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| hormone | One of many types of circulating chemical signals in all multicellular organisms that are formed in specialized cells, travel in body fluids, and coordinate the various parts of the organism by interacting with target cells |
| target cell | cell that has a receptor for a particular hormones |
| exocrine gland | Glands, such as sweat glands and digestive glands, that secrete their products into ducts that empty onto surfaces, such as the skin, or into cavities, such as the interior of the stomach |
| endocrine gland | A ductless gland that secretes hormones directly into the bloodstream |
| prostaglandin | One of a group of modified fatty acids secreted by virtually all tissues and performing a wide variety of functions as messengers |
| pituitary gland | An endocrine gland at the base of the hypothalamus; consists of a posterior lobe (neurohypophysis), which stores and releases two hormones produced by the hypothalamus, and an anterior lobe (adenohypophysis), which produces and secretes many hormones that regulate diverse body functions |
| diabetes mellitus | condition that occurs when the pancreas produces too little insulin |
| ovary | In animals, the structure that produces female gametes and reproductive hormones |
| testis | The male reproductive organ, or gonad, in which sperm and reproductive hormones are produced |
| puberty | period of rapid growth and sexual maturation during which the reproductive system becomes fully functional |
| scrotum | external sac containing the testes |
| sminiferous tubules | one of hundreds of tiny tubules in the testes in which sperm are produced |
| epididymis | A long coiled tube into which sperm pass from the testis and are stored until mature and ejaculated |
| vas deferens | The tube in the male reproductive system in which sperm travel from the epididymis to the urethra |
| urethra | A tube that releases urine from the body near the vagina in females or through the penis in males; also serves in males as the exit tube for the reproductive system |
| penis | external male reproductive organ |
| follicle | A microscopic structure in the ovary that contains the developing ovum and secretes estrogens |
| ovulation | The release of an egg from ovaries. In humans, an ovarian follicle releases an egg during each menstrual cycle |
| fallopian tube | A tube passing from the ovary to the vagina in invertebrates or to the uterus in vertebrates |
| uterus | A female reproductive organ where eggs are fertilized and/or development of the young occurs |
| vagina | Part of the female reproductive system between the uterus and the outside opening; the birth canal in mammals; also accommodates the male's penis and receives sperm during copulation |
| menstrual cycle | A type of reproductive cycle in higher female primates, in which the nonpregnant endometrium is shed as a bloody discharge through the cervix into the vagina |
| corpus luteum | name givien to a follicle after ovulation because of its yellow color |
| menstruation | phase of the menstrual cycle during which the lining of the uterus, along with blood and unfertilized egg, is discharged through the vagina |
| sexually transmitted disease | disease spread from one person to another during sexual contact |
| zygotes | The diploid product of the union of haploid gametes in conception; a fertilized egg |
| implantation | process in which a blstocyst attatches itself to a wall of uterus |
| differentation | process in which cells become specialized in structure and function |
| gastrulation | The formation of a gastrula from a blastula |
| neurulation | development of the nervous system |
| placenta | A structure in the pregnant uterus for nourishing a viviparous fetus with the mother's blood supply; formed from the uterine lining and embryonic membranes |
| fetus | An unborn or unhatched vertebrate that has passed through the earliest developmental stages; a developing human from about the second month of gestation until birth |
