Gastrointestinal Anatomy and Physiology Underpinning Pathology and Therapeutics 1

Question 1

What are the GIT activities physiological functions (7)

Answer 1

1. Secretion - Exocrine: Digestive enzymes; Lubricating, protective agents (water, mucus, bicarb) - Coordinating mediators (transmitters (paracrine)/ hormones (endocrine))
2. Digestion - Mechanical breakdown of foodstuffs - Chemical (acid) & enzymatic actions
3. Absorption - Nutrient uptake
4. Motility - Mixing (digestion) - Propulsion (absorption & elimination)
5. Excretion / Elimination - Undigested fibre & biliary (fat-sol) waste - Contribution is small compared to kidney & lung
6. Immunological defence - Secretory IgA; Lymphatics in submucosa - Peritoneum (lymph and mononuclear phagocyte system) - Pathol - Contribution to inflammatory pathologies
7. Biotic fermentation vessel - Harbours important microbial populations

Question 2

What are the teeth functions (2)

Answer 2

1. Mastication
2. beginning the formation of bolus small enough for swallowing (deglutition)

Question 3

What are the tongue functions (3)

Answer 3

1. taste
2. manipulation of food into bolus
3. swallowing

Question 4

What is the uvula function (2)

Answer 4

1. sensation coordinating swallowing
2. protect nasal and bronchial passages during deglutition & reflux/emesis, so to prevent choking

Question 5

Tonsils & adenoid functions (2)

Answer 5

1. Lymphoid tissue
2. immune surveillance and response

Question 6

What are the salivation glands (4)

Answer 6

1. Sublingual
2. submandibular
3. parotid
4. Under neural reflexive control (anticipatory)

Question 7

What are the salivation functions (4)

Answer 7

1. Bolus formation and lubrication
2. Digestion: Salivary amylase, Lingual lipase
3. Resistance to infection: Secretory IgA, Lysozyme – anti-microbial
4. Moist buccal/sublingual mucosa promotes absorption that avoids first-pass metabolism

Question 8

what is tonsillar hypertrophy (3)

Answer 8

1. Infection-associated mononucleosis can cause massive tonsillar and adenoid enlargement with airway obstruction
2. requiring removal if not responsive to steroids.
3. tonsillar enlargement; typical cause of sleep apnoea, often treated by tonsillectomy.

Question 9

What are drug-induced (cocaine abuse) deformities (5)

Answer 9

1. Intranasal & pharyngeal damage by vasoconstriction leading to tissue necrosis

Can case:

2. Saddle nose deformity
3. loss of nasal septum and turbinates,
4. thickening of the maxillary sinus membranes
5. Nasopalatal defect (perforation)

Question 10

What are the emergency treatments to clear upper airway obstruction (3)

Answer 10

1. Coughs
2. Back slaps
3. Abdominal thrusts as a last resort (Heimlich Manoeuvre)

Question 11

What happens in hiatus Hernia (5)

Answer 11

1. Part of the stomach that joins the oesophagus (gullet) becomes pushed upwards, passing through the hole (hiatus) in the diaphragm.
2. The sphincter retaining stomach acid loses function.
3. Acid refluxes (leaks upwards) into the oesophagus (gullet).
4. Acute symptoms – epigastric discomfort: heartburn/cough.
5. Long-term injury / oesophageal cancer.

Question 12

What are the layers of gut wall (5)

Answer 12

1. Lumen
2. Mucosa - Epithelium, Lamina propria, Muscularis mucosa (folds)
3. Sub-mucosa - Glands/nerves (secretions)
4. Muscularis - Circ/Long musc & nerves (motility)
5. Serosa - Connective tissue

Question 13

What are the cells lining the villus (6)

Answer 13

1. Enterocyte: microvilli (brush border) - absorptive cell
2. Goblet (mucus-producing)
3. Enterochromaffin - e.g. 5HT producing
4. Secretory Pariental (acid)/Zymogenic (Pro-enzyme producing) e.g. Chief (pepsinogen)
5. Stem cell (Cryptal)
6. Paneth cell (defensins)

Question 14

What is the villus structure (3)

Answer 14

1. Cells on the outside with stem cells at the bottom to renew old cells at the top
2. Arteriole at the beginning → venule at the end
3. Lymphatic (lacteal) supply in the middle - drainage of nutrients

Question 15

What is Peritoneum (3)

Answer 15

1. Fluid-filled compartment (sac) surrounding many of the ventral abdominal organs (much of GIT).
2. Highly vascularized.
3. A convenient site for dialysis exchange therapy

Question 16

What is dialysis exchange therapy in comparison to haemodialysis (4)

Answer 16

1. Less effective than haemodialysis
2. carries a risk of potentially fatal infection (peritonitis);
3. can be continuous, automated/ambulatory (CAPD)
4. can be improvised (e.g. field hospital conditions).