Chapter 45 Chapter 45 Hormones and the Hormones and the Endocrine SystemEndocrine System

• 1. Define the following terms:1. Define the following terms:

• A. hormoneA. hormone

• B. target cellsB. target cells

• C. endocrine systemC. endocrine system

• D. endocrine glandsD. endocrine glands

• HormoneHormone: member of a class of signaling : member of a class of signaling molecules produced by glands in molecules produced by glands in multicellular organisms that are multicellular organisms that are transported by the circulatory system to transported by the circulatory system to target distant organs to regulate target distant organs to regulate physiology and behaviorphysiology and behavior

Target Cell: any cell that has a specific Target Cell: any cell that has a specific receptor for an antigen or antibody or receptor for an antigen or antibody or hormone or drughormone or drug

Endocrine Glands:Endocrine Glands:

• Are glands of the endocrine system that Are glands of the endocrine system that secrete their products, hormones, secrete their products, hormones, directly into the blood rather than directly into the blood rather than through a duct.through a duct.

• The major glands of the endocrine The major glands of the endocrine system include the pineal gland, pituitary system include the pineal gland, pituitary gland, pancreas, ovaries, testes, thyroid gland, pancreas, ovaries, testes, thyroid gland, parathyroid gland, hypothalamus gland, parathyroid gland, hypothalamus and adrenal glandsaand adrenal glandsa

Intercellular Intercellular communicationcommunication

• The The endocrine system endocrine system releases hormones into the blood. releases hormones into the blood. Regulate growth, development & organism processesRegulate growth, development & organism processes– Hormones can reach all cellsHormones can reach all cells– Response is slowResponse is slow– Action can remain a long timeAction can remain a long time

• The nervous system releases neurotransmitters that affect The nervous system releases neurotransmitters that affect specific neuronal cells.specific neuronal cells.– Neurotransmitters reach few cellsNeurotransmitters reach few cells– The response is rapidThe response is rapid– The action is briefThe action is brief

• Give an example of how the nervous Give an example of how the nervous system and the endocrine system system and the endocrine system interact to create behavior. Howinteract to create behavior. How

Nervous system overlapNervous system overlap

• Neurosecretory cells found in the brain also Neurosecretory cells found in the brain also release hormones called release hormones called neurohormonesneurohormones

• Some neurohormones also f(x) as Some neurohormones also f(x) as neurotransmitters.neurotransmitters.

• Nervous system plays a role in regulating Nervous system plays a role in regulating some parts of the endocrine systemsome parts of the endocrine system– Regulation of circadian and seasonal rhythmsRegulation of circadian and seasonal rhythms– Regulation of reproductive cyclesRegulation of reproductive cycles

Intercellular Intercellular signalingsignaling

• Endocrine SignalingEndocrine Signaling: Secreted into : Secreted into blood, act anywhereblood, act anywhere

• Paracrine SignalingParacrine Signaling: Diffuse locally : Diffuse locally & trigger response in neighboring & trigger response in neighboring cellscells

• Autocrine SignalingAutocrine Signaling: Diffuse locally : Diffuse locally & trigger response in secreting cell& trigger response in secreting cell

• Synaptic SignalingSynaptic Signaling: : Neurotransmitters, diffuse across Neurotransmitters, diffuse across synapsesynapse

• Neuroendocrine SignalingNeuroendocrine Signaling: : Neurohormones diffuse into blood, Neurohormones diffuse into blood, act anywhere (secreted from nerve act anywhere (secreted from nerve cells.cells.

Types of secreted signaling Types of secreted signaling hormoneshormones

• 3 classes of hormones3 classes of hormones– Proteins and peptides (under 30 aaProteins and peptides (under 30 aa’’s)s)

– Amines (derived from a single aa)Amines (derived from a single aa)

– Steroids Steroids

• Pheromones are volatile signals between organismsPheromones are volatile signals between organisms

• 3. Compare hormones, local 3. Compare hormones, local regulators and phermones.regulators and phermones.

