Intro to GI Physiology Flashcards
What are long GI reflexes? What is a classic example?
The submucosal plexus is also known as […] plexus and it controls […] and […]
Meissner’s
GI secretion
Blood flow
- What does it mean to say that the microvilli that line the gut are an example of countercurrent blood flow?
- How / when does this make the microvilli particulary susceptible to damage?
What are the 3 parts of the small intestine, from proximal to distal.
Duodenum
Jejunum
Ileum
What are the 4 main functions of the GI tract?
What are the 3 parts of the large intestine, from proximal to distal.
Cecum
Colon
Rectum
What are intrinsic gut reflexes? What’s a classic example?
The enteric nervous system can be thought of as a sub-branch of the […] nervous system
Autonomic
What are the 3 main mechanisms that are used to regulate the GI tract?
Endocrine
Neurocrine
Paracrine
The myenteric plexus is also known as […] plexus and it controls […]
Auerbach’s
GI motility
True or false: substances that enter the GI tract are considered outside as long as they remain in the lumen.
True
What is the peristaltic reflex?
Explain what is seen in this image.
SNS (postganglionic) and PSNS (preganglionic) synapse on the plexi of the gut, which then affect the function of the gut wall cells. The gut wall also contains sensory neurons which can effect both the enteric plexi and/or send signals up to the prevertebral ganglia of SNS, the spinal cord, or the vagus nerve (up to brainstem).
What is a longer GI reflex? What are some classic examples?
Of the 4 main functions of the GI tract, which 2 are the most regulatable?
Motility
Secretion
Describe the general path that is taken by anything that enters the mouth.
IN GENERAL, how is blood flow regulated to the GI tract?
Same as what we learned for HLK
For intrinsic factors, pO2 is a major regulator. As oxygen decreases, local factors like adenosine and NO are released to cause vasodilation.
For extrinsic factors, the sympathetic NS can regulate blood flow to gut (ex: during exercise, SNS vasoconstricts vessels to gut to reduce blood flow)
What are the 4 main layers of tissue that make up the barrier between the abdominal cavity and the lumen of the GI tract?
From internal to external:
- Mucosa
- Submucosa
- Muscularis externa
- Serosa
Describe in VERY GENERAL terms the anatomy of the gut wall.
Will learn more about this in later lectures, but in general:
Mucosa
- Specialized epithelium with microvilli
- Lamina propria (capillaries, nerve endings, immune cells)
- Muscularis mucosa (circular and longitudinal muscle)
Submucosa
- Major blood vessels and lymph vessels as well as submucosal nerve plexus (secretion and vasomotion)
Muscularis externa
- Circular muscle and myenteric nerve plexus (gut motility)
Serosa
- Longitudinal muscle
