week 10 - disorders of the GI system Flashcards
What is the function of the digestive system?
To digest food from a high molecular weight to a low molecular weight.
To absorb substances across the GI tract wall
What is the tube wall of the entire GI system made of?
- Mucosa - made up of epithelium, its function is absorption and has gland cells for secretion
- Sub mucosal plexus - Has nerves to regulate the gut
- Smooth muscle - Circularly orientated structure
- Myenteric Plexus - Contains more neurones
- Smooth Muscle within Serosa - Longitudinally orientated structure
What are the 2 movements of the GI tract?
Rhythmic Segmentation
Propulsive Peristalsis
What is rhythmic segmentation?
Nonadjacent segments of intestine contract and relax alternately to mix the chyme
What is propulsive peristalsis ?
wave of contraction followed by wave of relaxation to move food down the GI tube
What are the 3 sphincters of the GI system and what are the functions of all 3?
- Lower oesophageal
2.Pyloric - Ileocecal
The function is to ensure food travels in one direction and to prevent reflux
Give a brief summary of the hormone gastrin ?
Gastrin is released by g cells in the stomach.
Stimulates motility and stimulates the release of acid in the stomach (response to food)
Give a brief summary of the hormone secretin in the GI system?
Secretin is secreted by S cells in duodenum when there is low pH in the duodenum
Give a brief summary of the hormone CCK in the GI system?
CCK is secreted by the intestines in response to fat/protein rich chyme.
It allows for the slowing down of gastric emptying so food can be digested.
Involved in satiety (feeling full) by feeding back to the brain to inhibit appetite
Give a brief summary of the hormone leptin in the GI system?
It is a hormone produced by fat cells.
If you have more body fat, you have more leptin.
Leptin travels from bloodstream to hypothalamus where it suppresses your appetite.
Therefore, if you have more leptin due to more body fat then you have less food intake
What happens if you have a leptin secretion deficiency?
Suffer from hyperplasia, obesity
Give a brief summary of the hormone ghrelin in the GI system?
Ghrelin signals hunger.
Made by endocrine cells of the GI tract.
It acts on receptors of the hypothalamus to signal hunger.
What can happen if you have high levels of ghrelin?
Can lead to Prader Willis syndrome - leads to a voracious appetite, obesity as the high ghrelin levels keep signalling hunger
Give a brief summary of the peptide YY3-36 in the GI system?
Produced by the stomach cells.
Reduces ghrelin secretion
Give a brief summary of the CB1 receptor in the GI system?
Has effects similar to cannabis
If it is activated to results in a reduction in satiety signals. Relaxation, pain reduction effects.