GIT and CNS Physiology MCQs | MCQ Quiz | OmpathStudy Kenya

Practice 71 MCQs on GIT and CNS Physiology MCQs with OmpathStudy. Built for Kenyan medical and health students to revise key concepts and prepare for exams.

Questions, Answers & Explanations

1. Q1. Which single statement below, about the stomach, is correct?

   • Acid secretion occurs in response to secretion of the hormone, carbonic anhydrase
   • Glands called Peyer's patches are responsible for acid secretion
   • The vagus nerve inhibits acid secretion after a meal has been consumed **D. Pepsinogen and gastric lipase are secreted into the lumen of the stomach**

   Answer: Acid secretion occurs in response to secretion of the hormone, carbonic anhydrase

2. Q2. Water transport can occur from the lumen of the intestine to the bloodstream, or vice versa. Which statement is correct?

   • A "flip-flop" mechanism efficiently transports water directly across the enterocyte membrane
   • Water flows into the gut from the mucosa during digestion of starch and protein to reduce luminal osmolality **C. Water is mostly absorbed by movement between enterocytes via tight junctions**
   • Dietary intake of water is always greater than water movement in the small intestine

   Answer: A "flip-flop" mechanism efficiently transports water directly across the enterocyte membrane

3. Q3. Which statement about intestinal "brakes" and "accelerators" is FALSE? A. Dietary starch is a potent stimulator of small intestinal motility because it causes insulin release from the pancreas

   • Food in the stomach causes gastrin release, which stimulates acid secretion
   • Short-chain fatty acids refluxing from colon to caecum promote ileocaecal motility
   • Lipid in the duodenum reduces motility and switches from "fasting" to "feeding" pattern.

   Answer: Food in the stomach causes gastrin release, which stimulates acid secretion

4. Q4. Which statement about fat digestion and absorption is correct?

   • Fatty acids are absorbed mainly via FABP and FAT/CD36 in the distal duodenum
   • Medium-chain triglycerides (MCT) enter lymphatics; long-chain triglycerides enter portal blood
   • Partial digestion products form mixed micelles with cholesterol/phospholipids, enhancing absorption **D. Triglycerides must be emulsified and digested before fatty acids are transported**

   Answer: Fatty acids are absorbed mainly via FABP and FAT/CD36 in the distal duodenum

5. Q5. Which statement about protein digestion is most correct? A. Products of protein digestion are absorbed as free amino acids or di-/tripeptides

   • Gastric digestion of all proteins is equally efficient due to antral grinding
   • Chief cells secrete chymotrypsin, elastase, and carboxypeptidase A
   • Only one of 14 amino acid transporters absorbs digested protein products

   Answer: Gastric digestion of all proteins is equally efficient due to antral grinding

6. Q6. Which statement about dietary fibre is most correct?

   • Fermentation end products are mainly malic, succinic, and propionic acids
   • Soluble/insoluble fibres are completely fermented within 24 hours in vitro **C. Fiber sources such as Hemicelluloses, pectins, and inulin ferment rapidly to SCFAs with trophic colon effects**
   • Stool bulking occurs mainly via insoluble fibres like cellulose

   Answer: Fermentation end products are mainly malic, succinic, and propionic acids

7. Q7. Which statement about absorption is most correct? A. Glucose absorption is associated with sodium uptake

   • Fructose is absorbed more rapidly than glucose
   • Galactose and fructose share the same brush-border transporter
   • Most water absorption occurs in the colon

   Answer: Fructose is absorbed more rapidly than glucose

8. Q8. Which statement about the oral phase of digestion is INCORRECT?

   • ~2% of food energy is expended in chewing/swallowing
   • Swallowing involves 14 muscle groups over ~10 seconds in healthy subjects
   • Tooth enamel biofilm contains salivary/bacterial enzymes **D. Salivary amylase digests dextran film from dietary sucrose**

