Unit 10 The Human Body Ch. 39 Endocrine & Reproductive Systems

The Endocrine System The endocrine system is made up of glands that release their products into the bloodstream These products deliver messages throughout the body The endocrine system is made up of glands that release their products into the bloodstream These products deliver messages throughout the body

Hormones Hormones - chemicals released in 1 part of the body, that travel through the bloodstream, & affect activities of cells in other parts of the body; “chemical messengers” Target cells (receptor cells) - cells that have receptors for a particular hormone Hormones - chemicals released in 1 part of the body, that travel through the bloodstream, & affect activities of cells in other parts of the body; “chemical messengers” Target cells (receptor cells) - cells that have receptors for a particular hormone

Glands A gland is an organ that produces & releases a substance, or secretion Exocrine glands - release their secretions (hormones) through ducts (tubes), directly to the organs that use them A gland is an organ that produces & releases a substance, or secretion Exocrine glands - release their secretions (hormones) through ducts (tubes), directly to the organs that use them

Glands Endocrine glands - release their secretions (hormones) directly into the bloodstream

Major Endocrine Glands

Hormone Action Steroid hormones: Because they are lipids, they can cross cell membranes, passing directly into the cytoplasm & the nuclei of target cells Steroid hormones: Because they are lipids, they can cross cell membranes, passing directly into the cytoplasm & the nuclei of target cells

Hormone Action Nonsteroid hormones: They generally cannot pass through the cell membrane of their target cells Nonsteroid hormones: They generally cannot pass through the cell membrane of their target cells

Prostaglandins Prostaglandins - modified fatty acids that produce cells, affecting other nearby cells & tissues (“local hormones”) Ex.) some cause smooth muscle tissue to contract Prostaglandins - modified fatty acids that produce cells, affecting other nearby cells & tissues (“local hormones”) Ex.) some cause smooth muscle tissue to contract

Control of the Endocrine System Like most systems of the body, the endocrine system is regulated by feedback mechanisms that function to maintain homeostasis Ex.) Pancreas releasing insulin: blood sugar level increases after lunch, pancreas releases insulin, blood sugar level decreases, pancreas stops releasing insulin Like most systems of the body, the endocrine system is regulated by feedback mechanisms that function to maintain homeostasis Ex.) Pancreas releasing insulin: blood sugar level increases after lunch, pancreas releases insulin, blood sugar level decreases, pancreas stops releasing insulin

Human Endocrine Glands The human endocrine system regulates a wide variety of activities Any improper functioning of an endocrine gland may result in a disease or disorder The human endocrine system regulates a wide variety of activities Any improper functioning of an endocrine gland may result in a disease or disorder

Human Endocrine Glands The major glands of the endocrine system are: the pituitary gland, the hypothalamus, the thyroid gland, the parathyroid glands, the adrenal glands, the pancreas, & the reproductive glands

Pituitary Gland Pituitary gland - divided into 2 parts: anterior & posterior; it secretes 9 hormones that directly regulate many body functions & controls the actions of several other endocrine glands

Pituitary Gland Hormones

Hypothalamus The hypothalamus controls the secretions of the pituitary gland The close connection between the hypothalamus & the pituitary gland, means that the nervous & endocrine systems can act together to help coordinate body activities The hypothalamus controls the secretions of the pituitary gland The close connection between the hypothalamus & the pituitary gland, means that the nervous & endocrine systems can act together to help coordinate body activities

Thyroid Gland The thyroid gland has the major role in regulating the body’s metabolism Releases thyroxin which increases metabolism, & cellular respiration The thyroid gland has the major role in regulating the body’s metabolism Releases thyroxin which increases metabolism, & cellular respiration

Thyroid Gland Unable to produce thyroxin produces condition known as cretinism 2 effects of cretinism are dwarfism & severe mental retardation Can be prevented by adding small amounts of iodine to table salt Unable to produce thyroxin produces condition known as cretinism 2 effects of cretinism are dwarfism & severe mental retardation Can be prevented by adding small amounts of iodine to table salt

Parathyroid Glands The 4 parathyroid glands are found on the back surface of the thyroid gland Hormones from the thyroid gland & the parathyroid glands act to maintain homeostasis of calcium levels in the blood The 4 parathyroid glands are found on the back surface of the thyroid gland Hormones from the thyroid gland & the parathyroid glands act to maintain homeostasis of calcium levels in the blood

Adrenal Glands There are 2 adrenal glands that sit on top of the kidneys, like little hats The adrenal glands release hormones that help the body prepare for & deal with stress There are 2 adrenal glands that sit on top of the kidneys, like little hats The adrenal glands release hormones that help the body prepare for & deal with stress

Adrenal Glands The 2 hormones secreted by the adrenal glands are: epinephrine and norepinephrine The hormones produce the “fight or flight” response to stress The 2 hormones secreted by the adrenal glands are: epinephrine and norepinephrine The hormones produce the “fight or flight” response to stress

