MDS PREP
What is the condition characterized by the lack of intrinsic factor, leading to vitamin B12 malabsorption?
1) Pernicious anemia
2) Celiac disease
3) Lactose intolerance
4) Crohn's disease
Physiology
Answer: 1
Pernicious anemia is caused by the lack of intrinsic factor, which leads to impaired vitamin B12 absorption and subsequent megaloblastic anemia.
What is the difference in the generation of the Resting Membrane Potential (RMP) in neurons and muscle cells?
1) Neurons have a higher RMP than muscle cells
2) Muscle cells have a higher RMP than neurons
3) The mechanism of RMP generation is different in neurons and muscle cells
4) The ionic gradients involved in RMP generation are the same in both neurons and muscle cells
Answer: 4) The ionic gradients involved in RMP generation are the same in both neurons and muscle cellsExplanation: The RMP in both neurons and muscle cells is generated primarily by the difference in potassium ion concentration across the cell membrane. The concentration gradient of K+ is maintained by the sodium-potassium ATPase pump, which pumps 3 Na+ ions out and 2 K+ ions into the cell, contributing to the negative resting membrane potential.
What is the effect of fluorescent lighting on detecting scleral icterus?
1) It enhances the visibility of scleral icterus.
2) It does not affect the visibility of scleral icterus.
3) It makes it more difficult to detect scleral icterus.
4) It causes a false-positive result for scleral icterus.
Fluorescent lighting enhances the visibility of scleral icterus, making it easier to detect jaundice.
What is the primary function of the enteric nervous system in the gastrointestinal tract?
1) Controlling digestive enzyme secretion
2) Regulating the absorption of nutrients
3) Coordinating muscular contractions and peristalsis
4) Secreting hormones that regulate digestion
E) Controlling blood flow to the GI tract
The enteric nervous system, also known as the gut-brain, is a network of neurons that controls the muscular activity of the gastrointestinal tract. It is capable of operating independently of the central nervous system but can be modulated by it. Its main function is to regulate motility and secretion within the GI tract, which includes coordinating peristaltic contractions that propel food and facilitate mixing and absorption.
The primary regulators of gastric emptying are:
1) Vagal reflexes
2) Intestinal hormones
3) Local neural reflexes
4) All of the above
Gastric emptying is regulated by a combination of vagal reflexes, intestinal hormones such as secretin and cholecystokinin, and local neural reflexes known as the enterogastric reflex. These mechanisms work in concert to modulate the rate of emptying based on the needs of the body.
What is the threshold for glucose excretion in the urine in a healthy individual?
1) 100 mg/100 ml
2) 180 mg/100 ml
3) 200 mg/100 ml
4) 250 mg/100 ml
Physiology
Answer: 3
The threshold for glucose excretion is when the plasma glucose reaches approximately 200 mg/100 ml, causing some glucose to be filtered into the urine.
Which part of the autonomic nervous system is responsible for the regulation of the visceral organs during rest and digestion?
1) Sympathetic nervous system
2) Parasympathetic nervous system
3) Enteric nervous system
4) Sensory nervous system
The parasympathetic nervous system is involved in the regulation of the body's rest and digest functions. It operates to conserve energy and restore the body to a state of equilibrium. It acts on various visceral organs, such as the heart, gastrointestinal tract, and bladder, to slow down the heart rate, increase glandular secretions, and promote peristalsis for food assimilation.
What is the typical pH of gastric chyme when it enters the duodenum?
1) 1.0-2.0 (very acidic)
2) 2.0-4.0 (slightly acidic)
3) 4.0-6.0 (weakly acidic)
4) 6.0-8.0 (slightly alkaline)
E) 8.0-10.0 (alkaline)
Gastric chyme, which is the mixture of food and gastric juice, is highly acidic due to the presence of hydrochloric acid secreted by parietal cells. The pH typically ranges from 1.0 to 2.0 when it enters the duodenum. This acidity helps to denature proteins and provides the optimal environment for pepsin activity. Once in the duodenum, the chyme is neutralized by the secretion of bicarbonate from the pancreas and bile from the liver.