Brainscape's Knowledge GenomeTM

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


See full index

Gastrointestinal > GI 2 > Flashcards

GI 2 Flashcards

1
Q

What are the physiological functions of mucosal tissue in the digestive system?

A
  • Gas exchange
  • Food absorption
  • Sensory activities
  • Reproduction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where can M cells be found?

A

In the epithelial layer which covers Peyer’s patches; identified by characteristic membrane ruffles

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

How do M cells work?

A

1) They take up antigen by endocytosis and phagocytosis
2) Antigen transported across M cells in vesicles and released at the basal surface
3) Antigen is bound by dendritic cells which activate T cells

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

What is the composition of different antibodies in the intestine?

A
  • IgA is 80%/5g a day
  • IgM 15%
  • IgG 5%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How are T cells in the gut specialised?

A
  • 90% T cells with 80% CD8+ (=intraepithelial lymphocytes)
  • Activated appearance with restricted antigen receptor
  • Expression of a4:b7 integrin anchors them in the epithelium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How do intraepithelial lymphocytes (IELs) work?

A
  • Epithelial cells undergo stress (virus, infection, damage to toxic peptides)
  • Express/display signals which activate IELs
  • Activated IEL kills cell via perforin/granzyme pathway
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the action of histamine in the digestive system?

A
  • Secreted by the enterochromaffin-like cells in the gastric glands in response to stimulation by acetylcholine
  • Binds to H2 receptors with subsequent activation of adenylyl cyclase
  • The increase in cAMP increases the number of proton pumps, increasing gastric acid secretion from parietal cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the action of acetylcholine in the digestive system?

A
  • Released by parasympathetic cholinergic neurons
  • Binds to muscarinic (M3) ACh receptors on parietal cells with subsequent activation of PLC
  • The increase in intracellular Ca2+ evokes cell signalling pathways that increase the number of proton pumps, increasing gastric acid secretion from parietal cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the action of gastrin in the digestive system?

A
  • Released by G cells
  • Binds to CCK2 receptors on parietal cells with subsequent activation of PLC
  • The increase in intracellular Ca2+ increases the number of proton pumps, increasing gastric acid secretion from parietal cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the action of somatostatin in the digestive system?

A
  • Secreted by D cells in the gastric glands
  • Binds to SST2R receptors, inhibiting adenylyl cyclase
  • The decrease in cAMP results in decrease gastric acid secretion from parietal cells
  • Somatostatin binding to SST2R receptors on enterochromaffin cells results in reduced histamine release and decreased gastric acid secretion from parietal cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the four different sections of the colon?

A

1) Ascending
2) Transverse
3) Descending
4) Sigmoid

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

What does the large intestine comprise of?

A
  • Caecum and appendix
  • Colon
  • Rectum
  • Anal canal and anus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the longitudinal smooth muscle layer in the large intestine

A
  • Caecum and colon -> divided into 3 strands known as teniae coli
  • Rectum and anus -> encircled as normal
  • Internal anal sphincter -> markedly thickened
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the haustra?

A

Sac-like bulges which very slowly change location due to the activity of the teniae coli and the circular muscle layers

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

Describe the action of the ileocaecal valve?

A
  • Maintains a positive resting pressure
  • Relaxes due to distension of the duodenum
  • Contracts due to distension of the ascending colon
  • Controlled by vagus nerve, sympathetic nerve, enteric neurones and hormonal signals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does the caecum receive material from the terminal ileum?

A
  • The gastroileal reflex

- Entry permitted due to gastrin and CCK opening ileocaecal valve

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

What is the structure of the appendix?

A
  • Blind ended tube
  • Composed of lymphoid tissue
  • Connected to distal caecum via appendiceal orifice
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the primary functions of the colon?

A

1) Absorption of Na+, Cl-, H2O and short chain fatty acids
2) Secretion of K+, HCO3- and mucus
3) Storage of colonic contents
4) Periodic secretion of faeces

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

What are the 3 patterns of motility in the large intestine?

A

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

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

What are the major functions of the liver?

A

1) Metabolism of carbohydrates, fats and proteins
2) Hormone activation/deactivation
3) Storage of vitamins, iron, copper and glycogen
4) Synthesis of proteins
5) Protection through Kupffer cells and immune factors
6) Detoxification
7) Bile secretion

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

What does neutral/slightly alike bile serve to assist?

A
  • Micelle formation
  • Neutralising acidic chyme
  • pH adjustment for digestive enzyme action
  • Protection of mucosa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does the primary juice secreted by hepatocytes into the canaliculi contain?