• 4. Describe the pathway for water-4. Describe the pathway for water-soluble hormones.soluble hormones.

Types & Chemical classes of Types & Chemical classes of hormoneshormones

• Water soluble Water soluble hormones bind to hormones bind to plasma membrane receptorsplasma membrane receptors– Proteins & peptides under 30 aaProteins & peptides under 30 aa– Amines, derived from a single aaAmines, derived from a single aa

• Steroid hormones bind to Steroid hormones bind to intracellular receptors, lipid intracellular receptors, lipid solublesoluble– Derived from cholesterolDerived from cholesterol– Act inside a cell membraneAct inside a cell membrane

• Pheromones are signals between Pheromones are signals between organismsorganisms

Water soluble Water soluble hormones Fig. hormones Fig.

45.5a45.5a• Intracellular response Intracellular response

can becan be– Activation of an enzymeActivation of an enzyme– Change in uptake or Change in uptake or

secretion of chemicalssecretion of chemicals– Rearrangement of Rearrangement of

cytoskeletoncytoskeleton– Transcription of Transcription of

particular genesparticular genes

Water soluble hormonesWater soluble hormones• Can activate second messenger Can activate second messenger

pathwayspathways

Lipid soluble Lipid soluble hormoneshormonesFig. 45.5bFig. 45.5b

• DiffusionDiffusion• Formation of Formation of

hormone/receptor hormone/receptor complexcomplex

• Activation of Activation of transcriptiontranscription

• Production of mRNAProduction of mRNA

• Discuss Lipid Soluble hormonesDiscuss Lipid Soluble hormones

Different effects from one Different effects from one hormonehormone

Human endocrine glandsHuman endocrine glands

Simple hormonal Simple hormonal pathwaypathway

Glucose homeostasisGlucose homeostasis

• Glucagon and insulin are produced Glucagon and insulin are produced in 2% of the cells in the pancreasin 2% of the cells in the pancreas– Islets of Langerhans are scattered Islets of Langerhans are scattered

throughout the pancreasthroughout the pancreas– Glucagon is produced by Glucagon is produced by alpha cellsalpha cells– Insulin is produced by Insulin is produced by beta cellsbeta cells

• Glucagon and insulin are Glucagon and insulin are antagonistic hormones that regulate antagonistic hormones that regulate glucose in the blood at 90mg/100mLglucose in the blood at 90mg/100mL

Effects of insulin and Effects of insulin and glucagonglucagon

• Insulin stimulates all body cells except Insulin stimulates all body cells except brain cells to take up glucosebrain cells to take up glucose

• Insulin slows glycogen breakdown in the Insulin slows glycogen breakdown in the liverliver

• Insulin inhibits gluconeogenesis and Insulin inhibits gluconeogenesis and production of glucose from glycerol.production of glucose from glycerol.

• Glucagon increases glucose in the blood.Glucagon increases glucose in the blood.– Glucagon stimulates hydrolysis of glycogen in Glucagon stimulates hydrolysis of glycogen in

the liver and conversion of amino acids and the liver and conversion of amino acids and glycerol to glucoseglycerol to glucose

– Only liver cells are sensitive to glucagon.Only liver cells are sensitive to glucagon.

Glucose Glucose homeostasihomeostasi

ss

DiabetesDiabetes

• Diabetes mellitus has two different causesDiabetes mellitus has two different causes1.1. Type I the immune system destroys beta cells Type I the immune system destroys beta cells

leading to lack of insulinleading to lack of insulin

2.2. Type II is a deficiency of insulin or reduced Type II is a deficiency of insulin or reduced sensitivity of insulin receptorssensitivity of insulin receptors

• Glucose levels in the blood exceed the Glucose levels in the blood exceed the reabsorbing abilities of the kidneyreabsorbing abilities of the kidney

• The body turns to fat to produce glucose, The body turns to fat to produce glucose, which produces acidic blood (ketosis)which produces acidic blood (ketosis)

