Tutorial Workbook 1017MSC T3 2023 Module 5 Gastrointestinal System.pdf

Foundation Year Health Anatomy & Physiology Systems 2 1017MSC T3 2022 Tutorial Work Book Module 5 Gastrointestinal System School of Pharmacy and Medical Science Griffith University Gold Coast

1 Checklist Module 5: Gastrointestinal Tract: Topics 5.1, 5.2, 5.3, 5.4, 5.5 a) Reviewed minilectures b) Completed online quizzes c) Attended tutorial sessions d) Completed workbook tasks pp 1-21 e) Completed reflection in workbook

2 Module 5: Gastrointestinal System 5.1: Functional anatomy of the GIT Label the following diagrams. Salivary Glands Parotid gland Sublingual gland Submandibular gland Pharynx Stomach Pancreas Spleen Large intestine Transverse colon Descending colon Ascending colon Cecum Sigmoid colon Rectum Appendix Anal Canal Anus Ileum Jejunum Duodenum Small intestine Gallbladder Liver Oesophagus Tongue Mouth (oral cavity) Soft palate Palatoglossal arch Hard palate Oral Cavity Palatine tonsil Tongue Oropharynx Lingual tonsil Epiglottis Hyoid Bone Laryngopharynx Oesophagus Uvula

3 Gastrointestinal tract activities: Label Below 1. What does the term essential mean when used to describe some amino acids and fatty acids? Essential means we need these nutrients in our diet to maintain health and normal function of the body. Food Pharynx Oesophagus Propulsion Swallowing (oropharynx) Peristalsis (oesophagus, stomach, small intestine, large intestine) Ingestion Mechanical Breakdown Chewing (mouth) Churning (stomach) Segmentation (small intestine) Digestion Stomach Absorption Lymph Vessel Blood vessel Mainly H2O Faeces Anus Large intestine Small intestine Defecation

4 We can not synthesise these nutrients or molecules ourselves and rely on other organisms or animals for their synthesis. 2. Name the 5 physiological processes of the GIT. a) ingestion b) propulsion c) digestion (mechanical and chemical) d) absorption e) defaecation 3. What are Peyer’s patches and where are they found? Aggregated lymphoid follicles found in the lamina proporia of the small intestine. Their numbers increase as you progress further down the small intestine. An important part of the immune system, monitoring intestinal bacteria populations, and protecting the submucosa against bacteria that breach the epithelium of the SI. 4. How does segmentation differ from peristalsis ? Segmentation: Rhythmic local constriction of the small intestine: mixing and churning. Primarily for the mechanical breakdown of foodstuffs as food is moved forward, then backward, and then mixed together with digestive juices. Some propulsion may also occur with segmentation. Peristalsis: The propulsion of chyme distally along the tract toward the anus with a little bit of mixing along the way. Peristalsis is superimposed on segmentation, so food is mixed and moved slowly in a net oral- analward direction 5. Name the four basic layers of the alimentary canal (and their functions). 1) Mucosa (inner layer) contains columnar epithelium: secretes, absorbs and protects. 2) Submucosa is areola connective tissue: contains blood vessels and lymphatics, the submucosal nerve plexus, glands and lymphoid follicles. 3) Muscularis externa consists of two smooth muscle layers (longitudinal, circular): responsible for motility and segmentation and peristalsis.

5 4) Serosa (outermost layer) connective tissue for protection. 6. How does GIT activity change with the following: Sympathetic dominance Inhibits gut activity; especially secretary activity. First synapse at outlying ganglia, allowing for widespread effect, so reduction in blood flow occurs along entire gut (mostly post-ganglionic sympathetic neurons on GIT) Parasympathetic dominance Stimulates gut activity, especially motility. Increased blood flow and activity of the gut stimulation results in localised effects (preganglionic neurons, close to target). 7. Explain the long and short reflexes involved in routine digestion and absorption in the GIT. Mechanoreceptors and chemoreceptors throughout the wall dot eh gastrointestinal tract monitor the structural and chemical conditions within the lumen in order to maintain the perfect environment for digestion and absorption. This stimulates bot intrinsic and extrinsic control mechanisms. The short reflex acts within the enteric nerve plexus (the gut brain) to the wall of GI tract: myenteric and submucosal nerve plexi. The long reflexes involve autonomic nerves, responding to external stimuli such as sight, smell and taste. Visceral afferent are processed in the CNS. Visceral efferent then act on the local intrinsic nerve plexus in the GIT. These reflexes influence contractions of smooth muscle and endocrine gland activity in the GIT. The stomach and small intestine also have hormone-secreting cells that release hormones to elicit secretion or contraction (e.g. gastrin, secretin, cholecystokinin). 8. Outline the structure and function of the Enteric Nervous System, including its subdivisions. The gut brain (short reflexes) located entirely in the wall of the GIT. - the inhouse or intrinsic nerve supply of the GIT. Can operate autonomously – 100 million neurons.

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