A
  • IgA
  • Bile acids, mainly cholic and chenodeoxycholic acids
  • Water and electrolytes: Na+, K+, Ca2+, Cl- and HCO3-
  • Bilirubin
  • Lipids and phospholipids
  • Cholesterol
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How does cholelithiasis or gallstones occur?

A

Concentration of bile in the gall bladder (caused by reabsorption of water) produces a supersaturated solution that is unstable; cholesterol may crystallise and over time grow into a gall stone

24
Q

What is enterohepatic recycling?

A

Most bile salts entering the duodenum are reabsorbed by active transport in the terminal ileum; a fraction of primary biliary acids are dehydroxylated by bacteria in the gut to form the secondary bile acids

25
Q

What are the two phases of drug metabolism?

A

1) Phase I (oxidation, reduction or hydrolysis) - makes drug more polar, adds a chemically reactive group to permit conjugation
2) Phase II (conjugation) - adds an endogenous compound increasing polarity

26
Q

What is the cytochrome P450 (CYP) family of monooxygenases?

A

Haem proteins located in the endoplasmic reticulum of liver hepatocytes (and elsewhere) mediating oxidation reactions (phase 1) of many lipid soluble drugs

27
Q

How does sodium absorption take place in the jejunum and duodenum?

A
  • Postprandial secondary active coupled cotransport of Na+/amino acid and Na+/glucose
  • Na+/H+ exchange at both apical (NHE2 and NHE3) and basolateral (NHE1) membranes
28
Q

How does sodium absorption take place in the ileum and proximal colon?

A

Na+/H+ and CI-/HCO3- exchange in parallel; Mainly in inter digestive period; Regulated by intracellular cAMP, cGMP and Ca2+, all reduce NaCl absorption

29
Q

How does sodium absorption take place in the distal colon?

A

Epithelial Na+ channels (ENaC) are highly efficient and important in Na+ absorption; Increased by aldosterone but not regulated by cAMP or cGMP

30
Q

What are the three actions of aldosterone regarding ENaC channels?

A

(i) Opens ENaC (seconds)
(ii) Inserts more ENaC into membrane from intracellular vesicle pool (minutes)
(iii) Increases synthesis of ENaC and Na+/K+-ATPase (hours)

31
Q

What are the cellular mechanisms of chloride absorption?

A
  • Passively via transcellular or paracellular routes
  • In the small and large intestine driving force provided by lumen negative potential
  • Cl–HCO3- exchange (ileum, proximal and distal colon)
  • Parallel Na+-H+ and Cl–HCO3- exchange (ileum and proximal colon)
32
Q

What are the cellular mechanisms of chloride secretion?

A
  • Occurs at basal rate at crypt cells but overshadowed by absorption
  • Three processes on the basolateral membrane:
    1) Na+/K+ATPase
    2) Na+/K+/2Cl- co-transporter (NKCC1)
    3) K+ channels (IK1 and BK)
33
Q

What can diarrhoea result in?

A

1) Dehydration (Na+ and H2O loss)
2) Metabolic acidosis (HCO3- loss)
3) Hypokalaemia (K+ loss)

34
Q

What are the causes of diarrhoea?

A

1) Impaired absorption of NaCl
2) Excessive secretion
3) Hypermotility
4) Non-absorbable or poorly absorbable solutes in the lumen

35
Q

What are transaminases?

A
  • Hepatic enzymes, usually intracellular but released from hepatocytes in context of hepatocellular injury
  • Catalyse gamma-amino group transfers
  • e.g. aspartate/alanine -> ketoglutarate
36
Q

Describe alanine aminotransferase (ALT).

A
  • More sensitive than AST
  • Predominantly cytosol-located
  • Predominantly Liver
  • Short Half-Life circa 47hrs
37
Q

Describe aspartate aminotransferase (AST).

A
  • In cytosol and mitochondria
  • Present in Liver, Heart, Pancreas, Skeletal muscle, Brain, Lungs, RBCs, WBCs
  • Half Life Circa 17hrs
38
Q

What are the modifiable risk factors for oesophageal cancers (adenocarcinoma and squamous cell carcinoma)?

A
  • Convincing -> body fatness and alcoholic drinks

- Probable -> drinking mate

39
Q

What are the modifiable risk factors for stomach cancer? (all convincing evidence)

A
  • Body fatness (cardia)
  • Alcoholic drinks (3/day)
  • Foods preserved by salting
40
Q

What are the modifiable risk factors for liver cancer?

