Physiology and Pharmacology of Salivary and Gastric Secretion and Gastric Motility Flashcards
What are the three pairs of salivary glands?
Parotid
Submandibular
Sublingual
Where is the parotid gland located?
Below ear and over the masseter
Where is the submandibular gland located?
Under lower edge of mandible
Where is the sublingual gland located?
In floor of mouth under tongue
What makes the saliva anti-bacterial?
Lysozymes, lactoferrin and immunoglobulisn
What - in the saliva - digests complex carbohydrates?
Amylase
How does the saliva neutralise acid?
Bicarbonate
In the formation of saliva, what does primary secretion?
Acinus
In the formation of saliva, what does secondary secretion?
Duct cells
What does the formation of saliva require?
ATP
What cells produce a primary secretion with Na+, K+, Cl- and HCO3- content similar to plasma, plus mucus and amylase?
Acinus
What cells modify secretion by removing Na+ and Cl- and to a lesser extent adding K+ and HCO3- no movement of H2O - hence diluting?
Duct cells
How much saliva a minute do we actively produce when salivating?
5ml
What two things reflex regulate (neuronal control) the rate of formation of saliva?
- Simple unconditioned reflex (citrus fruits)
2. Conditioned (acquired) reflex
In the simple (unconditioned) control of salivary secretion, what can activate pressure receptors in the mouth?
Food
In the simple (unconditioned) control of salivary secretion, what happens after pressure receptors are activated by food?
Impulses are send via afferent nerves
Where is the salivary centre?
In the medulla
In the aquired (conditioned) control of salivary secretion, where does the signal go before reaching the salivary centre in the medulla?
Cerebral cortex
What occurs as a result of the salivary centre in the medulla, sending impulses via extrnisic autonomic nerves - both paraysmpathetic and sympathetic stimulation?
Salivary glands increase production
What stimulation is the dominant role in normal saliva production?
Parasympathetic
What nerves does the parasympathetic stimulation control?
Glossopharyngeal and facial nerves
In parasympathetic stimulation of saliva secretion, what receptors are mediated to produce large volumes of watery saliva?
M3 muscarinic acetylcholine receptors
At what times is sympathetic stimulation dominant at?
Stressful times - dry mouth when nervous!
In the sympathetic stimulation of saliva secretion, what do postganglionic fibres from superior cervical ganglia cause?
Small volume, thick, mucus rich saliva, mediated by B1-adrenoceptors
How much capacity does the stomach have?
50 > 1000ml
What nerve causes relaxation of the stomach to accomodate food from the oesophagus?
Vagus
What two acids are secreted in the stomach, for the start of protein digestion?
Pepsin and hydrochloric acid
Where does the stomach secrete gastric juice from?
Gastric pits in the gastric mucosa
What wave strength determines the escape of chyme through the pyloric sphincter?
Antral ave
What do gastric factors and duodenal factors govern?
Antral wave
What does distention of the stomach increase?
Motility, due to stretch of smooth muscles
When smooth muscles of the stomach are stretched, what is stimulated, increased and released?
Intrinisc nerve plexuses, increased vagus nerve activity and gastrin release
What reflex can delay empyting of the stomach?
Enterogastric reflex
What does the enterogastric reflex do by signals from the intrinisc nerve plexus and autonomic nervous sytem?
Decrease antral peristalic activity
Name two enterogastrones?
Secretin and cholecystokinin (CKK)
What do release of enterogastrones from the duodenum inhibit?
Stomach contraction