Pharmacology I: Biochemical Signalling BPS2011 Notes

Summary:

The BPS2011 Pharmacology I: Biochemical Signalling notes cover various topics including the gastrointestinal tract, regulation of the gastrointestinal tract, gut contractility, DNA and protein, proteins as sensors, nuclear hormone receptors, G-protein coupled receptors, coupling and signal transduction pathways, ion channels, carriers, and transport proteins, enzymes, kinases, and kinase-linked receptors.

Excerpt:

Pharmacology I: Biochemical Signalling BPS2011 Notes

Gastrointestinal Tract

Function:
– Digest food and absorption of nutrients and water

Processes:

• Motility: Ingestion, mastication (chewing), deglutition (swallowing), peristalsis (contraction and relaxation of smooth muscles), and segmentation
  • Deglutition (swallowing): buccal phase (voluntary – tongue pushes a bolus to oropharynx), pharyngeal stage (involuntary – pharynx to esophagus via medulla oblongata), and esophageal stage (involuntary – bolus pushed by peristalsis).
  • Chyme: acidic fluid of gastric juices and digested food. Moves from the stomach to the small intestine (duodenum).
• Secretion: exocrine and endocrine
  • Salivary glands: Contain acinar cells that secrete salivary amylase that turn starch into sugars.
• Absorption: of water, ions, and small molecules
• Storage and elimination of waste
• The immune barrier to protect GIT from ingested pathogens

Stomach

• Function:
  • The temporary reservoir of dietary food and liquids
  • Mixing of food and water with gastric secretory products (acid and gastrin)
  • Grinding food decreases the size of particulates and enhances digestion
  • Regulating exit of chyme into the duodenum in response to stimuli
• Structure and components:

Biochemical Signalling

• • Lumen: lined with mucus-producing epithelial tissues arranged to form gastric
    pits
  • Gastrin: Peptide hormone released from G cells in the stomach to stimulate
    gastric acid (HCl) secretion to:
    – Release and activate pepsin from pepsinogen in chief cells
    – Trigger somatostatin release from D cells
    – Breakdown proteins to aid in digestion
    – Kill bacteria or foreign pathogens that are ingested or manage to infiltrate the GIT
    – Inactivate salivary amylase
  • Gastric acid (HCl): is secreted from Parietal cells and functions to :
    – pumps H+ into the lumen of the stomach via the H-K-ATPase pump in exchange K+ enters the Parietal cell.
    – CL- from blood capillaries travels into Parietal cells via Cl- channel to compensate for the electrical gradient produced by H+ and HCl secretion.