Unit XII (63-67) - Gastrointestinal Physiology Flashcards
Ptyalin in the saliva hydrolyzes starch into which disaccharide? A. Fructose B. Glucose C. Lactose D. Maltose E. Sucrose
D. Maltose
Ref: Guyton, Ch.66 pg. 834
Which of the following pancreatic enzymes leads to digestion of proteins into individual amino acids? A. Trypsin B. Carboxypolypeptidase C. Chymotrypsin D. Aminopolypeptidase
B.
Ref: Guyton p 835
Which of the following is not a potential stimulus for gastric acid secretion?
a. Norepinephrine secretion resulting from stimulation of sympathetic nerves.
b. Vagal nerve activity resulting from the sight of food.
c. The presence of undigested protein in the pyloric antrum.
d. Acetylcholine release stimulated by gastric stretch receptors acting on nerves of the ENS.
e. Histamine release from cells in the gastric mucosa.
A
Cunningham Ch. 29
Which gastrointestinal hormone is released in response to digestive products in the intestines and causes gallbladder contraction and release of bile, inhibits stomach contraction, and inhibits appetite?
a. Gastric inhibitory peptide
b. Cholecystokinin
c. Gastrin
d. Secretin
b. Cholecystokinin
Which of the following is true regarding hydrochloric acid secretion in the parietal cells?
a. H+ is secreted from the apical membrane of the parietal cell via facilitated diffusion
b. H+-K+ ATPase works at the basolateral membrane to load the parietal cell with hydrogen ions
c. Bicarbonate is formed by carbonic anhydrase and transported out of the parietal cell by the bicarbonate chloride cotransporter
d. H+ is pumped into the lumen by active transport from a H+-K+ ATPase at the apical membrane of the parietal cell
d. H+ is pumped into the lumen by active transport from a H+-K+ ATPase at the apical membrane of the parietal cell
Saliva contains high concentrations of which two ions?
a. bicarbonate and sodium
b. sodium and chloride
c. chloride and bicarbonate
d. bicarbonate and potassium
d. bicarbonate and potassium
The extrinsic innervation of the gut consists of:
a. The enteric nervous system.
b. The myenteric and submucosal plexuses.
c. Sympathetic (splanchnic) and parasympathetic (vagus) nerves.
d. Sympathetic (vagus) and parasympathetic (splanchnic) nerves.
e. The pelvic nerve
C
Cunningham Ch. 27
What are the anatomical differences between the esophagus of dogs, cats and horses?
Dogs, cattle and sheep, its entire length is striated muscle
Cats, horses and humans, the proximal esophagus has striated muscle and the distal esophagus smooth muscle.
Which of the following hormones stimulates insulin release? A. Gastrin B. CCK C. Gastric Inhibitory Peptide D. Motilin
C. Now known as glucose dependent insulinotrophic peptide
Ref. Guyton 802
Which of the following are effects of the gastric hormone secretin?
a. Stimulation of mucosal endothelial growth
b. Promotion of insulin secretion
c. Promotion of bicarbonate secretion
d. Stimulate gastric acid secretion
c. Promotion of bicarbonate secretion
Intrinsic factor must be present in gastric secretions to allow for adequate absorption of vitamin \_\_\_\_ in the ileum. Without intrinsic factor, pernicious anemia can occur. A. B6 B. B12 C. C D. D E. E
B. B12
Ref: Guyton, Ch. 67 pg. 844
Inhibition of the enzyme carbonic anhydrase is likely to have what effect on gastric pH?
a. Decrease gastric pH
b. Increase gastric pH
c. Have no effect on gastric pH
B
Cunningham Ch. 29
- The term slow waves as applied to the gut refers to:
a. Slowly moving fronts of electrical activity that are propagated down the enteric nervous system.
b. Slowly moving fronts of electrical activity that result from coordinated changes in cell membrane potential occurring throughout the smooth muscle of the intestinal wall.
c. Slowly moving fronts of ingesta that proceed down the intestine in response to peristaltic movement.
d. Slowly moving fronts of action potentials that are constantly passing over the gut smooth muscle.
e. Slowly moving fronts of peristaltic contractions that pass uniformly over the entire small intestine during the digestive
period.
