The upper GI tract Flashcards
Regulation of saliva secretion
-Regulated by ANS
-Small amount continuously secreted, increased due to ANS stimulation
- Food chemicals stimulate taste receptors
- sensory impulse sent to brainstem salivary nuclei
- parasympathetic activity activity initiated
- parasympathetic fibres terminate on the smooth muscle fibre that surrounded the salivary nuclei
Pathophysiology of the oesophagus - dysphagia
Defined as difficulty, discomfort or pain in swallowing
Commonly a consequence of a neuromuscular disease
Difficult to treat with pharmacotherapy
mechanical obstruction = majority of cases
motor disorders = minority of cases
Functional dysphagia
Oesophageal spasm pharmacotherapy
Long acting nitrates - causes inhibition of contraction
Calcium channel blockers - reduced calcium entry into smooth muscle cells and reduces contraction amplitude
Injection of type A botulinum toxin - contains a protease that targets a protein involved in the CA2+ exocytosis of ach from presynaptic membrane
Stomach structure
Functions are - reservoir, partial digestion, limited absorption and regulated release of chyme into duodenum
Regulation of parietal cell HCL secretion
- Regulated process
- Ach, Gastrin and Histamine stimulate HCL secretion
Gastritis
Inflammation of the gastric mucosa leading to discomfort and tenderness.
Acute gastritis is the injury of the protective mucosal barrier by drugs, chemicals or infection
Chronic gastritis commonly occurs in the elderly and is usually due to the thinning or breakdown of the stomach wall. Leads to chronic fundal or anstral gastritis
Treatment = remover trigger or decrease acid
Prokinetic drugs
Enhance coordinated GI motility without purgation (cleansing)
Aim is to increase ACH without pattern interference to enhance stomach motility
Ulcer formation
Located in the stomach
Normally the mucus cells in the neck of the gastric glands secrete and bicarbonate ions to create a chemical barrier to protect the stomach from digesting itself
Acid and pepsin can destroy mucosa and form holes through submucosa into the muscularis forming ulcers
Triggers of ulcer formation
Smoking
High alcohol intake
Bacterial infection
Aims of therapy
healing of ulcer
Prevention of recurrence
Avoidance by a combination of drug therapy and lifestyle modifications
Proton pump inhibitors
Irrervirsible inhibition of the H+ / k+ ATPase
- binds covalently to enzyme
- marked inhibiton of basic acid secretion, stimulated acid secretion
- NO EFFECT on release of pepsin
TREAT WITH PPI FOR 4-8 WEEKS
Due to adverse drug reactions, it is recommended that PPIS are prescribed for the shortest possible duration
Bismuth subsalicylate
is a medicine that relieves diarrhoea, nausea, heartburn, and other stomach problems
strongly adheres to proteins
forms a complex gel with mucus
promotes increases mucus production and bicarbonate release
Antacids
Neutralise gastric acid
Aim to keep PH rise more less than 4
Aluminium compounds
- Reacts slowly with HLC
- gradual and prolonged action
- forms a protective coat over ulcer
- adsorbs pepsin
- constipating
Magnesium compounds
-very little absorbed
- gut stimulant and provides a laxative effect
- can cause phosphate depletion
