Brainscape's Knowledge GenomeTM

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


See full index

Gastroenterology > Physiology > Flashcards

Physiology Flashcards

1
Q

Function of mouth and oropharynx?

A

Chops and lubricates food, starts carbohydrate digestion, propels food to oesophagus

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

Function of oesophagus?

A

Propels food towards the stomach

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

Function of stomach?

A

Stores/churns food, continues carbohydrate, initiates protein digestion, regulates delivery of chyme (fluid that is passed from stomach to intestine, acidic and uneven) to duodenum

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

Function of small intestine?

A

Principal site of digestion and absorption of nutrients

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

Function of the large intestine?

A

Colon reabsorbs fluids and electrolytes, stores faecal matter before delivery to rectum. No absorption occurs here.

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

Function of rectum and anus?

A

Regulated expulsion of faeces

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

4 layer generalised structure of the GI wall?

A
  1. Mucosa
  2. Submucosa
  3. Muscularis Externa
  4. Serosa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What layer is the submucous (Meissner’s) plexus contained within?

A

The submucosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What layer is the myenteric (Auerbach’s) plexus contained within?

A

Muscularis externa

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

GI motility is mostly due to activity of _____1______
Circular muscle contraction results in _____2_______
Longitudinal muscle contraction results in ______3______
Muscularis mucosae contraction results in _______4_________

A

1 smooth muscle
2 lumen becomes narrower and longer (it is squeezed against pressure so by narrowing it, it becomes longer)
3 intestine becomes shorter and fatter (by shortening it, it becomes fatter)
4 change in absorptive and secretory area of mucosa (folding), mixing activity. All contents are evenly mixed and exposed to epithelium.

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

In the stomach, small, and large intestine spontaneous electrical activity occurs as __1___ waves - rhythmic patterns of membrane depolarization and repolarization that spread from cell to cell via __2___ junctions

A

1 slow

2 gap

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

Spontaneous activity across the coupled GI cells is driven by specialised pacemaker cells called ________ which are largely located __________

A

interstitial cells of Cajal (ICCs)

between the circular and longitudinal muscle layers

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

Smooth muscle in the GI tract is _______ which means _______

A

single unit smooth muscle
the electrical excitation spreads from cell to cell (not all are directly innervated though) and the contraction happens at the same time as a wave.

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

Slow wave activity happens all the time- fed or starving state however _______________________________

A

Depolarising slow waves do not necessarily result in contraction

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

Contraction in the intestines occurs only if ___________________1______________________
____2______ of slow wave is ultimately what influences whether contraction will happen.

A

1) the slow wave amplitude is sufficient to reach a threshold to trigger smooth muscle cell calcium action potentials (spikes)
2) Starting point

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

3 things that can influence whether slow wave aptitude reaches threshold?

A

Neuronal stimuli
Hormonal stimuli
Mechanical stimuli

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

Parasympathetic nerve supply of the GI system is by _____1______ and _______2_______

Preganglionic fibres releasing Ach synapse with ganglion cells within ______3_____

Excitatory influences result in increased __________________4____________________________

Inhibitory influences result in relaxation ____________________5______________________

A

1) Vagus nerves
2) Sacral nerves S2-4
3) the enteric nervous system
4) gastric, pancreatic and small intestinal secretion, blood flow and smooth muscle contraction
5) of some sphincters, receptive relaxation of stomach

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

Sympathetic nerve supply of the GI system is by _______1_________

Preganglionic fibres (releasing ACh) synapse in the _____2_______

Postganglionic fibres (releasing NA) innervate mainly _____3_____

Excitatory influences ____4_____

Inhibitory influences ______5_________

A

1) thoracolumbar region
2) directly onto cells
3) enteric neurons
4) Increase sphincter tone
5) Decrease motility, secretion and blood flow

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

The enteric nervous system is

A

a division of the autonomic nervous system that governs the GI tract

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

Explain what happens in peristalsis

A

Behind the food bollus the circular muscle contracts and the longitudinal muscle relaxes

In front of the food bollus the circular muscle relaxes and the longitudinal muscle contracts

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

What is segmentation?

A

rhythmic contractions of the circular muscle layer that mix and divide luminal contents. The position of the contractions varies so food is propelled forward and backwards with no overall direction of movement. This finely chops up the chyme and delays any forward movement allowing time for both digestion and absorption. This occurs in the small intestine in the fed state and in the large intestine where it is called haustration.

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

What is colonic mass movement?

A

A powerful sweeping contraction that forces faeces into the rectum – occurs a few times a day often after a meal.

Propels faeces in to the rectum (normally nearly empty) triggering the defaecation reflex in response to rectal stretch

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

What is migrating motor complex?

