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LS Chapter 20 Endocrine/Reproduction System Endocrine System produces chemicals that control many of the body’s daily activities. It also regulates long-term changes such as growth and development. Made up of; Glands (organs that produces or releases a chemicals) These tubes deliver chemical directly into the bloodstream Blood carries the chemicals to specific locations within the body HORMONES are the chemicals products. They turn on, turn off, speed up, or slow down the activities of different organs and tissues. Nerve impulses from the brain release hormones. NERVOUS SYSTEM regulates activities and the endocrine system regulates them also by sending hormones through the blood. THEY WORK TOGETHER What is ADRENALINE? When a hormone enters the bloodstream it affects some organs because each has a specific chemical structure. It interacts with a specific target cell. Target Cells recognize the hormone’s chemical structure. The hormone and the target cell fit together the way a key fits into a lock. Functions The endocrine glands include; Hypothalamus is a tiny part of the brain near the middle of your head. It is the link between the two systems. Pituitary gland is just below the hypothalamus. It is the size of a pea and it controls many body activities. Signal from the hypothalamus tell it to release hormones. Helps maintain homeostasis. 671 Thyroid (All p.669) Parathyroid Adrenal Thymus Pancreas Ovaries in females Testes in males Reproductive System An EGG is the female sex cell. A SPERM is a male sex cell. Each one contains half the chromosomes (23). Joined together they are complete with a total of 46 chromosomes. The joining of both is called FERTILIZATION or Sexual Reproduction. A ZYGOTE is a fertilized egg. Male Reproductive System Produces sperm and the hormone testosterone. Testes (produces sperm) Scrotum (external skin covering the testes) * Once the sperm forms in the testes they travel through other structures. Sperm mixes with fluids called semen. Penis (Semen leaves the body through this organ as well as urine through the urethra.) When semen passes through the urethra, muscles near the bladder contract to prevent urine and semen from mixing. Female Reproductive System R Role; to produce eggs. If it is fertilized it will be nourished and develop into a baby. Ovaries - Produce eggs. Fallopian tubes - Also called oviducts. They are passageways for eggs to travel from the ovary to the uterus. Uterus - Hollow muscular organ about the size of a pear. If an egg is fertilized it attaches to the wall of the uterus. If not is breaks down and leaves through the cervix. Vagina - Birth canal or muscular passageway that a baby would leave the mother’s body. Menstrual Cycle Monthly cycle of changes that occurs in a female reproductive system. An egg develops in an ovary and the uterus prepares for the arrival of an EMBRYO. About half way into the cycle a mature egg is released from the ovary into a fallopian tube. The process in which the egg gets released is called ovulation. If it does not get fertilized it will break down. This is called menstruation. Human Life Cycle A ZYGOTE develops first into an embryo and then a fetus. (Baby) Amniotic Sac is a membrane that surrounds the embryo and develops into a fluid-filled sac. Another membrane forms which helps the placenta to form; the placenta is the link between the embryo and the mother. The blood vessels are located next to the mother’s vessels. NO blood mixes but other substances are exchanged. Umbilical Cord is a rope like structure that forms between the fetus and the placenta. It contains blood vessels that link the fetus to the mother. After 9 months to 40 weeks a baby is ready to be born. Birth takes place in three stages; 1. Labor 2. Delivery 3. Afterbirth Multiple Births Identical Twins A sperm fertilizes one egg. The single egg splits and forms two identical embryos. Fraternal Twins Two different sperm fertilize two separate eggs. Each of the eggs develops into an embryo.