B
Cunningham Ch. 28
The ____________ reflex occurs as a result of distension of the stomach and duodenum after a meal and is transmitted by way of the autonomic nervous system.
a. Defecation
b. Enterogastric
c. Gastrocolic
d. Gastroileal
c. Gastrocolic
What factor does not contribute to depolarization of intestinal smooth muscle?
a. Stretching of the muscle
b. Sympathetic stimulation by norepinephrine release
c. Stimulation by several gastrointestinal hormones
d. Parasympathetic stimulation by acetylcholine
b. Sympathetic stimulation by norepinephrine release
Which of the following causes decreased blood flow to the gastrointestinal tract? A. CCK B. Bradykinin C. Adenosine D. Sympathetic stimulation
D. sympathetic stimulation
Ref. 805
Which of the following hormones inhibits small intestinal peristalsis? A. Gastrin B. CCK C. Insulin D. Secretin E. Motilin F. Serotonin
D. Secretin
Glucagon can also inhibit motility in small intestine
Guyton 13th ed Ch. 64
Irritation of the peritoneum results in which of the following neurologic reflexes?
a. peritoneointestinal reflex – the strong inhibition of excitatory enteric nerves resulting in intestinal paralysis
b. peritoneoenteritis reflex - the strong inhibition of excitatory enteric nerves resulting in intestinal paralysis
c. peritoneointestinal reflex – the strong excitation of the enteric nervous system inducing hypermotility
d. renointestinal reflex - the moderate inhibition of excitatory enteric nerves resulting in intestinal paralysis
a. peritoneointestinal reflex – the strong inhibition of excitatory enteric nerves resulting in intestinal paralysis
The enteric nervous system is composed mainly of two plexuses. Which one controls mainly gastrointestinal secretion and local blood flow?
a. Myenteric plexus
b. Mucosal plexus
c. Submucosal plexus
d. Parasympathetic plexus
Answer: c
Guyton (12th ed.) p. 755
List the steps in HCL production by the parietal cell
- H2O + CO2 + carbonic anhydrase = H2CO3 (carbonic acid)
- Carbonic acid dissociates into:
a. H+ - active transport in the apical membrane into the lumen
b. Bicarb - exchanged with Cl in the basolateral membrane - Cl diffuses through the apical membrane into the lumen
- In the lumen H+ + Cl- = HCl
Which of the following hormones stimulates gastric acid secretion? A. Gastrin B. CCK C. Secretin D. Motilin
A. Gastrin
Ref. Guyton 802
An animal is presented to you with aspiration pneumonia (the result of food material entering the lower respiratory tract). Which of the following lesions would be a likely cause?
a. Loss of myenteric plexus function in the pharynx and upper esophagus
b. Loss of slow-wave activity in the pharynx and upper esophagus
c. A lesion in the brainstem
d. A lesion in the trachea
e. None of the above
C
Cunningham Ch. 28
What is the source of the most important signal that regulates gastric emptying? A. Stomach B. Duodenum C. Ileum D. Colon
B. Duodenum
Guyton 13th ed p. 811
Which of the following is required for normal absorption of cobalamin in the ilium?
a) enterokinase
b) glucose-dependent insulinotropic peptide
c) intrinsic factor
d) pepsinogen
Answer C
Guyton pg. 844
Damage to which of these neurologic structures can result in paralysis of the swallowing mechanism?
A. CN V, IX, X, & swallowing center of the brainstem
B. CN V, IX, & X
C. CN V, VII, & XII
D. CN V, IX, X, XII, & swallowing center of the brainstem
Answer D
V - trigeminal - sensory to face and motor to m of mastication
IX - glossopharyngeal - muscles of swallowing
X - vagus - efferent
XII - hypoglossal - motor to tongue
efferent nerve fibers from swallowing center in the brainstem travel in the facial, vagus, hypoglossal and glossopharyngeal nerves and motor branch of trigeminal
Cunningham p 276
Which of the following is the most important enzyme for starch digestion?
a) Ptyalin
b) Pancreatic Amylase
c) a-dextrinase
d) maltase
B. pancreatic amylase
Ptyalin - (also an amylase but just in saliva)
Alpha dextrinase - disaccharides
Maltase - maltose
Guyton pg. 834
The myenteric plexus is inhibited by which of the following hormones? A. Gastrin B. CCK C. Secretin D. VIP - vasoactive inhibitory peptide
D. VIP (thought to be but not for sure)
Ref. Guyton 800
Which cell in the pyloric glands is responsible for secreting histamine in response to stimulation by gastrin?
