Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physiology 1 > Transport Along And Across The GI Tract > Flashcards

Transport Along And Across The GI Tract Flashcards

1
Q

What is emptying of the gastric resovoir controlled by?

A

Tonic contractions and peristaltic waves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are tonic contractions controlled by?

A

Depolarisation of pacemaker and interstitial cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Where do tonic contractions start/end?

A

Starts from the fundus and sweeps the length of the stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does backflow into the stomach allow?

A

Churning of the digestor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How is churning initiated?

A

Thick muscular walls of the antrum contract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How does the stomach store food?

A

Proximal muscles relaxes to store food at low pressure

Means acids, enzymes and mechanical things can act on it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a disorder of gastric emptying?

A

Gastric stasis (gastroparesis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why is gastric emptying carefully regulated?

A
  • avoid swamping the dueodenum
  • allow enough acidification/ neutralisation
  • allow enough mechanical breakdown
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

When are indigestible materials removed from the stomach?

A

Every so often a housekeeping process takes place

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the sieving effect?

A

Viscous and solid matter are retained in the stomach (by the pyloric sphincter)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is gastric emptying dependant upon? (2 things)

A

Propulsive force generated by tonic contractions of proximal stomach

Stomachs ability to differentiate types of meals ingested and their components

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What food types affect gastric emptying?

A

Fatty, hypertonic and acidic chyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why do fats affect gastric emptying?

A

They need to be emulsified, so they take time to clear out of the duodenum for more stuff to come through

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why does acidic chyme affect gastric emptying?

A

Acid needs to be neutralised before travelling too far into the duodenum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What effect do fats, acids and hypertonic chyme have on gastric emptying?

A

Decrease the force and rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How long is the lag phase for a liquid meal?

A

None

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How long is the lag phase with semisolid pulp?

A

10 (ish) mins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How long is the lag phase with solid pulp?

A

20 (ish) minutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the order of food types when compared to the rate of gastric motility?

A

Carbs > proteins > fatty food > indigestible solids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What effect does hyperosmolar chyme have on gastric emptying and why?

A

Decreases because it changes the osmotic pressure of duodenal contents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does BER do?

A

When hormones are released, the smooth muscle can depolarise and contract rhythmically

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does BER stand for?

A

Basic electric rhythm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What hormones inhibit gastric emptying?

A

Somatostatin, secretin, CCK and GIP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What two things can lead to decreased gastric motility?

A

Injury to intestinal wall and bacterial infections

Vagal innervation when the duodenum is over distended

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What do stomach muscle cells do?

A

Produce electric depolarisations from resting potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What type of control is the fundus under?

A

Vagal excitatory control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How often do ripples occur at BER?

A

3 waves/ min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What chemicals control gastric motility?

A 
Cholecystokinin (CCK) 
Secretin
VIP
Somatostatin 
Gastrin releasing peptide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How do the chemicals (CCK, VIP, secretin and somatostatin) affect fundic motor activity?

A

Decrease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What chemical increases fundic contractions?

A

Motilin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What chemicals increase colonic/ intestinal motility?

A

Cholecystokinin (CCK), gastrin and motilin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What chemical decreases intestinal/ colonic motility?

A

Secretin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What feedback system does gastric emptying work under?

A

Negative feedback systems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What stimulates the vagovagal reflex?

A

Antral and duodenal overdistension and duodenal chemical stimulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What contracts in response to antral or duodenal rhythm?

A

Pyloric sphincter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What food group in the duodenum cause contraction of the pylorus?

A

Fatty acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What are the four types of motility in the intestine?

A

Segmentation, peristalsis, migrating motor complex and mass movements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Where does peristalsis take place?

A

Stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is segmentation in the intestine?

A

Mixing contractions - stationary contraction and relaxation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What are the three phases of motor activity?

A

1- quiescence/ quiet period
2- irregular propulsive contractions
3- burst of uninterrupted phasing contractions (peristaltic rush)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Where does segmentation originate from?

A

Pacemaker cells (ICC)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What does segmentation cause?

A

The slow migration of chyme towards the ileum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What are the two layers of intestinal muscle and which is where?

A

Longitudinal (outside)

Circular (inside)

44
Q

What do each of the intestinal muscles do behind the bolus of food?

A

Circular contracts behind the bolus of food and the longitudinal relaxes

45
Q

What is the migrating motor complex?

A

Highly organised cyclically recurring sequence of events

46
Q

When does the migrating motor complex occur (MMC)?

A

Between meals when the stomach and intestine is empty

47
Q

Where does the migrating motor complex (MMC) start?

A

Lower portion of the stomach

48
Q

What does the migrating motor complex (MMC) involve?

A

Burst of high frequency, large amplitude contractions that migrate along the length of the intestine and die out

49
Q

What is the interval between different phase 3’s in the migrating motor complex (MMC)?

A

90-120 mins

50
Q

What are the 3 functions of the migrating motor complex (MMC)?

A
  • Removes dead epithelial cells by abrasion
  • prevents bacterial overgrowth
  • prevents colonic bacteria from entering the small intestine
51
Q

What are contractions coordinated by in the migrating motor complex (MMC)?

A

Pacemaker cells under the control of the enteric nervous system

52
Q

Where are contractions initiated from in the MMC?

A

Vagus nerve in the upper tract

53
Q

What inhibits the release of motilin?

A

Feeding

54
Q

What does ICC stand for and what are they?

