MDS PREP
Norepinephrine is stored at the
1. Preganglionic parasympathetic nerve endings
2. Postganglionic parasympathetic nerve endings
3. Preganglionic sympathetic nerve endings
4. Postganglionic sympathetic nerve endings
Physiology
Answer: 2
Norepinephrine is stored at the Postganglionic parasympathetic nerve endings
What is the typical rate of gastric emptying in healthy individuals?
1) 0.5-1.5 liters per hour
2) 1-2 liters per hour
3) 2-4 liters per hour
4) 4-6 liters per hour
E) It varies with the type and amount of food consumed
The rate of gastric emptying is influenced by the type and amount of food consumed. In healthy individuals, it typically takes 1-4 hours for the stomach to empty its contents into the duodenum. The rate of emptying can be slower with high-fiber or high-fat meals and faster with liquids. Factors such as gastric motility, the presence of gastric emptying hormones, and the presence of food in the intestine also play a role in this process.
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.
What happens to the osmolarity of tubular fluid as it ascends the Loop of Henle?
1) It becomes hypertonic
2) It remains isotonic
3) It becomes hypotonic
4) It fluctuates significantly
As tubular fluid ascends the Loop of Henle, its osmolarity becomes hypotonic due to the reabsorption of sodium and chloride without water.
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.
The pancreas has which of the following cell types?
1) Alpha cells
2) Beta cells
3) Delta cells
4) All of the above
The pancreas contains several types of cells, including alpha cells that secrete glucagon, beta cells that produce insulin, and delta cells that secrete somatostatin. Each type has a specific function in regulating metabolism and digestion.
What is the primary effect of parathyroid hormone on serum calcium levels during pregnancy?
1) Decreases serum calcium levels
2) Increases serum calcium levels by mobilizing calcium from maternal bones
3) Has no effect on serum calcium levels
4) Increases serum calcium levels by enhancing calcium absorption in the gut
Answer: 2) The primary effect of parathyroid hormone during pregnancy is to increase serum calcium levels by mobilizing calcium from maternal bones for fetal use.
What is the primary mechanism of the inhibitory postsynaptic potential (IPSP) in the nervous system?
1) Activation of sodium channels causing depolarization
2) Activation of potassium channels causing hyperpolarization
3) Activation of chloride channels causing depolarization
4) Activation of calcium channels causing hyperpolarization
Answer: 2) Activation of potassium channels causing hyperpolarizationExplanation: IPSPs are typically generated when a neurotransmitter binds to GABA receptors on the postsynaptic membrane of a neuron, causing potassium channels to open and leading to efflux of K+ ions. This hyperpolarizes the neuron, reducing the likelihood of an action potential.