CHAPTER 39Endocrine 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. 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 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.

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 THE REPRODUCTIVE SYSTEM Puberty – period of rapid growth and sexual

maturation when the reproductive organs are fully developed

Male Reproductive SystemMain 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 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

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

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