C HAPTER 39 Endocrine system and Reproductive system

39-1 E NDOCRINE S YSTEM Hormones – chemicals released in one part of the body that travel through the bloodstream and affect the activities of cells in other parts of the body. Regulated by feedback mechanisms to maintain homeostasis. Target Cells—The cells that hormones bind to and affect. Exocrine Glands – release secretions directly into the organs that use them. Ex: Sweat, tears, digestive juices. Endocrine Glands – release secretions directly into blood stream. Ex: Hormones!

39-2 H UMAN E NDOCRINE G LANDS Pituitary Gland Divided into two parts: Anterior and Posterior. Base of the skull, secretes 9 hormones that directly regulate many body functions and endocrine glands. See pg for hormones. Hypothalamus Attached to the posterior pituitary, controls the secretions of the pituitary gland through the usage of control hormones. Allows the nervous and the endocrine systems to work closely together.

Thyroid Gland Wraps around trachea, major role in regulating metabolism by releasing 2 hormones with opposite effects. Parathyroid Gland Attached to thyroid, maintain homeostasis and calcium levels in blood Ex: if blood calcium levels are high, releases calcitonin to reduce calcium absorption; if levels are low, releases PTH to increase absorption of calcium Adrenal Glands Sit at the top of the kidneys, release hormones that help the body prepare for stress. Cortex – produces corticosteroids. Cortisol Medulla – releases epinephrine and norepinephrine (adrenaline) Fight or Flight response begins here!

Pancreas Has exocrine and endocrine functions Releases digestive enzymes into the small intestine (exocrine) and releases hormones (insulin and glucagon) into the blood to regulate blood sugar levels Reproductive Glands Serve two functions: To produce gametes and also to secrete sex hormones. Ovaries – produce ova (eggs), secrete estrogen and progesterone (hormones) Testes – produce sperm, produce testosterone (hormone)

39-3 T HE R EPRODUCTIVE S YSTEM Puberty – period of rapid growth and sexual maturation when the reproductive organs are fully developed

Male Reproductive System Main function is to produce and deliver sperm Structures  scrotum – external sac that holds the testes  seminiferous tubules – produces sperm  epididymis – stores mature sperm  vas deferans – some sperm move into this tube  urethra – tube that connects to the vas deferens and leads to the outside of the body  penis – anatomical structure of a male  semen – combination of sperm and seminal fluid

Female Reproductive System Main function to produce ova and nourish the embryo – produce one mature egg each month Structures Follicles – clusters of cells surrounding an egg Ovulation – mature egg is released Fallopian tubes – tube that moves the egg to the uterus Uterus – organ where embryo grows Vagina – canal that leads to the outside of the body Menstrual cycle (4 phases) Follicular phase – follicle matures and uterine lining thickens Ovulation – egg released into fallopian tube Luteal phase – at beginning of luteal phase is best chance for pregnancy; also when embryo implants in uterus Menstruation – occurs if egg is not fertilized, uterine lining and ova exit the body

39-4 F ERTILIZATION AND D EVELOPMENT Fertilization – process of an egg being joined by a sperm (N+N=2N) Zygote – fertilized egg cell Implantation – blastocyst attaches itself to the uterine wall Gastrulation – formation of three cell layers Neurulation – development of the nervous system Placenta – connection between mother and embryo

Fetus – after eight weeks of development Control of development Still an unknown process End of three months all organs are developed Later Development – 4 th 5 th and 6 th month – tissues and organs become more highly developed Last 3 Months – organ systems develop further and fetus grows in size

Childbirth Hormone – Oxytocin – Causes contractions to start – cervix expands and baby is pushed out of the vagina Infancy – first 2 years of life Childhood – from infancy to puberty Adolescence – from puberty to adulthood Adulthood – years of age and beyond