Regulation Of GI function Flashcards
When sensory cells are stimulated, what do they send out a signal to do?
Stimulate smooth muscles
Stimulate release of hormones
What do sensory cells detect?
Osmolarity PH Stretch Nutrient/metabolite conc Irritation of mucous membranes NOT PAIN
What type of feedback is digestion (mainly) and what coordinates it?
Negative feedback
Neural and hormonal regulation
In short reflex arcs of the GI tract, which nervous system is stimulated? Where are these nerve cells?
Enteric nervous system
In the wall of the GI tract
In long reflex arcs of the GI system,what nervous system is stimulated?
Autonomic
Parasympathetic speeds up digestion
Sympathetic slows down digestion
Most reflex arcs are stimulatory. What is the neurotransmitter for this?
Acetylcholine
What are complex reflex arcs?
Simple reflex arcs connected by interneurons
In the parasympathetic ANS, where do pre ganglionic fibres run?
Vagus nerve
In the parasympathetic ANS, where do post ganglionic fibres run? What do they connect to?
Wall of the GI tract
Connect to the enteric nervous system
In the sympathetic nervous system, where do the pre ganglionic fibres run, and what is the neurotransmitter?
Splanchnic nerves
Acetylcholine
In the sympathetic nervous system, where do the post ganglionic fibres run and what is their neurotransmitter?
Run through organ of innervation or hypogastric nerves
Noradrenaline
What do entero-enteric reflexes do?
Coordinate activity between different parts of the GI tract
What are the three phases of regulation?
Cephalic (head)
Gastric (stomach)
Intestinal
What stimulates the cephalic phase to cause a release of more gastric juices and which NS controls this?
Emotion
ANS
The gastric phase is coordinated by which nervous system and which main hormone?
ANS
ENS
Gastrin
Which nervous systems and hormones coordinate the intestinal phase?
ANS
ENS
Secretin, CCK, GIP
Where is the site of appetite regulation?
Hypothalamus
What does the ventro lateral hypothalamus cause?
Food searching
What does the ventro medial hypothalamus cause?
Refusal of food (inhibit appetite)
The hypothalamus regulates appetite. What are the 3 theories as to how it does this?
Measures levels of fat, glucose or CCK
What is motility?
Coordinated contraction of smooth muscle in the GI tract
What are the 4 types of motility?
Segmental
Peristalsis
Anti peristalsis
Mass movement
What is segmental motility?
The mixing of contents and mechanical breakdown
What is peristalsis?
The movement of intestinal contents in aboral direction
What is anti peristalsis?
The movement of intestinal contents in an oral direction
What is mass movement?
The emptying of entire sections of the GI tract
Eg. Evacuation of colon contents to rectum
In the membrane potential of groups of pacemaker cells, there are approx. 5 per minute of…
Repetitive and spontaneous oscillations
If a stimulus is present in pacemaker cells, an action potential causes smooth muscle contraction. The strength of contraction is dependent on what?
The frequency of action potentials
