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Male Sexual Response: Erection During sexual arousal, a PNS reflex promotes the release of nitric oxide
Nitric oxide causes erectile tissue to fill with blood
Expansion of the corpora cavernosa: Compresses their drainage veins
Retards blood outflow and maintains engorgement The corpus spongiosum functions in keeping the urethra open during ejaculation Ejaculation
Ejaculation At ejaculation, sympathetic nerves serving the genital organs cause: Reproductive ducts and accessory organs to contract and empty their contents The bladder sphincter muscle to close, preventing the expulsion of urine Bulbospongiosus muscles to undergo a rapid series of contractions Propulsion of semen from the urethra Human Life Cycle
Human Life Cycle Figure 27.5 Spermatogenesis
Spermatogenesis The sequence of events that produces sperm in the seminiferous tubules of the testes Each cell has two sets of chromosomes (one maternal, one paternal) and is said to be diploid (2n chromosomal number)
Humans have 23 pairs o...
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