Alimentary Canal Flashcards

1
Q

What is the function of the mouth?

A

Foodstuffs broke down by chewing (mastication): saliva is added as a lubricant

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2
Q

What is the function of the oesophagus?

A

Conduit between the mouth and the stomach

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3
Q

What is the function of the stomach?

A

Digestion of proteins; foodstuffs reduced to liquid from. Also plays a role in storage and sterilisation

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4
Q

What is the function of the pancreas?

A

Digestive enzymes for digestion (duh), helps with the absorption of fats, carbohydrates and proteins

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5
Q

What is the function of the liver?

A

Secretes bile salts to aid the absorption of fats in the ileum

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6
Q

What is the function of the gallbladder?

A

Stores and concentrates bile

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7
Q

What is the function of the small intestine?

A

Final stage of chemical digestion and nutrient absorption

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8
Q

What is the function of the large intestine?

A

Water absorption, bacterial fermentation and formation of faeces

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9
Q

Describe the length, diameter and organisation of the GI tract

A

Approx. 8m long, varying diameter and organisation of cells vary depending on function

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10
Q

Describe the difference in the microscopic composition of the GI tract?

A

Mouth, anal canal and oesophagus - stratified squamous epithelium

Stomach and intestines - simple columnar epithelium

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11
Q

What are the four layers common to the GI tracts length?

A
  • Mucosa
  • Submucosa
  • Muscularis externa
  • Serosa/Aventitia
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12
Q

What structures comprise the mucosa?

A

Epithelium, lamina propria and muscularis mucosae

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13
Q

What is the function of the mucosa?

A
  • Synthesis and secretion of enzymes

- bAbsorbs products of digestion

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14
Q

What is the lamina propria?

A

Loose connective tissue containing glands and blood/lymph vessels

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15
Q

What is the muscularis externa?

A

A thin layer of muscle

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16
Q

What is the structure of the submucosa?

A

Thick irregular connective tissue

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17
Q

What is the function of the submucosa?

A

Supports the mucosa

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18
Q

What structures permeate the submucosa?

A

Neurones, blood vessels (to the mucosa, adventitia and muscularis external)

19
Q

What is the network of neurones in the submucosa known as?

A

Meissner’s Plexus (parasympathetic)

20
Q

Where are submucosal glands located?

A

Oesophagus and duodenum

21
Q

What is the muscularis externa?

A

Two layered ring of muscle

22
Q

What are the functions of the two layers of muscle in the muscularis externa? What two processes do these functions accommodate?

A

Inner - circular muscle - contraction of GI tract lumen
Outer - longitudinal - constriction of tube length

Allows peristalsis and segmentation

23
Q

What neural system lies between the layers of the muscularis externa?

A

Auerbach’s Myenteric Plexus

24
Q

What is the enteric nervous system comprised of?

A

Submucosal (Meissner’s) and Myenteric (Auerbach’s) plexi

25
Q

What is the function of the enteric nervous system?

A

Independent control of the GI tract

26
Q

What is the difference between the serosa and the adventitia?

A

Both outer layer of connective tissue for the alimentary canal

Location is the difference

Serosa = inside the peritoneal cavity

Adventitia = outside the peritoneal cavity

27
Q

What division of the autonomic nervous system governs long reflexes in the alimentary canal?

A

Parasympathetic

28
Q

What division of the autonomic nervous system governs short reflexes in the alimentary canal?

A

Sympathetic

29
Q

What nerve delivers parasympathetic innervation?

A

Vagus nerve (X) except salivation (facial VII and glossopharyngeal IX)

30
Q

What is the effect of the parasympathetic system in the GI tract?

A

Increases gut motility and secretion

31
Q

What nerve delivers sympathetic innervation to the GI tract?

A

Splanchnic

32
Q

What is the effect of the sympathetic nervous system in the GI tract?

A

Inhibitory (except salivation) - decreases secretion and motility

33
Q

What three branches of the descending aorta supply the GI tract?

A

Celiac trunk, superior and inferior mesenteric artery

34
Q

What organs does the celiac trunk supply?

A

Stomach, small intestine, pancreas and liver

35
Q

What organs does the superior mesenteric artery supply?

A

Small intestine, caecum, ascending colon and transverse colon

36
Q

What organs do the inferior mesenteric artery supply?

A

Descending colon, sigmoid colon and rectum

37
Q

What vein(s) drain from the stomach?

A

Gastric veins

38
Q

What vein(s) drain from the pancreas?

A

Splenic vein

39
Q

When organs drain into the superior mesenteric vein?

A

Small intestine, caecum, ascending and transverse colon

40
Q

What organs drain into the inferior mesenteric vein?

A

Descending colon, sigmoid colon and rectum

41
Q

Where do the gastric, splenic and mesenteric veins drain into?

A

Hepatic portal vein

42
Q

Outline the route to the inferior vena cava from the hepatic portal vein

A

Hepatic portal vein (through the liver) to the hepatic vein to the inferior vena cava

43
Q

What is the purpose of the hepatic portal system?

A

Clean blood in liver before reoxygenation in the cardio-pulmonary system