Question

Skeletal muscle fibers may enter tetanus, but cardiac myocytes do not. The physiologic basis for this is

Select one:

a. Voltage-gated sodium channels remain inactivated longer in skeletal muscle fibers

b. Parasympathetic activity prevents calcium channels from reopening during an action potential

c. The absolute refractory period is longer in cardiac myocytes

d. Voltage-gated calcium channels remain open longer in skeletal muscle fibers (in response to a single depolarization).

Which of the following structures is commonly altered as a form of male birth control?

Select one:

a. The seminal vesicle (seminal gland)

b. The urethra

c. The epididymis

d. The ductus deferens

e. The prostate gland

Answer 1

c. The absolute refractory period is longer in cardiac myocytes

Explanation: The refractory period of cardiac muscle is longer than that of skeletal muscle. This prevents cardiac muscle fibers from tetanus and ensures that each contraction is followed by enough time to allow the heart chamber to refill with blood before the next contraction.

d. ductus deferens

Explanation: Male birth control or Male contraceptives are methods of preventing pregnancy that solely involve the male physiology. The most common kinds of male contraception include condoms, outercourse, and vasectomy.

Vasectomy is the cutting of the vas deferens and the ligation of the cut end to abdominal wall. this helps to prevent ejaculation of the sperm to outside and into the female genital tract.