacent cells within a small segment of the tract
Local factors affect only a part of the tract
Ph factors,Chemicals and physical stimuli coordinate conditions
Where are motor neurons situated that affect neural mechanisms?
Situated in the Myenteric plexus
What is control of Digestive function?
Movements along the digestive tract and Secretory control
What do motor neurons do in digestive control?
They control glandular secretions and smooth muscle contraction
What are the short reflexes in the digestive tract?
Only controls a small segment of the tract
Is responsible for local reflexes
It operates entirely outside of the CNS
It involves motor,sensory and interneurons
What are long reflexes of the digestive tract?
Higher control of glandular and digestive activities
Large scale peralstaltic waves
Also involves inter and motor neurons
May involve parasympathetic nerve fibers that synapse in the myenteric plexus (glosspharengeal,vagus and pelvic nerves)
Where are the peptide hormones produced?
In the entero-endocrine cells in the digestive tract and reaches target after distribution in bloodstream
What is the control of production of acid and enzymes by the gastric mucosa?
Controlled by CNS
Regulated by short reflexes of the ENs
Regulated by hormones
What are the 3 phases of gastric control?
Cephalic
Intestinal
Gastric
What are the 2 reflexes in the small intestine?
The gastroileal and gastroenteric reflex
What is the gastroenteric reflex ?
It stimulated motility and secretion along the small intestine
What is the Gastroileal reflex?
Allows materials to pass from small intestine to large intestine and also triggers relaxation of the ileo Cecil valve
What are the hormones in the duodenal entero endocrine cells?
Gastrin
Secretin
Enterocrinin
Cholecystotokinin
Gastric inhibitory peptide
Vasoactive intestinal peptide
What is the purpose of Gastrin?
It is produced by the g cells in the duodenum
When it is exposed to incompletely digested proteins it promotes increased stomach motility and acid and enzyme production stimulation
What is the purpose of secretin?
It is released when Chyme arrives at the duodenum and increases secretion of Bile and buffers by liver and pancreas
What is the purpose of the Gastric Inhibitory Peptide?
It is secreted when fats and carbohydrates enter the small intestine
What is the Cholecystotokinin?
It is secreted in the duodenum
And when lipids and proteins ate partially digested
It relaxes he hepatopancreatic sphincter and gallbladder and ejects bile and pancreatic juices in the the duodenum
It accelerates pancreatic production and secretion of digestive enzymes
What is the purpose of vasoactive intestinal peptide?
It stimulates secretion of intestinal glands
Dilates regional capillaries and inhibits acid production
What is the purpose of enterocrinin?
It is released when chime enters the small intestine
And stimulates mucin production by the submucosal glands of the duodenum
How long does intestinal absorption take?
About 5 hours (for materials to reach duodenum to end of illeum)
What does the movement of the mucosa do to increase absorptive effectiveness?
Constantly change environment around the epithelial cells and stir and mix intestinal content
What are the moments in the large intestine?
Through gastricileal and gastricenteruc reflexes It allows for materials to move from into cencum while you eat
What is moment from the cecum to the transverse Colon slow?
To allow for hours of water absorption
What type of churning is done in the large intestine ?
Haustrak churning which mixes content of the adjacent haustra
What are mass movements in the large intestine?
Movements from the transverse colon to the rest of the large intestine and results in large peralstaltic contractions
Where is the stimulus dimension of stomach and duodenum relayed?
It is relayed over intestinal nerve plexuses
What are the two positive feedback loops?
The short reflex
Which triggers peralstaltic actions in the Rectum
And Long reflex
Which is coordinated by the parasympathetic system and stimulates mass movements
What are the rectal stretch receptors?
The Long reflex
Causes relaxation of the internal analysis sphincter
And mediated by parasympathetic international of pelvic nerves
A somatic reflex
The motor commands are carried by the pudenal nerves and stimulation of the contraction of the external anal sphincter
What does the parasympathetic innervation of neural mechanism di?
Prepare digestive tract for activity
What does the sympathetic nivveration of the neural mechanism do?
It inhibits gastrointestinal activity
