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Kofi: Pure Clinical Sem 3 > GI: Introduction > Flashcards

GI: Introduction Flashcards

1
Q

What are the implications of the external environment?

A
  • You have to ingest food, digest food, absorb food and egest what not needed
  • Stop toxin/infection entering
  • Very thin epithelium
  • Need water in gut lumen for chemical reactions and cant lose to external world
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2
Q

What are the waste products that are not ingested in the gut?

A
  • Bilirubin

- Cholesterol

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3
Q

What are the areas of mechanical disruptions in the GI tract?

A
  • Mouth/Teeth

- Stomach

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4
Q

What are the muscular actions of the stomach?

A
  • Vigorous contractions of the stomach cause food to be liquefied.
  • Upper area create basal tone (tonic)
  • Lower area has powerful peristaltic contractions that effectively grind food and mix stomach contents. Every 20 seconds proximal to distal
  • Has additional inner oblique layer of muscle
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5
Q

How does the stomach resist rise in intraluminal pressure?

A

Eat quicker that digest

  • Stomach can distend due to rugae (temporary folds)
  • Receptive relaxation occurs to allow food to enter stomach without raising intragastric pressure to much and prevents reflux of stomach content during swallow
  • Vagally stimulated relaxation
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6
Q

What is the purpose of the colon?

A
  • Contents are only evacuated several times a day
  • Acts as a temporary storage
  • Gastrocolic reflex
  • Mass movements to rectum which is normally empty
  • Final water absorption
  • Final electrolyte absorption
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7
Q

What are the contents of the stomach for chemical digestion?

A
  • Acid

- Pepsin

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8
Q

What are the defences of the GI tract?

A
  • Saliva
  • HCl
  • Liver (kupffer cells)
  • Peyer’s Patches (Lymphoid follicles, Submucosa, mainly in terminal ileum)
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9
Q

What are broad functions of the oesophagus?

A
  • Rapid transport of bolus to stomach through thorax
  • Upper oesophageal sphincter prevents air from entering GI tract
  • Lower oesophageal sphincter prevents reflux into the oesaphagus
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10
Q

What are broad functions of the the stomach?

A
  • Storage facility
  • Produce chyme
  • Infections control (HCL)
  • Secrete intrinsic factor (Vit B12)
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11
Q

What are broad functions of the the stomach?

A
  • Storage facility (receptive relaxation)
  • Produce chyme
  • Infections control (HCL)
  • Secrete intrinsic factor (Vit B12)
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12
Q

What are the broad functions of the duodenum?

A
  • Start of small intestine
  • Neutralisation/osmotic stabilisation of chyme (HCO3 secretions)
  • Digestion wrapping up (pancreatic secretions, bile)
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13
Q

What are broad functions of Jejunum/ileum?

A
  • Final digestion
  • Nutrient absorption mainly in the jejunum
  • Water/electrolyte absorption mainly in ileum
  • Bile recirculation in ileum
  • B12 absorption in the terminal ileum
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14
Q

What is the structure of the peritoneum?

A
  • Parietal peritoneum in contact with abdomen
  • Visceral in contact with organs
  • Space between parietal and visceral peritoneum with fluid
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15
Q

How is the gut controlled?

A
  • Autonomic nervous system
  • Enteric nervous system
  • Hormones and paracrine secretions
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16
Q

What presynaptic nerves formed by the sympathetic nervous system to supply the Gut?

A
  • Greater splanchnic nerve (T5-T9)
  • Lesser splanchnic nerve (T10-T11)
  • Least (T12)
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17
Q

What is the purpose of the splanchnic nerves?

A

-Synapse with pre-vertebral ganglia
(Coeliac, Renal, superior mesenteric, inferior mesenteric and others)
-Mainly innervate blood vessels
-Generally inhibits GI function
-Post ganglionic fibres extend to myenteric and submucosal plexus and release norepinephrine
-Reduces motility

18
Q

What are the nerves from the parasymapthic nervous system to the gut?