A

A powerful sweeping contraction from stomach to terminal ileum

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

Explain tonic contractions

A

These are sustained contractions:

  • low pressure - organs with a major storage function (e.g. stomach)
  • high pressure - sphincters
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How many sphincters are there? What is there order from mouth to anus?

A 
6
Upper oesophageal sphincter 
Lower oesophageal sphincter 
Pyloric sphincter 
Ileocaecal  valve 
Internal (smooth muscle)  and External (skeletal muscle) anal sphincters where internal sits within external bu both are at same level.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Function of upper oesophageal sphincter?

A

This is skeletal muscle and it relaxes to allow swallowing and closes during inspiration

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

Function of the lower oesophageal sphincter?

A

Relaxes to permit entry of food to the stomach and closes to prevent reflux of gastric contents to the oesophagus

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

Function of Pyloric sphincter?

A

Regulates gastric emptying, usually prevents duodenal gastric reflux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Function of Ileocaecal valve?

A

Regulates flow from ileum to caecum- distension of ileum opens, distension of proximal colon closes

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

Why is it difficult to lose weight once it is gained?

A

Increased body fat alters brain function. Long term obesity induces brain re-programming. Your brain views the extra weight as normal and dieting as threat to body survival.

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

The site of integration of feeding behaviour is the ____1_____
The neural centre responsible is the _______2______
The three basic concepts that underly this control mechanism are _________3___________

A

1 brain
2 hypothalamus
3 satiety signalling, adiposity negative feedback signalling and food reward

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

Definition of satiation

A

Sensation of fullness generated during a meal

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

Definition of satiety

A

Period of time between termination of one meal and the initiation of next

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

Definition of adiposity

A

The state of being obese

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

Five examples of satiation signals are…

A 
Cholecystokinin (CCK)
Peptide YY (PYY3-36) 
Glucagon-like peptide 1 (GLP-1) 
Oxyntomodulin (OXM)
Obestatin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is the hunger signal?

A

Ghrelin

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

Long term control of weight is by two hormones, describe these.

A

Leptin - made & released from fat cells
Insulin - made & released from pancreatic cells
Levels in blood increase as more fat is stored
In the brain they tell the brain to alter energy balance and eat less and increase energy burn.
In the obese state this malfunctions

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

If you have reduced leptin what happens?

A

The body mimics starvation- you have no appetite control- you are constantly hungry

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

Does injecting individuals with leptin work to reduce their weight?

A

Injecting lectin works in individuals who lack leptin

However, the vast majority of obese individuals have high levels of leptin and they have increased leptin resistanc.

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

The stomach is a ____1__ shaped bag that relaxes receptively driven _____2___ to accommodate food from the oesophagus

A

1) J

2) vagus

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

What are the 2 mechanical regions of the stomach?

A

Orad- fundas and proximal body

Caudad- distal and antrum

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

In the orad region of the stomach there is no ____1____ activity instead contractions are due to the _____2_____
The result is intermittent propulsion of products to the _____3_____ and stomach size _____4______

A

1) slow wave
2) thin musculature
3) caudad region
4) decreases as it empties

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

What does the minimal mixing of products in the orad region of the stomach allow?

A

Carbohydrate partial digestion by salivary amylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

In the caudad region ____1___ occur continuously but not all reach threshold. Velocity of contraction ___2____ towards the junction overtaking the movement of ____3___ which results in ______4_____ of chyme allowing _______5_________

A

1) slow waves
2) increases
3) chyme
4) retropulsion
5) mixing of gastric products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Strength of antral wave determines escape of chyme through pyloric sphincter this is governed by ?

A

Gastric and duodenal factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

The rate of emptying of the stomach is proportional to ….

A

the volume of chyme in the stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

The duodenum must be ready to receive chyme, how can it delay stomach emptying?

A

Neuronal response: the enterogastric reflex – decreases antral activity by signals from intrinsic nerve plexuses and the ANS
Hormonal response – release of enterogastrones [e.g cholecystokinin CCK)] from duodenum inhibits stomach contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What are the 2 secretory regions of the stomach?

A

the oxyntic gland area (proximal stomach including the fundus and body)
the pylorlic gland area (distal stomach, designated the antrum)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What do D cells secrete?

What is its purpose?

A

Somatostatin

inhibits HCl secretion

50
Q

What do Enterochromaffin-like cells secrete?

What is its purpose?

A

Histamine

stimulates HCl secretion

51
Q

What do G cells secrete?

What is its purpose?

A

Gastrin

stimulates HCl secretion

52
Q

What do chief cells secrete?

