Endocrine System Hormones Reproduction 2006-2007

Hormones Why are hormones needed? chemical messages from one body part to cells in other parts of body communication needed to coordinate whole body maintaining homeostasis energy production growth development maturation reproduction growth hormones

Endocrine System Endocrine system releases hormones glands which secrete chemical signals into blood chemicals cause changes in other parts of body slow, long-lasting response growth hormones sex hormones response hormones metabolism hormones and more…. Hormones coordinate slower but longer–acting responses to stimuli such as stress, dehydration, and low blood glucose levels. Hormones also regulate long–term developmental processes by informing different parts of the body how fast to grow or when to develop the characteristics that distinguish male from female or juvenile from adult. Hormone–secreting organs, called endocrine glands, are referred to as ductless glands because they secrete their chemical messengers directly into extracellular fluid. From there, the chemicals diffuse into the circulation.

Regulation by chemical messengers Neurotransmitters released by neurons Hormones release by endocrine glands endocrine gland neurotransmitter axon hormone carried by blood receptor proteins receptor proteins target cell

Body Regulation Nervous system & Endocrine system work together hypothalamus “master nerve control center” receives information from nerves around body about internal conditions communicates with pituitary gland “master gland” releases many hormones sexual development, growth, milk production, pain-relief hormones

specific body condition Negative Feedback Response to changed body condition every time body is high or low from normal level a signal tells the body to make changes that will bring body back to normal level once body is back to normal level, signal is turned off hormone 1 gland lowers body condition high specific body condition

Maintaining homeostasis Feedback Maintaining homeostasis hormone 1 gland lowers body condition high specific body condition low raises body condition gland hormone 2

Dynamic Equilibrium and Feedback Loops Two Hormones Working in Opposite Ways to Regulate a “set point” Feed Back Loop One Hormone “feeds-back” to Regulate another Hormone or Product

Controlling Body Temperature Nervous System Control Feedback Controlling Body Temperature nerve signals brain sweat dilates surface blood vessels high body temperature low constricts surface blood vessels shiver brain nerve signals

Regulation of Blood Sugar Endocrine System Control Feedback Regulation of Blood Sugar insulin body cells take up sugar from blood liver stores sugar reduces appetite pancreas liver high blood sugar level (90mg/100ml) low liver releases sugar triggers hunger pancreas liver glucagon

Let’s Review ?? 2006-2007

What do they do? Maintain homeostasis Start a new process Body Temperature Maintain homeostasis blood sugar level temperature control Start a new process growth fetal development sexual development

Negative Feedback Negative feedback every time body is high or low from normal level a signal tells the body to make changes that will bring body back body temperature control of blood sugar

Sex & Growth Hormones Large scale body changes how do they work turn genes on start new processes in the body by turning genes on that were lying “dormant”

Responding to hormones Lock and key system hormone fits receptor on “target” cell target cell secreting cell non- target cells can’t read signal can’t read signal

Hormone Action at Target Cells Protein Hormone Two Messengers One Messenger Steroid Hormone Nonsteroid hormone (first messenger) Target cell membrane Receptor Target cell membrane Receptor cAMP (second messenger) Hormone-receptor complex Altered cellular function Nucleus Enzyme activities DNA Altered cellular function Protein synthesis Nucleus Cytoplasm Cytoplasm mRNA Steroid hormones Act Directly on DNA Protein Hormones affect Enzyme Activities and Cell Function

Glands Pineal Pituitary Thyroid Adrenal Pancreas Ovary Testes melatonin Pituitary many hormones: master gland Thyroid thyroxine Adrenal adrenaline Pancreas insulin, glucagon Ovary estrogen Testes testosterone

Pituitary gland hormones Sex & reproductive hormones FSH follicle stimulating hormone stimulates egg & sperm production LH luteinizing hormone stimulates ovaries & testes prepares uterus for fertilized egg oxytocin stimulates childbirth contractions releases milk in nursing mothers prolactin milk production in nursing mothers hormones hormones

Reproductive hormones Testosterone from testes sperm production & secondary sexual characteristics Estrogen from ovaries egg production, preparing uterus for fertilized egg & secondary sexual characteristics

Male reproductive system Sperm production over 100 million produced per day! ~2.5 million released per drop!

seminiferous tubule sperm spermatocytes

Main Functions of Male Repro System Sperm production in paired testes Requires lower temperature Scrotum adaptation for max. sperm production Flagellum Mitochondria 2. Delivery of Sperm into Female’s Reproductive Tract Head Nucleus

Male reproductive system Testes & epididymis sperm production & maturation Glands seminal vesicles, prostate, bulbourethal produce seminal fluid nutrient-rich

Male reproductive system Testicles produces sperm & hormones Scrotum sac that holds testicles outside of body Epididymis where sperm mature Vas deferens tubes for sperm to travel from testes to penis Prostate, seminal vesicles, Cowper’s (bulbourethal) glands nutrient rich fluid to feed & protect sperm