a. Parietal cells
b. Chief cells
c. Enterochromaffin-like cells
d. Goblet cells
c. Enterochromaffin-like cells
Which of the following aspects of colon physiology is common to many species, irrespective of interspecies anatomical differences in colon structure? a. Rapid flow of ingesta b. Adaptive relaxation c. Retropulsion, or antiperistalsis d. Haustra formation
C
Cunningham Ch. 28
Which of the following is characteristic of the inter digestive phase of small intestinal motility?
a. Migrating motility complexes consisting of waves of peristaltic contractions that pass over the entire length of the small intestine
b. Rhythmic segmentation
c. Short waves of peristalsis that die out after a few centimeters
d. Complete relaxation of small intestinal smooth muscle
A
Cunningham Ch. 28
This reflex results when food stretches the stomach allowing for the stomach reducing the tone of the muscular wall
a. Vasovagal reflex
b. Gastrocolic reflex
c. Gastroenteric reflex
d. Gastroesophageal reflex
a. Vasovagal reflex
Most proteins are absorbed through intestinal epithelial cells in the form of dipeptides, tripeptides, and a few free amino acids. By what mechanism are most absorbed? A. Co-transport B. Facilitated diffusion C. Simple diffusion D. Primary active transport
Answer A. Co-transport
Guyton Pg 841
Action potentials in the GI smooth muscle are potentiated by the influx of which ion? A. Cl- B. Na C. Ca D. K
C.
Ref. 799
Parietal cells within the gastric glands release __________, which is needed for absorption of vitamin B12 in the ileum.
a. Intrinsic factor
b. Hydrochloric acid
c. Cortisol
d. Histamine
a. Intrinsic factor
Which of the following best describes the motility of the proximal region of the monogastric stomach?
a. Rhythmic segmentation
b. Peristalsis
c. Retropulsion
d. Adaptive relaxation
D
Cunningham Ch. 28
Which of the following ions has higher concentrations in saliva compared to plasma?
a. Calcium
b. Chloride
c. Potassium
d. Sodium
c. Potassium
What factor within the duodenum cannot initiate enterogastric inhibitory reflexes?
a. Distension of the duodenum
b. Irritation in the duodenal mucosa
c. Alkalitity of the duodenal chyme
d. Osmolality of the chyme
c. Alkalitity of the duodenal chyme
Which one of the following hormones is secreted by K cells?
a. Cholecystokinin
b. Secretin
c. Motilin
d. Gastric inhibitory peptide
d. Gastric inhibitory peptide
Which nerve controls the external anal sphincter?
a. Pelvic nerves
b. Pudendal nerve
c. Myenteric plexus
d. Obturator nerve
b. Pudendal nerve
Which of the following accurately describes forward movement of a food bolus through the gastrointestinal tract?
A. The swallowing center is located in the medulla and pons of the CNS.
B. The movement of a food bolus through the esophagus is passive and only performed by smooth muscle.
C. The stomach processes food and has no storage capacity.
D. Having hunger pangs (I.e. being “hangry”) does not exist, and the stomach does not contract strongly with prolonged emptying.
A. The swallowing center is located in the medulla and pons of the CNS.
Which of the following gasses are formed from bacteria in the large intestine? A. Methane, nitrogen, carbon dioxide B. Oxygen, carbon monoxide, methane C. Hydrogen, methane, and carbon dioxide D. Carbon monoxide, methane, hydrogen
Answer C. Hydrogen, methane, and carbon dioxide
Guyton Pg 849
Which one of the following electrolytes has the highest concentration in bile secreted from the gallbladder?
a. Na
b. K
c. Ca
d. Cl
a. Na
The main driving force for hydrochloric acid secretion by the parietal cells is…
a. H-K ATPase
b. Cl-HCO3 antiporter
c. Na-K ATPase
d. Cl diffusion
a. H-K ATPase
Which of the following is most responsible for creating an action potential in gastrointestinal smooth muscle and accounts for the long duration of action potential seen?
a. Chloride channels b. Calcium-sodium channels c. Fast sodium channels d. Potassium channels
b. Calcium-sodium channels
Which of the following is not a natural ligand for receptors in the pancreas?
a. Cholecystokinin
b. Acetylcholine
c. Gastrin
d. Secretin
C
Cunningham Ch. 29
Chloride is absorbed in which primary locations in the gastrointestinal tract? A. proximal small intestine & ileum B. duodenum C. ileum D. colon
Answer A
pg. 839
Which of the following cells are considered the pacemakers of the GIT? A. G cells B. Cells of Cajal C. I cells D. K cells
B.