   Answer: ~2% of food energy is expended in chewing/swallowing

9. Q9. Which statement about stomach lining cells is correct? A. Mucous cells secrete the glycoprotein mucin

   • Chief cells secrete the hormone gastrin
   • Parietal cells secrete pepsinogen
   • G Cells secrete hydrochloric acid

   Answer: Chief cells secrete the hormone gastrin

10. Q10. Which statement about pancreatic enzyme secretion is correct?

    • Pepsinogen is the chief protein-digesting enzyme
    • Pancreatic α-amylase hydrolyzes starch to free glucose **C. Enteropeptidase converts trypsinogen to trypsin by cleaving an inhibitory peptide**
    • Pancreatic HCl secretion is required for duodenal enzyme pH

    Answer: Pepsinogen is the chief protein-digesting enzyme

11. Q11. Which statement about post-meal motility is correct?

    • Migrating motor complex drives peristalsis after a meal
    • Insulin slows gastric emptying
    • Stomach increases tone at meal start to expel contents via pylorus **D. Partially digested fat/starch in the duodenum slows intestinal motility**

    Answer: Migrating motor complex drives peristalsis after a meal

12. Q12. Which best describes colonic microbiota functions?

    • Daily fibre intake underestimates fermentable material in the colon **B. All of the options given are correct**
    • Acetate, propionate, butyrate are main SCFAs from fermentation
    • Acetate buffer suppresses pathogenic bacteria growth

    Answer: Daily fibre intake underestimates fermentable material in the colon **B. All of the options given are correct**

13. Q13. What explains fibre's protective effect against colon cancer?

    • Propionic acid inhibits liver fatty acid synthesis
    • Butyric acid silences the SLC5A8 tumor suppressor gene
    • None of these options are correct **D. Butyric acid stimulates colon antioxidant defenses**

    Answer: Propionic acid inhibits liver fatty acid synthesis

14. Q14. Which best describes vitamin absorption? A. All of the options given are correct

    • Vitamin E is absorbed by a peroxidized fatty acid-binding protein
    • Thiamine pyrophosphate must be dephosphorylated for absorption
    • Dehydroascorbic acid (oxidized vitamin C) uses a glucose transporter

    Answer: Vitamin E is absorbed by a peroxidized fatty acid-binding protein

15. Q15. Which best describes the intestine's role in obesity?

    • Obesity results from deranged gut hormones (e.g., low PYY) **B. Gut/brain signaling controls energy intake within 2% even in morbid obesity**
    • Gluttony overrides strong satiety signals regularly
    • Processed food flavors override satiety post-meal

    Answer: Obesity results from deranged gut hormones (e.g., low PYY) **B. Gut/brain signaling controls energy intake within 2% even in morbid obesity**

16. Q16. Which is true about pancreatic secretions vs. plasma? A. Higher secretion rate increases bicarbonate/sodium; plasma has less bicarbonate

    • Higher secretion increases bicarbonate but decreases chloride
    • Higher secretion increases osmolarity/pH; plasma is lower
    • Higher secretion increases bicarbonate/potassium; plasma has lower levels

    Answer: Higher secretion increases bicarbonate but decreases chloride

17. Q17. Which has little effect on pancreatic secretion?

    • Acetylcholine **B. Sympathetic stimulation**
    • Secretin
    • Cholecystokinin

    Answer: Acetylcholine **B. Sympathetic stimulation**

18. Q18. Defective parietal cells cause malabsorption of which vitamin?

    • Vitamin B1
    • Vitamin B2
    • Vitamin B13 **D. Vitamin B12**

    Answer: Vitamin B1

19. Q19. Which is absorbed by passive diffusion via concentration gradient?

    • Sodium **B. Potassium**
    • Calcium
    • Phosphate

    Answer: Sodium **B. Potassium**

20. Q20. How much of the ~9L daily GI tract water exits in feces? A. 100 ml

    • 1000 ml
    • 1500 ml
    • 500 ml

    Answer: 1000 ml

21. Q21. Saliva contains which carbohydrate-digesting enzyme?

    • Pepsin **B. Amylase**
    • Trypsin
    • Lipase

    Answer: Pepsin **B. Amylase**

22. Q22. Proteins are primarily digested to and absorbed as: A. Amino acids

    • Glycerides
    • Nucleic acids
    • Fatty acids

    Answer: Glycerides

23. Q23. The major chemical digestive activity in the stomach is:

    • Starch breakdown **B. Protein breakdown**
    • Fat breakdown
    • Fibre breakdown

