| A | B |
|---|
| Endocrine glands | An organ of the endocrine system that produces and releases its chemical products directly into the blood stream |
| Hormones | The chemical product of the endocrine gland that speeds up or slows down the activities of an organ |
| Target cells | A cell in the body that recognizes a hormone’s chemical structure; cell to which a hormone binds |
| Hypothalamus | A tiny part of the brain that links the nervous system and the endocrine system |
| Negative feedback | A process in which a system is turned off by the condition it produces |
| Egg | A female sex cell |
| Sperm | A male sex cell |
| Fertilization | The joining of a sperm and an egg cell |
| Zygote | A fertilized egg, produced by the joining of a sperm and an egg |
| Chromosomes | A rod-shaped cellular structure made of condensed chromatin; contains DNA, which carries the genetic information that controls inherited characteristics such as eye color and blood type |
| Testes | Organ of the male reproductive system in which sperm and testosterone are produced |
| Testosterone | A hormone produced by the testes that controls the development of physical characteristics in men |
| Scrotum | An external pouch of skin in which the testes are located |
| Semen | A mixture of sperm cells and fluids |
| Penis | The organ through which both semen and urine leave the male body |
| Ovaries | An organ of the female reproductive system in which eggs and estrogen are produced |
| Estrogen | A hormone produced by the ovaries that controls the development of adult female characteristics |
| Uterus | The hollow muscular organ of the female reproductive system in which a baby develops |
| Vagina | A muscular passageway through which a baby leaves the mother’s body |
| Menstrual cycle | The monthly cycle of changes that occur in the female reproductive system, during which an egg develops and the uterus prepares for the arrival of a fertilized egg |
| Ovulation | The process in which a mature egg is released from the ovary into an oviduct;Occurs halfway through the cyle |
| Menstruation | The process that occurs if fertilization does not take place, in which the thickened lining of the uterus breaks down and blood and tissue then pass out of the female body via the vagina |
| Embryo | A developing human during the first eight weeks after fertilization has occurred |
| Amniotic sac | A fluid filled sac that cushions and protects a developing fetus in the uterus |
| Placenta | A membrane that becomes the link between the developing embryo or fetus and the mother |
| Umbilical cord | A ropelike structure that forms in forms in the uterus between the embryo and the placenta |
| Fetus | A developing human from the ninth week of development until birth |
| Adolescence | The stage of development between childhood and adulthood when children become adults physically and mentally |
| Puberty | The period of sexual development during the teenage years in which the body becomes able to reproduce. |
| Peer pressure | The pressure from friends and classmates to behave in certain ways |