Ref. 798
Which of the following hormones inhibits gastric acid secretion? A. Gastrin B. CCK C. Secretin D. Motilin
C.
Ref. Guyton 802
Which of the following causes the GI smooth muscle hyperpolarization? A. Stretch B. Acetylcholine C. Hormones D. Norepinephrine
D. Norepi
Ref. Guyton 799
The rectosphincteric reflex is integrated in the:
a. Brainstem.
b. ENS.
c. Lumbar spinal cord.
d. Sacral spinal cord
D
Cunningham Ch. 28
Pepsin becomes inactivated and has no proteolytic activity above:
a. pH 3
b. pH 5
c. pH 7
d. pH 9
b. pH 5
Bile salts have two primary actions, what are they?
a. (1) act as a detergent or emulsifying agent to decrease surface tension and (2) facilitate absorption from the intestinal tract
b. (1) act as a detergent to increase surface tension and (2) facilitate absorption from the intestinal tract
c. (1) induce absorption of food from the gastrointestinal tract and (2) induce digestion of chylomicrons within the lymphatic system
d. (1) regulate electrolyte absorption and secretion within the intestinal tract and (2) digest fatty acids
a. (1) act as a detergent or emulsifying agent to decrease surface tension and (2) facilitate absorption from the intestinal tract
Glucose is transported into the cell via: A. Facilitated diffusion B. Primary active transport C. Secondary active co - transport D. Secondary active counter transport
C. Secondary active co transport occurs more commonly in GI and renal cells, in all other cells glucose enters the cell via facilitated diffusion.
Ref: Guyton p 840
Which factor(s) stimulate pepsinogen secretion by the peptic cells?
a. Acetycholine only
b. Acetylcholine and gastrin
c. Acetylcholine and secretin
d. Cholecystokinin only
Answer: a
Guyton (12th ed.) p. 779
The normal resting membrane potential of gastrointestinal smooth muscle cells is:
a. -80 to -90 mV
b. -105 to -110 mV
c. -50 to -60 mV
d. -30 to -40 mV
c. -50 to -60 mV
Which of the following can occur as complications to chronic gastritis? I. Achlorhydria II. Ulcerative colitis III. Peptic ulcer IV. Pernicious anemia
a) III, IV
b) I, IV
c) I, III, IV
d) I-IV
Answer: c
Source: Guyton ed 13, Ch 67, page 844
The control of glandular secretion is mostly due to local stimulation in which of the following locations?
a. Jejunum
b. Salivary
c. Rectum
d. Pancreas
a. Jejunum
- A unique feature of gastrointestinal (GI) smooth muscle cells is that:
a. Their resting transcellular electrical potential has the positive pole on the outside surface of the cell membrane.
b. Action potentials, or spikes of membrane depolarization, are not associated with muscle contractions.
c. Muscle contractions are stimulated by partial depolarization of the membrane.
d. There are spontaneous, rhythmical undulations in the electrical potential across the cell membrane.
e. Contraction of the muscles is never influenced by nervous activity.
D
Cunningham Ch. 28
Which hormone is released from the G cells, stimulating mucosal growth?
a. Gastrin
b. CCK
c. Secretin
d. GIP
a. Gastrin
Conditions in the duodenum, such as low pH or high fat concentration, can reflexively inhibit gastric emptying. Which reflex arc is involved in this inhibition?
a. Parasympathetic nervous system
b. GI enteric nervous system
c. GI endocrine system
d. All the above
D
Cunningham Ch. 28
The neurotransmitters in the gut are:
a. NO and Ach as excitatory, and substance P and VIP as inhibitory.
b. NO and Ach as inhibitory, and VIP and substance P as inhibitory.
c. NO and VIP as excitatory, and Ach and substance P as inhibitory.
d. NO and VIP as inhibitory, and Ach and substance P as excitatory.
e. NO and substance P as inhibitory, and Ach and VIP as excitatory.
D
Cunningham Ch. 27