Pancreas The pancreas has both exocrine & endocrine functions It is a digestive gland whose enzymes help break down food However, different cells in the pancreas release hormones into the blood The pancreas has both exocrine & endocrine functions It is a digestive gland whose enzymes help break down food However, different cells in the pancreas release hormones into the blood

Pancreas Insulin & glucagon are released from the pancreas to help keep the blood glucose level stable Insulin stimulates liver cells to remove sugar from the blood & store it as glycogen Glucagon stimulates the liver to break down stored glycogen & release sugar back into the blood Insulin & glucagon are released from the pancreas to help keep the blood glucose level stable Insulin stimulates liver cells to remove sugar from the blood & store it as glycogen Glucagon stimulates the liver to break down stored glycogen & release sugar back into the blood

Pancreas Diabetes mellitus - when the pancreas does not produce insulin There are 2 types of diabetes, Type I and Type II Type I requires daily injections of insulin, due to the fact that the body produces no insulin Diabetes mellitus - when the pancreas does not produce insulin There are 2 types of diabetes, Type I and Type II Type I requires daily injections of insulin, due to the fact that the body produces no insulin

Pancreas Type II develops in people after the age of 40, produces normal insulin but cells don’t respond properly to the hormone Usually controlled through diet, exercise, & medication taken orally Type II develops in people after the age of 40, produces normal insulin but cells don’t respond properly to the hormone Usually controlled through diet, exercise, & medication taken orally

Reproductive Glands The gonads are the body’s reproductive glands They serve 2 important functions: the production of gametes & the secretion of sex hormones The gonads are the body’s reproductive glands They serve 2 important functions: the production of gametes & the secretion of sex hormones

Reproductive Glands The female gonads are the ovaries - which produce eggs, & the hormones estrogen & progesterone The male gonads are the testes - which produce sperm, & the hormone testosterone The female gonads are the ovaries - which produce eggs, & the hormones estrogen & progesterone The male gonads are the testes - which produce sperm, & the hormone testosterone

The Reproductive System Reproduction is the formation of new individuals If any other system of the body failed, the result would be fatal, not the case with the reproductive system Reproduction is important for continuation of the species, but not for that organism to survive Reproduction is the formation of new individuals If any other system of the body failed, the result would be fatal, not the case with the reproductive system Reproduction is important for continuation of the species, but not for that organism to survive

Sexual Development For the 1st 6 weeks of development, male & female embryos are identical During the 7th week, primary reproductive organs begin to develop Hormones produced by those organs (gonads), will determine whether the embryo develops physically into a male or female For the 1st 6 weeks of development, male & female embryos are identical During the 7th week, primary reproductive organs begin to develop Hormones produced by those organs (gonads), will determine whether the embryo develops physically into a male or female

Sexual Development Neither the testes nor the ovaries are capable of producing active reproductive cells until puberty Puberty - a period of rapid growth & sexual maturation, when the reproductive system becomes fully functional Neither the testes nor the ovaries are capable of producing active reproductive cells until puberty Puberty - a period of rapid growth & sexual maturation, when the reproductive system becomes fully functional

The Male Reproductive System The main function of the male reproductive system is to produce & deliver sperm Scrotum - external sac that holds the gonads, (external to reduce heat so sperm won’t die) Seminiferous tubules - tiny tubules tightly coiled where the sperm are produced The main function of the male reproductive system is to produce & deliver sperm Scrotum - external sac that holds the gonads, (external to reduce heat so sperm won’t die) Seminiferous tubules - tiny tubules tightly coiled where the sperm are produced

The Male Reproductive System Sperm - male sex cells (gametes)

The Male Reproductive System Epididymis - structure that sperm move into, to mature & be stored until released Vas deferens - tube that carries sperm from the epididymis, to the urethra, to be released Penis - urethra carries sperm out of body through the penis Epididymis - structure that sperm move into, to mature & be stored until released Vas deferens - tube that carries sperm from the epididymis, to the urethra, to be released Penis - urethra carries sperm out of body through the penis

The Male Reproductive System

The Female Reproductive System The main function of the female reproductive system is to produce ova (eggs) In addition, the female reproductive system prepares the female’s body to nourish a developing embryo The main function of the female reproductive system is to produce ova (eggs) In addition, the female reproductive system prepares the female’s body to nourish a developing embryo

The Female Reproductive System Follicles - each ovary contains 400,000 clusters of cells surrounding a single egg, to help it mature Ovulation - when a follicle has completely matured, its egg is released Follicles - each ovary contains 400,000 clusters of cells surrounding a single egg, to help it mature Ovulation - when a follicle has completely matured, its egg is released

The Female Reproductive System Egg - female sex cells (gametes) Fallopian tubes - tube from each ovary, that carries the egg to the uterus Egg - female sex cells (gametes) Fallopian tubes - tube from each ovary, that carries the egg to the uterus

