Ch 45.Hormones and the Endocrine System - Region 14 · PDF fileEstradiol in female birds and...
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ch 45Hormones and the endocrine system 8th ed.notebook 1 December 19, 2013 Ch 45.Hormones and the Endocrine System
Transcript of Ch 45.Hormones and the Endocrine System - Region 14 · PDF fileEstradiol in female birds and...
ch 45Hormones and the endocrine system 8th ed.notebook
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Ch 45.Hormones and the Endocrine System
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hormone = chemical signal that is secreted into body fluids ﴾ex. blood﴿ and communicates regulatory messages within the body
Target cells = cells that respond to hormones have specific receptors for the hormone
Two long distance controling systems:1. endocrine system = all of an animals's hormone secreting cells chemical signaling2. nervous system= electrical signals
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endocrine glands hormone secreting organductless
ex. thyroid, pituitary
exocrine glandshormone secreting organshave ducts
ex. sweat, mucus glands, pancreas
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regulatory system in conjunction with nervous system• two are highly integrated• endocrine organs and tissues contain neurosecretory cells ﴾specialized nerve cells﴿ that secrete hormones
some chemicals are both hormones in endocrine system and signals in the nervous system
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hormones have many functions:a. maintain homeostasis epinephrineb. regulate growth and development human growth hormonec. reproduction follicle stimulating hormone
local regulators: molecules that act over short distances and reach target cells by diffusion
Ex. paracrine signaling secreted and trigger a response in neighboring cells autocrine signaling secreted molecules act on secreting cell itself
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neurotransmittersdiffuse across synapses
neurohormones diffuse into bloodstream and trigger responses in target cells in body
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most receptors are on the cell surface, but some are in the cytoplasm (remember steroid receptors??)
water soluble receptors are on the cell surface, lipid soluble are intracellular
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Water soluble hormones:• method of secretion exocytosis• mode of travel in bloodstream freely• location of receptors plasma membrane• examples
Epinephrine secreted by adrenal glandsgoes into bloodstreambinds to Gprotein coupled receptor in plasma membrane cascade of eventsactivates enz. for glycogen breakdown and inactivation of
enz for glycogen synthesis
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Lipid soluble hormones:
• method of secretion diffuse from endocrine cells• mode of travel in bloodstream bound to transport proteins• location of receptors intracellular signal receptors• Example
Estradiol in female birds and frogsreceptor is in liver cells activates transcription of gene
for the protein vitellogenin vitellogenin is secreted and transported in blood to
reproductive systemcauses production of yolk
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Receptors for water soluble and fat soluble hormones
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Cell surface hormone receptors trigger signal transduction
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Steroid hormone receptors directly regulate gene expression
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Epinephrine: One hormone different effects due to different signal transduction pathways
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Signaling by local regulators
Ex. cytokines (immune response), growth factors (stimulate cell proliferation and differentiation)
Ex. nitric oxide: neurotransmitter and local regulatorlow oxygen blood vessel walls secrete NO, this activates an
enzyme that relaxes smooth muscle cells = vasodilation to improve blood flow to tissues
in males, NO promotes vasodilation into penis to trigger an erection; Viagra interferes with the breakdown of NO in the tissues to keep the erection
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Prostaglandins
modified fatty acids first discovered in prostate gland, but many cells secrete them
in semen helps women's uterine wall contract to help sperm reach egg placenta helps labor contractions immune system promote fever and inflammation, intensify pain regulate platelet aggregation blood clotting
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Negative feedback Mechanism
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Positive Feedback Mechanism
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Examples of regulatory systems ininvertebrates• hydra a hormone that stimulates budding and growth, but prevents sexual reproduction
http://images.search.yahoo.com/images/view
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mollusk Aplaysia hormone that stimulates laying thousands of eggs, but inhibits feeding and locomotion activities that interfere with reproduction
Crustaceans• hormones for growth and reproduction, water balance, movement of pigments in eyes, • regulation of metabolism
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Crustaceans Insects and crustaceans • ecdysone hormone to trigger molting• brain hormone ﴾BH﴿controls prothoracic glandsthat produce ecdysone• juvenile hormone ﴾JV﴿ secreted by glands behind brain, promotes retention of larval characteristics high JV, ecdysone stimulates molting larger
larvaless JV produces pupa stage ﴾metamorphosis replaces larval stage﴿
use synthetic JV to inhibit insects from becoming reproducing adults
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Hormones in insects
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Chemical signals and their modes of actionspheromones = hormones secreted by organisms used in mateattraction
growth factors peptides and proteins that stimulate cellreproduction have specific target cells• ex. epidermal growth factors accelerate epidermal
development• insulin like growth factors made by liver, essential for
skeletal development• transforming growth factor
enhance strength of synapses between neurons in brain
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another regulator = nitric oxideif secreted by neurons neurotransmitter if secreted by white blood cells, kills bacteria and cancer cells in body fluids if released by endothelial cells in blood vessels, dilates vessel walls
Prostaglandins modified fatty acids in semen stimulate contraction of smooth muscles inwall of uterus ﴾help sperm get to egg﴿
if secreted by placenta help induce labor by making uterine muscles more excitable
in vertebrate defense systems induce fever andinflammation, intensify pain
aspirin and ibuprofen inhibit prostaglandin synthesis
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Prostaglandin E (PGE) cause muscles to relax in lungs, dilates blood vessels, promotes oxygenation of blood
Prostaglandin F (PGF) signals muscles to contract, constricts vessels, reduce blood flow
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Hormones are involved in signal transduction pathways
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signals produce different results depending on the receptorneed appropriate receptors