    Answer: Starch breakdown **B. Protein breakdown**

24. Q24. Which is true about pancreatic secretions?

    • CCK causes bicarbonate release
    • Secretin causes enzyme release
    • Gastrin stimulates enzyme release **D. CCK stimulates enzyme release**

    Answer: CCK causes bicarbonate release

25. Q25. The hormone that inhibits gastric secretion and motility is:

    • Gastrin
    • Histamine **C. Secretin**
    • Pepsin

    Answer: Gastrin

26. Q26. How are fat components absorbed in the small intestine?

    • Receptor proteins carry fatty acids to bloodstream
    • Fatty acids are actively transported **C. Lipid components diffuse through enterocyte membranes**
    • Lipid components diffuse directly into liver bloodstream

    Answer: Receptor proteins carry fatty acids to bloodstream

27. Q27. Which is a water-soluble vitamin?

    • Vitamin D **B. Vitamin C**
    • Vitamin E
    • Vitamin K

    Answer: Vitamin D **B. Vitamin C**

28. Q28. How long for food to pass completely through the large intestine?

    • 10 minutes
    • 1 hour
    • 5 hours **D. 20 hours**

    Answer: 10 minutes

29. Q29. Citric acid cycle is part of what metabolic pathway? a) Amphibolic

    • Anabolic
    • Catabolic
    • None of the above

    Answer: Anabolic

30. Q30. What is the amount of protein lost as obligatory loss?

    • 10–20 gms
    • 50–60 gms **c) 20–30 gms**
    • 60–70 gms

    Answer: 10–20 gms

31. Q31. Regarding glycolysis, which statement is incorrect?

    • Principle route of metabolism
    • Provides ATP in the absence of oxygen **c) Plays a role in metabolism of fructose and maltose**
    • Plays a role in production of Acetyl CoA in the citric acid cycle

    Answer: Principle route of metabolism

32. Q32. Deficiency of which vitamin is the main cause of night blindness? a) Vitamin A

    • Thiamine (Vitamin B1)
    • Riboflavin (Vitamin B2)
    • Vitamin B12

    Answer: Thiamine (Vitamin B1)

33. Q33. Deficiency of which vitamin is the main cause of beriberi?

    • Vitamin A **b) Thiamine (Vitamin B1)**
    • Riboflavin (Vitamin B2)
    • Vitamin B12

    Answer: Vitamin A **b) Thiamine (Vitamin B1)**

34. Q34. Which of the following would tend to decrease hunger?

    • Increased release of endorphins
    • Increased ghrelin release by the stomach **c) Increased release of PYY by the intestine**
    • Increased release of NPY by the hypothalamus

    Answer: Increased release of endorphins

35. Q35. Deficiency of which vitamin is most likely to cause impaired blood clotting?

    • Vitamin A
    • Vitamin C
    • Vitamin D **d) Vitamin K**

    Answer: Vitamin A

36. Q36. The first stage in using triglycerides for energy is hydrolysis to which substances?

    • Acetyl CoA and glycerol
    • Cholesterol and fatty acids
    • Glycerol 3-phosphate and cholesterol **d) Glycerol and fatty acids**

    Answer: Acetyl CoA and glycerol

37. Q37. Which of the following best describes glucose formation from amino acids? a) Gluconeogenesis

    • Glycogenesis
    • Glycogenolysis
    • Glycolysis

    Answer: Glycogenesis

38. Q38. The defecation reflex is integrated in the:

    • Brain stem
    • Pons
    • Medulla **d) Spinal cord**

    Answer: Brain stem

39. Q39. The CNS includes all the following except:

    • Spinal cord
    • Medulla oblongata **c) Autonomic ganglia**
    • Diencephalon

