G1 - Introduction to GI Tract and Mobility

Question 1

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

Answer 1

alimentary canal

Question 2

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

Answer 2

mouth and oropharynx

Question 3

what is the function of the oesophagus?

Answer 3

muscular tube that propels food to the stomach

Question 4

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

Answer 4

stomach

Question 5

what is the function of the small intestine?

Answer 5

principle site of digestion and absorption of material s

Question 6

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

Answer 6

large intestine

Question 7

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

Answer 7

rectum and anus

Question 8

what are the accessory structures of the GI system?

Answer 8

• salivary glands
• pancreas
• liver and gall bladder

Question 9

motility definition

Answer 9

Mechanical activity mostly involving smooth muscle

Question 10

What is secretion required for?

Answer 10

digestion
protection
lubrication

Question 11

What does digestive secretions contain?

Answer 11

Water, electrolytes and organic compounds

Question 12

Digestion definition

Answer 12

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

Question 13

What is the conversion of carbohydrates to monosaccharides mediated by?

Answer 13

amylase and disaccharide

Question 14

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

Answer 14

Proteases, dipeptidases and tripeptidases

Question 15

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

Answer 15

lipases

Question 16

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

Answer 16

absorption

Question 17

What seperates and controls the movement of alimentary canal?

Answer 17

sphincters

Question 18

Where does protein digestion begin?

Answer 18

stomach

Question 19

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

Answer 19

propulsive

Question 20

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

Answer 20

mixing

Question 21

What contractions are maintained for long lengths of time?

Answer 21

tonic

Question 22

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

Answer 22

Enzymatic Hydrolysis

Question 23

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

Answer 23

Mucous Membrane

Question 24

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

Answer 24

• capillaries
• enteric neurones
• immune cells

Question 25

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

Answer 25

mucularis mucosae | - changes shape and surface area of the intestine

Question 26

What nerve network does the submucosa contain?

Answer 26

submucous plexus

Question 27

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

Answer 27

circular

Question 28

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

Answer 28

longitudinal

Question 29

What nerve network does the Muscularis Externa contain?

Answer 29

myenteric plexus

Question 30

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

Answer 30

serosa

Question 31

What does circular muscle contraction do to the lumen?

Answer 31

lumen becomes narrower and longer

Question 32

What does longitudinal muscle contraction do to the intestine?

Answer 32

intestine becomes shorter and fatter

Question 33

What does muscularis mucosae contraction do to the mucosa?

Answer 33

Changes absorptive and secretory area of mucosa and mixing activity

Question 34

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

Answer 34

Functional Syncytium

Question 35

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

Answer 35

gap junction

Question 36

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

Answer 36

- intrinsic and extrinsic nerves | - numerous hormones

Question 37

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

Answer 37

slow waves

Question 38

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

Answer 38

Interstitial Cells of Cajal

Question 39

When will contraction if of smooth muscle cells occur?

Answer 39

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

Question 40

Upstroke of the SMC potential is mediated by?

Answer 40

voltage- gated Ca2+ channels

Question 41

downstroke of the SMC action potential is meditated by?

Answer 41

voltage gated K+ channels

Question 42

Force of contraction of SMC is related to what?

Answer 42

number of action potential discharges

Question 43

what determines the basic electrical rhythm (BER)?

Answer 43

slow wave

Question 44

Whether slow wave amplitude reaches the threshold depends on what?

Answer 44

- neuronal stimuli - hormonal stimuli - mechanical stimuli

Question 45

what is the BER frequency of the stomach?

Answer 45

3 waves per minute

Question 46

what is the BER frequency in the small intestine?

Answer 46

duodenum - 12 waves | ileum - 8 waves

Question 47

what is the BER frequency in the large intestine?

Answer 47

proximal colon - 12 waves | distal colon - 16 waves

Question 48

What is considered the 'brain of the gut'?

Answer 48

enteric nervous system

Question 49

What are ganglia of the enteric nervous system connected by?

Answer 49

Interganglionic Fibre Tracts in the myenteric and submucous plexus

Question 50

what regulates motility and sphincters?

Answer 50

myenteric plexus

Question 51

what modulates epithelia and blood vessels?

Answer 51

submucosus plexus

Question 52

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

Answer 52

- sensory neurons - interneurons - effector neurons

Question 53

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

Answer 53

Synapse with ganglion cells within the ENS

Question 54

what are the excitatory influences of parasympathetic innervation?

Answer 54

- Increased gastric, pancreatic and small intestinal secretion, - increases blood flow - increased smooth muscle contraction

Question 55

what are the inhibitory influences of parasympathetic innervation?

Answer 55

- Relaxation of some sphincters, | - receptive relaxation of stomach

Question 56

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

Answer 56

Synapse in the prevertebral ganglia. Postganglionic fibres innervate mainly enteric neurons but also other structures

Question 57

what are the excitatory influences of sympathetic innervation?

Answer 57

Increased sphincter tone

Question 58

what are the inhibitory influences of sympathetic innervation?

Answer 58

Decreased motility, secretion and blood flow

Question 59

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

Answer 59

peristalsis

Question 60

What triggers peristalsis?

Answer 60

distension of the gut wall

Question 61

Name of a short reflex in the GI system?

Answer 61

Intestino- intestinal inhibitory reflex

Question 62

Name of a long reflex in the GI system?

Answer 62

Gastroileal systema

Question 63

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

Answer 63

segmentation

Question 64

what is colonic mass movement?

Answer 64

powerful sweeping contraction that forces faeces into the rectum

Question 65

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

Answer 65

tonic contractions

Question 66

what is Migrating motor complex?

Answer 66

powerful sweeping contraction from stomach to terminal ileum

Question 67

what is the function of sphincters?

Answer 67

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

Question 68

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

Answer 68

location - upper end of oesophagus function - relaxes to allow swallowing - closes during inspiration

Question 69

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

Answer 69

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

Question 70

what the the location and function of the pyloric sphincter?

Answer 70

location - between stomach and duodenum function - regulates gastric emptying - usually prevents duodenal gastric reflux

Question 71

what the the location and function of the Ileocaecal valve ?

Answer 71

location - between small and large intestine function - regulates flow from ileum to caecum - distension of ileum opens, distension of proximal colon closes

Question 72

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

Answer 72

location - anus function - defaecation