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GI Physiology > G1 - Introduction to GI Tract and Mobility > Flashcards

G1 - Introduction to GI Tract and Mobility Flashcards

1
Q

what is the series of hollow organs running from the mouth to the anus (oral to aboral)?

A

alimentary canal

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2
Q

What part of the GI system chops food, lubricates it, starts carbohydrate digestion and propels food to the oesophagus?

A

mouth and oropharynx

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3
Q

what is the function of the oesophagus?

A

muscular tube that propels food to the stomach

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4
Q

what part of the GI Tract stores food temporarily, continues carbohydrate digestion, initiates protein digestion and regulates delivery of chyme to the small intestine?

A

stomach

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5
Q

what is the function of the small intestine?

A

principle site of digestion and absorption of material s

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6
Q

what part of the GI tract reabsorbs fluids and electrolytes, stores faecal matter before delivery to rectum?

A

large intestine

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7
Q

what part of the Gi tract stroes and regulates expulsion of faeces?

A

rectum and anus

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8
Q

what are the accessory structures of the GI system?

A
  • salivary glands
  • pancreas
  • liver and gall bladder
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9
Q

motility definition

A

Mechanical activity mostly involving smooth muscle

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10
Q

What is secretion required for?

A

digestion
protection
lubrication

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11
Q

What does digestive secretions contain?

A

Water, electrolytes and organic compounds

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12
Q

Digestion definition

A

chemical breakdown by enzymatic hydrolysis of complex foodstuffs to smaller, absorbable, units

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13
Q

What is the conversion of carbohydrates to monosaccharides mediated by?

A

amylase and disaccharide

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14
Q

What is the conversion of proteins to amino acids, dipeptides and tripeptides mediated by?

A

Proteases, dipeptidases and tripeptidases

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15
Q

What are fats converted to monoglycerides and free fatty acids mediated by?

A

lipases

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16
Q

What is the name for the transfer of the absorbable products of digestion from the digestive tract to the blood or lymph?

A

absorption

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17
Q

What seperates and controls the movement of alimentary canal?

A

sphincters

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18
Q

Where does protein digestion begin?

A

stomach

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19
Q

What movement sends food in a normal manner through the alimentary canal?

A

propulsive

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20
Q

What movements send chyme backwards and forwards to extend the time for digestion

A

mixing

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21
Q

What contractions are maintained for long lengths of time?

A

tonic

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22
Q

What process describes the chemical breakdown of complex foodstuffs into smaller, absorbable units?

A

Enzymatic Hydrolysis

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23
Q

What layer in the mucosa of the GI Tract wall contains epithelial, exocrine and endocrine cells?

A

Mucous Membrane

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24
Q

What is contained in the lamina propia of the GI Tract?

A
  • capillaries
  • enteric neurones
  • immune cells
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25
Q

What is the layer of smooth muscle in the mucosa layer of the GI tract wall called and its function?

A

mucularis mucosae

- changes shape and surface area of the intestine

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26
Q

What nerve network does the submucosa contain?

A

submucous plexus

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27
Q

What are the fibres like in the smooth muscle of the inner layer of muscularis externa?

A

circular

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28
Q

What are the fibres like in the smooth muscle of the outer layer of muscularis externa?

A

longitudinal

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29
Q

What nerve network does the Muscularis Externa contain?

A

myenteric plexus

30
Q

What is the outer connective tissue layer of the GI tract known as?

A

serosa

31
Q

What does circular muscle contraction do to the lumen?

A

lumen becomes narrower and longer

32
Q

What does longitudinal muscle contraction do to the intestine?

A

intestine becomes shorter and fatter

33
Q

What does muscularis mucosae contraction do to the mucosa?

A

Changes absorptive and secretory area of mucosa and mixing activity

34
Q

What is formed when many cells are depolarised and contract at the same time, acting as one?

A

Functional Syncytium

35
Q

Adjacent smooth muscle cells are coupled by what to allow spread of electrical currents from cell to cell?

A

gap junction

36
Q

What is spontaneous activity of the GI tract modulated by? (2)

A
  • intrinsic and extrinsic nerves

- numerous hormones

37
Q

What is the term describing rhythmic patterns of membrane depolarisation and repolarisation that occurs in the stomach, small intestine and large intestine?

A

slow waves

38
Q

What pacemaker cells are electrically coupled to smooth muscle cells and cause slow waves?

A

Interstitial Cells of Cajal

39
Q

When will contraction if of smooth muscle cells occur?

A

if the slow wave amplitude is sufficient to trigger SMC action potentials

40
Q

Upstroke of the SMC potential is mediated by?

A

voltage- gated Ca2+ channels

41
Q

downstroke of the SMC action potential is meditated by?

A

voltage gated K+ channels

42
Q

Force of contraction of SMC is related to what?

A

number of action potential discharges

43
Q

what determines the basic electrical rhythm (BER)?

A

slow wave

44
Q

Whether slow wave amplitude reaches the threshold depends on what?

A
  • neuronal stimuli
  • hormonal stimuli
  • mechanical stimuli
45
Q

what is the BER frequency of the stomach?

A

3 waves per minute

46
Q

what is the BER frequency in the small intestine?

A

duodenum - 12 waves

ileum - 8 waves

47
Q

what is the BER frequency in the large intestine?

A

proximal colon - 12 waves

distal colon - 16 waves

48
Q

What is considered the ‘brain of the gut’?

A

enteric nervous system

49
Q

What are ganglia of the enteric nervous system connected by?

A

Interganglionic Fibre Tracts in the myenteric and submucous plexus

50
Q

what regulates motility and sphincters?

A

myenteric plexus

51
Q

what modulates epithelia and blood vessels?

A

submucosus plexus

52
Q

The enteric nervous system co-ordinates muscular, secretive and absorptive activities via what?

A
  • sensory neurons
  • interneurons
  • effector neurons
53
Q

What do preganglionic fibres synapse at when parasympathetically innervating the GI tract?

A

Synapse with ganglion cells within the ENS

54
Q

what are the excitatory influences of parasympathetic innervation?

A
  • Increased gastric, pancreatic and small intestinal secretion,
  • increases blood flow
  • increased smooth muscle contraction
55
Q

what are the inhibitory influences of parasympathetic innervation?

A
  • Relaxation of some sphincters,

- receptive relaxation of stomach

56
Q

What do preganglionic fibres synapse with when sympathetically innervating the GI tract?

A

Synapse in the prevertebral ganglia.

Postganglionic fibres innervate mainly enteric neurons but also other structures

57
Q

what are the excitatory influences of sympathetic innervation?

A

Increased sphincter tone

58
Q

what are the inhibitory influences of sympathetic innervation?

A

Decreased motility, secretion and blood flow

59
Q

A wave of contraction that normally proceeds along the gut in the aboral direction? It is a local reflex

A

peristalsis

60
Q

What triggers peristalsis?

A

distension of the gut wall

61
Q

Name of a short reflex in the GI system?

A

Intestino- intestinal inhibitory reflex

62
Q

Name of a long reflex in the GI system?

A

Gastroileal systema

63
Q

Rhythmic contractions of circular muscle layer that mix and divide luminal contents?

A

segmentation

64
Q

what is colonic mass movement?

A

powerful sweeping contraction that forces faeces into the rectum

65
Q

What is the name for sustained contractions found in the sphincters of the GI tract?

A

tonic contractions

66
Q

what is Migrating motor complex?

A

powerful sweeping contraction from stomach to terminal ileum

67
Q

what is the function of sphincters?

A

essentially as one way valves by maintaining a positive resting pressure relative to two adjacent structures

68
Q

what the the location andd function of the Upper oesophageal sphincter?

A

location
- upper end of oesophagus

function

  • relaxes to allow swallowing
  • closes during inspiration
69
Q

what the the location andd function of the lower oesophageal sphincter?

A

location
- lower end of oesophagus

function

  • relaxes to permit entry of food to the stomach
  • closes to prevent reflux of gastric contents to the oesophagus
70
Q

what the the location and function of the pyloric sphincter?

A

location
- between stomach and duodenum

function

  • regulates gastric emptying
  • usually prevents duodenal gastric reflux
71
Q

what the the location and function of the Ileocaecal valve ?

A

location
- between small and large intestine

function

  • regulates flow from ileum to caecum
  • distension of ileum opens, distension of proximal colon closes
72
Q

what is the location of the external and internal anal spinchters?

A

location
- anus

function - defaecation

GI Physiology (5 decks)

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