    Answer: Spinal cord

40. Q40. The CNS connects with PNS through all except: a) Postganglionic autonomic fibers

    • Preganglionic autonomic fibers
    • Somatic motor fibers
    • Autonomic sensory fibers

    Answer: Preganglionic autonomic fibers

41. Q41. Parietal lobe neglect: a) Inability to use skeletal muscles on opposite side of the body

    • Inability to use skeletal muscles on same side of the body
    • Results from damage to primary sensory cortex
    • Causes loss of sensation on same side

    Answer: Inability to use skeletal muscles on same side of the body

42. Q42. All of the following are descending motor tracts, except:

    • Rubrospinal tract **b) Spinotectal tract**
    • Reticulospinal tract
    • Corticobulbar tract

    Answer: Rubrospinal tract **b) Spinotectal tract**

43. Q43. Corticospinal tract originates from all the following, except:

    • Premotor area in frontal lobe **b) Prefrontal area in frontal lobe**
    • Supplemental motor area in frontal lobe
    • Somatic sensory area in parietal lobe

    Answer: Premotor area in frontal lobe **b) Prefrontal area in frontal lobe**

44. Q44. Representation in primary motor area:

    • Is ipsilateral
    • Is upright **c) Is disproportionate to actual size of body parts**
    • All the above

    Answer: Is ipsilateral

45. Q45. Primary motor area receives input from all except:

    • Basal ganglia
    • Cerebellum **c) Hypothalamus**
    • Thalamus

    Answer: Basal ganglia

46. Q46. Primary motor area projects to all the following except: a) Primary somatic sensory area

    • Premotor area
    • Supplemental motor area
    • Brainstem motor nuclei

    Answer: Premotor area

47. Q47. Premotor area includes all the following except: a) Broca’s area

    • Head rotation area
    • Supplemental motor area
    • Hand skills area

    Answer: Head rotation area

48. Q48. Supplemental motor area is involved in all the following except:

    • Adjusting posture **b) Orienting responses**
    • Motor programming
    • Coordinating bilateral movements

    Answer: Adjusting posture **b) Orienting responses**

49. Q49. Components of the vestibular apparatus include all except:

    • Crista ampullaris
    • Vestibular hair cells **c) Vestibular nucleus**
    • Saccule

    Answer: Crista ampullaris

50. Q50. Crista ampullaris is sensitive to:

    • Sound vibrations
    • Force of gravity
    • Linear acceleration **d) Angular acceleration**

    Answer: Sound vibrations

51. Q51. Vestibular hair cells:

    • Have cilia all over surface
    • Are innervated by cochlear nerve
    • Are stimulated by neurotransmitter from nerve terminals **d) Are sensitive to mechanical stimuli**

    Answer: Have cilia all over surface

52. Q52. Hair cells of cristae are stimulated by:

    • Bending of stereocilia in any direction
    • Movement of endolymph in any direction **c) Bending of stereocilia toward kinocilium**
    • Bending away from kinocilium

    Answer: Bending of stereocilia in any direction

53. Q53. Maculae of vestibular apparatus:

    • Stimulated by endolymph flow
    • Stimulated when standing, inhibited lying down
    • Alter discharge by head tilt **d) Contain otoconia that press on hair cells**

    Answer: Stimulated by endolymph flow

54. Q54. Basal ganglia include all except:

    • Caudate nucleus **b) Dentate nucleus**
    • Subthalamic nucleus
    • Substantia nigra reticulata

    Answer: Caudate nucleus **b) Dentate nucleus**

55. Q55. Neurotransmitters in basal ganglia include all except:

    • GABA
    • Dopamine
    • Glutamate **d) Glycine**

    Answer: GABA

56. Q56. Functions of basal ganglia include all except:

    • Scanning **b) Initiation of reflex movements**
    • Postural regulation
    • Executing learned movement patterns

