Gastroentology Flashcards
(135 cards)
Which of the following cranial nerves innervate the taste buds at the back of the throat (epiglottis)?
a) Cranial nerve VII
b) Cranial nerve IX
c) Cranial nerve X
d) Cranial nerve XII
e) Cranial nerve I
c) Cranial nerve X
aka Vagus nerve (taste epiglottis, back of the throat)
Largest immune organ
Gut
Which of the following processes associated with swallowing are under autonomic control?
a) Oral phase
b) Pharyngeal phase
c) Mastication
d) Bolus formation
b) Pharyngeal phase
Explanation:
- During this phase swallowing is normally involuntary.
- Impulses from pharyngeal sensory receptors travel to the brainstem swallow centre to initiate a series of involuntary pharyngeal muscle contractions.
- Soft palate elevates and palatopharyngeal folds appose and close the nasopharynx. Larynx elevates, vocal cords appose and epiglottis becomes horizontal, leading to closure of the trachea.
- Respiration is inhibited.
During the pharyngeal phase of swallowing:
- What causes closure of the naso-pharynx?
- What occludes the respiratory tract?
- Soft palate elevates and palatopharyngeal folds appose and close the nasopharynx.
- Larynx elevates, vocal cords appose and epiglottis becomes horizontal, leading to closure of the trachea.
Oesophogeal dysphagia
Difficulty in swallowing caused by failure of smooth muscle fibres to relax, which can cause the LOS to remain closed and fail to open
Oropharyngeal dysphagia
Difficulty in preparing and transporting food bolus through the oral cavity or initiating the swallow.
Arises from abnormalities of the muscles, nerves or structures of the oral cavity, pharynx and upper oesophageal sphincter.
Purpose of Gut Motility (4)
- Move food through the tube (peristalsis, colonic mass movements);
- Mix the food with secretions (grinding/trituration and segmentation),
- Migrating Motor Complex – fasting.
- Keep food in place – sphincters.
Which of the following are NOT functions of saliva?
a) Lubrication
b) Facilitates taste
c) Facilitates speech
d) Begins chemical digestion of peptides
e) Begins chemical digestion of lipids
f) Begins chemical digestion of carbohydrates
g) Stimulates mucosal repair and re-growth
h) Targets oral bacteria
d) Begins chemical digestion of peptides
List consequences of xerostomia (5)
- Tooth decay
- Oesophogeal erosions
- Difficulty swallowing food (poor nutrition)
- Difficulty with speech
- Opportunistic infection (candida albicans)
In HCl secretion from parietal cells, what does ‘G’; ‘H’ and ‘A’ stand for in relation to the hormones involved?
And what does GRP stand for?
Gastrin
Histamine
Acetylcholine (from parasympathetic nervous system)
Gastrin-releasing peptide
What is the primary ionic component of gastric acid:
1) At rest
2) When stimulated by food
1) NaCl (at rest)
2) HCl (when stimulated, by food)
When stimulated parietal cells
a) Change morphology
b) Secrete pepsinogen
c) Secrete somatostatin
d) Apically secrete HCO3-.
e) Secrete NaCl
a) Change morphology
Explanation:
Change is accommodating the release of gastric acids.
Cytoskeletal rearrangement and fusion of tubulovesicular vesicles into canalicular membrane. Greatly increases both surface area of apical membrane (5-10 fold) of parietal cell as well as number of H+/K+ pumps, K+ and Cl- channels.
Name the 3 phases of Gastric Secretion
Cephalic
Gastric
Intestinal
Cephalic Phase of Gastric Secretion
The smell, sight, taste, thought, and swallowing of food initiate the cephalic phase, which is primarily mediated by the vagus nerve
Gastric Phase of Gastric Secretion
Gastric: the food distends the gastric mucosa, which activates a vagovagal reflex as well as local ENS reflexes.
Partially digested proteins stimulate antral G cells.
Intestinal Phase of Gastric Secretion
Intestinal:
- AAs and peptides in the proximal small intestine stimulates acid secretion by stimulating duodenal G cells to secrete gastrin.
- Peptones stimulate an unknown endocrine cell to release an additional humoral signal that has been referred to as entero-oxyntin.
- AAs absorbed by the proximal part of the small intestine stimulate acid secretion.
Expression of what in the distal ileum facilitates recycling of bile acids to the liver?
a) Na+-taurocholate co-transporting polypeptide (NTCP)
b) Organic anion transporting proteins (OATPs)
c) Bile salt export pump (BSEP)
d) Apical sodium-dependent bile transporter (ASBT)
b) Organic anion transporting proteins (OATPs)
Bile acids
a) Chemically breakdown dietary lipids
b) Increase the efficiency of absorption of vitamins A, D, E and K.
c) Digest fatty acids.
d) Inhibit lipid diffusion in the duodenal contents.
e) Stimulate secretion of micelles.
b) Increase the efficiency of absorption of vitamins A, D, E and K.
Secretory diarrhoea - cause and effect
Caused by increased Cl- secretion. Water follows leading to fluid loss.
Osmotic diarrhoea - cause and effect
- caused by enterotoxins
- results in osmotic movement of water into the gut lumen
Regarding nutrient digestion and absorption, select the CORRECT answer.
a) Gastric amylase begins breakdown of carbohydrates in the stomach.
b) Lingual lipase is secreted by duodenal enterocytes.
c) Proteins must be broken down into monomers in order to be absorbed.
d) The majority of digestive enzymes are secreted from duodenal crypts.
e) Absorption of carbohydrate monomers is dependent upon brush border hydrolases.
e) Absorption of carbohydrate monomers is dependent upon brush border hydrolases.
Dietary disaccharides and breakdown products of larger carbohydrates are further digested by brush border hydrolases: Sucrase, isomaltase, glucoamylase, lactase.
Lactose intolerance - symptoms and cause
- diarrhoea, intestinal cramps and flatus
- Lactose-rich foods are poorly absorbed and remain in the intestinal lumen
Identify the site of action of a) pepsin; b) trypsin; c) peptidases in the digestion of proteins.
a) Pepsin - activated from pepsinogen in stomach
b) Trypsin - pancreatic enzyme active in lumen of duodenum
c) Peptidases - brush border (bound to enterocyte membranes and intracellular hydrolysis)
Arrival of fatty acids in the duodenum stimulate I cells to secrete
a) Cholecystokinin
b) Secretin
c) Acetylcholine
d) Gastrin
e) Somatostatin
f) Lipase
g) Colipase
h) Enterokinase
a) Cholecystokinin
