MDS PREP
What is the primary function of the juxtaglomerular apparatus (JGA)?
1) Regulation of blood volume and blood pressure
2) Formation of urine
3) Secretion of renin
4) Concentration of urine
The primary function of the juxtaglomerular apparatus (JGA) is the secretion of renin, which regulates blood volume and blood pressure.
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.
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 primary site of vitamin B12 absorption in the intestine?
1) Stomach
2) Duodenum
3) Jejunum
4) Ileum
The primary site of vitamin B12 absorption in the intestine is the ileum, where it binds to intrinsic factor for absorption.
What are the main characteristics of type I (slow twitch) muscle fibers?
1) High myoglobin content and oxidative metabolism
2) Low myoglobin content and oxidative metabolism
3) High actin and myosin content for rapid contraction
4) Large diameter and high glycolytic enzyme activity
Type I fibers are also called slow-twitch fibers due to their high myoglobin content, which supports aerobic metabolism and allows for sustained contractions over time.
What is the osmolarity of the tubular fluid leaving the early distal tubule?
1) Isotonic to plasma
2) Hypertonic
3) Hypotonic
4) Variable
The osmolarity of the tubular fluid leaving the early distal tubule is hypotonic, as it has lost solutes while retaining water.
What is the role of the corpus luteum in the second half of the menstrual cycle?
1) It secrets FSH
2) It secrets LH
3) It secrets estrogen and progesterone
4) It secrets inhibin
The corpus luteum secretes estrogen and progesterone during the second half of the menstrual cycle, which are essential for maintaining the uterine lining.
What is the primary function of the macula densa?
1) Filtration of blood
2) Regulation of glomerular filtration rate
3) Secretion of renin
4) Reabsorption of glucose
The primary function of the macula densa is to regulate glomerular filtration rate by sensing sodium chloride concentration in the tubular fluid.