Gastrointestinal: Swallowing and Mastication Flashcards
List the three salivary glands and where they secrete.
Parotid- upper 2nd molar
Submandibular- under lower edge of the mandible
Sublingual- floor of the mouth
What are the functions of saliva?
Lubrication Solvent Antibacterial Carbohydrate digestion Neutralises acid Sucking in infancy
What cells are respinsible for the primary secretion of saliva?
Acinur cells
What is secondary secretion and what cells carry it out?
Cells modify secretion by removing sodium and chlorine and adding carbonate and potassium- DUCT CELLS
When is the level of bicarbonate in the saliva highest?
During high flow rates
Describe the unconditioned production of saliva/
Chemo/oressure receptors detect food bolus
Visceral afferents to salivary centre in medulla
Autonomic nerve impulses
Salivary gland increase production
Describe conditioned production of saliva.
See/hear/think about food Cerebral cortex Salivary centre of medulla Autonomic nerves Saliva production
What parasympathetic nerves are responsible for saliva production
Glossopharyngeal
Facial
What effect does parasympathetic stimulation have on saliva?
Increase production
Watery and enzyme rich
What affect does sympathetic stimulation have on salivat production
Small volume
Thick
MUcus rich
Describe peristalsis in the oesophagus.
Circular fibres behing bolus squeeze
Longitudinal fibres in front shorten
What controls peristalsis in the oesophagus?
Enteric nervous system
What happens to the lower oesophageal sphincter in swallowing?
Opens within response to swallowing and closes after passage of bolus to prevent reflux
What is the function of the stomach
Mixes food with gastric secretions to produce chyme
Stores food before passing it into the small intestine for digestion and absorption
What controls gastric motility?
Pacemaker cells
in the fundus
What do the pacemaker cells do
Establish a basal electrical rhythm
How does the electrical rhtythm spread?
From fundus to pyloric schincter
What gastric factors determine the rate of stomach emptying?
Distention- increases motility due to stretch of smooth muscel which stimulates increased vagus nerve activity and gastrin increase
Constituency of chyme- finely divided, thick liquid chyme speeds up emptying
What duodenal factors determine the rate of gastric emptying?
Neuronal- enterogastric reflex- decreases peristalsis through signals fromt he intrinsic nerve plexus and the autonomic nervous system
Hormonal- enterogastrone release inhibits stomach contraction
Name two entergastrones
Secretin
CCK
How does fat affect gastic emptying?
Fats take a long time to digest- slows it down
How does acid affect gastic empyting?
If duodenum detects acid- will inhibit stomach peristalsis due to the fact it need to wait for alkaline solutions from the pancreas
How does hypertonicity affect gastric emptying
– products of carbohydrate and protein digestion are osmotically active and draw water into the small intestine – danger of reduced plasma volume and circulatory disturbances
Slows down emptying
How does distention affect gastic emptying?
distention in the duodenum slows down gastic emptying
