The Endocrine System Teenagers, Hormones and Shaving Cream…Oh My!

Endocrine System Hormones 2007-2008

Regulation Why are hormones needed? chemical messages from one body part to another communication needed to coordinate whole body homeostasis & regulation metabolism growth development maturation reproduction growth hormones

Regulation & Communication Animals rely on 2 systems for regulation endocrine system system of ductless glands secrete chemical signals directly into blood chemical travels to target tissue slow, long-lasting response nervous system system of neurons transmits “electrical” signal & release neurotransmitters to target tissue fast, short-lasting response 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

Classes of Hormones Protein-based hormones Lipid-based hormones polypeptides small proteins: insulin, ADH glycoproteins large proteins + carbohydrate: FSH, LH amines modified amino acids: epinephrine, melatonin Lipid-based hormones steroids modified cholesterol: sex hormones, aldosterone insulin

How do hormones act on target cells Lipid-based hormones hydrophobic & lipid-soluble diffuse across membrane & enter cells bind to receptor proteins in cytoplasm & nucleus bind to DNA as transcription factors Protein-based hormones hydrophilic & not lipid soluble can’t diffuse across membrane receptor proteins in cell membrane trigger secondary messenger pathway activate internal cellular response enzyme action, uptake or secretion of molecules…

Action of lipid (steroid) hormones target cell blood S S 1 protein carrier S 2 cytoplasm receptor protein 4 transcription factor S 3 DNA 5 mRNA protein plasma membrane nucleus ex: growth factors (hair, bone, muscle, gametes)

Action of protein hormones signal-transduction pathway 1 signal protein hormone P plasma membrane activates ion channel or enzyme receptor protein 2° messenger transduction transduction: the action or process of converting something and especially energy or a message into another form ATP activates enzyme 2 secondary messenger system cytoplasm activates enzyme produces an action 3 response target cell

Signal Transduction pathway 1 protein hormone P activates enzyme G protein cAMP 3 receptor protein 2 ATP GTP activates enzyme secondary messenger system activates enzyme 4 cytoplasm produces an action 5

Action of epinephrine (adrenalin) adrenal gland 1 epinephrine activates adenylyl cyclase G protein cAMP 3 receptor protein 2 ATP GTP activates protein kinase-A cytoplasm 4 released to blood activates phosphorylase glycogen glucose liver cell 5

Benefits of a 2° messenger system 1 signal Activated adenylyl cyclase receptor protein 2 Not yet activated amplification 4 amplification 3 Every where but here! cAMP amplification 5 GTP G protein protein kinase 6 amplification Amplification! enzyme 7 amplification FAST response! product

Maintaining homeostasis Negative Feedback Model for anterior pituitary hormone 1 gland lowers body condition high specific body condition low raises body condition gland hormone 2

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 low liver releases sugar triggers hunger pancreas liver glucagon

Insulin Unlocks gated glucose channels Decides if glucose burned or stored as glycogen or converted to fat Secreted in direct response to amount of glucose Fat storage hormone

Cause of heart disease? Inflammation causes: Reduce inflammation: High blood pressure Heart disease Over activity of the immune system Reduce inflammation: Moderate exercise Improve diet with low carbs Lower stress and cortisol levels

increased water reabsorption Endocrine System Control Feedback Blood Osmolarity ADH pituitary increased water reabsorption increase thirst nephron high nephron blood osmolarity blood pressure JuxtaGlomerular Apparatus low nephron (JGA) increased water & salt reabsorption adrenal gland renin aldosterone angiotensin

Nervous & Endocrine systems linked Hypothalamus = “master control center” nervous system receives information from nerves around body about internal conditions regulates release of hormones from pituitary Pituitary gland = “master gland” endocrine system secretes broad range of hormones regulating other glands hypothalamus anterior pituitary posterior

MASTER (gland) and Servant link

Thyroid gland Hypothalamus anterior pituitary gonadotropic hormones: follicle- stimulating hormone (FSH) & luteinizing hormone (LH) Mammary glands in mammals Muscles of uterus Kidney tubules posterior thyroid-stimulating hormone (TSH) antidiuretic (ADH) Adrenal cortex Bone and muscle Testis Ovary Melanocyte in amphibian adrenocorticotropic hormone (ACTH) melanocyte-stimulating hormone (MSH) oxytocin prolactin (PRL) growth hormone (GH)

Hormones of the Anterior Pituitary Sung to the tune of “ABC” song! Come on, Sing along now……… ACTH, LH, FSH, GH, TSH, PROLACTIN…and MSH!

metamorphosis & maturation Homology in hormones What does this tell you about these hormones? How could these hormones have different effects? prolactin growth hormone same gene family gene duplication? amphibians metamorphosis & maturation birds fat metabolism fish salt & water balance mammals growth & development milk production The most remarkable characteristic of prolactin (PRL) is the great diversity of effects it produces in different vertebrate species. For example, prolactin stimulates mammary gland growth and milk synthesis in mammals; regulates fat metabolism and reproduction in birds; delays metamorphosis in amphibians, where it may also function as a larval growth hormone; and regulates salt and water balance in freshwater fishes. This list suggests that prolactin is an ancient hormone whose functions have diversified during the evolution of the various vertebrate groups. Growth hormone (GH) is so similar structurally to prolactin that scientists hypothesize that the genes directing their production evolved from the same ancestral gene. Gene duplication!

Regulating metabolism Hypothalamus TRH = TSH-releasing hormone Anterior Pituitary TSH = thyroid stimulating hormone Thyroid produces thyroxine hormones metabolism & development bone growth mental development metabolic use of energy blood pressure & heart rate muscle tone digestion reproduction The thyroid gland produces two very similar hormones derived from the amino acid tyrosine: triiodothyronine (T3), which contains three iodine atoms, and tetraiodothyronine, or thyroxine (T4), which contains four iodine atoms. In mammals, the thyroid secretes mainly T4, but target cells convert most of it to T3 by removing one iodine atom. Although both hormones are bound by the same receptor protein located in the cell nucleus, the receptor has greater affinity for T3 than for T4. Thus, it is mostly T3 that brings about responses in target cells. tyrosine + iodine thyroxine

Goiter Iodine deficiency causes thyroid to enlarge as it tries to produce thyroxine

Regulation of Blood Calcium Endocrine System Control Feedback Regulation of Blood Calcium calcitonin  kidney filters Ca++ Ca++ deposited in bones high blood calcium level (10 mg/100mL)  Ca++ uptake in intestines low activated Vitamin D parathyroid bones release Ca++  kidney reabsorbs Ca++ Parathyroid hormone

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

A man in MENOPAUSE? As my wife and I sat on the couch one night this past winter, reading and half-watching the inevitable HGTV, I started sweating hard and my face got so fevered and flushed that I felt as if I were peering into an oven. I turned to Deb and said, “Man, I’m having a wicked hot flash.” And she said, “Me, too.” Then we laughed. You laugh a lot — unless your hormones are making you cry — when you’re having menopause with your wife. I was in the middle of treatment for an aggressive case of prostate cancer last winter, and it included a six-month course of hormone therapy. My Lupron shots suppressed testosterone, which is the fuel for prostate cancer. Hand in hand with the hot flashes came the food cravings. I lusted after Cheetos and Peanut Butter M&M’s, maple-walnut milkshakes, and spaghetti and meatballs buried in a blizzard of Parmesan. Isn’t it funny how cravings very rarely involve tofu, bean curd or omega-3 oils?

You don’t have it as bad as these kids! Don’t you just hate puberty sometimes? Acne, voice cracking, getting your period when you’re not ready, mood swing, etc? You don’t have it as bad as these kids!

Disorders of sexual differentiation Pseudo-hermaphrodites have phenotype opposite gonadal tissue Androgen Insensitivity Syndrome: female phenotype, XY genotype, has gene for mutated testosterone receptor, becomes default female 5-alpha Reductase Deficiency: born with female phenotype, XY genotype, at puberty more testosterone is produced so finally get high enough levels to begin testes descending and male 2۫ sex characteristics.

The Endocrine Glands HW Pass Question: What is a Hypophysis Operation? 1 2 3. The Endocrine Glands 4 5 6.. HW Pass Question: What is a Hypophysis Operation? 7. 8.

Any Questions?? Robert Wadlow 1918-1940 8' 11" 2007-2008