Human Reproduction Chapter 4 Pages 108-119

Humans have both Primary and Secondary Sexual Characteristics Primary Sex characteristics are present at birth. Include body structures directly involved in reproduction such as testes, ovaries, and external genitalia. Secondary sex characteristics refer to other visible changes that occur during puberty such as changes in height and body shape.

Puberty Puberty is the maturation into an adult body capable of sexual reproduction. In males, puberty usually begins age 11-13 until around 18.

Puberty

Male Secondary Sexual Characteristics Secondary characteristics in males help distinguish male from female but not directly involved in reproduction: growth spurt; Facial, underarm, and pubic hair; deepening of voice.

Male Secondary Sexual Characteristics arrive during Puberty Begins when hormones released from the pituitary gland in the brain stimulate the testes to produce more male sex hormone called testosterone.

Male Reproductive System The male sex cell is a sperm cell The whole purpose of the male reproductive system is to produce sperm AND to deliver sperm to the egg.

Structure of Human Sperm Cell The Sperm Cell has three regions: Head – contains haploid nucleus, acrosome Middle piece – mitochondria Tail – flagellum List the functions of each section of sperm

Sperm are MUCH smaller than egg

Male Reproductive Structures Two testes – outside body Produce and nourish sperm Produce testosterone Scrotum – sac containing testes Seminiferous tubules – coiled tubes in testes Where diploid cells undergo meiosis haploid sperm Epididymis – where mature sperm are stored.

Male Reproductive Structures Vas deferens – tube carries sperm to urethra Urethra – tube leading to outside of body located in the penis Penis – specialized organ to enter female during sexual intercourse

Male Reproductive Structures Accessory Glands secrete seminal fluid (sugar for energy): Seminal vesicles prostate gland Cowper’s gland (Bulbourethral gland) Semen = Sperm + seminal fluid

Sperm Production and Development Sperm begin as diploid cells Undergo meiosis  haploid Begins in seminiferous tubules Finish maturing in epididymis About 74 days to mature 200-300 million sperm produced each day Why so many? Immature sperm = spermatozoa Sperm cells are continually being produced by the testes, but not all areas of the seminiferous tubules produce sperm cells at the same time. Oneimmature germ cell takes as long as 74 days to reach final maturation, and during this growth process there are intermittent resting phases

Check your Understanding HW: Read pages 108-110 Answer CYU p111

Male Reproductive System

Sperm Production and Development Sperm begin as diploid cells in seminiferous tubules Undergo mitosis to increase in number Gradually pushed closer to center Undergo meiosis  haploid Finish maturing in epididymis 200-300 million sperm produced each day Why so many?