A

Interstitial cells of Cajal

Cell types found in the submucosa and submucosal plexus

55
Q

What do ICCs do?

A

Form synaptic connections with GI smooth muscle fibres, due to their complex network between the smooth muscle layers

56
Q

How is motor activity in the small intestine (while fed) controlled?

A

Locally by the ENS but can be enhanced or suppressed by extrinsic innervation

57
Q

What effects does increased sympathetic activity have on motor activity in the small intestine?

A

Inhibits motility

58
Q

What effect does increased parasympathetic activity have on motor activity in the small intestine?

A

Stimulates motility

59
Q

What outside factors can affect motility in the small intestine (and which way)?

A

Pain and fear decrease motility

60
Q

Where are fermenting chambers found?

A

Large intestine

61
Q

What do fermenting chambers do?

A

Allow the hydrolysis of fibrous and indigestible nutrients

62
Q

What are the three steps in the motility of the large intestine?

A

Haustral contractions, peristalsis and mass movement

63
Q

What are the features of haustral contractions?

A

Intensive mixing, fermentation and slow propogation/ slow aboral flow

64
Q

What initiates peristalsis in the large intestine?

A

Distension

65
Q

How does colonic evacuation happen?

A

Powerful contractions of the mid -> transverse colon that moves colon contents into rectum

66
Q

What’s the cause of diarrhoea and constipation?

A

Disorders of motility, fluid secretion and absorption

67
Q

What is diarrhoea?

A

Frequent (>3 times/day) discharge of liquid faeces

68
Q

What is constipation?

A

Difficulty/ some constraint in opening and emptying bowels

69
Q

What are the two intrinsic neuronal plexuses in the gut?

A

Submucosal (meissner) plexus

Myenteric (Auerbach) plexus

70
Q

What does the meissner plexus do?

A

Regulates the digestive glands

71
Q

What does the Auerbach plexus do?

A

Connected with gut motility

72
Q

What are the intrinsic controls of the gut?

A

Nerve plexuses near the GI tract initiate short reflexes

Short reflexes are mediated by local enteric plexuses

73
Q

What are the extrinsic controls of the gut?

A

Long reflexes arising within or outside the GI tract

Involve CNS centres and extrinsic autonomic nerves

Parasympathetic reflexes

74
Q

What are the three adaptations of the small intestine for absorption?

A

Epithelial folds, villi, microvilli

75
Q

What are crypt cells important for?

A

Signalling and defence

76
Q

Where are the stem cells in the small intestine?

A

Crypt cells

77
Q

What is transcellular?

A

Transport through a cell

78
Q

What is paracellular?

A

Transport between cells

79
Q

What are the features of paracellular transport?

A

Passive, selective, variable and regulated

80
Q

How can carbs be absorbed?

A

Only as monosaccharides

81
Q

What breaks complex carbs down?

A

Amylase

82
Q

What converts disaccharides to monosaccharides?

A

Specific brush border enzymes (sucrase)

83
Q

What converts glucose oligomers to glucose?

A

Glucoamylase

84
Q

How are glucose and galactose absorbed?

A

Secondary active transport process (sodium glucose pump transport mechanism thingy)

85
Q

How is fructose absorbed?

A

GLUT5 and GLUT2

86
Q

How are proteins broken down into polypeptide chains or oligopeptides?

A

Pepsins or pancreatic proteases

87
Q

How are amino acids transported?

A

On a sodium coupled carrier system (like the glucose one)

88
Q

How are some di and tri peptides transported?

A

On a carrier system that uses an inwardly directed H+ gradient

89
Q

What happens once the amino acid is in the cell?

A

It’s really easy to transport it into the capillary as they have specific transporters

90
Q

What % of dietary lipids do TGs make up?

A

90%

91
Q

What is the other 10% of non-TG dietary lipids made up of?

A

Phospholipids, cholesterol, fat soluble vitamins (A, D, E, K)

92
Q

Where are most dietary TGs digested?

A

In the small intestine

93
Q

What is the solubility of TGs?

A

Insoluble

94
Q

What must happen before triglycerides can be fully digested?

A

Must be dissolved in the aqueous phase

95
Q

What are the two phases in the digestion and absorption of lipids?

A

Emulsification and miscelle formation

96
Q

What % of fats are broken down by gastric lipase?

A

10-30%

97
Q

What are the two enzymes that break down fats?

A

Pancreatic and gastric lipase

98
Q

What does lipase action require?

A

Bile salts

99
Q

How does pancreatic lipase work?

A

Binds to the surface of the small emulsion particles

100
Q

How are miscelles absorbed?

A

Fuse with the brush border and the mono and triglycerides are emptied into the enterocyte

101
Q

What happens to the TGs once they’re inside the enterocyte?

A

Resynthesised and aggregate. They get surrounded by apolipoproteins and form chylomicrons

102
Q

What happens once chylomicrons have been made in the enterocyte?

A

They are extruded into the lymphatic system via the lacteals, then into the blood via the thoracic duct

103
Q

Where can you find the thoracic duct?

A

Near the subclavian vein

104
Q

What causes the lymph drainage from the small intestine to appear milky?

A

Lots of lipids being absorbed -> lots of chylomicrons

105
Q

What is steatorrhoea?

A

Excess fat in faeces

106
Q

What illnesses can lead to steatorrhoea?

A

Gallstones, pancreatitis, crohns and liver disease

Physiology 1 (65 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions