Endocrine System Hormones Homeostasis Regents Biology 2009 2010

Endocrine System Hormones & Homeostasis Regents Biology 2009 -2010

Homeostasis u maintaining internal balance in the body organism must keep internal conditions stable even if environment changes also called “dynamic equilibrium” u example: body temperature humans: w too cold = shiver w too warm = sweat Regents Biology lizard: w too cold = bask in sun w too warm = hide in shade

Regulation How we maintain homeostasis u nervous system u nerve signals control body functions endocrine system hormones chemical signals control body functions Regents Biology

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

Hormones Why are hormones needed? chemical messages from one body part to cells in other parts of body u communication needed to coordinate whole body u maintaining homeostasis u Regents Biology growth hormones

Endocrine System Endocrine system releases hormones u glands which secrete (release) chemical signals into blood Regents Biology chemicals cause changes in other parts of body w growth hormones w sex hormones w response hormones w metabolism hormones w and more….

Responding to hormones Lock and key system u hormone fits receptor on “target” cell target cell secreting cell Regents Biology can’t read signal nontarget cells can’t read signal

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

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

Negative Feedback Response to changed body condition u if body is high or low from normal level u signal tells body to make changes that will bring body back to normal level once body is back to normal level, signal is turned off gland hormone 1 lowers body condition high Regents Biology specific body condition

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

Everyone’s doing it, so Ask Questions!! Regents Biology 2006 -2007

Endocrine System Hormones & Reproduction Regents Biology 2009 -2010

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

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

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

Male reproductive system Sperm production over 100 million produced per day! Regents u Biology ~2. 5 million released per drop! u

seminiferous tubule spermatocytes Regents Biology

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

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

Female reproductive system Regents Biology

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

Female reproductive system Regents Biology

Egg maturation in ovary releases progesterone maintains uterus lining Regents Biology produces estrogen

LH Menstrual cycle Controlled by interaction of 4 egg development hormones FSH & LH u estrogen u progesterone FSH ovulation = egg release corpus luteum u estrogen progesterone lining of uterus Regents Biology days 0 7 14 21 28

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

Female hormones FSH & LH u u u Estrogen u u u released from pituitary stimulates egg development & hormone release peak release = release of egg (ovulation) 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 u stimulates blood supply to lining of uterus u decreasing levels causes menstruation Regents Biology u

Fertilization Regents Biology

Placenta Food & gases diffuse across blood vessels Regents Biology

Any Questions? ? Regents Biology