Female reproductive system

Female reproductive system Ovaries produces eggs & hormones Uterus nurtures fetus; lining builds up each month Fallopian tubes tubes for eggs to travel from ovaries to uterus Cervix opening to uterus, dilates 10 cm for birthing baby Vagina birth canal for birthing baby

Female reproductive system

Egg maturation in ovary releases progesterone maintains uterus lining produces estrogen

Menstrual cycle Controlled by interaction of 4 hormones FSH & LH estrogen progesterone FSH ovulation = egg release egg development corpus luteum estrogen progesterone lining of uterus days 7 14 21 28

Menstrual Cycle Summary Chart Follicle Stage ↑FSH Follicle develops Follicle produces Estrogen Egg Matures Estrogen Thickens Uterus lining Lasts 10-14 days Low Estrogen + progesterone allows FSH to be released again from pituitary Day 14 4. Menstruation Sudden decrease in estrogen and progesterone Shedding of Uterine Lining 2. Ovulation ↑ LH released Mature egg released Ovulation Lasts 10-12 days 3. Corpus Luteum Stage Ruptured follicle becomes the Corpus Luteum (yellow Body) Corpus luteum produces Progesterone Uterus lining becomes thicker, prepares For possible fertilization Corpus luteum Degenerates Causing Progesterone + estrogen to Drop

Human Menstrual Cycle

Female hormones FSH & LH Estrogen Progesterone released from pituitary stimulates egg development & hormone release peak release = release of egg (ovulation) Estrogen released from ovary cells around developing egg stimulates growth of lining of uterus decreasing levels causes menstruation Progesterone released from “corpus luteum” in ovaries cells that used to take care of developing egg stimulates blood supply to lining of uterus

Fertilization

Fertilization Occurs In the Fallopian Tubes Day 4 4 cells 2 cells Zygote Morula Day 7 Fertilization Blastocyst Day 0 Implantation of blastocyst Uterine wall Egg released “ovulation” ovary

Early Embryonic Development All divisions of A zygote after Fertilization are Mitotic cell divisions Called Cleavage

The Three Germ Layers Differentiation of Cells Endoderm: Lining of Digestive And Respiratory tracts, Liver and Pancreas Mesoderm: Muscles and Skeleton, Circulatory and Reproductive systems Ectoderm: Nervous System Epidermis of skin

Multiple Births Fertilization is the fusion of a sperm and an egg to form a zygote, the single cell from which all cells of the human body are derived. When an egg is fertilized, the remarkable process of human development begins. 1.If two eggs are released during ovulation, each can be fertilized by a sperm. What do you think would be the result? Explain your answer. 2.If one zygote splits into two, each can continue development on its own. What do you think would be the result? Explain your answer. 3.Triplets are three babies born at the same time. Describe three ways that triplets could develop.

Human Embryo: 3-8 weeks Gestation Note, the period from week 12 to week 38 is considered Fetal Development

Fetus to Baby In spite of the placental “barrier” Small molecules and Viruses can still cross And affect the baby Alcohol (FAS) Carbon Monoxide (Smoking) Narcotics (Heroine, Crack) HIV Measles Chicken Pox Antibodies Rh incompatibility

It’s All About HORMONES Got Questions ?

Actions of Insulin and Glucagon Following a Meal Regulation of Blood Sugar Levels to Maintain Homeostasis Beta cells release insulin into the blood Body cells absorb glucose Blood glucose level increases Liver converts glucose in to glycogen Blood glucose level decreases Homeostasis: Normal blood glucose level Blood glucose level increases Blood glucose level decreases Missed a Meal Liver converts glycogen to glucose Alpha cells release glucagon into blood

Female reproductive cycle Feedback Female reproductive cycle egg matures & is released (ovulation) builds up uterus lining estrogen ovary corpus luteum progesterone FSH & LH fertilized egg (zygote) maintains uterus lining HCG yes pituitary gland corpus luteum pregnancy GnRH no progesterone corpus luteum breaks down progesterone drops menstruation maintains uterus lining hypothalamus

. Homeostasis biological processes which keep temperature & other body variables within a certain range For example, temperature, weight, hydration (fluids; H2O) content of blood (acidity, oxygen, fat, glucose) Homeostasis is maintained by both (1) internal biological processes and (2) external behaviors. Set Point: homeostasis relies upon set points for each body variable, that is, a specific narrow range of acceptable values which the body must maintain. For example, the human body temperature generally stay between roughly 36.5 and 37.5 degrees Celsius (97.7 and 99.5 degrees Fahrenheit)

The Thyroid Gland Location: found in the neck, just below the larynx and in front of the trachea

Thyroxine Iodine-containing hormone secreted by the thyroid gland Regulates rate of metabolism in body Increases rate of protein, carbohydrate, and fat metabolism Increases rate of cellular respiration Necessary for normal mental and physical development

TSH-releasing factor stimulates Thyroxine Factory hypothalamus TSH-releasing factor stimulates Low-level stimulates High-level inhibits FEED BACK LOOP anterior pituitary thyroxine TSH stimulates thyroid RELEASES