A
  • Convincing -> aflatoxins (product of aspergillum fungus + contaminant of grains and peanuts), alcoholic drinks and body fatness
  • Probable -> coffee decreases risk
41
Q

What are the modifiable factors which increase risk of colon and rectum cancers?

A
  • Convincing -> processed meat, alcoholic drinks, body fatness, attained adult height
  • Probable -> red meat
42
Q

What are the modifiable risk factors which decrease risk of colon and rectum cancers?

A
  • Convincing -> physical activity (moderate and vigorous)

- Probable -> wholegrains, foods containing dietary fibre, calcium supplements, dairy products

43
Q

What are the guidelines on food consumption in line with cancer prevention?

A
  • Red meat -> if >90g/day reduce to 70g/day
  • Processed meat -> avoid completely as it is carcinogenic
  • 30g/day of dietary fibre
44
Q

What are the 5A’s of behaviour change counselling?

A

1) Ask
2) Assess
3) Advise
4) Agree
5) Assist

45
Q

What are aminotransferases?

A
  • Deranged in all pathologies
  • Marked increase in hepatocellular pathologies
  • Levels do not reflect extent or outcomes
  • <500 U/L in obstructive jaundice except acute phase with passage of obstruction into CBD
46
Q

What is alkaline phosphatase? (ALP)

A

Enzyme which catalyses the hydrolysis of a number of organic phosphate esters; half life of 1 week -> slow to rise, slow precipitation following resolution of pathology

47
Q

What are the origins of alkaline phosphatase (ALP)?

A
  • Biliary (epithelial cells of ducts) - cholestasis enhances synthesis and release of ALP
  • Bone
  • Placenta
  • Intestine
  • Kidney
48
Q

What is gamma-glutamyl transpeptidase? (GGT)

A
  • Enzyme involved in gluthionine metabolism, transfer of amino acids across cellular membranes and leukotriene metabolism
  • Diagnostic marker for liver or cholestatic diseases
  • Can determine whether ↑ALP is bone/liver origin
  • Levels can increase with consumption of alcohol
49
Q

Where is gamma glutamyl transpeptidase (GGT) found?

A

Cell membranes of:

  • Liver
  • Heart
  • Brain
  • Bile duct
  • Kidneys
  • Gallbladder
  • Pancreas
  • Spleen
  • Seminal vesicle
  • NOT BONE
50
Q

How can glutamylt transpeptidase (GGT) be “induced”?

A
  • Drugs: anticonvulsants, TCAs, paracetamol

- Diseases: diabetes mellitus, pancreatic disease, COPD, renal disease

51
Q

What is bilirubin?

A
  • Predominantly a product of heme breakdown
  • Transported to liver bound to albumin
  • Uptake into the hepatocytes
  • Undergoes conjugation
  • Excreted via urine/faeces (Urobilinogen/Stercobilinogen)
52
Q

What is prothrombin time? (PT)

A
  • Liver is responsible for synthesis of most clotting factors
  • Measure of time taken for prothrombin to be converted to thrombin
  • Elevated PT may reflect reduced synthetic functionality
53
Q

What are some causes of increased PT?

A
  • Liver pathology meaning not enough synthesis
  • Drugs (inc Warfarin)
  • Bile malabsorption causing relative vitamin K deficiency
  • Consumptive coagulopathies
  • Congenital coagulopathy
54
Q

What are some liver function patterns and probable causes?

A
  • ALT/AST > ALP; hepatocellular injury
  • ALT/AST < ALP; cholestasis
  • AST:ALT ratio > 2; alcohol
55
Q

What are the causes of unconjugated hyperbilirubinaemia?

A

1) Increased bilirubin production - extra/intravascular hemolysis; extravasation of blood into tissues
2) Impaired hepatic bilirubin uptake - heart failure; portosystemic shunts; drugs rifampicin, probenecid
3) Impaired bilirubin conjugation - hyperthyroidism; CN2; Gilberts; advanced liver disease

56
Q

What are the causes of conjugated hyperbilirubinaemia?

A

1) Extrahepatic Cholestasis (Biliary Obstruction) - cholelithiasis; primary sclerosing cholangitis; cholangiocarcinoma; head of pancreatic tumour; acute/chronic pancreatitis
2) Intrahepatic Cholestasis - sepsis/hypoperfusion states; cirrhosis; infiltrative diseases; acute hepatitis; TPN
3) Drugs - alkylated steroids; rifampicin; chlorpromazine; herbs

Gastrointestinal (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions