Chapter 36-1 Reproductive Systems

Chapter 36-1 Reproductive Systems Bio 30 NWRC

Human Male Reproductive System The male reproductive glands are the testes which are stored in the scrotum (outside of the body cavity) The development of sperm requires a temperature slightly cooler than the body temp

Sperm Cells

Sperm Cells • •

The Head. This has two important features. The acrosome contains lytic enzymes which are released when the sperm reaches an ovum. These enzymes digest the outer membrane of the egg, allowing penetration of the sperm. The head also contains a single set of chromosomes derived from the male. This will include either an 'X' or 'Y' chromosome, because of the way the XY separate during meiosis.

Sperm Cells • The Middle Section. • This part, immediately behind the head, contains numerous mitochondria. These respire sugars in the semen to generate ATP in order to provide the energy for movement of the tail.

Sperm Cells • The Tail. • This contains microfilaments running the length of the tail (Rhythmic contraction of the filaments causes the tail to wave and move against the fluid environment, providing forward motion.

Path of Sperm Cells •

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Vas Deferens The vas deferens is a small tube that connects the epididymis and ejaculatory duct. It ascends as part of the spermatic cord through the lower abdominal wall into the pelvic cavity, and transmits the sperm to the ejaculatory ducts. Epididymis: A structure within the scrotum attached to the backside of the testis. The epididymis is a coiled segment of the spermatic ducts that serves to store, mature and transport spermatozoa

Path of Sperm

Male Hormones

• Testosterone: is a steroid hormone. In mammals, testosterone is primarily secreted in the testes of males (and also the ovaries of females), although small amounts are also secreted by the adrenal glands. It is the principal male sex hormone. It is necessary for the production of sperm and secondary sex characteristics (hair growth, muscle development etc.)

Male Hormones • 3 Hormones influence testosterone production • Gonadotropin-releasing hormone 1 (GNRH1), is a hormone responsible for the release of FSH (follicle stimulating hormone) and LH (luteinizing hormone) from the anterior pituitary. GNRH1 is synthesized and released by the hypothalamus. Both travel through the bloodstream to the testes. FSH promotes production of sperm and LH stimulates production of testosterone.

Human Female Reproductive System

Human Female Reproductive System • Oocytes (immature eggs) are produced in the ovary • Once every 28 days (approx) the oocyte development is stimulated and an egg is released. • It travels through the oviduct (fallopian tube) to the uterus.

Human Female Reproductive System (video clip) Conception Ovulation

Female Hormones • Estrogen and progesterone are the main steroid hormones made by the ovaries. The anterior pituitary also produces LH and FSH which effect estrogen and progesterone levels. Estrogen affects the secondary sex characteristics in women (breasts and fatty tissue increase, menstrual cycle begins)

Sex Cell Production • Egg Formation – Unequal division of the cytoplasm means that meiosis of the egg cell results in only one viable egg cell

Sex Cell Production • Sperm formation follows general pattern of meiosis and results in 4 viable sperm.

The Menstrual Cycle (FFL) • FFL – Flow, Follicular, Luteal • Flow stage-1-5 days Menstrual cycles are counted from the first day of menstrual flow, because the onset of menstruation corresponds closely with the hormonal cycle.

The Menstrual Cycle • The menstrual cycle may be divided into several phases, and the length of each phase varies from woman to woman and cycle to cycle. Menstrual flow is the uterus shedding the blood, and tissues which build up on the lining of the uterus (the endrometrium)

The Menstrual Cycle • Follicular stage- Day 6-14 At the beginning of the follicular phase, FSH and LH levels are increased. In the early follicular phase, after menstrual flow has ended, the lining of the uterus is at its most thin.

The Menstrual Cycle • Later in the follicular phase, proliferation (or thickening) of the uterine lining occurs. This thickened lining is preparing for a possible pregnancy.

The Menstrual Cycle • Luteal stage-Day 15-28 The luteal phase of the menstrual cycle begins as ovulation occurs and continues until Day 1 the next period. (Remember, Day 1 is the day flow starts).During the luteal phase of the menstrual cycle, estrogen and progesterone increase, and work together to create changes in the lining of the uterus that prepare it to accept an embryo, should conception occur. When conception ( pregnancy) does not occur, estrogen and progesterone levels decline, and the lining of the uterus, called the endometrial lining, begins to shed, which leads to menstruation again. • End of 36-1

Assessment • 1. FSH and LH are regulated by negative feedback processes involving hormones (testosterone estrogen and progesterone). These hormones regulate sex cell production

Assessment • 2. Refer to hand outs!

Assessment • 3. Sugars are produced by the seminal vesicles and provide energy for the sperm cells. An alkaline solution is produced by the prostate gland and bulbbourethral glands to neutralize any acidic conditions the sperm cells may encounter is the urethra or vagina

Assessment •

4. The endrometrium sheds the blood, tissue fluid, mucus and epithelial cells. After about 5 days the endrometrium begins to repair itself, after about 12 days ovulation occurs. The follicle is changed to the corpus luteum which produces large amounts of progesterone and some estrogen. Late in the cycle the CL breaks down and stops producing hormones. The endrometrium detaches and the cycle begins again