MDS PREP
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
The threshold for glucose excretion in the urine in a healthy individual is approximately 180 mg/100 ml, above which glucose appears in the urine.
Which hormone is primarily responsible for the conversion of 7-dehydrocholesterol to cholecalciferol in the skin?
1) Parathyroid hormone (PTH)
2) Vitamin D
3) Ultraviolet B (UV2) light
4) 25-hydroxyvitamin D3
Ultraviolet B (UVB) light is primarily responsible for the conversion of 7-dehydrocholesterol to cholecalciferol (vitamin D3) in the skin.
What is the function of the pineal gland in regulating circadian rhythms?
1) It produces melatonin in response to light exposure
2) It produces cortisol to maintain wakefulness
3) It regulates body temperature
4) It is not involved in circadian rhythms
Physiology
Answer: 1
The pineal gland produces melatonin, a hormone that helps regulate sleep-wake cycles. Melatonin is synthesized and released in response to darkness, signaling the body to prepare for sleep.
Which of the following is NOT a function of the submucosal plexus in the gastrointestinal tract?
1) Controlling local blood flow
2) Regulating the motility of the gastrointestinal tract
3) Secretion of gastrointestinal hormones
4) Controlling the contractions of the longitudinal muscle layer
E) Stimulating the release of digestive enzymes
The submucosal plexus, or Meissner's plexus, is primarily involved in the regulation of gastrointestinal secretion and local blood flow, not motility. The myenteric plexus is responsible for controlling the motility of the GI tract. However, the submucosal plexus can influence motility indirectly through its interactions with the myenteric plexus.
What is the primary type of receptor involved in the sympathetic nervous system's response at the neuromuscular junction?
1) Muscarinic receptors
2) Nicotinic receptors
3) Alpha-1 receptors
4) Beta-2 receptors
Answer: 2) The primary type of receptor involved in the sympathetic nervous system's response at the neuromuscular junction is the nicotinic receptor, which is an intrinsic ligand-gated ion channel.
What is the primary function of the reticular activating system during wakefulness?
1) It initiates REM sleep
2) It suppresses sensory input
3) It filters and modulates sensory information
4) It maintains the overall level of arousal and alertness
The reticular activating system (RAS) is involved in the regulation of wakefulness and arousal by modulating the transmission of sensory information to the thalamus and cortex and by influencing the release of neurotransmitters that promote alertness.
What is the primary mechanism by which insulin stimulates glucose uptake in the liver?
1) Induction of glucokinase
2) Increase in glycolysis rate
3) Inhibition of gluconeogenesis
4) Stimulation of glycogenolysis
Answer: 1) Induction of glucokinaseExplanation: Insulin enhances glucose uptake in the liver by inducing the synthesis of glucokinase, an enzyme that converts glucose into glucose-6-phosphate. This "glucose trapping" mechanism keeps intracellular glucose levels low and promotes further glucose entry into the cell.
Which cranial nerve is involved in the parasympathetic innervation of the lacrimal gland and pupillary constriction?
1) Cranial nerve III (Oculomotor)
2) Cranial nerve VII (Facial)
3) Cranial nerve X (Vagus)
4) Cranial nerve V (Trigeminal)
The vagus nerve, also known as the tenth cranial nerve, provides the parasympathetic innervation to various organs, including the lacrimal gland for tear production and pupillary constriction via the ciliary ganglia.