Lecture 8 Flashcards
What is saliva production stimulated by?
Sight, smell of food, inhibition during sleep, stimulated by acid in oes
What are the contents of saliva?
Electrolytes, high HCO3-, mucins, salivary enzymes, lactoferrin, lysozyme
What is xerostomia?
Loss of saliva.
What are the symptoms of xerostomia?
Drying of mouth, oral infections, dental decay, loss of taste (saliva irrigates taste buds)
What can lead to decrease of salivary secretion?
Sjogrens disease, which causes loss of salivary secretion because of chronic inflammation of salivary glands. Also decreased by anticholenergic drugs.
What are the major roles of the stomach?
- Acts as a reservoir for food during initial digestion, allowing food to pass through in controlled amounts of semi-liquid paste
- Adjusts the osmolality of contents before they enter the small intestine
- Antrum acts as a grinding mill, pylorus regulates size of particles that can pass through to the duodenum
- Secretion of acid
- Other secretions: intrinsic factor, pepsinogen, mucus, prostaglandins, HCO3-
What does the control of gastric emptying require?
Intact antrum, pylorus, and duodenum for normal function
Normal vagal function to coordinate activity
Normal hormonal function
What are the 4 steps that occur in the stomach during food digestion?
1) Relaxation of fundus (vagovagal reflex)
2) Contraction of body and antrum
3) Pylorus contracts
4) Mixing by retropulsion
Define neurotransmitter
Molecules that transmits a signal from one neuron to another
Define autocrine
Molecule released by a cell that targets itself
Define paracrine
Molecule released by a cell that targets adjacent cells
Define endocrine
Molecule released by endocrine cells into circulation to target distant cells
What are the two types of abnormal gastric emptying?
Rapid and delayed
What can cause rapid gastric emptying?
- After gastric surgery, dumping syndrome can occur.
- Drugs that speed up gastric emptying - prokinetics
Give an example of a prokinetic drug
Metoclopramide - release of ACh at myenteric plexus
What are the symptoms of dumping syndrome?
Nausea, vomiting, cramping, diarrhoea
What happens in dumping syndrome?
Food moves too quickly from stomach into duodenum and so are not completely digested as the antrum and pylorus are removed. Undigested food particles result in a hyperosmolar chyme in small bowel. Rapid fluid shift into gut causes intestinal distension which leads to pain. Osmotic effect results in diarrhoea.
What can cause delayed gastric emptying?
Diabetic gastroparesis, drugs that delay gastric emptying
What is diabetic gastroparesis due to? What does it lead to?
Due to autonomic neuropathy. Leads to variable rate of glucose absorption. Upper abdominal discomfort.
Give an example of a drug that delays gastric emptying
Anticholinergic drugs