A
  • Vagus nerve

- Pelvic splachnic nerves (S2-S4)

19
Q

What does the right and left vagus become in the gut?

A
  • Right vagus becomes posterior vagal trunk

- Left vagus becomes anterior vagal trunk

20
Q

What is the functions of the parasymapathetic system on the gut?

A
  • Pre ganglionic fibres (long) synapse in walls of the viscera
  • Post ganglionic fibres (short) release Acetylcholine and peptides (GIP and VIP)
  • Innervate smooth muscle/endocrine and secretory
21
Q

Which parts of the GI tract does the Pelvic nerve innervate?

A

-Transverse colon to Anal canal

22
Q

Which parts of the GI tract does the vagus nerve innervate?

A

-Oesaphagus to Transverse colon

23
Q

What are the features of the enteric nervous system?

A
  • Divisions of the nervous system
  • Can operate completely independently
  • Exists from the oesophagus to anus
  • It has 2 main plexuses: Submucosal and Myenteric
24
Q

What is another name for the submucosal plexus?

A

-Meissner’s Plexus

25
Q

What is another name for the myenteric plexus?

A

-Auerbach’s Plexus

26
Q

What is the function of the submucosal and myenteric plexuses?

A

Submucosal

  • Secretions
  • Blood flow

Myenteric
-Motility

27
Q

What is the route that hormones take in the GI tract?

A
  • Released from endocrine cells
  • Pass into portal circulation
  • Pass through the liver
  • Enter systemic circulation to end up close to their release point
28
Q

How is H+ production inhibited?

A

Somatostatin

  • Released by D cells in antrum of stomach and pancreas
  • Stimulated by H+ (low pH) on stomach lumen. Food is buffer so when it leaves the stomach pH drops
  • Inhibits G cells
  • Stomach distension reduces due to reduced vagal activity
  • Inhibits histamine release
29
Q

What is the action of Gastrin in the gut?

A
  • Acts on G cells in antrum of stomach

- Increase gastric acid secretion

30
Q

What is the action of cholecystokinin?

A
  • I cells in duodenum and jejunum

- Increases pancreatic/gallbladder secretions

31
Q

What is the control of the release of CCK?

A
  • Stimulated by fat and protein
  • Gall bladder contracts
  • Pancreas stimulated
32
Q

What is the action of secretin?

A
  • Increases HCO3 from pancreas/gallbladder

- Decrease gastric acid secretion

33
Q

What is the control of release of secretin?

A
  • Release stimulated by H+ and fatty acids

- Released from S cells in the duodenum

34
Q

What is the action of GIP?

A
  • Increases insulin

- Decreases gastric acid secretion

35
Q

What is the control of GIP release?

A
  • Cells in the duodenum and jejunum

- Stimulated by sugars, amino acids and fatty acids

36
Q

Why does appendicitis present with central abdominal pain initially?

A
  • Visceral peritoneum involved

- Visceral afferents accompany sympathetic motor fibres back to spinal sensory ganglia

37
Q

Why does pain localise to the Right iliac fossa (suprapubic region)?

A
  • Involvement of the parietal peritoneum
  • Due to somatic sensory pain
  • Pain is localised
38
Q

Where can visceral pain from foregut, midgut and handout structures be felt?

A

Foregut - Epigastric
Midgut - Periumbilical
Hindgut - Suprapubic/hypogastric

39
Q

Which muscles in the GI tract are not smooth muscle and instead skeletal muscle?

A
  • Pharynx
  • Upper 1/3 of oesaphagus
  • External anal sphincter (voluntary control)
40
Q

What are the types of motility that occur in the GI tract?

A

Peristalsis

  • Contraction proximal to contents and relaxation distal
  • Propels contents in one direction

Segmentation

  • Contraction splits contents then releaxes
  • To and fro movement that mix contents

Mass movement

  • Occurs in distal colon
  • Rapid movement of contents into rectum
  • Gastrocolic reflex

Kofi: Pure Clinical Sem 3 (44 decks)

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