What is its purpose?

A

Pepsinogen

inactive precursor of the peptidase, pepsin. Note: pepsin once formed activates pepsinogen (autocatalytic)

53
Q

What do parietal cells secrete?

What is the purpose of these secretions?

A

HCl
activates pepsinogen to pepsin
denatures protein
kills most (not all) micro-organisms ingested with food

Intrinsic factor and Gastroferrin
bind vitamin B12 and Fe2+ respectively, facilitating subsequent absorption

54
Q

What is the only absolutely essential function of the stomach?

A

produce intrinsic factor- it aids the absorption of vitamin B12. If there is no intrinsic factor is vitamin B12 cannot be absorbed, will get a type of anaemia.

55
Q

What are the three phases of gastric acid secretion and inhibition?

A

Cephalic phase
Gastric phase
Intestinal phase

56
Q

Describe the cephalic phase that results in gastric acid secretion

A

(‘in the head’) – before food reaches the stomach preparing it stomach to receive food. This is driven directly and indirectly by the CNS and vagus nerves (CN X).

57
Q

Describe the gastric phase that results in gastric acid secretion

A

Occurs when food is in stomach. It involves both physical and chemical mechanisms. Distension of the stomach due to the food activates reflexes that cause acid secretion.

58
Q

Describe the cephalic phase that results in gastric acid inhibition

A

Vagal nerve activity decreases upon cessation of eating and following stomach emptying

59
Q

Describe the gastric phase that results in gastric acid inhibition

A 
antral pH falls when food exits stomach (due to decreased buffering of gastric HCl) – release of somatostatin from D cells recommences, decreasing gastrin secretion
prostaglandin E2 (PGE2) continually secreted by the gastric mucosa acts locally to reduce histamine- and gastrin-mediated HCl secretion
60
Q

Why doesn’t the stomach digest itself?

A

It has a sticky protective mucus layer that prevents protons from reaching the surface but even if they do they are neutralised by bicarbonate contained within the layer.

61
Q

How does perastalsis in the interdigestive or fasting state occur?

A

Migrating motor complex

62
Q

Describe the migrating motor complex

A

occurs between meals every 90 – 120 min
strong peristaltic contraction slowly passing length of the intestine
clears small intestine of debris, mucus and sloughed epithelial cells between meals – ‘housekeeper function’

63
Q

What is the migrating motor complex inhibited by?

A

feeding and vagal activity

64
Q

Seven hormonal secretions of the small intestine?

A 
gastrin
secretin
cholecystokinin 
GIP
glucagon like peptide 1
motlilin
ghrelin
65
Q

What does secretin from the small intestine promote and what is it released from?

A

from S cells of duodenum, released in response to H+ and fatty acids in lumen
promotes secretion of pancreatic and biliary HCO3-

66
Q

What does motilin from the small intestine promote and what is it released from?

A

from M cells of duodenum and jejunum, secreted during fasting state
initiates the migrating motor complex

67
Q

Succus (juice) of the small intestine varies throughout what things does the secretion usually contain?

A

mucus – for protection/lubrication (from goblet cells)

aqueous salt - for enzymatic digestion (mostly from the crypts of Lieberkühn)

68
Q

Pancreatic endocrine secretions?

A

insulin and glucagon into the blood

69
Q

Pancreatic exocrine secretions?

A

digestive enzymes (acinar cells), aqueous NaHCO3- solution (duct cells) – secreted to the duodenum collectively as pancreatic juice

70
Q

Duct cells secrete 1 – 2 litre of _____1______into the duodenum per day
This neutralises acidic ___2___ entering the duodenum
provides optimum ___3__ for pancreatic enzyme function
protects the mucosa from ____4_____

A

1) alkaline (HCO3- - rich) fluid
2) chyme
3) pH
4) erosion by acid

71
Q

What must all carbohydrate be converted to for absorption?

A

Monosaccharides glucose, galactose or fructose

72
Q

Describe the role of alpha amylase in carbohydrate absorption

A

breaks down linear internal α-1,4 linkages but not terminal α-1,4 linkages. Hence, no production of glucose
cannot cleave α-1,6 linkages at branch points (in amylopectin) or α-1,4 linkages adjacent to branch points
products are thus linear glucose oligomers (maltotriose, maltose) and α-limit dextrins.

73
Q

What do Oligosaccharidases do?

A

Break down oligosaccharides into monosacharrides

74
Q

Four examples of Oligosaccharidases?

A

Lactase
Maltase
Sucrase
Isomaltase

75
Q

Where does digestion of glucose, galactose and fructose take place? ie the products of carbohydrate digestion?