there are species differences in response to same hormone
Ex. thyroxine in humans and some vertebrates works in metabolic regulation in frogs triggers metamorphosis from tadpole to adult, stimulates reabsorption of tail
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Vertebrate Endocrine System
Tropic hormones hormones that trigger other endocrine glands
*FSH follicle stimulating hormone*LH Leutinizing hormone*TSH thyroid stimulating hormone*ACTH adrenocorticotropic hormone
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Humans have 9 endocrine glands
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Hypothatlamus and pituitary glands regulate many functions of the endocrine system
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• hypothalamus integrates the nervous and endocrine system\
• neurosecretory cells produce hormones releasing hormonesstimulate anterior pituitary to secrete
hormonesinhibiting hormones prevent the anterior pituitary from
secreting hormones• posterior pituitary gland stores and secretes hormones produced
by hypothalamus
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hormones made by hypothalamus and released by posterior pituitary gland:
• oxytocinstimulates contraction of uterus during childbirthstimulates contraction of mammary glands secretion regulated by nervous system
• Antidiuretic hormone promotes retention of water by kidney secretion regulated by salt/water balance
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Anterior pituitary hormones:1. Growth hormone (protein)
for growth and metabolism regulated by hypothalamus hormones acts on tissues via growth factorsGigantism excessive growth hormone during development
http://www.gigantism.com/robertwadlow.jpg
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Acromegaly excessive growth hormone as adult
http://www.healthline.com/galeimage?contentId=gem_01_00025&id=gem_01_img0011
http://www.cs.umass.edu/~elm/images/acromegaly_classic_woman.gif
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Hypopituitary dwarfism childhood growth hormone deficiency
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1296707&rendertype=figure&id=F3
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2. Prolactin (protein)*stimulates milk production and secretion*regulated by hypothalamus hormones
3. Gonadotrophins (glycoprotein)*Follicle stimulating hormone (FSH)
stimulates production of sperm and eggregulated by hypothalamus hormones
*Leutinizing hormone (LH)stimulates ovaries and testesregulated by hypothalamus hormones
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4. Thyroid stimulating hormone (TSH) *stimulates thyroid gland*secretion regulated by thyroxine in blood*secretion regulated by hypothalamus hormones
5. Adrenocorticotropic hormone (ACTH)*stimulates adrenal cortex secretion of glucocorticoids*secretion regulated by hypothalamus hormones and glucocorticoids
6. Melanocyte stimulating hormone (MSH)*role in fat meabolism
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7. Endorphins peptides*inhibit pain perception*have same effects as heroin or other opiate drugs
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Pineal Gland:*located in the brain*secreted melatonin involved in rhythms associated with
reproduction*secretion regulated by light and dark cycles
http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/otherendo/pineal.html
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Thyroid gland: *located in throat two lobes*triidothyronine (T3) and thyroxine (T4)*stimulates and maintains metabolism*secretion regulated by TSH
http://www.drsinha.com/images/thyroidgland.jpg
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hyperthyroidism excessive thyroid hormonessymptoms high body temp, sweating, weight loss, irritability,
high blood pressure
hypothyroidism not enough thyroid hormonesinfants cretinismadults weight gain, lethargy, cold intoleranceGoiter iodine deficiency causes enlarged thyroid gland
http://images.search.yahoo.com/images/view
goitercretinism
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Calcitonin*lowers blood calcium*regulated by calcium in blood
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Parathyroid glands* 4 small glands on surface of thyroid gland* secrete parathyroid hormone (PTH)* increases blood calcium levels regulated by calcium in blood
causes osteoclasts to break down bone releases calcium*stimulates kidneys to reabsorb calcium* stimulates kidneys to convert Vitamin D to active form
hypoparathyroidism = lack of PTH*calcium levels drop*causes convulsive contractions of
skeletal muscle
http://images.search.yahoo.com/images/view?
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Pancreas*located near stomach*both endocrine and exocrine functions
exocrine secretion of bicarbonate ions and digestive enzymes
endocrine insulin and glucagon secreted by islets of Langerhans
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Insulin protein produced by beta cells*lowers blood glucose levels* all body cells except brain cells take up glucose*slows glycogenolysis*inhibits gluconeogenesis*regulated by glucose in blood
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Hypoinsulism diabetes mellitus*develops due to heredity and obesity*high blood sugar levels sugar eliminated in urine
symptoms: excessive urination and excessive thirst
severe: fat substitutes for glucose as major fuel source which lead to acidic metabolites causes life threatening lowering of blood pH
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Type I diabetes mellitus = insulin dependent*autoimmune disorder*appears in childhood* treatment: insulin injections or insulin pump
Type II diabetes mellitus = noninsulin dependent*target cells usually not responsive to insulin* increased risk over age 40*90% of diabetes cases
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Glucagon protein secreted by alpha cells of pancreas* raises blood glucose levels* stimulates glycogenolysis in liver and skeletal muscles*regulated by glucose level in blood
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Adrenal glands*located on top of kidneys* adrenal cortex = outside of gland
reacts to stress secretes corticosteroids*glucocorticoids raise blood glucose levels
regulated by ACTH (neg. feedback)used in meds. to decrease inflammation
*mineralocorticoidsex. aldosterone affects salt/water balance, promotes
reabsorption of sodium, excretion of potassium secretion regulated by potassium in blood
*Androgens = sex hormones female sex drive secrete small amts. of estrogens and progesterone
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*adrenal medulla = inside of gland related to nervous systemepinephrine (adrenaline) and norepinephrine (noradrenaline)
released in times of stress (sympathetic NS)
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Gonadal glands: 1. Testes
androgens (testosterone)*sperm production*development of secondary male sex characteristics*regulated by FSH and LH
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2. Ovariesa. estrogen steroid
*stimulates uterine lining growth*regulates secondary female sex characteristics*regulated by FSH and LH
b. Progestins (progesterone) steroid*promote uterine lining growth*regulate FSH and LH
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