The Female Reproductive System Uterus - location of egg a couple days after ovulation, where embryo develops if fertilization takes place Cervix - the outer end of the uterus Vagina - a canal that leads to the outside of the body Uterus - location of egg a couple days after ovulation, where embryo develops if fertilization takes place Cervix - the outer end of the uterus Vagina - a canal that leads to the outside of the body

The Female Reproductive System

The Menstrual Cycle Menstrual cycle - when an egg develops & is released from an ovary The menstrual cycle has 4 phases: follicular phase, ovulation, luteal phase, & menstruation Menstrual cycle - when an egg develops & is released from an ovary The menstrual cycle has 4 phases: follicular phase, ovulation, luteal phase, & menstruation

The Menstrual Cycle The Follicular Phase Development of an egg Ovulation Lasts 3-4 days, a mature egg is released into 1 of the fallopian tubes The Follicular Phase Development of an egg Ovulation Lasts 3-4 days, a mature egg is released into 1 of the fallopian tubes

The Menstrual Cycle Luteal Phase The remaining ruptured follicle, which continues to release hormones Menstruation - when the lining of the uterus sheds, lasts about 3-7 days (period) Luteal Phase The remaining ruptured follicle, which continues to release hormones Menstruation - when the lining of the uterus sheds, lasts about 3-7 days (period)

Sexually Transmitted Diseases Sexually transmitted diseases - diseases spread from 1 person to another through sexual contact Common STDs are chlamydia, syphilis, & gonorrhea (caused by a bacteria) Sexually transmitted diseases - diseases spread from 1 person to another through sexual contact Common STDs are chlamydia, syphilis, & gonorrhea (caused by a bacteria)

Sexually Transmitted Diseases Others caused by viruses include: HIV, hepatitis B, genital herpes, & genital warts

Fertilization When an egg is fertilized, the process of human development begins In this process, a single cell, the size of a period at the end of a sentence, undergoes cell divisions that results in the formation of a new human being When an egg is fertilized, the process of human development begins In this process, a single cell, the size of a period at the end of a sentence, undergoes cell divisions that results in the formation of a new human being

Fertilization Fertilization - the process of a sperm joining an egg, usually occurs in the fallopian tube Zygote - a fertilized egg Fertilization - the process of a sperm joining an egg, usually occurs in the fallopian tube Zygote - a fertilized egg

Early Development The stages of early development include: implantation, gastrulation, & neurulation Implantation - when the blastocyst implants itself in the uterine wall At this point, cells differentiate - develop into specific types of tissues in the body The stages of early development include: implantation, gastrulation, & neurulation Implantation - when the blastocyst implants itself in the uterine wall At this point, cells differentiate - develop into specific types of tissues in the body

Early Development Gastrulation - the formation of 3 cell layers; the beginning of all of the organs & tissues of the embryo will form from these 3 layers

Early Development Neurulation - the development of the nervous system, occurs shortly after gastrulation

Early Development Placenta - connections between mother & developing embryo The embryo needs a supply of nutrients & oxygen, & a way to get rid of carbon dioxide & wastes Nutrients & oxygen diffuse from the mother’s blood into the baby’s blood Placenta - connections between mother & developing embryo The embryo needs a supply of nutrients & oxygen, & a way to get rid of carbon dioxide & wastes Nutrients & oxygen diffuse from the mother’s blood into the baby’s blood

Early Development At the same time, carbon dioxide & metabolic wastes diffuse from the baby’s blood into the mother’s blood, to be excreted The placenta is the embryo’s organ of respiration, nourishment, & excretion At the same time, carbon dioxide & metabolic wastes diffuse from the baby’s blood into the mother’s blood, to be excreted The placenta is the embryo’s organ of respiration, nourishment, & excretion

The Placenta

Early Development Fetus - after 8 weeks of development, the embryo is then called a fetus The umbilical cord connects the fetus to the placenta Pregnancy, is divided into 3 trimesters, during the 3rd, the organ systems mature, & the fetus grows in size & mass Fetus - after 8 weeks of development, the embryo is then called a fetus The umbilical cord connects the fetus to the placenta Pregnancy, is divided into 3 trimesters, during the 3rd, the organ systems mature, & the fetus grows in size & mass

Later Development

Childbirth After 9 months, the fetus is ready for birth Oxytocin, a hormone released from the pituitary gland, causes contractions to begin The contractions become more frequent & powerful After 9 months, the fetus is ready for birth Oxytocin, a hormone released from the pituitary gland, causes contractions to begin The contractions become more frequent & powerful

Childbirth The cervix opening expands until it is large enough for the baby’s head to pass through Contractions of the uterus force the baby out through the vagina The cervix opening expands until it is large enough for the baby’s head to pass through Contractions of the uterus force the baby out through the vagina