    Answer: Scanning **b) Initiation of reflex movements**

57. Q57. Parkinson’s disease results from damage of:

    • Caudate nucleus
    • Subthalamic nucleus
    • Globus pallidus **d) Substantia nigra**

    Answer: Caudate nucleus

58. Q58. Manifestations of Parkinsonism include all except: a) Kinetic tremors

    • Rigidity
    • Bradykinesia
    • Disturbance of speech

    Answer: Rigidity

59. Q59. Limbic system functions in emotional behavior involve all except:

    • Homeostasis
    • Somatic motor responses
    • Memory consolidation **d) Generalized sympathetic stimulation**

    Answer: Homeostasis

60. Q60. Hyperkinetic features in Huntington's disease are due to loss of:

    • Nigrostriatal dopaminergic neurons
    • Intrastriatal cholinergic neurons
    • GABAergic and dopaminergic neurons **d) Intrastriatal GABAergic and cholinergic neurons**

    Answer: Nigrostriatal dopaminergic neurons

61. Q61. Most prominent growth of anterior corpus callosum occurs at:

    • 6–12 months
    • 6–15 years **c) 3–6 years**
    • None of the above

    Answer: 6–12 months

62. Q62. Blood flow to the brain is approximately:

    • 2–3 litres/min
    • 2–3 ml/sec **c) 700–900 ml/min**
    • None of the above

    Answer: 2–3 litres/min

63. Q63. Which of the following mechanisms is currently implicated in learning and memory?

    • Modulation of release of neurotransmitters in postsynaptic neurons
    • Modulation of neurotransmitter receptor synthesis
    • Formation of new neurons
    • Spatial organization of association areas **E. All of the above**

    Answer: Modulation of release of neurotransmitters in postsynaptic neurons

64. Q64. Which statement is false about the basal ganglia?

    • Basal ganglia are gray matter structures deep within the white matter
    • Pathologies result in movement disorders
    • The basal ganglia initiate and maintain motor output **D. The basal ganglia output is excitatory**
    • The basal ganglia project to areas involved in motor control and cognition

    Answer: Basal ganglia are gray matter structures deep within the white matter

65. Q65. β (Beta) waves of the EEG:

    • Are observed during relaxed wakeful state
    • Are faster than alpha waves but slower than theta waves
    • Disappear when the person becomes alert **D. Are observed during REM sleep**
    • Mostly on the occipital lobe

    Answer: Are observed during relaxed wakeful state

66. Q66. The prefrontal area is concerned with all the following, except:

    • Adjusting behavior
    • Motor guidance within the surrounding environment **C. Planning timing of movements**
    • Recall of memories
    • Decision making

    Answer: Adjusting behavior

67. Q67. Mass movements are often stimulated after a meal by distention of the stomach (gastrocolic reflex). Mass movements often lead to: a. Bowel movements

    • Gastric movements
    • Esophageal contractions
    • Pharyngeal peristalsis

    Answer: Gastric movements

68. Q68. Postganglionic parasympathetic neurons innervating GI smooth muscle are located in: a. Myenteric plexus

    • Submucosal plexus
    • Paravertebral ganglia
    • Prevertebral ganglia

    Answer: Submucosal plexus

69. Q69. In healthy humans, the earliest a test meal reaches the cecum is about: a. 4 hours

    • 6 hours
    • 9 hours
    • 12 hours

    Answer: 6 hours

70. Q70. Normally, the main function of the colon is absorption of: a. Na, Cl, and H2O

    • Triacylglycerols
    • Secondary bile acids
    • Iron

    Answer: Triacylglycerols

71. Q71. The optimum pH for the activity of pepsin is:

    • Less than 1 **b. Between 1.6 and 3.2**
    • Between 3 and 5
    • Between 6 and 7

    Answer: Less than 1 **b. Between 1.6 and 3.2**