Reproduction Purpose of life… Survival Reproduction to ensure the continuation of species We can create new individuals who have characteristics of both parents!

Stages of Human Development Sexual reproduction requires the fertilization of an ovum (from the mother) by a spermatozoan (from the father) Fertilization is the fusion of an ovum and a spermatozoa Genetic material becomes fused and produces a cell made of 23 pairs of chromosomes for a totral of 46(half from mom and half from dad) This cell is called a Zygote

Life Stage Approx. Age Stages during Pregnancy Zygote Fertilization to 2 weeks Embryo 2 to 9 weeks Fetus 9 weeks to birth Stages after Birth Baby Birth to 2 years Early Childhood 2 to 6 years Childhood 6 to 10 years Adolescence 10 to 18 years Adulthood 18 to 70 years Old Age 70 years to death

Puberty: The reproductive system becomes functional during adolescence. Puberty is when the body undergoes physical, anatomical and psychological changes to prepare for the ability to reproduce. Generally, occurs between the ages of 10 and 14 years old The beginning of puberty is marked by an increase of hormones. Sperm and ova production begins at the onset of PUBERTY

Hormones are chemical messengers, transported by the blood and control the activity of one or more organs They are secreted (made) by glands, released into the bloodstream and stimulate activity in an organ or tissue somewhere else in the body

Hormones and the glands that make them are part of endocrine system. The endocrine system regulates the body’s activities, growth, response to stress, reproduction and regulation of metabolism

Glands that control puberty… Puberty is triggered by two hormones secreted by the pituitary gland Pituitary gland: it is the size of a grape and found at the base of the brain. The two hormones produced are FSH (follicle-stimulating hormone) and LH (luteinizing hormone). These stimulate the maturation of the ova or the production of spermatozoa.

Glands continued… In women: FSH and LH also stimulate the ovaries to produce the female sex hormones: estrogens and progesterone In men: FSH and LH stimulate the testicles to produce the male sex hormone, testosterone. This causes several physical and psychological changes: the primary and secondary sexual characteristics

Effect of hormones on the Body Txbk p. 142, fig. 5.22 OVARIES -Stimulate maturity of ova -Stimulate production of female sex hormones Estrogens and Progesterone FSH and LH ORGANISM -Primary sexual characteristics develop -Secondary sexual characteristics develop Pituitary Gland TESTICLES -Stimulate production of spermatozoa -Stimulate production of male sex hormones FSH and LH Testosterone

Sexual Characteristics in Females txbk p. 142, fig. 5.23 Types of changes Observable phenomena Physiological (primary) Menstrual Cycle begins Genital organs mature Anatomical (Secondary) Silhouette changes (fatty tissue accumulates(breasts and hips) Pelvis widens Underarm and Pubic hair appears Psychological Physical attraction Libido Need for autonomy Sense of responsibility to reproduce

Sexual Characteristics in Males p. 143, fig 5.24 Types of changes Observable phenomena Physiological (primary) Testicles mature and lower Anatomical (Secondary) Skeletal & muscle growth Bone density increases Larynx enlarges Facial, Underarm and Pubic hair appears. General hairiness increases Psychological Physical attraction Libido Need for autonomy

Male Hormones In puberty, the release of FSH stimulates spermatogenesis (the production of sperm) The cells that line the testicles undergo meiosis to produce spermatozoa (sperm) Since these cells are under constant renewal, the testicles can produce roughly 120 million sperm per day.

Erection and Ejaculation The travel of Sperm: Seminiferous Tubules–Epididymis -Vas deferens- Ejaculatory duct -Urethra Erection and Ejaculation Once formed the sperm enter the vas deferens for collection until they are expelled through the urethra The penis contains elastic spongy tissue that fills with blood during sexual arousal. This causes swelling of tissues and causes an erection.

With stimulation, the sperm is then pushed down towards the urethra, mixes with the seminal fluid to create semen until the resulting pressure causes ejaculation (the expulsion of semen by the penis) The acid in urine kills sperm, so it is important that the two do not mix So during an erection, two ring-shaped muscles contract, making it impossible to urinate

FYI Need erection to ejaculate, but do not need to ejaculate if an erection occurs. There is approximately 350 million sperm/ejaculation. Sperm can live in a woman for 24 to 72 hours

Hormones and the Female Body Estrogen Involved in the menstrual cycle (the changing of the endometrium) Affects body shape and growth Breasts, wider hips, body hair Progesterone Prepares the uterus for implantation Causes the mammary glands (produce milk) to develop in pregnant women

Oogenesis Between 3 and 7 months of fetal life, cells near surface of ovaries undergo mitosis They enter meiosis, but stop halfway through (meiosis I) They are called primary oocytes and are enveloped in protective cells called follicles. Starting at puberty, one oocyte per menstrual cycle can reach maturity and develop into an ovum. This process is called oogenesis (the production of ovum through meiosis)

p. 144 At puberty: there are about 700 000 oocytes capable of becoming ova. About 400 of these oocytes will become ova throughout a female’s lifetime. To be considered fertile, a woman must be able to produce mature ova.

Ovarian Cycle: p. 145 Series of changes that ovarian follicles undergo every month. Process by which a single ovarian follicle matures in order to release an ovum and changes into a corpus luteum to encourage the implantation of the ovum in the uterus.

Ovarian Folicle (Days 1-13) FSH stimulates maturation of ovarian follicle containing oocyte. Follicle releases more estrogen, which stimulates release of more FSH and LH Estrogen thickens the lining of uterus

Ovulation (14th day) Increase in LH and FSH causes the ovarian follicle to burst and releases the oocyte into the fallopian tube.

Stage 3 (days 15-28) LH promotes the healing of the ovarian follicle and transforms the follicle into the corpus luteum. The corpus luteum produces progesterone to prepare the body to receive a fertilized ovum and stops production of FSH and LH so more ova won’t mature and be released. Thickens the uterine lining (endometrium).

If ovum is fertilized, it will then implant in the uterus (The woman becomes pregnant). If ovum is not fertilized, menstruation starts. Uterine lining and unfertilized ovum are expelled, and corpus luteum disintegrates, causing progesterone production to decrease. (day 1-5 of menstrual cycle)

Ovum Ovarian folicles Haploid oocyte Endometrium

The Menstrual Cycle (p. 147) The menstrual cycle represents all the periodic changes that take place in the uterus. Phase Event Hormones Menstrual Phase (days 1 to 5) Bleeding occurs- expulsion of the uterine lining and unfertilized ovum Progesterone production decreases Proliferation Phase (days 6 to 14) Lining of the uterus begins to thicken Production of estrogen increases Secretory Phase (days 15 to 28) Lining of the uterus continues to thicken Progesterone production increases

p. 148 The ovarian cycle and the menstrual cycle are controlled by the hormonal cycle!!