Endocrine and nervous Endocrine and nervous system interactions in system interactions in

vertebratesvertebrates

Hypothalamus and posterior Hypothalamus and posterior pituitarypituitary• The hypothalamus is The hypothalamus is

the relay between the the relay between the nervous & endocrine nervous & endocrine systemssystems

• Axons project to Axons project to posterior pituitary and posterior pituitary and release release neurohormones neurohormones – Antidiuretic hormone Antidiuretic hormone

(ADH)(ADH)• Promotes water retention Promotes water retention

in kidneysin kidneys

– OxytocinOxytocin• Uterine contractions & Uterine contractions &

milk productionmilk production

• xx

Hypothalamus and anterior Hypothalamus and anterior pituitarypituitary

Tropic: affects endocrine glands

Anterior pituitary: Tropic Anterior pituitary: Tropic hormoneshormones

• Gonadotropins--Follicle stimulating Gonadotropins--Follicle stimulating hormone (FSH) and leutinizing hormone hormone (FSH) and leutinizing hormone (LH)(LH) stimulate activities of ovaries and stimulate activities of ovaries and testestestes

• Thyroid stimulating hormone (TSH)Thyroid stimulating hormone (TSH) stimulates production and relase of stimulates production and relase of thyroid hormonesthyroid hormones

• Adrenocorticotropic hormone (ACTH)Adrenocorticotropic hormone (ACTH) promotes production and secretion of promotes production and secretion of steroid hormones from the adrenal gland.steroid hormones from the adrenal gland.

Anterior pituitaryAnterior pituitary• Growth Hormone: (tropic & nontropic):Growth Hormone: (tropic & nontropic):

– Stimulate bone & cartilage growth in Stimulate bone & cartilage growth in childrenchildren

– Regulates metabolism in adultsRegulates metabolism in adults• Hypothyroid: lethargicHypothyroid: lethargic• Hyperthyroid: Graves DiseaseHyperthyroid: Graves Disease

• Non-Tropic Hormones:Non-Tropic Hormones:– Prolactin stimulates mammary gland Prolactin stimulates mammary gland

growth and milk synthesis in mammals.growth and milk synthesis in mammals.– Melanocyte stimulating hormone inhibits Melanocyte stimulating hormone inhibits

hungerhunger -endorphins dull the perception of pain -endorphins dull the perception of pain

(some drugs cause the brain to secrete)(some drugs cause the brain to secrete)

Thyroid hormone T3 & Thyroid hormone T3 & T4T4

• Plays an important role in developmentPlays an important role in development– Controls metamorphosis of tadpole into frog.Controls metamorphosis of tadpole into frog.

• Required in bone formation and Required in bone formation and branching of neurons during branching of neurons during developmentdevelopment– Inherited conditions of thyroid deficiency Inherited conditions of thyroid deficiency

can lead to cretinismcan lead to cretinism

• Maintains homeostasis in blood Maintains homeostasis in blood pressure, heart rate, muscle tone, pressure, heart rate, muscle tone, digestion and reproductiondigestion and reproduction

• TH increases oxygen use and cellular TH increases oxygen use and cellular metabolism.metabolism.

• GravesGraves’’ disease is hyperthyroidism. disease is hyperthyroidism.• Hypothyroidism leads to weight gain, Hypothyroidism leads to weight gain,

lethargy lethargy

Calcium RegulationCalcium Regulation• Thyroid Hormone: Thyroid Hormone:

CalcitoninCalcitonin– Increases activity of Increases activity of

osteoblasts that increase bone osteoblasts that increase bone deposition.deposition.

• Parathyroid hormone (PTH) Parathyroid hormone (PTH) leads to release of calcium leads to release of calcium into the blood.into the blood.– Breaks down bone & slows Breaks down bone & slows

bone growthbone growth– Stimulates liver and kidney to Stimulates liver and kidney to

produce calcitriol from produce calcitriol from Vitamin DVitamin D• Calcitriol increases absorption of Calcitriol increases absorption of

calcium in the GI tract.calcium in the GI tract.

Adrenal gland and short Adrenal gland and short term stressterm stress

Adrenal gland and long term stress

• ss

• ss