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Chapter 39

Chapter 39. Endocrine system and Reproductive system. 39-1 Endocrine System. 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.

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Chapter 39

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  1. Chapter 39 Endocrine system and Reproductive system

  2. 39-1 Endocrine System • 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. • EndocrineGlands – release secretions directly into blood stream. • Ex: Hormones!

  3. 39-2 Human Endocrine Glands • 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. 1004 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.

  4. Thyroid Gland • Wraps around trachea, major role in regulating metabolismby releasing 2 hormones with opposite effects. • Ex: if blood calcium levels are high, releases calcitonin to reduce calcium absorption; if levels are low, releases PTH to increase absorption of calcium • Parathyroid Gland • Attached to thyroid, maintain homeostasis and calcium levels in blood • 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!

  5. 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)

  6. 39-3 The Reproductive System • Puberty – period of rapid growth and sexual maturation when the reproductive organs are fully developed

  7. 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

  8. 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

  9. 39-4 Fertilization and Development • 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

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

  11. 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 – 25 - 35 years of age and beyond

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