The dartos and cremaster muscles are important to the integrity of the male reproductive system. Which of the following best describes the role they play?
They regulate the temperature of the testes.
They contract to allow ejaculation.
They contract to push sperm along the ductus deferens.
They are responsible for penile erection.
The Correct Answer is A
A. They regulate the temperature of the testes: Viable sperm production, or spermatogenesis, requires a temperature approximately 2 to 3 degrees Celsius below core body temperature. The dartos muscle wrinkles the scrotal skin to reduce heat loss, while the cremaster muscle elevates the testes closer to the pelvic cavity. These muscles respond to environmental cold to maintain optimal thermal conditions.
B. They contract to allow ejaculation: Ejaculation is primarily driven by the rhythmic contractions of the bulbospongiosus and ischiocavernosus muscles. The smooth muscle of the ductus deferens also contracts via sympathetic stimulation. The dartos and cremaster muscles serve a thermoregulatory purpose rather than a direct mechanical role in the expulsive phase of the male sexual act.
C. They contract to push sperm along the ductus deferens: Peristaltic waves in the thick muscularis layer of the ductus deferens are responsible for the rapid transport of sperm during arousal. The cremaster and dartos are located in the spermatic cord and scrotal wall, respectively. They lack the anatomical connection required to propel luminal contents through the internal duct system.
D. They are responsible for penile erection: Erection is a vascular event mediated by the parasympathetic nervous system, leading to the engorgement of the corpora cavernosa and corpus spongiosum with blood. It is not caused by the contraction of the scrotal or spermatic cord muscles. The dartos and cremaster do not influence the hydraulic mechanism of the penis.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is E
Explanation
A. a tertiary follicle: This term refers to a mature, fluid-filled antral follicle that contains the oocyte before it is released. While the tertiary follicle is the structure that ruptures, it is the cellular unit within it that is ovulated. The follicle remains in the ovary to become the corpus luteum.
B. a secondary follicle: A secondary follicle is an immature stage of follicular development characterized by the presence of a small, fluid-filled antrum. It has not yet reached the maturity required for ovulation. It contains a primary oocyte that has not yet completed its first meiotic division.
C. a primary oocyte: The primary oocyte is arrested in prophase 1 from before birth until just before ovulation. The LH surge triggers the completion of meiosis 1, transforming the primary oocyte into a secondary oocyte. Therefore, the cell released during ovulation has already progressed past the primary stage.
D. a primary follicle: This is an early stage of follicular development consisting of a primary oocyte surrounded by one or more layers of cuboidal granulosa cells. It is far from the stage of maturity required for ovulation. Many primary follicles exist in the ovary but only one typically matures monthly.
E. a secondary oocyte: Upon the LH surge, the primary oocyte completes its first meiotic division to become a secondary oocyte and a first polar body. This is the specific cell stage that is released from the ovary during ovulation. It remains arrested in metaphase 2 until fertilization occurs.
Correct Answer is B
Explanation
A. is easily broken and replaced often: The epithelial cells of the nephron loop are durable and maintained through normal cellular repair mechanisms. They are not designed to be "broken" or frequently replaced as a standard part of renal function. The structural integrity of the tubule is essential for maintaining the osmotic gradients in the medulla.
B. aids in the passive movement of water out of the tubule: The descending limb of the nephron loop is composed of simple squamous epithelium that is highly permeable to water but relatively impermeable to solutes. As filtrate descends into the hypertonic renal medulla, water moves out of the tubule by osmosis. This process significantly concentrates the tubular fluid.
C. aids in the passive excretion of nitrogenous waste: The primary role of the thin descending limb is water conservation rather than the excretion of wastes like urea or creatinine. Nitrogenous waste excretion occurs primarily through filtration at the glomerulus and secretion in the convoluted tubules. The loop focuses on the concentration and dilution of urine.
D. helps to pack a greater number of nephron loops into a smaller space: The thinness of the segment refers to the height of the epithelial cells (simple squamous) rather than the overall diameter of the tube for packing purposes. This anatomical design is a functional adaptation for rapid osmotic diffusion. It allows for the concentration of urine without requiring active transport in this segment.
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