Gastro II Flashcards
What is the role of non-GIT hormones in hormonal GIT regulation? Give an example.
They can influence the growth and development of GIT. For example, growth hormone or thyroid hormone.
Where do GIT hormones (in general) exert their area of influence?
They can either influence activities outside the GIT or inside the GIT.
Give an example of a GIT hormone that influences activities outside the GIT and how it does so.
Ghrelin is released by glands in the stomach when you’ve been fasting for a long time. This will travel via the bloodstream to the hypothalamic feeding center in the brain. The effect is to stimulate hunger and increase appetite.
What hormone has the opposite effects to Ghrelin?
Leptin - it induces satiety and decreases appetite.
What is the effect of Leptin? Where is it produced (is it a GIT hormone)?
Leptin is produced by fat cells after overeating (it is not a GIT hormone). It will induce satiety in the hypothalamus and decrease appetite.
Hormonal regulation of GIT activity occurs via the […] system, which is located in the […]
Hormonal regulation of GIT activity occurs via the diffuse endocrine system, which is located in the mucosa
What are the 5 most important GI hormones?
Gastrin, CCK, secretin, GIP, VIP
GIT regulatory hormones are mostly of the type […]
Peptides
What is the typical path of GIT regulatory hormones produced in the GIT?
- Released into hepatic portal vein
- Goes to liver
- Goes to heart
- Travels through systemic circulation
- Reaches target cells
Why do GIT hormones pass through the liver before reaching the circulation?
Because the blood that they’re being carried in will have toxins from what we’ve ingested. We don’t want these in the bloodstream, so the liver filters them.
Do GIT regulatory hormones have one or multiple targets?
They can have multiple targets that can be excitatory or inhibitory.
GIT hormones can interact with […]
one another and with neurotransmitters
The propulsion of food in the GIT is driven by what force(s)?
It is mainly driven by gradients in pressure. Variations in resistance are normally insignificant.
How are gradients in pressure generated for propulsion in the GIT?
By coordinated contractions of muscular elements in the GIT wall. These contractions can be segmentation or peristalsis.
What is the difference between segmentation and peristalsis? What do they have in common?
Similarity: they are both generated by circular muscles.
Segmentation = rings of circular muscle are contacting at alternating points in the GIT. This movement is good for mixing.
Peristalsis = circular muscle is contracting in a wave that propagates one after the next. This pushes contents forward.