1. The Reproductive System

2. 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 (half from mom and half from dad)
This cell is called a zygote

3. 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

4. Puberty In adolescence the reproductive system becomes functional
Puberty is when the body changes to prepare for the ability to reproduce, generally between the ages of 10 and 14 years old
The beginning of puberty is marked by an increase of hormones

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

6. Hormones and the glands that make them are part of the system called the endocrine system
The endocrine system is responsible for regulating the body’s activities, growth, response to stress, reproduction and regulation of metabolism

7. Puberty is triggered by two hormones secreted by the pituitary gland
This gland is the size of a grape and found at the base of the brain
The two hormones produced are follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
These stimulate the maturation of the ova or the production of spermatozoa

8. 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, primarily testosterone
This causes several physical and psychological changes: the primary and secondary sexual characteristics

9. Effect of hormones on the Body
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

10. Sexual Characteristics: Female
Primary
Menstrual cycle begins
Genital organs mature
Secondary
Psychological changes
Underarm hair appears
Breasts develop
Pelvis widens
Pubic hair appears
Fatty tissue accumulates (hips and breasts)

11. Sexual Characteristics: Male
Primary
Testicles mature and lower
Secondary
Psychological changes
Facial hair appears
Larynx enlarges
Skeletal muscle growth
Bone density increases
Underarm hair appears
General hairiness increases
Pubic hair appears

12. Hormones and the Female Body
To be considered fertile, a woman must be able to produce mature ova
This process is called oogenesis (the production of ovum through meiosis) *

13. At puberty: 700 000 cells capable of becoming ova called oocytes
Typically one oocyte per menstrual cycle will develop into an ovum via hormonal influence
In a lifetime some 400 oocytes will become ova
Each oocyte is surrounded by a layer of cells called the ovarian follicle

14. Around the middle of the menstrual cycle the ovarian follicle bursts, releasing the oocyte into the fallopian tube; this is called ovulation
The oocyte moves to the uterus via the fallopian tube where, undergoing more changes along the way
If fertilized, it will then implant in the uterus and if not it will be expelled from the body during menstruation

15. The Menstrual Cycle
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 estrogens increases
Secretory Phase (days 15 to 28)
Lining of the uterus continues to thicken
Progesterone production increases

16. Male Reproductive System and 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

17. Erection and Ejaculation
Once formed the sperm enter the vas deferens for collection until they are expelled through the urethra
The acid in urine kills sperm, so it is important that the two do not mix
During an erection two ring shaped muscle contract, making it impossible to urinate

18. When sexual arousal occurs the penis becomes filled with blood, resulting in swelling of the tissues and the erection of the penis
With stimulation the sperm is 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)