A

Duodenum and Jejenum

76
Q

Glucose and galactose are absorbed by ______1____ and fructose is absorbed by _____2_______Exit for all monosaccharides is mediated by facilitated diffusion by __3___

A

1) secondary active transport (SGLT1)
2) facilitated diffusion (GLUT-5).
3) GLUT-2

77
Q

Explain the mode of operation for SGLT1

A
  1. 2 Na+ binds:
  2. Affinity for glucose increases, glucose binds:
  3. Na+ and glucose translocate from extracellular to intracellular:
  4. 2 Na+ dissociate, affinity for glucose falls:
  5. Glucose dissociates:
  6. Cycle is repeated
    The transporter is also permeable to water and each cycle thousands of water molecules are moved from the lumen and into the enterocytes and ultimately back into the rest of the body.
78
Q

Protein must (after the first six months of life) be digested to ___1___ and amino acids for efficient absorption ___2__ major pathways exist

A

1) oligopeptides

2) four

79
Q

Initial digestion of proteins in the stomach involves…

A

denaturation by HCl

cleavage into peptides by pepsin

80
Q

Digestion of proteins in the duodenum involves…

A

5 pancreatic enzymes
some are exopeptidases that break peptide bonds from end-pieces of terminal amino acids and some are endopeptidases that break peptide bonds of nonterminal amino acids (i.e. within the molecule).

81
Q

Where can additional break down of oligopeptides take place after digestion in duodenum and stomach

A

At the brush border or in cytoplasm of enterocytes

82
Q

Amino acids are transported across the apical membrane via a variety of amino acid transporters. Oligopeptides are transported across the apical membrane by the _______1________ (IMPORTANT KNOWLEDGE)
Oligopeptides with the cytoplasm are hydrolysed to amino acids by ____2_____ within the enterocyte
Amino acids exit the enterocyte across the basolateral membrane by several, _______3______

A

1) H+/oligopeptide co-transporter, PepT1
2) peptidases
3) Na+-independent. transporters

83
Q

For digestion an absorption what must lipids be converted from and too?

A

Must be converted from solid fat and oil masses into an emulsion of small oil droplets suspended in water

84
Q

What enzyme aids the breakdown of TAGs?

A

Lipases

85
Q

In the stomach what stimulates release of gastric lipase?

A

secreted in response to gastrin from chief cells

86
Q

What stimulates secretion of pancreatic lipase?

A

CCK

Note CCK also stimulates bile flow

87
Q

Describe the role of bile salts, where are they released from and into, why?

A

Bile salts released into the duodenum in bile from the gall bladder in response to CCK act as detergents to help emulsify large lipid droplets to small droplets

88
Q

Where are the final products of lipid digestion stored in and released from?

A

Mixed Micelles

89
Q

3 ways different lipids are absorbed?

A

Short chain and medium fatty acids diffuse through the enterocyte, exit through the basolateral membrane and enter the villus capillaries

Long chain fatty acids and monoglycerides are resynthesized to triglycerides in the endoplasmic reticulum and are subsequently incorporated into chylomicrons

Cholesterol is transported by endocytosis

90
Q

Ca2+ absorption can occur by two mechanisms- passive and active. With [Ca2+] in chyme < 5 mM absorption is mainly ___1_____

A

1) active

91
Q

It is __1___ iron form that can be absorbed and this binds to ___2____ in the stomach

Reduction of Fe3+ is done by ________3_________

A

1 Fe2+
2 gastroferrin
3 HCl, vitamin C or brush border cytochrome b ferric reductase

92
Q

Fat soluble vitamins? What is needed for these to be absorbed?

A

bile secretion

intact intestinal mucosa

93
Q

In the large intestine electrolyte absorption which drives the absorption of water is mediated by ____1_____

Ion secretion is mediated by _______2______

A

1) surface epithelial cells (colonocytes)

2) crypt cells

94
Q

The large intestine is divided into a series of saccule called ______ and these are not static

The process of _____ is a very slow form of segmentation this allows time for _______

A

haustra
haustration
fluid and electrolyte reabsorption

95
Q

3 patterns of motility in the large intestine?

A

Haustration (non-propulsive segmentation)
Peristaltic propulsive movements (mass movement)
Defaecation (periodic egestion)

96
Q

The internal anal sphincter is controlled by ____1______ fibres which relax involuntarily. The external anal sphincter is controlled by a ____2______ nerve supply

When the rectum is distended activation of rectal stretch receptors occur and the ____3______ reflex is initiated and relaxes the ___4____ sphincter. If defecation is not desired, ________5________ can delay it.

A

1) parasympathetic fibres
2) somatic
3) rectosphincteric
4) internal
5) voluntary contraction of the external sphincter

97
Q

Four things commensal bacteria do in the large intestine?

A

increase intestinal immunity by competition with pathogenic microbes
promote motility and help maintain mucosal integrity
synthesise vitamin K2 and free fatty acids (from carbohydrate) that are absorbed
activate some drugs (e.g. used in treatment of IBD)

98
Q

Medical word for vomiting?

A

emesis

99
Q

Where is vomiting co-ordinated?

A

Vomiting centre in the medulla oblongata of the brain stem

100
Q

Explain the overall events in vomiting

A

Suspension of intestinal slow wave activity
Retrograde contractions from ileum to stomach
Suspension of breathing (closed glottis - prevents aspiration)
Relaxation of LOS- contraction of diaphragm and abdominal muscles compresses stomach
Ejection of gastric contents through open UOS
Repeats of the cycle

101
Q

What areas of the brain apart from the vomiting centre also receive info in vomiting

A

CTZ - chemoreceptor trigger zone within the area postrema (AP)
NTS – nucleus tractus solitarius

102
Q

Role of 5HT3 receptor in vomiting

A

Systemic toxins or toxic materials in the gut lumen stimulate vomiting by this pathway
Enterochromaffin cells in the mucosa are stimulated by this stimuli and these cause depolarization of sensory afferent terminals in mucosa via the 5Ht3 receptors.
This then allows action potential to be discharged to brain where it can be coordinated by vomiting centre in medulla

103
Q

Absorbed toxic materials and drugs in blood stimulate vomiting through

A

CTZ within the AP of brainstem (as it lacks an effective blood brain barrier)

104
Q

Mechanical stimuli in the pharynx or pathology within in the GI tract stimulates vomiting through

A

Vagal afferents to brainstem (CTZ and NTS

105
Q

Motion sickness stimulates vomiting through

A

Vestibular nuclei

106
Q

Stimuli within the CNS stimulate vomiting through

A

Cerebral cortex, limbic system

107
Q

Water ingested and secreted is normally in balance with the water ____1____
To maintain this balance some water is therefore secreted in the faeces along with ________2_________

A

1) absorbed

2) bacteria, cellulose and bilirubin

108
Q

Intestinal fluid movement is always coupled to ___1___ movement.
Reabsorption of __2__ provides a (local) osmotic force for reabsorption of __3___

A

1) solute
2) Na+
3) water

109
Q

________1_________are the major mechanisms of postprandial Na+ absorption in the jejunum.

These are both examples of ____2____ active transport and ultimately results in the lumen being more negative which therefore allows parallel absorption of __3__.

A

1) Na+/glucose and Na+/amino acid cotransport
2) secondary
3) Cl

110
Q

___________ in the jejunum- stimulated by alkaline environment of the lumen and is mainly involved in keeping the pH constant.

A

Na+/H+ exchange

111
Q

___________ exchange in parallel occurs in the ileum and proximal colon and is the primary mechanism of Na+ absorption in the interdigestive period, but does not contribute greatly to postprandial (after eating a meal) absorption

A

Na+/H+ and CI-/HCO3-

112
Q

______________ Occurs in the colon (distal particularly) and is regulated by aldosterone

A

Epithelial Na+ channels (ENaC)

113
Q

Cl secretion occurs from ____ cells rather than villus.

A

crypt

114
Q

What ion secretion is important in many diarrhoeas?

A

Cl-

115
Q

_________ is involved in Cl secretion on the apical membrane

Normally there is little secretion of Cl- occurs because apical CFTR is ______________

A

CFTR

either closed, or not present

116
Q

CFTR can be indirectly activated by

A

bacterial enterotoxins
hormones and neurotransmitters
some immune cell products
some laxatives

117
Q

Activation of CFTR is a result of secondary messenger molecules which are

A 
o	cAMP (e.g. cholera toxin, VIP, histamine)
o	cGMP (e.g. heat stable enterotoxin, guanylin)
o	Ca2+ (e.g. acetylcholine, bradykinin, 5-HT)
118
Q

Diarrhoea is defined as….

A

loss of fluid and solutes from the GI tract in excess of 500 ml per day

119
Q

Four main causes of diarrhoea

A

impaired absorption of salts, excessive secretions, non-absorbable solutes or hypermotility.

120
Q

Only a small fraction (5%) of bile salts entering the duodenum is lost in the faeces; most is reabsorbed by _____1_____ in the _____2______ and undergoes ______3_______

A

1) active transport
2) terminal ileum
3) enterohepatic recyling

Gastroenterology (28 decks)

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